[Todd Becker]: It is great, I am happy to join you.

[Damien Blenkinsopp]: So you have got a very interesting site, which is pretty much very dedicated to the topic of hormesis, which is called getting stronger. Could you tell me particularly what prompted you to take an interest in hormesis and this topic when you first started out?

[Todd Becker]: Well, it wasn’t any one thing. I just noticed certain patterns in what made me healthier and it really came from a variety of different areas. I would say probably one of the most pivotal experiences was learning that I could improve my eyesight without glasses, and that was probably almost 15 years ago, and understanding that the eye can respond to stimuli and the vision can improve, very [inaudible 00:03:18] to the way that weightlifters gain muscular strength by going into the gym and training. And then I started to think about how that is try about so many aspects of physiology from the immune system, which benefits by being tested and exposed and I think autoimmune and immune problems come from an underactive immune system or an overactive immune system.

It is not trained properly, thinking about how calluses form on the feet when you walk barefoot and how when I started doing barefoot running rather than these cushy shoes providing benefit by cushioning me and protecting me or actually weakening me and by exposing my feet and my calves and knees and really the whole musculature to the shock that it was designed to withstand actually got stronger and less prone to injury and then thinking about how bones and the skeletal system responds and it really almost requires stress when astronauts go out into space and experience weightlessness. They rapidly lose bone density and it is hard for them to regain when they return, so really just starting to think about the body as an adaptive system and think about the factors that influence that.

Then I did some reading and I think for me it was just the concept that lies really at the nexus of all of those different adaptive phenomenon.

[Damien Blenkinsopp]: So how long have you been playing around with this idea?

[Todd Becker]: I think if you go back to the vision improvement idea that is 15 years and even before that I think another experience that led into this low carb dieting, which I first encountered in the mid 90s, I didn’t really realize at first that ketosis is a form of hormesis but what happened is I started to think about this framework and how much you can explain with it. And of course it doesn’t explain everything and it is certainly not the only factor in health but I think it is an important one and it has been overlooked so that is why i felt that there would be an intro in a blog that really focused on that concept.

[Damien Blenkinsopp]: Right, I like the way you put it. It is a nice framework to be able to look at things and I know you have done a bunch of your own experiments, so that is what I wanted to talk about. Before that, give people an idea of how broad this is. There are a whole number of topics you have looked at and referenced, like exercise you brought up, phytonutrients in plants, like some of the things that we thought had antioxidative and protective effects actually are working on a basis of hormesis as well. You talk about sunlight, radiation – have you looked at the topic of pesticides?

[Todd Becker]: A little bit. I would say that I guess when we talk about phytonutrients these are really natural pesticides if you think about it in this biological arms race where plants want to avoid being eaten and predators want to eat them. So they develop more and more effective toxins to scare you off but predators that are able to detoxify those natural pesticides get the spoils. So it is kind of this back and forth but as far as artificial pesticides there is probably some element that we know there has been a somewhat controversial analysis of dioxin which is highly toxic and actually has some hormetic benefits at low dose. So even artificial toxins can play that role.

[Damien Blenkinsopp]: Yeah, you are aware of the work of Dr. Bruce Ames?

[Todd Becker]: Yes, right, I think he was instrumental there and he certainly has been critical of modern toxicology and the sort of linear, no threshold concept that everything is toxic down to the tiniest measurable dose. Even though he developed some of the institutional tests, like the Ames tests that are used to look at mutogenicity or carcinogenicity, he is critical of over-extrapolating with those tests. But just for your listeners who don’t really understand the technical concept of hormesis it is really the idea that something that is damaging or toxic at higher doses can actually be beneficial at lower doses. At first that seems like a paradox but then you realize that evolution required us to survive in the face of all kinds of stresses including toxins and UV radiation and heat and cold and if we didn’t have some method of fending off those stresses either by adapting to them and defending ourselves against them or repairing ourselves or our DNA once we have been exposed, we would perish.

So I think most organisms have some hormetic mechanisms that allow them to adapt to harsh environments and survive. The key is what is that level? What is that sort of magic dose that gives you stimulating effect as opposed to the inhibitory or detrimental effect and it can vary quite a bit. I mean, some substances like alcohol, for example, show hormetic effects at much doses than some, say, metals that are considered much more highly toxic and only showed the [inaudible 00:08:18] effect at much lower doses. And there are a couple of researchers who really have done a lot of good work to kind of document the ranges in which different stresses are hormetic.

[Damien Blenkinsopp]: Yeah, it is very difficult to kind of assess where it is going to be overwhelming. I guess it is not what doesn’t kill you makes you stronger, it is more like what doesn’t overwhelm your system makes you stronger.

[Todd Becker]: Yeah, I think the other interesting thing is if you look at the work of people like Edward [inaudible 00:08:46] that these are the guys who are really documenting all of this [inaudible 00:08:51] sort of static type of hormesis where they will expose say a worm or a plant or a microbe or an animal to toxins and they will find that dose that is causing damage or disease and that dose that is causing a benefit. But what I am also interested in here is the idea that this can be a dynamic type of range that progressively you can become more and more tolerant by gradually exposing yourself to increasing stresses. of course there is always a limit and you can only tolerate so much radiation or UV or exercise or cold and there is a limit. But i think you would be surprised at what that range might be.

[Damien Blenkinsopp]: All right, so going back to your analogy of strength training because I think most people understand strength training and that you are not going to walk in and lift 100 kg the first time, but if you start at 50 kg or whatever as your level, after a couple of weeks you work up to 60 kg and after some recovery you kind of go through this process. You can eventually move up to that 100 and you can say it is very similar and you have an ability to kind of get stronger across all of these different stressors and deal with all of them. Is that the way you look at it?

[Todd Becker]: Exactly. I think that the principle is the same, the details are different in each case. And you hit on I think a key principle of doing this [inaudible 00:10:13], which is gradulous. A lot of people jump in too quickly, have a negative experience, and conclude that they can’t do it. I think a classic example is exposure to cold. After initial, awful exposure people say, ‘I could never do that.’ Or fasting is another good example. Some people try to just jump in and skip meals all day and they will get ravenously hungry or have hypoglycemia and they will conclude that they are incapable of it, not realizing that if you had built up to it gradually you can adapt. So I think that is a key aspect there.

The other thing which you touched on a little bit is rest and intermittency. Weight lifters go in and they will lift heavy weights but they are essentially causing microtrauma or tears to their muscle fibers and they have to allow for the damage to be repaired. And this is true in any kind of overtraining where you are running anything. If you don’t allow that period of recovery you are not going to get the benefit. So I think gradualism and then a progressive increasing and allowing adequate rest and repair, I think these are probably the factors that people overlook and leave them to conclude that this doesn’t really work.

[Damien Blenkinsopp]: Yeah, that reminds me of one of my buddies at University who used to come with us to the gym once every three months and he would hit it really, really hard and he would go home and he would feel horrible for three days and be in so much pain and he wouldn’t come for another three months. You would never get anywhere of course, doing that, and he would be through a lot of pain. So that was a nice analogy. That is not the way to go about getting stronger as the theme of your blog. It is really to take it gradually, as you say, with all of these things.

So what are the mechanics behind how this works? Do we have any ideas about it or is the science very vague at the moment still?

[Todd Becker]: I think you can cluster these things into a few different categories. One is physical changes to tissue, so the example of building muscle. You stimulate – you apply physical stress and cause some damage or change and then allow the tissue to remodel. The same thing is true with bone that you apply to stress. And part of it is directly within the tissue, part of it is the nervous system, part of it is stimulation of hormones, growth hormones, but there is response. Another really interesting example is vision improvement and particularly reversing myopia.

This is a very interesting stressor where by incremental defocus and by causing a slight blur, you actually induce differential growth in the scleral tissue of the eye by stimulating neuromodulators that actually grow differentially and cause the eye to change shape. It happens very gradually over many, many cycles, but there have been experiments in chicks and chimpanzees and then most recently in humans, that fitting people with concave or convex lenses, plus or minus lenses, induce these changes in growth literally within a matter of minutes and hours.

So there are these physical stressors – calluses are another example of a physical stressor that causes growth factors to build up the tissue. So that is one type of hormesis. Then I think there are metabolic processes – for example, real shifts in nutrient balance, for example ketosis, deprivation of carbohydrate and sugar, causes a shift in expression levels of different lipases that causes a reduction in insulin and causes hormonal shifts that actually up-regulate the ability to digest fats. And again, this is a process that might happen over weeks. So there are kind of different time scales.

[Damien Blenkinsopp]: Yeah, just to jump in there – it can be different according to the person where they are starting from, the condition of their body and potentially even their genetics, as to how quickly your – if their ability is to adapt to them.

[Todd Becker]: Certainly – let’s take another example as the tanning of skin. Some people can readily respond by producing the melanin that allows them to tolerate UV and get a suntan and is actually protected. Others, probably some of your buddies from the northern part of the UK may have very fair skin or reddish hair and don’t have quite that same ability. Metabolically some people can induce lactates that allows them to digest milk very rapidly. Others have very low or little ability to [inaudible 00:14:41] significant genetic variation there.

[Damien Blenkinsopp]: Yeah, and here increasingly we have got this biosis when people have problems with their gut, which is pretty common these days. I don’t know if you know a guy called [Chris Cressor 00:14:52]?

[Todd Becker]: Sure.

[Damien Blenkinsopp]: He talks now about using probiotics like kefir but in very small doses to start with, otherwise it kind of overwhelms the gut microbiome. So it seems like he is using some similar principle to hormesis there and with his patients or people who have problems. It has to start very, very small but eventually it gets to a large extent where the gut is able to digest and use it afterwards.

[Todd Becker]: And really that is a good example that sort of also follows the model of what is called oral immunotherapy. It used to be thought that people who had, for example, severe peanut allergies just that there was no hope. They had to take immunosuppressant drugs for the rest of their life and children who were vulnerable to this just had to stay away from even the slightest dust from peanuts in the air. But then there was some really good research that showed that very gradually reintroducing an allergen like peanut under the tongue in extremely minute amounts allowed the immune system to learn to tolerate it to the point where there was no problem anymore. I think that is another good example of that gradual exposure.

[Damien Blenkinsopp]: That is an interesting one because that is where the immune system is overactive in response to a stressor. And then you are teaching it to just be balanced. So it is kind of a slightly different twist to it.

[Todd Becker]: Yeah, well we are talking about allergies and autoimmune disease and I think it is very relevant to point out this recent book that I got very excited about called An Epidemic of Absence by Moises Velasquez-Manoff, and he really updated the hygiene hypothesis, which a lot of people are familiar with which basically holds that allergy and autoimmune disease that has become prevalent in the western world ever since we have instituted a lot of hygiene measures and cleanliness and since people have moved off of farms and paradoxically we have conquered infection, but allergy and autoimmune have gone up. And the idea is that somehow we are not getting exposed to allergens.

But what Manoff does in his book is how is this in terms of the what is called the old friends hypothesis and the idea is that we co-evolved with [inaudible 00:17:07] organisms in our gut, parasites that we lived with basically for evolutionary reasons to outsource some of the functions of our immune systems to those organisms. And that sort of took some of the work away that our own immune systems have to do. But now that we have pretty much banished them through better hygiene we don’t have parasites anymore, our diets have changed so that the microbiome in our guts – we wash ourselves and we don’t have the benefit of the service that they were providing.

So all we are left with is an undertrained immune system with the sort of reserve or the emergency system, the IGV system that just goes crazy whenever it has the slightest insult, and so the idea is let’s reintroduce some of the old friends. But what is particularly interesting in the book is he goes through one autoimmune or allergy disorder after another and shows that there is sort of a critical period in infancy or childhood where if you don’t get that exposure you are prone to these autoimmune disorders.

[Damien Blenkinsopp]: So that is the idea of balance again. It keeps going back to this balance and this is why I wanted you to come on and talk about this, because you have actually tried to identify balance for hormesis using heart rate variability. In my own experience, I have had back injuries and I have had various things where you want to get stronger, you want to recover, and you understand that this concept of hormesis can help you, as you pointed out with your eyesight, right?

But if you push it too far you potentially go backwards rather than forwards. It is the same as like my friend from the university who is going to the gym and pushing it too far and is actually going backwards instead of forwards. And in my training over the years, experimenting with different things, I have often done that as well and figured out that I needed more recovery and I didn’t have this balance.

I have eventually come back to trust numbers. So I thought it was interesting that you were using heart rate variability to look at a little bit and understand if the hormetic effect was having a positive impact or not.

[Todd Becker]: Sure. Now, I know you are a big biomarker guy and you like numbers and I am a little bit more cautious about that. I would certainly like there to be a magic number that I could follow. I have done a little bit of experimentation with a glucose meter, which kind of helped me understand how I responded to diet and exercise in terms of glucose. And I found it a little bit useful but also potentially misleading. I have friends who are sort of in the quantified self movement who measure just about everything and kind of I think go overboard with it But one thing I have seen is that it is very hard to take a single number in isolation because there are always exceptions or what you might be looking at is not a cause but a consequence, so it is difficult.

I stumbled on heart rate variability and what i like about it is it is not just some random measurement of some intermediate metabolite in your body which may reflect oxidation or inflammation but who is to say what the right level is. In the case of heart rate variability you are actually measuring something very close to real function and what I found before finding HRV is to try as much as possible to look at functional measures of strength or performance.

[Damien Blenkinsopp]: Sure, could you give an example?

[Todd Becker]: So the vision is pretty easy, right? You can read a Snellen chart and see when you lift weights and you know how much weight you are lifting. So when you run you can use speed, right? These are very objective things but what I like about HRV, so what do you do in terms of just overall metabolic health? Is there something that sums it up?

[Damien Blenkinsopp]: Why don’t you just take a step back there and clarify? When you were talking about the running and the speed and if it is improving then when you are doing is having a good, positive hormetic effect, right? But if it is going backwards, if you are taking longer times, then you know that you are going backwards – just to clarify for the audience.

[Todd Becker]: Exactly, and there is no question. If you are overtraining and you are running slower, then okay.

[Damien Blenkinsopp]: Right, if you are lifting less weight, which happened to me with many of my experiments back in the days, I would be basically lifting less and you are like, ‘Okay, something is not going right here.’

[Todd Becker]: Right, so if you would like to find something like that for just overall metabolic health, that is a harder one. Maybe you feel good but subjective feelings may not be the whole thing. So what I like about HRV, heart rate variability, is I think it is sometimes not fully understood, what it is. What it is essentially is the variation in the heart beat. You can have a low heart rate but if the heart rate is getting exactly once per second that has got no variability, right?

So why is variability a good thing? And apparently it is. Apparently people who are very fit have a higher heart rate variability, which means there is more variation. Sometimes their heart will be 1.05 seconds and then 0.9 and then 1.03 and then 0.85 and then you look at the standard deviation of that or some transformation of that and the more variation beat to beat there is the better it is. But you would think, why is that good? Because we know of arrhythmias as being signs of pathology and certainly at some level they are.

[Damien Blenkinsopp]: Could you just – what is an arrhythmia?

[Todd Becker]: An arrhythmia would be not having an exactly precise regular beat, having some irregularity to it. And there is different deviations from the regular. So the question is why is it good to have this variability and I was kind of searching for this but I read this book, an older book by James Gleek, called Chaos. It was written in the 80s that in chaos really describes what are called non-linear systems which underlie a lot of what is going on in biology or in the brain and in society.

There are a lot of effects that aren’t just additive but interact with each other in very complex ways. So he had this insight, which is basically non-linear processes are necessary for homeostasis, the ability to handle a stress or a deviation, and come back into control. If you have a linear system and you give it a slight nudge, you cause some [inaudible 00:23:27] to it and it tends to go off course and stay off course. In non-linear systems they have all these interactive components and if you give it a nudge it tends to return to a center, what they call an attractor in mathematical terms. In biological terms, if you have a fever your body acts to cool yourself. If your blood pH drifts there is something that pulls it back. If you eat a big meal and your blood glucose gets too high, the insulin turns on and brings it back within range. So there are these feedback systems that tend to bring you back to center.

So what is interesting is that you have got these two systems which work in cooperation – the parasympathetic and the sympathetic nervous system. And the parasympathetic system is generally the one that kind of calms you down and gives you this resilience where sympathetic is the fight or flight which you need to energize yourself but if it goes too strong it can cause stress, high cortisol and eventually the parasympathetic system has to bring you back down to normal after you have met the stressor, some type of event that you have to deal with. Now, if you are adaptive you can switch between these two systems readily and the key one is the parasympathetic one because the sympathetic one tends to drive, just very strongly and calming down and bring – changing your ability to go at full strength and then slower and adapt to the day is really an adaptive strength. If you look at people who are older and have Parkinson’s and walk very stiff or rigid and you measure their gait or their heart rate it is very regular, very stiff. It doesn’t deviate. If you surprise them, shock them, ask them to suddenly run or something, they have great difficulty shifting into that higher gear and people who are stressed out likewise have great difficulty turning down the stress and shifting. So it is a sign of health to be able to shift gears quickly and be adaptive. And essentially that is what HRV is measuring.

If your heart rate naturally can sort of move around to these different frequencies then it can quickly tune into the faster one or the slower one and it can move quickly. If it is locked into a steady beat it is just harder for it to change and I think this manifests itself in a lot of ways.

[Damien Blenkinsopp]: So you see it as a measure of your ability to adapt to stressors, which is actually similar to some of the other discussions we have had. I don’t know if you have tried this but if you looked at your HRV when you are lying down versus standing up. So in our first episode Andrew Flatt was talking about how standing up is a slight stressor. So you can see how it impacts the HRV and you have a slightly different score and you are basically applying a very, very slight stressor to yourself just by standing.

[Todd Becker]: Yeah, and people even look at how quickly can your HRV when you stand or sit come back to equilibrium. That is sort of a secondary measure and athletes who can run and then sit down and bring their heart rate down quickly are typically the ones who are fit. But if you look at disease states, cardiovascular problems, cancer, infections, these show up very quickly in reduced HRV and it is kind of almost a leading indicator of a problem so it is has even been introduced diagnostically and i think it is pretty powerful. And I find that is useful because we are all individuals as a tool for self-discovery. You can find out what tends to drive your HRV up or down and I learned a lot of things that I was very surprised about myself.

[Damien Blenkinsopp]: Yeah, and like you I have been fascinated by this measure and if you read around it is really applicable to so many useful things as well. I have seen people applying it to willpower and there are studies on willpower and of course we all want more willpower. There are a whole range of uses for this but what have you specifically applied it to and found that was most interesting?

[Todd Becker]: Well, I tried a lot of things relating to exercise and found some of the normal things that athletes find which is that when you work out very intensely it drives the HRV down and it takes a while to come back up. And when it is back up you are rested and ready to go, and that is what everybody knows. But then I just tried different foods and definitely noticed a big effect except the one thing I did notice is that I practice intermittent fasting which means that I eat one or two meals in a part of the day, typically dinner or lunch and dinner, and fast a lot of the rest of the day. And I found that well into the fast my HRV would tend to go up and then after a meal it would go down. So that was kind of interesting.

[Damien Blenkinsopp]: Did you notice an increase in your base line? If we talk about the daily – the specific time you are doing the experiment versus changes which tend to be longer-term?

[Todd Becker]: Oh yes, I definitely have noticed that. So let me get to that after and I will tell you a few specific ones and then I will get into the baseline. So that was a big one and the other really big one which really surprised me is cold showers. So i thought I am going to get in the cold shower and see what happens and I am sure what will happen is my heart rate will go up, which typically means my HRV will go down because it is not precise, but they tend to be inversely correlated, right?

, I am somewhat adapted to the cold showers and I have been doing that for several years. I get in the shower and actually measure it while I am in the shower and my heart rate goes down and my HRV goes up. And I get out of the shower and it has gone up by ten points. And that is kind of the average, it goes up by ten points literally within 3 to 5 minutes and it stays high the whole day, which also corresponds to my subjective feeling that cold showers are a real mood elevator for me, unlike caffeine or sugar or whatever, which is just kind of a quick thing and then it fades. I do that and then I am good for the whole day and it is consistent and it is a big effect. So that was a big positive effect. So fasting and cold showers are kind of the two things that really drive it up.

[Damien Blenkinsopp]: So the cold there is a cold exposure, basically, so it is a minor cold – ?

[Todd Becker]: Yes, cold exposure. So I get in a pretty cold shower and I am in there for several minutes. I used to, when I started that, I would shiver quite a bit. But that only lasts a little bit.

[Damien Blenkinsopp]: So, that’s a pretty cold shower?

[Todd Becker]: Yeah, and I do ocean swimming and things like that which is really fun. But then I found some negatives and of course I found that if I worked out really intensely, I could drive my HRV down really low, which worried me. But it would come back as hot tubs that are really hot that would also drive it down. The other thing that would really drive it down was alcohol. Usually it would be maybe two or three drinks and one drink didn’t have much effect but two or three drinks would really drive it down.

[Damien Blenkinsopp]: Is this like for a few hours, say for the rest of the day?

[Todd Becker]: A few hours or the evening. And then I thought about this and this was really interesting. I thought, wow. The cold showers surprised me because I thought that was definitely going to get my heart rate up and it didn’t. And alcohol, that will make me relax so my heart rate will slow and my HRV will go up, right? No. My heart rate goes up and basically the body is trying to deal with the alcohol. It is a depressant so it is trying to fight that and you are impairing yourself and I think this was a real insight because what is HRV? It is your resilience, your ability to take on the next stress and you may think that if you have had a few beers that you can handle things but actually you handle them a lot more poorly. Driving, of course, is an example but your judgement goes way down.

[Damien Blenkinsopp]: Yeah, that is very interesting. You see a lot of fights with alcohol, for example. And that is because people are not able to adapt to them and they are overreacting and not able to deal with emotional stressors around them.

[Todd Becker]: Yeah, the adjustment goes way off. So basically these things that are kind of relaxing can impair HRV and then things that are stimulating, the cold shower or fasting, which also tends to sharpen your focus and help the HRV. Then the other effect is – these are the immediate effects.

[Damien Blenkinsopp]: So just going back to the heat exposure, I do saunas, infrared saunas, and I have been doing that daily for the heat shock protein benefits, amongst others. I don’t know if you have done that and unfortunately I am going to have to track the HRV specifically around that and I am going to have to start doing that to see what happens. Do you think that would be similar to the hot bath?

[Todd Becker]: I think so, but here is the other half of the story because these are the immediate effects, right? The things that you notice within hours or minutes, but then you have got to look at the compensatory effect of what happens later. So for example exercise obviously impairs your fitness temporarily but you wouldn’t do it if – one of the reasons you do it is to become stronger and get fitter. So you do it and then the next day your HRV is actually a little bit higher. It may take two days or whatever the recovery period is so there is almost this ratcheting effect where you temporarily drive it down and then it kind of comes back up to an even higher level and I think that is pretty interesting. So the question is which things work that way and which things are just direct? So the cold showers brings the HRV up and then I don’t see a fading of that. Exercise I see it going down and then it comes up stronger and I think hot tubs and saunas are a little that way where it drives it down, but I think it actually can improve.

[Damien Blenkinsopp]: Do you think this could be in relation to the way your body perceives the intensity of the stressor? Maybe heat is a larger stressor than cold so your cold shower just happens that it is at the right balance?

[Todd Becker]: It may be and also heat on some level relaxing and another level is a stressor, so it may be the degree. And it is similar with alcohol. Moderate alcohol didn’t have the same effect as –

[Damien Blenkinsopp]: Yeah, so if you had like a tiny sip of alcohol potentially your HRV could have risen a little bit?

[Todd Becker]: A little bit more. So let’s go to the baseline question. So I have actually increased my baseline HRV over a couple of months significantly and there is a lot of noise and fluctuation if you look at my graft but what I did is I am careful not to overtrain and I noticed that can really set me back. Then with alcohol I have realized that one or two drinks, I feel the buzz. It is social, it is fine. And I really cut myself off there and I drink less. And that has really helped the HRV come up quite a bit. So I am just kind of paying attention to the things that really set me back and that is probably the main change and then it has come up about ten points.

[Damien Blenkinsopp]: Yeah, so I mean it is important to point out also that as you age it gets lower, so that is another reason you kind of want the baseline to be going up rather than going down. As you said earlier it is an indicator of general health but as age also so you could say biological aging. So I have noticed with intermittent fasting that is the one where I have been looking at it the most and I have done – I did one month on intermittent fasting and then two weeks off and then back to intermittent fasting again. and I am about ten points higher pretty much every day. It takes a little bit, a little while to climb back up to where it was if I stop intermittent fasting. But after about a week it tends to be about ten points higher than when I am not intermittent fasting, so that is about three months of data so far. But for me it seems – and I feel, of course – I mean, a lot of people talk about the benefits of intermittent fasting but I feel much better and much more energy throughout the day and so on.

[Todd Becker]: One thing I did that really drove it up and of course you can’t do this all the time, I took a vacation. And it went way up. Obviously, that was useful.

[Damien Blenkinsopp]: Yeah, that is a really important point you bring out here because especially you are from the US and very well known for having not taken any holiday or you have your standard two weeks, I believe, in the US?

[Todd Becker]: Right.

[Damien Blenkinsopp]: But of course, many people work in corporate and if they are not taking their holidays at all. You see a big increase in HRV like that and that is a really big sign that you are probably really overdoing it and you need to emphasize more some time out. I don’t know if you thought of it that way, when you saw those numbers, maybe I should do this more often?

[Todd Becker]: Sure, I tend to lead a life that even though it is busy I don’t feel stressed out and I really feel in balance. So I wasn’t feeling overworked but of course maybe I was fooling myself.

[Damien Blenkinsopp]: I mean, this is the beauty of trying to quantify stuff because I will give you an example. My dad, he is a workaholic and he always has been. And so he doesn’t – when he goes on holiday he falls asleep. And my impression is that he is highly strung. So he is working and I feel the same way when I am working and I have often had the case where I am working hard and then I will take a holiday and I will get sick when I am on holiday. And it is kind of like your body is just trying to manage the day to day and why you are stressed is just dealing with it. But as soon as it has an opportunity to let go. It would be like okay, you can recover now and I can be a bit sick.

[Todd Becker]: Isn’t that true? That is a common effect, you finish your exams and you come home and you get a flip, right? But my vacations tend to be somewhat active with cycling, body surfing, running, and so I wasn’t just sitting on the couch all day either but I was really enjoying myself and that was the key.

[Damien Blenkinsopp]: Great, some great insights there. Have you found any other areas with HRV as being useful besides these we have already spoken about?

[Todd Becker]: There is Dave Asprey who has written something and he has a little company and an app he has created to use HRV to detect food sensitivities.

[Damien Blenkinsopp]: Yes, they are actually using heart rate. We actually had Rhonda Collier on the last episode. She is the CEO of Sweetwater, who is behind that app.

[Todd Becker]: Exactly.

[Damien Blenkinsopp]: That one is based on pulse rate but she does some very interesting stuff on the stress side, splitting out the frequencies. And I haven’t played around with the app a lot on the stress side, but I think you have to get into it quite a bit to find some benefits. She certainly has over time, but she has been using it for a very long time.

So coming back to the whole hormesis side, I don’t know if there are any other biomarkers besides HRV? You have mentioned the difficulties of trying to assess, basically saying how much oxidative stress do you need versus not? It is very hard to say what is going to be beneficial versus what is going to be overwhelming for your body, which is why you are looking at the endpoint, the end result?

[Todd Becker]: Yeah, the functional endpoint and what really matters in terms of performance.

[Damien Blenkinsopp]: So obviously you brought up some others which are more specific to whatever you are doing, how fast you are running and so on. Is there anything else you have come across that you have found useful for looking at hormesis and how to balance it?

[Todd Becker]: Not in terms of quantitative measures. I think in this discussion we have really focused a lot on the physical side of hormesis but I think it applies quite well also to psychology and to sort of the spiritual side of health because really what is stress? There are physical stresses but what we are really talking about is your reaction to events, right? And so how you handle stress I think is very important to health and there is this concept out there that we are overstressed, that modern life causes not just physical but psychological ailments because of too much stress.

I think what they are talking about there is chronic, repetitive, daily stress that we are not handling well but I think the underappreciated side of stress is that we need it and particularly we need it at certain frequency and certain natural contexts and we need intense stress. Our body, we evolved to be able to handle it and if we protect yourself from psychological stress we actually become more vulnerable to it. I think that exposing yourself to intense physical exercise actually makes you more psychologically resilient but I think it is also important to confront fears, anxieties, and push yourself to higher levels and also to become comfortable with discomfort just in general. In fact, it is even sort of a psychological benefit to things like cold showers and that you are throwing yourself into what you perceive to be an intensely uncontrollable, disagreeable situation and you are pushing through it and you develop more resilience to it.

[Damien Blenkinsopp]: Right, because you talked about this on your blog and I started doing the cold showers, as I mentioned to you. And you say that you are tensing your muscles and you are psychologically preparing yourself for it and it is quite a horrible shock when you start but later on you start really noticing it. I mean, I found this after a few weeks or something and I guess that is what you found over time. Do you still find that you react a little bit to the shock of the cold?

[Todd Becker]: Yeah, and it is less and less. And there is this theory called the component process theory of emotion that Solomon and others sort of pioneered and Solomon was looking at – he was trying to explain addiction and also thrill seeking and he said these are really sort of the opposite sides of the point. A thrill seeker is somebody who does skydiving and the first time they do it they are confronted with this intense, paralyzing fear. It is uncomfortable. But when they land there is this euphoric afterglow that tends to last for a lot of the day. But the more they do it the event itself becomes less and less uncomfortable and the afterglow effect becomes stronger and stronger so it becomes pleasurable.

Cold showers, it is a little bit like that. Exercise can be like that. And you said it is the flip side of addiction. In addiction people pursue a direct pleasure, whether it is alcohol, drugs, sex, gambling – whatever it is, it gets their dopamine going right away. But then when they stop it there is this down or withdrawal. So this is the reverse to where the more they do it they become tolerant to the pleasure and it is less fun but the down becomes greater, so they get into this addictive cycle because they just need to do the addictive activity just to get back to normal.

So exposing yourself to hormetic stress is kind of the opposite of addiction and what I find is that it makes you more resilient to just daily stressors, arguments and things that come up at work and it increases what I call my background level of pleasure. I mean, I am just basically always happy and things don’t throw me off or blow me out and I think it is because by forcing yourself to expose to these intense stresses, you develop this resilience. It is something that has kind of gone away from the kind of lives that people, pioneers who lived away from civilization, had to face these natural stressors – the weather, hardship, lack of food, moving around. And the fact that we are more protective and that we live in an environment that is so regulated from stress I think we failed to develop this resilience. And so by engaging in some of these activities I think you get an enormous psychological benefit in addition to the purely physical.

[Damien Blenkinsopp]: Right, so that is a great overview. Basically the way you are using hormesis is if you can do this in lots of different aspects of your life then they are all kind of tied into your organism and HRV is like an endpoint measure which is global, so it is useful because it is like if my HRV is higher today I am going to be more resilient to emotional stress. No matter what it is if I have to be motivated to do something or take on a new challenging task like if I got higher HRV some days then it is probably going to be an easier day to start something new.

I have been looking at that a bit because I have heard about this, but I don’t know if you have – when you notice that your HRV is high if you find it easier to start more challenging tasks or take on conflicts or these kind of more mental challenges and I don’t know if you have noticed anything about that?

[Todd Becker]: Definitely, and I think that is the case.

[Damien Blenkinsopp]: Great, so what you are doing in terms of your routine and where you use biomarkers or you don’t, you have already talked a little bit about where you have seen them be useful or not, but on a week-to-week basis what kind of things are you tracking in your life?

[Todd Becker]: Quantitative things?

[Damien Blenkinsopp]: Right, whether it be HRV – what is kind of your routine for using any type of data about your health?

[Todd Becker]: I would love for there to be an app that really gave me information that I found useful and used all the time. And I understand companies like Apple are kind of moving into that space. And there are a lot of devices out there. So I am always interested in them but I just haven’t been convinced in their utility. And I am also a little bit hesitant to become too tied to tracking. I want to be much more tuned to my actual experience and try to find ways to use that as much as possible. I am a bit of an advocate also of simple finds, like relying as little as possible on external things, whether they be glasses or supplements or devices so that I can be fully present.

But if I can find a few things to track and if they are pretty robust I will go for them. So HRV is probably – I mean, I was experimenting with a glucose monitor and that was helping a little bit but I didn’t find it necessarily reliable. So the HRV is maybe the closest I have found so far, although I don’t know if I am at a level where I fully trust it yet. So I don’t know if there is any you find particularly useful?

[Damien Blenkinsopp]: Yeah, I track a lot of stuff and I kind of bring new ones in and then throw them out as they become inconvenient. Also one of the biggest challenges I think right now is the convenience. If we had a watch or some device which tracked everything accurately in the background it would be really easy to have interesting data. But on the HRV I use the averages, seven-day rolling averages, because it does go up a little bit and down. There is a little bit of variance in it and also just in the way you are measuring it you can introduce little differences based on emotional stress and other aspects so you have to watch out a little bit for that. So I find that I am really watching more closely the seven-day rolling average.

[Todd Becker]: I tend to agree. I think the weekly average is just about right and that seems to correspond to something that I see as a real shift.

[Damien Blenkinsopp]: Yeah, and I feel remarkably different when I am ten points higher on that average, so that is what I am trying to do, get it as high as possible. So just out of interest, I don’t know if you are lying down or you are standing up, what HRV score are you?

[Todd Becker]: Yeah, so I do it sitting and I am using the RMSSD, the natural log times 20, so on that scale I am typically in the range of in the morning 70 to 80. And on really good days I have actually hit 90, which doesn’t happen very often. And on sort of off days I might be in the 60s. But I would say kind of typically bouncing around between 70 and 80.

[Damien Blenkinsopp]: Right, you are a bit better than me. don’t get up to the 90s. My high is at the 80s. I am normally between 70 and 80 when I am intermittent fasting. Otherwise I can be between 60 and 75, maybe a little bit lower at 60 to 70 and it will go as low as the 50s on bad days. But I am actually dealing with some health issues so I think that is responsible for that mess.

[Todd Becker]: Certainly. I wouldn’t consider myself an athlete, I would just sort of consider myself generally fit for being 58 years old. So to me as long as it is sort of in that range I am happy and as an indicator that it is sort of a warning sign if it were to plunge, I start to look into it.

[Damien Blenkinsopp]: When mine plunges I take the day off. I have had some really crazy crashes and sometimes I don’t know what is going on and you have got a virus or something. I got a crazy flu virus from my nephew just recently and it took me out for a week. But I knew about it the day it was hitting because of the HRV. Even if I felt not so bad in the morning, the HRV showed it beforehand.

[Todd Becker]: Yeah, I think you’re right – fatigue, infection, and it picks those things up right away. And intoxication.

[Damien Blenkinsopp]: Alcoholic intoxication. Well Todd, thank you so much for your insights today about hormesis, which is really very a broad and interesting framework to look at all sorts of things we could be doing to improve our bodies in terms of performance and so on, and your experience with HRV has been very interesting to hear.

[Todd Becker]: Well, I have enjoyed talking to you. Thanks for the opportunity.

[Damien Blenkinsopp]: Hi Ronda, great to have you on the podcast.

[Ronda Collier]: Hi Damien, thanks for having me.

[Damien Blenkinsopp]: That’s great. I did see you briefly last year in the Quantified Self. Do you go to that conference every year?

[Ronda Collier]: Yeah, we have been the last – well, there have only been two and we have been at both of them. We presented at breakout sessions for heart rate variability. So they are pretty popular.

[Damien Blenkinsopp]: Yeah, and do you meet a lot of providers of HRV? You have been in this segment since 2011. How has it changed since then? How many players were there doing HRV stuff back then and how has it changed now? Are there different types of players? I noticed your proposition is changing a bit.

[Ronda Collier]: Yeah, back in the old days and really before smart phones, heart rate variability systems were big and clunky and expensive if you wanted to measure some of the standard HRV values like LFHV, which we can talk about. And nobody really heard of them quite frankly. I only know because that is our space. I think Heartmath really brought heart rate variability closer to the consumer with their M-wave products.

[Damien Blenkinsopp]: So they were the first ones, although theirs is actually a bit different to the standard.

[Ronda Collier]: Yeah, theirs is different and Heartmath is really more about coherence training, which is wonderful in itself, but they really had people talking about it in some of the more esoteric books, if you will. But I ran across Heartmath in reading some books for actually researching my thesis.

[Damien Blenkinsopp]: So how long has Heartmath been around? I know you worked there for a little while.

[Ronda Collier]: Yeah, they have been around about 20 years, yeah, for a long time. So they have an extensive amount of research on heart rate variability that is pretty interesting. And then three years ago you had iFleet starting to come out and that was really it. And then you have Zumio came out with their camera sensor, which is not very accurate but yet sort of furthering the cause of heart rate variability, which is important.

And moving all the way up until today where we are seeing a few more players like iFleet more in that space, Bioforce really not displaying all the HRV parameters like Sweetwater is, more the number used for training.

But I think the big news in heart rate variability is the Samsung, the new Galaxy is announced to measure heart rate variability.

[Damien Blenkinsopp]: Wow, yeah, that’s a big deal.

[Ronda Collier]: And even though it is just with the camera sensor, just for your listeners, a camera sensor is never going to be accurate.

[Damien Blenkinsopp]: Right, that is something I wanted to talk about today because I know you plug in with a variety of sensors. We did talk in our first episode with Andrew Flatt about some different sensors and some of the different measures and obviously we want to make sure people understand the practicalities and the accuracy, depending on which one they decide to go with. I think that is an important point.

[Ronda Collier]: It is – and so even though the Samsung is using the camera sensor, they are talking about it. And now that is great, and it means it is showing up in the mainstream. So we are really excited. It is such an important parameter that has just been kept in the closet for some reason.

[Damien Blenkinsopp]: Right, so let’s just kind of dive into the kind of accuracy since we are talking about it anyway and we won’t have to circle back. Obviously the thing about the Samsung Galaxy is they didn’t want to provide something external to the phone, and they want to try to have the device within the phone. And besides the camera sensor, is there anything else you could use that would actually come with the phone that would be able to help you track heart rate?

[Ronda Collier]: The closest idea I can come up with for you here is there is a company called AliveCore that has an iPhone and Android case, and it is actually EKG accurate, which is what you really need for accurate heart rate variability and that is all that Sweetwater will support, anything that is close to EKG accurate.

[Damien Blenkinsopp]: How do you establish that standard, EKG accurate? Is there a certain – I don’t know, is there sensitivity in terms of the speed of the heartbeat it has to be able to pick up? Or how do you rate that?

[Ronda Collier]: There is obviously the sampling rate. It has to be twice the heart beat. It is called Nyquist frequency for electrical engineers. But really what you need in simple terms are accurate, beat-to-beat intervals.

[Damien Blenkinsopp]: So you are saying that it has to sample twice as fast as whatever heart rate you are trying to –

[Ronda Collier]: At a minimum, yeah. There is something called the Nyquist frequency in electrical engineering, so if you want to get an accurate digital sample it has to be at least twice the frequency of what you are sampling.

[Damien Blenkinsopp]: Right, and for the normal population what is the maximum heart rate you are trying to track?

[Ronda Collier]: Oh we track, gosh, as low as 30. And if you are below that you are pretty sick and you probably aren’t using our product. Then up to about 200.

[Damien Blenkinsopp]: 200, wow. So you have to be running?

[Ronda Collier]: Some athletes actually get up close to that. My personal max heart rate is about 170, but people do get up in the 200s and we can measure that as well. So you have a wide range. But really it is getting accurate, beat-to-beat intervals that is the most important.

[Damien Blenkinsopp]: Yeah, does that mean with all of the different sensors you work with – because you have the application which interprets the data, and you work with a bunch of sensors from different providers, quite a few companies. Do you only work with providers which have the specification you just gave us? Do all of them fit that?

[Ronda Collier]: That’s right, that’s right. We support lots of shelf chest straps, like a Polar or a Zephyr, and there are a lot of Bluetooth heart rate monitors out there now, but now all of them work with Sweetwater. Some of them simply don’t transmit our intervals at all, and that is the beat-to-beat interval. So when I refer to R-R, that means the beat-to-beat intervals.

[Damien Blenkinsopp]: Right, so you are saying that some of them only track the heart rate and they don’t track the difference?

[Ronda Collier]: That’s right. And then some transmit the R-R intervals, but they are not accurate.

[Damien Blenkinsopp]: Could you give us examples of that? Is it because they are dedicated to a different application? Why is that?

[Ronda Collier]: I think that a lot of the vendors are starting to realize they want to transmit R-R intervals, but they just haven’t spent the time on it yet I would imagine, because we have worked with several vendors who did not have accurate R-R intervals and then worked with us to get there. Their focus was to get the Bluetooth heart rate monitor out first with an accurate heart rate and the R-R intervals were a secondary item. Then once they worked with us they got those to be accurate.

So that is usually the vendor is not interested in the R-R interval or they are interested in getting them accurate.

[Damien Blenkinsopp]: Right, and you think this is something that is changing, whereas people were just kind of focused on heart rate a few years ago, or three or four years ago, so these censors came out which didn’t look at the R-R now. Now would say most of them have this on their agenda in some way? Or is it still –

[Ronda Collier]: Yeah, I would say so. There are a lot of off brands that we haven’t even heard of, much less tested, that our customers are finding and then emailing us saying that their HRV doesn’t look correct. So we go and usually write the vendor and ask them before we go purchase the item.

But yeah, there are a lot and I am really surprised at the number of small companies doing the Bluetooth, low-energy heart rate monitors.

[Damien Blenkinsopp]: I guess that technology is relatively cheap, so there are a lot of chest straps and things like this that have come out. They haven’t necessarily done the full technical specification?

[Ronda Collier]: That’s right. So anyone that is going to use a heart rate variability app such as Sweetbeat or Sweetbeat Life, I recommend going to our website and selecting one of those, because we have tested those and we have actually measured that the R-R intervals are close to being correct.

[Damien Blenkinsopp]: So I guess the lesson here is there is no specific industry standard used by everyone. So if you were going to get something like Sweetbeat you should definitely go to your website, like you say, and check which ones are relevant – and it is probably going to be like that for a while, I guess?

[Ronda Collier]: Yeah, yes. Even the ones that look like they are working, we do a detailed test. We are all engineers at Sweetwater – the founders are all three electrical engineers so we are very careful about making sure that one plus one equals two. So what we will do is say a three-minute Sweetbeat session and then we will dump the R-R intervals, and they better add up to three minutes.

[Damien Blenkinsopp]: Okay, and yours is always three minutes?

[Ronda Collier]: For the HRV reading, yes, that is for the athletic reading. But you can do five minutes or eight minutes, but the R-R intervals need to add up. And some of the heart rate monitors don’t and so we work with the vendors to try to get that more accurate, because we want to support them.

[Damien Blenkinsopp]: Yeah, and it is better for everyone if you can support more sensors. So there are a bunch of different things coming out. There are the chest straps, which we have spoken about – so you are working with Polar, 60Beat, Zephyr, and Wahoo. And then there are biosensors, where you have these plastics that stick to you, basically?

[Ronda Collier]: Yeah, we just released our second product called Sweetbeat Life, and Sweetbeat Life works with what is called the health patch, which is a product by Vital Connect. So the health patch looks like a big band-aid, about three inches long, and that is an FDA-approved, single-lead EKG. It also measures respiration, body temperature, body surface temperature, calories burned – accurate, by the way, because it is measuring your body temperature and heart rate – as well as activity.

It is a real doozy, it has got everything in one. We are really excited about that because we are going to get a whole bunch of new metrics and be able to correlate that with heart rate variability and stress and provide more information.

[Damien Blenkinsopp]: That is great. How long does someone wear a patch like that for? How long does it work for?

[Ronda Collier]: That is a great question because we came up with a use model that Vital Connect never considered. Their original use model was it comes with a separate module, the patches are disposable and so you plug the module in and stick it on and their use model was you could wear it for three days until the battery dies.

[Damien Blenkinsopp]: It’s 24 hours?

[Ronda Collier]: You can, yeah, if that is what you want to do. What we do is we just keep the plastic that goes on the back and rather than have to put a chest strap on in the morning when you are doing your morning HRV reading you actually reach over and grab your patch, stick your module in, and stick it on. And so I get the patch to last for over a month.

[Damien Blenkinsopp]: You basically have this sticky part on you and then you just plug the electric part in every morning?

[Ronda Collier]: I peel the band-aid off, like take the band-aid off, and you pull the module out to save the battery, and I just have that sitting by my bedside. And in the morning I grab the band-aid and I stick the module back in and stick it back on.

[Damien Blenkinsopp]: Oh, so it sticks on and off without a problem, basically?

[Ronda Collier]: It does, and it is funny – different skin types can do it more than others. But if you are laying flat on the bed for your HRV morning reading it works pretty well for like a month.

[Damien Blenkinsopp]: You said two interesting things there. The first was you said FDA-approved for EKG. So does the FDA approve certain monitors and sensors and say they are EKG standard?

[Ronda Collier]: You go through a process, basically, to get a device clearance. But yeah, so this particular one is FDA approved. And for over-the-counter, obviously, because we are selling it to consumers.

[Damien Blenkinsopp]: Do all of them have to be FDA approved?

[Ronda Collier]: No, this is a consumer product. Although we – our product is we want to have values that are clinical grade and we do tests to make sure they are accurate. And I do want to note that HRV is very sensitive to the data going in. So if you have the wrong R-R intervals or the wrong interbeat intervals you are not going to get accurate data. So it is super sensitive. So anyone who is interested in HRV, make sure that you are aware that you have a quality heart rate monitor, whatever that is.

[Damien Blenkinsopp]: Definitely, and I want to talk more about the accuracy and use cases. The other interesting thing that you said though was you are using it and it sounds like you are using the HRV for training in the morning. Is that your main use for it? How else do you use it yourself?

[Ronda Collier]: Well, I use it for HRV for training in the morning. I also use it to track my circadian rhythm. I am really curious what is going on with me, quite frankly, at naptime in the afternoon. And it is very interesting – my parasympathetic nervous system actually increases in the afternoon?

[Damien Blenkinsopp]: Is that because you have a nap?

[Ronda Collier]: Yes, I will back up. Heart rate variability has a circadian rhythm, and I look to be curious, to see what is going on. And sure enough at 2:30 in the afternoon my parasympathetic or HF, HRV parameter increases.

I also use it especially early on with Sweetbeat. I used it when I was sitting at my desk to figure out what was going on and why I would get triggered. Because you are working all day and suddenly your neck hurts. And you are like, ‘What was I doing?’ You don’t even know because we do it all the time.

So I have actually learned that if a browser doesn’t load when I think it should, my face gets in the screen and I tense up.

[Damien Blenkinsopp]: You told me about this at Quantified Self. I think everybody hates that and we just don’t really realize how much.

[Ronda Collier]: Well, the important point here is that if you can learn one thing that you are doing all the time, then you can reduce your stress.

[Damien Blenkinsopp]: Yeah, and is that an HRV reading? You are using the stress monitor with your HRV app for that?

[Ronda Collier]: Right, right.

[Damien Blenkinsopp]: Okay, and previously we have talked a bit about HRV for training, so I think the audience has a reasonable grip of that and then how that works. And we didn’t look at all on the stress side, and that is a different calculation. Can you talk a little bit about what is behind that? How does it use HRV and how is it different with HRV for training calculation?

[Ronda Collier]: Yeah, absolutely, so the HRV for training calculation is based on – let me back up because I think it is better to give a high level of review. Heart rate variability, in itself, is just that – the variation of the heartbeats in the beat-to-beat intervals. It can be measured in several different ways. One is called time domain, or statistical analysis, like standard deviation. Root mean square of successive differences. The RMS, those are all typical statistical measures.

Then there is another way to measure the HRV and that is called frequency domain. And this is using [inaudible 00:16:43] fast forms and for you engineers out there, you kind of know what that is. And looking at the frequency components of the R-R intervals.

And then thirdly there is actually non-linear, which we are not using in Sweetbeat at this time. So the HRV for training uses a time domain parameter called RMSSD and that is a measure, it turns out, of your vagal tone. And the vagus nerve is the tenth of 12 cranial nerves in the nervous system, in the [inaudible 00:17:12] nervous system. And that particular piece of the nervous system is what gets fatigued during overtraining and endurance sports. So we measure that time domain measure for the HRV for training.

[Damien Blenkinsopp]: And you were saying that you specifically use that because the research has been based mostly on that measure?

[Ronda Collier]: Yes, that’s right.

[Damien Blenkinsopp]: So just one clarification on that – when you have actual score in Sweetbeat, the last time I spoke to you, you said it was based on 100. Is that the natural log of RMSSD times 20, or are you using something different? I think iFleet uses the natural log times 20.

[Ronda Collier]: Yeah, it is similar to iFleet but it is not the same.

[Damien Blenkinsopp]: So if you went out and got one and then a month later it broke or whatever and you went and got a different one, then you can’t have all of those values in Excel and compare it back for two months because they don’t necessarily fit?

[Ronda Collier]: No, no. And that’s actually a great point, Damien, because we have had people ask why is it different in iFleet? Because we use a different algorithm. We were 10,000 miles apart, having the same idea, but doing it differently.

[Damien Blenkinsopp]: So there is no industry standard, and it is basically because everyone decided it was going to be better to have it on a roughly 1 to 100 rating?

[Ronda Collier]: Yeah, it is a consumer thing. But there is an industry standard for HRV, but it is in numbers that a consumer would have a hard time with.

[Damien Blenkinsopp]: Could you give us a quick example?

[Ronda Collier]: Sure, so RMSSD, depending on who you are and HRV is very individual – while you sit there and in three minutes it can go between let’s say 60 and 68 – and it will sit there and vary because your nervous system is very dynamic. And then maybe the next day you get up and it is 54. So these numbers are just not easy for people to deal with.

So by scaling it from 0 to 100 it is easier for people to understand.

[Damien Blenkinsopp]: Yeah, that makes sense.

[Ronda Collier]: The stress level, so that is the HRV for training piece. And then the stress level, we actually use the frequency calculations of HRV and we measure the low-frequency components, which correspond, in simple terms, to the sympathetic nervous system. Actually, it is a combination of sympathetic and parasympathetic, but mostly sympathetic-dominant.

And then the high-frequency components, which are a measure of your parasympathetic branch of your autonomic nervous system. So for the stress level we look at those two and then we measure the balance between the two. So when you are sympathetic-dominant, you are stressed, sympathetic or fight-or-flight dominant, you are stressed. You want to actually be sympathetic-parasympathetic balanced.

But when you are really relaxing or just woke up in the morning and are sort of chilling, then you actually want to see yourself being a bit parasympathetic-dominant.

[Damien Blenkinsopp]: So if you are at work you would want to be a little bit sympathetic-dominant? So you are working on something and you are writing or doing a presentation?

[Ronda Collier]: Yeah, you normally would be. But you don’t want to be chronically that way.

[Damien Blenkinsopp]: Okay, so you are saying that balance would be 1-1, so LF and HF would be equal?

[Ronda Collier]: Yes.

[Damien Blenkinsopp]: What is bad? What kind of ratio is starting to look bad? Is it 2-1?

[Ronda Collier]: No, 2-1 is still pretty okay. You don’t want to be that way 27/7, but a lot of people are. When you start getting really bad is when you are over 4 or 5, which you would be surprised, is pretty darn common and people are even higher.

[Damien Blenkinsopp]: And you were saying it is throughout the day?

[Ronda Collier]: Every time you do a measure you are always – you are sitting at your desk and you can never, ever, get anywhere near 3, no matter what you do.

[Damien Blenkinsopp]: Even if you do some relaxation techniques, some people can’t get it down?

[Ronda Collier]: They can’t get it down.

[Damien Blenkinsopp]: That would actually probably be me, because mine won’t. I know there are some specific reasons, it is not because I am a really stressed out individual. But yeah, that would be me. And I was worried about it a bit more at first until I learned a bit more and I spoke to you at Quantified Self about it.

What is yours, for example? You were talking about when you get stressed at your computer. What does that tend to go up to? What would it normally be if you -?

[Ronda Collier]: I will qualify that with I have been meditating for a very long time. And I did a lot of coherence training with Heartmath for years, and so I will qualify that. But I am pretty balanced. Mine will go up to maybe 2 or 3, which is if I am really stressed. Otherwise I am usually anywhere between 0.8 to 1.5.

[Damien Blenkinsopp]: That sounds ideal, I guess? Is that?

[Ronda Collier]: Yeah, I am pretty balanced. I have worked hard to make my life that way, by the way. It was not always the case. I used to do chip design, which is very high pressure at Silicon Valley startup companies. I wish I had this app then because it would be interesting to see what I was running on, probably full time.

[Damien Blenkinsopp]: I was just going to ask you – that would be so interesting to know how that sort of evolved over time. And especially – this is when I started more meditation, this is when I did this, and you could see the steps down. Because I recently started – I didn’t really know how to track my meditation and if it was effective in any way. And I have been looking for a way to track it for a while.

So these days I go to the part and I switch on Heartmath. I have been using Heartmath to just track my meditation and it seems to be getting better, but honestly I don’t understand the difference between that and say the HRV for stress reading. Could you give me – like, could I use both of these for meditation and try and track how effective my meditation is? Or do you think that is not a reasonable use of it?

[Ronda Collier]: It is. This is a great question and we get this all the time in our support questions. Heartmath is a coherence training device or app, and what that does is get you into a state, basically getting your nervous system and all of your nervous system operating a – it’s called coherent, but in the frequency domain all you have is a little bit of energy at your breathing rate of 0.1 hertz.

[Damien Blenkinsopp]: You told me once before that this was in the LF zone?

[Ronda Collier]: And that falls into the LF. We don’t define what makes HF and what makes LF. So LF is 0.04 to 0.15 hertz, and HF is 0.15 hertz to 0.4 hertz, and that is an industry standard because we follow the HRV standards, and that is what it is.

So if you do coherence training you are going to have a huge spike if you are coherent at 0.1 hertz. And you won’t have anything anywhere else, because that is what coherent is. There is not going to be any energy in the HF range at all, or anywhere else, even in the VLF range, which are the very low frequencies.

So really it is a spike there at 0.1 hertz. And so that will show up as high stress in our app; however, if you are meditating and not doing regular breathing, your breathing normally and then you should be able to see your nervous system actually have a power increase. So that could be a measure of your meditative quality.

[Damien Blenkinsopp]: Do you mean the HF, the parasympathetic, would increase?

[Ronda Collier]: Actually, you could see the whole thing increase. It will stay balanced but the whole thing can increase.

[Damien Blenkinsopp]: I will go and try this for a few days. I go and meditate and I switch it on to the stress and then there is a chart in your app which looks at the LF and the HF and it shows it charting over time. Is that the screen you would look at?

[Ronda Collier]: That’s right, and Sweetbeat Life actually does it in real time now.

[Damien Blenkinsopp]: Okay, what is the difference?

[Ronda Collier]: It doesn’t show LF and HF graph in real time. Sweetbeat shows it in numbers in real time, but Sweetbeat Life, if you go to the landscape mode on the monitor screen, it shows it in real time. So it is a little more intuitive if you are meditating to look at a graph than read numbers.

Be aware though, if you have been doing Heartmath you just go coherent. When I meditate, I just automatically go coherent now so I don’t use it for that anymore. But I do use it in [inaudible 00:25:07].

[Damien Blenkinsopp]: Did you say you don’t go coherent in meditation anymore?

[Ronda Collier]: I do go coherent. All I have to do is think about meditating and I am coherent.

[Damien Blenkinsopp]: Oh, okay. And if you look at the research I am not actually sure that meditation correlates with coherence all the time. And actually if you look on the forums in various places, you will see some people who have been meditating for a while and they try to use Heartmath or something else and when they are in their usual meditation zone, they get a lack of coherence. THey go out of coherence and then when they focus on getting coherent, they go in under coherent. So I don’t know if there needs to be more research done around that. Do you know anything about that?

[Ronda Collier]: Once your nervous system is trained for coherence, and this is my experience, and our other founder Donna Lever, also as soon as she sits down to meditate, she is not trying to go coherent and she doesn’t have a device, but we go coherent. If you want to, you have to be mindful about not doing that regular breathing that brings you coherence. So there are a lot of meditative techniques where you breath in and hold at the top and focus and then that goes – so you just would do a different breathing technique.

[Damien Blenkinsopp]: Right, and breathing does seem to be essential. I think it makes quite a big difference in the Heartmath side. In your app – let’s move back to Sweetwater – does breathing make a big difference to stress numbers, the LF and the HF, in your app?

[Ronda Collier]: Absolutely. While we are not a coherence training device, if you go coherent you are going to see it. And so it will look like – you will see it once again as a spike at LF and so it will show up as stress.

[Damien Blenkinsopp]: Yeah, which in your app would be red, I am guessing?

[Ronda Collier]: That’s right, the stress levels are blue, green, yellow, orange, and red; however, you would be able to look at your power numbers and see what you are doing. You would want to see a super high power number in the LF.

[Damien Blenkinsopp]: Right, and so in your case when you were doing meditation, specifically, you would look at the LF and the HF screen, rather than the bar with the ratings? But just for general stress like you are talking about, you want to understand a situation like if you are stressed or not and if you are feeling a bit rough or looking at your screen and not feeling good or for presentation or whatever – would you use the LH-HF screen or would you use the bar with the red and the yellow and so on?

[Ronda Collier]: I think I would use the bar initially – for your listeners, definitely just use the bar and then once you start figuring out what you are looking at then you can actually look at the LF and HF and that can become second nature, once you are done with the bar then we tend to look at the geek screen at the LF and HF.

[Damien Blenkinsopp]: Right, and then as you said higher power is good as well as the ratio?

[Ronda Collier]: That’s right. When you are really feeling kind of dragging, if you look at the power numbers you could be – I am going to make numbers up. I have had listeners quote my numbers and there is so much variety in HRV numbers, so I am just going to use some average numbers. Some days your LF and your HF might be around 100 or less.

[Damien Blenkinsopp]: Both of them?

[Ronda Collier]: Yes, somewhere around there.

[Damien Blenkinsopp]: So is that a bad day?

[Ronda Collier]: For me that is a bad day. That is a low day where my energy is zapped or I have done something where I am emotionally or physically drained. Then there are other days where you are just on top of the world and you are at 2,000 to 3,000. So that is where you won’t see that from looking at the bar from blue to red, but you will see that looking at your numbers.

[Damien Blenkinsopp]: My numbers would be like – most of the time my LF is like 1,800 and my HF is like 200 or 300, if I am lucky. So if my HF isn’t high enough –

[Ronda Collier]: That’s right. And Heartmath should, over time, improve that.

[Damien Blenkinsopp]: It definitely helps and you can feel it. I guess you recommend to do this kind of thing, but once you identify something that is stressing you in your life and you do a Heartmath session or a meditative session and use the device, then you definitely come back afterwards and you have got more energy, you can get back to what you are doing, and it definitely makes a huge difference in my productivity. Once I discovered this it was pretty much a game changer for how I work.

[Ronda Collier]: Yeah, and you bring up a great point. One of the reasons that we created Sweetbeat was to not only provide you with feedback that you would go off and meditate or chill, but to provide you with real-time feedback so you can actually, right then and there, go, ‘Oh, I am doing this and I have been doing it all the time and I didn’t even know it.’ And then learn to actually correct your behavior right then and there. Put your shoulders back, uncross your legs, sit back, take a deep breath at your desk, and then reset.

[Damien Blenkinsopp]: Right, and so the idea is that you can be watching the screen and you can watch when your numbers readjust or go back to normal and then you can tell when you are in a better state.

[Ronda Collier]: That’s right, and then next time Sweetbeat gives you an alert if you change your stress state and you can program it to do that. So that is how I learned about the screen thing. Other customers have used it while they are driving and it starts beep, and they realize that they have just stressed out over something that they deal with every day. And so it brings to consciousness things that have been previously unconscious that are contributing to heart disease and hypertension in middle age.

[Damien Blenkinsopp]: Would you say this is the most common use case? I was going to ask what you find people are using the most. I guess you have this big database now with everyone’s data. I am not even sure if you have come to grips with that because you have all this data.

[Ronda Collier]: We have not come to grips with it yet. It is going to be a huge issue. What we do is when customers write in and want to know about their data we can help them with an analysis if we have time. We go ahead and look at some of their sessions and give them sort of a bird’s eye view of what is going on for them and so we are still doing that.

[Damien Blenkinsopp]: Yeah, but you can’t do things like understand what, on average, the users are using that for?

[Ronda Collier]: Oh we do, and we have done that. We have a large percentage – the micro market is lead athletes and even fitness enthusiasts using it to guide their training.

[Damien Blenkinsopp]: Right, so that is every morning as soon as they wake up?

[Ronda Collier]: That is that group. That group is also using it throughout the day, running 20, 30-minute sessions just to see how they are doing. Then there is the other market segment, which are quantified selfers and they are wanting to run it for like 8 hours.

[Damien Blenkinsopp]: Right, to see where they spike?

[Ronda Collier]: Absolutely. They want to run a session all day and then they want to sleep in it. They are just running it constantly.

[Damien Blenkinsopp]: When I first got mine I wanted to do it 24 hours and I think I even wrote to you about it.

[Ronda Collier]: Yeah, your phone won’t hold all that – there is a lot of data.

[Damien Blenkinsopp]: That’s what you told me.

[Ronda Collier]: But with the health patch we are working on making that a little easier for folks. So the health patch will make the full time monitoring much more accessible because it is actually comfortable and you don’t even know it is there. You can sleep in it without the strap on you, though some people don’t mind. I don’t sleep well with the strap, but the little health patch just sits there and it is not a big deal.

[Damien Blenkinsopp]: Anyway, the idea behind the 8-hour or the 24-hour is people are trying to figure out, and using the stress monitor, what kinds of things are triggering them throughout the day. This is what they are doing, right? They are just mapping the whole day and they are like, ‘Hmm, at 1 o’clock and 3 o’clock I got really stressed out, what was I doing?’ and that kind of thing?

[Ronda Collier]: Yeah, that’s right. And also they are tracking LF and HF. A lot of the folks have gotten big into looking at those numbers because once again, the stress meter only tells you the balance of LF and HF. The numbers themselves tell you the power levels.

[Damien Blenkinsopp]: So it is more interesting once you start looking at LF and HF?

[Ronda Collier]: People love the power levels, so yeah, it is really great and we were really pleased with that.

[Damien Blenkinsopp]: Yeah, is there a more detailed understanding though? As you have already described? A lot of people probably want to get their HF up higher and I guess there are two ways to look at it as the baseline, where you are from day-to-day. And I don’t know if you do kind of averages of how people evolve over time and they manage to address that kind of baseline versus –

[Ronda Collier]: You are bringing up a really important point for your listeners. Because HRV has a circadian rhythm, if you are going to do a day-to-day comparison you need to do it at approximately at the same time in the same position. If you are laying down and then stand up your heart rate increases to equalize the blood pressure. So really your position is important.

Also, your mental state will be important. So if you measure it at the same time each day but one day you are all stressed because something happened in your family, your HRV is going to be different. That is why we recommend that people do it first thing in the morning and really mindfully don’t start thinking about your day because that can affect the reading.

[Damien Blenkinsopp]: Yeah, what I do every morning now is I lie down and then I do a standing up reading as well. Which do you do? Do you both or do you just do lying down or standing up?

[Ronda Collier]: Well I just do lying down. I am lying in bed and I am not thinking, because once I get up then my mind starts thinking about my day and so that can affect the readings. We have done measurements where something was going on in my family and I was just sitting here and already had the strap on when I was testing in the early days and something happened and just from my thought and looking at what happened my stress soared right in front of my eyes and it was kind of crazy.

Our other founder, Joe Beth Dow, had the same thing happen. So really your mental and emotional state, if you are going to do the day-to-day comparison, you need to be mindful of that. And if you see it drop just really go inside and go, ‘What am I feeling sick? Or sad, or angry, or upset, or something like that.’

[Damien Blenkinsopp]: Right, to kind of detect if it is something you are causing yourself or if it is the underlying how you are feeling today, that is a good point.

[Ronda Collier]: That’s right. It can be physical, emotional, psychological, or environmental.

[Damien Blenkinsopp]: Yeah, I can definitely relate to what you are saying about it is easier when you are lying down when you first get up and then you tend not to think about it so much. But I do the lying down one and then I do the standing up one and I tend to start thinking about things. And I have to kind of catch myself, especially if I am thinking about work or something. So I think you are totally right about that, if you are going to do the standing one it is good to keep in mind that it is at the same time.

The other thing is movement. HRV for training is a very specific, three-minute reading. So you either do it lying down or standing up or sitting down.

[Ronda Collier]: Do your three-minute reading and you are done, yeah.

[Damien Blenkinsopp]: And you always do it the same just to keep it the same. How about movement? I guess some people doing these 8-hour cycles are also tracking all sorts of things throughout the day. Is it relevant to track HRV while you are moving? Is that an accurate reading? I had some experience with this before and I couldn’t really figure it out. What is your take on that?

[Ronda Collier]: That is another great question. You should see your heart rate variability changing through the day. When you go from sitting to standing or lying down to standing your heart rate should increase and your sympathetic should increase to increase that heart rate. So you should see nice cycles throughout the day. If you are not then that is a serious problem and that would be indicative of someone with some heart disease.

[Damien Blenkinsopp]: You are saying if the power levels aren’t changing, as you are doing different things?

[Ronda Collier]: That’s right, or even the stress level, which is the balance because I will repeat the example and when you are lying down and standing up – when you go supine to standing your sympathetic nervous system kicks in to increase your heart rate, to pump your blood, or to equalize the blood pressure. And that is normal.

For people who have low HRV to a point that maybe it is a heart disease, they have a hard time and their heart can’t respond and their nervous system is brittle, if you will. And so when they go from lying down to standing up their heart rate doesn’t increase the way it should.

And so if you were to go throughout your day in 8 hours and not see a lot of variety in your power levels and your stress levels, that would be a problem.

[Damien Blenkinsopp]: The HRV readings are accurate in terms of the LF and the HF – it is accurate data when you are moving around it is just that it is changing a lot. So your HRV should go down, I guess? In this case it is going to be the stress. So would you be more stressed when you are moving around, if I am walking or running it is going to be more sympathetic? Or can it vary per person?

[Ronda Collier]: It really depends. We were wearing it at CES the last year, or the last two years, and these kind of things usually stress me out. I guess I decided that I am not going to let trade shows stress me out anymore. I did, actually, mindfully because I will just go bonkers. And I needed to be present to go talk to all the people were were going to meet with.

And so I was walking around CES with a completely balanced green to yellow stress, which is pretty good. And really the numbers were high and I was just in a good space. Now, if you are running and exercising then your HRV is going to drop and that is just the nature of the beast.

But it is really more about that you are going to see the variation when you stand up and sit down and sit down and stand up or have an emotional stressor, or anger or environmental something coming at you.

[Damien Blenkinsopp]: Yeah, so it is not that there aren’t any people using this to track their exercise – are they tracking their HRV or their stress?

[Ronda Collier]: Oh, these guys use it for everything.

[Damien Blenkinsopp]: Is there any research behind that? What kind of understanding could you get?

[Ronda Collier]: Sweetbeat was not designed to be used while you exercise. There are some things you can glean from that. In fact, you can see where you hit aerobic to anaerobic if you know what you are looking at.

[Damien Blenkinsopp]: That is interesting.

[Ronda Collier]: It is, it is very interesting. We just having pursued that, but I can see it.

[Damien Blenkinsopp]: Can you give us a quick add to that or is it more complicated?

[Ronda Collier]: Yeah, it is okay – so your stress level goes up and your whole power levels just plummet. Your HRV plummets because everything is moving so quickly. And when you hit that threshold your stress level on the colored bar actually goes down when you hit that threshold, so that is the easiest way because your HF actually kicks in.

[Damien Blenkinsopp]: Your HF you are saying will go up when anerobic starts?

[Ronda Collier]: Yeah, and remember you are down in numbers in the teens now. So your listeners that want to try it, yeah.

[Damien Blenkinsopp]: Yeah, they should try that out.

[Ronda Collier]: Look at the geek screen and watch the numbers. Pay attention and then you will be in the red and then suddenly when you go a little harder it will back down and the bars will be like in the yellow and in the green.

[Damien Blenkinsopp]: Wow, that is really interesting. That would be interesting if you guys do something with that later.

[Ronda Collier]: And there is a bunch of research on that too. It is so dynamic and it is kind of hard to do in an app, but we think about it.

[Damien Blenkinsopp]: So I guess you will have some complicated algorithms you will have to develop and it might take some more research. It would be interesting if you could do that because currently the tests – I looked at different breath tests and so on you can do to establish anaerobic threshold. And it is not easy, you have to go to the labs and mess around. So eventually if we had an app like your iPhone app that would be really cool.

[Ronda Collier]: Yeah, I have done one and they pushed me too hard – I need to warm up. I do. And so they got completely wrong measures, said my max heart rate was like 150, which is just not true. I go to the gym and hit 165 all the time but I need to ramp up. So going on a full-force run in the first minute just doesn’t work for my body.

It would be cool to have an app that would let people – there needs to be a protocol because we have done enough looking into it with that, but not in the first minute, come on.

[Damien Blenkinsopp]: You have probably got your hands full with all the other stuff going on in your app already, so it is probably not for tomorrow. I just want to go back and we have touched on circadian rhythm a few times, saying how it distorts the figures. So I want to make sure the audience doesn’t get confused with that point. Is there a specific pattern? If I am looking at stress over the day, is there any way I can picture it in my mind so it will be a bit higher at this point or a bit lower at this point?

How do you look at the circadian rhythm? I guess the first thing to say is if you are doing HRV for training it should be at the same time every day? I woke up at one time at 4 o’clock in the morning, which I sometimes do, and then other times I will wake up at 8 o’clock and do my reading then. And one day I did it at 4 o’clock and it was completely different. It was actually a lot worse and I don’t know if that fits the typical theory. But I was like, ‘I think I better take this a bit later.’

[Ronda Collier]: It’s going to be individual, but typically – and I am just going to give you a typical case. Your HRV will be highest in the 6 am, 7 am, 8 am. And then it dips down in the early afternoon and then it comes back up in the evening.

[Damien Blenkinsopp]: And then it stays up during the night?

[Ronda Collier]: While you are sleeping your HF really should kick in and that is why people measure it when they are sleeping. If your HF isn’t kicking in then you are maybe not getting very good sleep.

[Damien Blenkinsopp]: That’s me, but we won’t get into that. That is why at 4 o’clock it was terrible. So you basically gave us the outline there. So in terms of stress that would be reflected in the stress levels as well, so you are saying in the afternoon you probably have the worst stress levels? It would be harder to be non-stressed in the afternoon, is that what you are saying?

[Ronda Collier]: Actually, I can give you mean. All I have is research numbers, so the only thing I can tell you from personally looking at the HF and LF numbers are that my HF kicks in the afternoon, which causes my heart rate to decrease, and I am sleepy.

[Damien Blenkinsopp]: Is that because you have trained yourself to have a nap?

[Ronda Collier]: But everything is low, so my HF will go from maybe 3,000 in the morning down to 900. But I am still HF-dominant, so once again, that goes back to the power numbers. They are just really – once people use Sweetbeat and get used to the stress levels then really dive into the power numbers because that is saying so much about what is going on for you.

[Damien Blenkinsopp]: And so your aim there is – 3,000 sounds incredible, like for my levels. You are saying that over time you would really like to get the HF up, that is the idea? To increase the power of the HF?

[Ronda Collier]: Yeah, most people want their HF up because they are sympathetic-dominant and kind of chronically stressed. So we have done a few case studies with yoga, so actually a young woman was one of the case studies in her early 20s who just felt stressed out, always. So her HRV was always on the low side and she was sympathetic-dominant. So she did yoga twice a week for six months and brought that into balance. She raised her power levels and brought herself much closer to balance.

[Damien Blenkinsopp]: How was she tracking that? Or how would you advise if someone is doing a long term intervention like that where they are doing classes twice a week or they are doing meditation once every day, how would you advise them to best use the app to track that?

[Ronda Collier]: I would do the HRV for training but if you are looking at LF and HF, I should mention this, it is better to have a five-minute reading or longer because with our algorithm, once again we use the industry standards for heart rate variability and there is what is called a short-term measure, which is five minutes, and a long-term measure, which is 24 hours.

So our algorithm is designed for a minimum 5-minute window. So you would not want to really use HRV for training because that is designed for the time domain accuracy and it is not the best. You are not going to get the most accurate LF and HF in the three minute, but you want a five minute.

[Damien Blenkinsopp]: Great, so your HRV for training switches on and off and it does the three minute and then it is finished. It is all built in so you don’t have to worry about that and it is going to do it for you?

[Ronda Collier]: Yeah, that’s right.

[Damien Blenkinsopp]: But what you are saying is that for the stress monitor it is labeled stress monitor in your app, as I remember, and that one you have to do for five minutes?

[Ronda Collier]: Yeah, at least. And usually you just want to put it on either right when you get up in the morning and do that, or still when you are kind of relaxed somewhere, maybe watching TV in the evening, or pick a time when you are kind of unwinding. So if you are doing the six-month intervention, pick a time a couple of times a week or every day that you go ahead and measure yourself and the history and the charting and you can see what your trends are.

[Damien Blenkinsopp]: So ideally that is the same time every day and should be the same activity, like you are saying – if it is always watching TV, although I think if you are watching an action film versus a romantic film or something it might have a little bit of an impact there too, so you have to watch out for that. Great.

[Ronda Collier]: That’s right, and if you have a favorite program that you always watch you should measure during that.

[Damien Blenkinsopp]: So you mentioned yoga – are there interventions that you know people have done in your user base? Are there examples of good things to try out in terms of experiments? What would be the top five things to try to raise the baseline?

[Ronda Collier]: Definitely yoga and meditation, those kind of go together. Nutrition, of all things, stop eating anything that is out of a box. Read the labels and if there an ingredient you can’t pronounce, don’t eat it.

[Damien Blenkinsopp]: So that would be easy if you start a diet on the first of the month. And then you can, over time, probably see some change over the next weeks if it is a positive change or a negative change?

[Ronda Collier]: That’s right, because our bodies are completely interdependent and interconnected. All the systems are connected to the other. Sweetbeat also has, which I haven’t mentioned, a food sensitivity test. And it allows you to test for foods that you may not be allergic to but you are sensitive to. And these foods can actually cause your heart rate to increase by quite a bit, even if you are just sitting.

So we have case study after case study of people sitting quietly at their desk, watching TV, or relaxing, and their heart rate goes up 20 beats after eating the offending food.

[Damien Blenkinsopp]: Did you base that on research? Where did that come from?

[Ronda Collier]: It’s called Dr. Coca’s Pulse Test – I think it is Coca’s Pulse Test. And Dr. Arthur Coca was a renowned immunologist in the 50s, founder of the journal of immunology, so he was quite well-known at the time. And he came up with this simple test to help his wife, who was having issues where they couldn’t find it in allergy tests, but they were suspecting that she was allergic. And so he came up with this pulse test for her and so she was able to fix a whole lot of ailments by using the pulse tests and eliminating offending foods.

And so all of the inflammation and all of that interacts with cortisol. There is stress cortisol and that is why I mentioned nutrition, because it is all interrelated and so if you are eating things that you could even be slightly sensitive to it can affect your heart rate variability.

[Damien Blenkinsopp]: Is it in peer-reviewed journals, this kind of research, as well? Or is it Dr. Coca’s? It sounds like it makes logical sense. Has anyone done any studies on it to validate it?

[Ronda Collier]: I could not find any peer-reviewed journals on this; however, they do teach it in medical school so a lot of allergists know about it. So yeah, it is very interesting that I have been unable to find any because we at Sweetwater go to the National Institute of Health database for our research. We want peer-reviewed research that will back up our algorithms. So yeah, the Coca pulse test, no, but a lot of functional medicine doctors, MD or not, use the pulse test and are familiar with it.

[Damien Blenkinsopp]: So it is worth finding out to see if there is something?

[Ronda Collier]: Absolutely.

[Damien Blenkinsopp]: Is there anything you would advice – and maybe you don’t know about this – but say if something is showing up and it looks like an analogy, what would be the next step for someone to try to get more validation around that? Have you got any suggestions, or is that something kind of out of your area?

[Ronda Collier]: Take it out of your diet. If you eat something, what the app does is if you are wearing a heart rate monitor it automatically will take your pulse at 30, 60, and 90 minutes. And assuming you are not out running or exercising, if your heart rate increases then that is not good.

So what you would do is note that and basically remove the offending food.

[Damien Blenkinsopp]: Yeah, so a lot of functional doctors these days advise – because a lot of the allergy tests aren’t that consistent either, so a lot of them advise you on elimination anyway. So I guess if you really wanted to validate it afterwards, don’t eat it for a month. And then eat it again and see what happens to you or if you feel worse, and again do the test with your app, for example. That is probably the next best thing to do?

[Ronda Collier]: That’s right. I wasn’t testing anything but I ate – and a reasonable, regular serving of cherries about a month ago. And I was just sitting at my desk and I was testing the Sweetbeat for something else and I wasn’t doing a food test, but I noticed my heart rate was 79. My resting heart rate is about 50 and I was like, ‘What is this all about?’

So I looked it up and a lot of people are sensitive to cherries. And I could feel my heart pounding. And so I am really aware, and I am going to retest cherries.

[Damien Blenkinsopp]: You are probably becoming a lot more aware about yourself and notice a lot more things because what I have found when you are using these kinds of apps it kind of validates tiny little – like if you feel a little bit off, it starts to validates you and you start to get more confidence in trusting yourself and starting to notice more because of that. So it is probably not something you are telling everyone, but using these HRV apps for this kind of apps for this kind of thing can help build your awareness of yourself over time as well.

[Ronda Collier]: That reminds me, sort of back to what people have done to improve their HRV. [inaudible 00:49:14] cofounder, walking in the park, in green – she learned a few things because her HRV was on the low side when we started Sweetwater and now even through a whole bunch of life events, a mother passing away and so her HRV has continued to increase through the years because she learned the things that increase it so she does them every day, versus doing them haphazardly.

[Damien Blenkinsopp]: Let’s get back onto the – what other kinds of things have we missed? We talked about yoga and meditation.

[Ronda Collier]: That is another one, we have done some research on – another one is acupuncture so we have done lots of case studies and actually there is peer-reviewed research on acupuncture. We have done some ourselves and your nervous system just balances and power levels increase during and after an acupuncture session, so that was another interesting one.

[Damien Blenkinsopp]: That is quite a controversial area. I know there is a lot of functional doctors who really support it and there is also a fair amount of research there. But when you bring up acupuncture a lot of people find it controversial still.

[Ronda Collier]: Well that is changing, and insurance reimburses acupuncture for people with arthritis. So Western medicine does acknowledge and that is why there are a lot of peer-reviewed papers surrounding acupuncture. They know and they can measure that the pain receptors have changed, specifically around the points for arthritis treatment.

[Damien Blenkinsopp]: Well here is the thing – I think acupuncture is a bit of an art, so some people might be better at it than others? Is that the way that it works? Could you evaluate the quality of the acupuncture you are getting based on the impact on HRV?

[Ronda Collier]: Yeah, absolutely. I have a good acupuncturist so I have seen my nervous system change about 20 to 30 minutes after the needles go in, which is about what you should expect. Another is chiropractic – we hold our stress in our bodies and there are, once again, peer-reviewed papers on chiropractic and HRV.

You can see whether the adjustment made a difference to you or not, so it is sort of an objective measure in general to some of these treatment venues that some people are not sure of, like acupuncture and chiropractic. You can actually measure whether it made a difference.

[Damien Blenkinsopp]: Yeah, so it is useful, especially if you are doing something new that you are not sure about, whether it is yoga or whatever you are trying that is new. I guess it also help your motivation, so if you can see the numbers changing it is this low thing, but if you can see that positive feedback you are like, ‘Oh, this is making a difference.’ Whereas sometimes – that can give you more motivation just to keep at it because you can see things changing.

So I know we have gone on quite a long time here and I wanted to make sure we cover a couple of other things, which is your new app and the correlation in particular, which has been added. Is there anything else new that has been added or is that the main thing?

[Ronda Collier]: Better graphing features and like I said, some of the real-time graphs. The Vital Connect patch so you can see real-time calories burned, once again accurate. I have a Fitbit so don’t get me wrong, but it is not accurate. Neither are the machines at the gym, by the way, but this gives a real accurate calorie burn.

It also gives – let’s see, respiration, body temperature, and calorie burn. It does measure number of steps and all that, as well as all of our HRV values.

What is new in Sweetbeat Life besides the Vital Connect patch, which has all that new information for you in real time – we have a correlation feature that allows you to basically correlate your HRV and stress levels to all the other parameters in the Vital Connect patch as well as correlate to your Fitbit, the number of steps you are taking, your calories burned, your calories eaten, and we also connect to Withings, so we have the withings scale and so your weight is in there as well as the Withings blood pressure.

One can learn what am I doing when my HRV is good? How many steps, how many calories? Or what am I doing when my weight is where I want or not want? I personally learned that it is not calories in versus calories out for me that helped me get to my desired weight – and we are talking three pounds here and it is important. It is the calorie out. I need to eat more and burn more and then I actually can lose weight easier. So that was important for me.

[Damien Blenkinsopp]: Right, so you are saying you saw a correlation with intake and activity levels?

[Ronda Collier]: That’s right, burning 1500 and eating 1200 I didn’t lose weight. But eating 1700 and eating 1400, I did. And so that was really important for me. And a lot of people will be concerned about what they are doing to maintain the proper blood pressure or stress levels and so on, so it is really a great tool to bring meaning to all this data.

[Damien Blenkinsopp]: And when did you launch this? I think it is the early stages in the understanding of the use cases.

[Ronda Collier]: Yeah, we launched in May. And if anyone does decide to try out Sweetbeat life, we have great videos embedded in all the screens now. For the correlation function we have put a lot of information on a very simple screen, so it is very important to watch the video and pay attention. Because once you know what you are looking at then you hit the buttons and there are all these buttons to see all this great information and you know what you are looking at.

But when you first go looking at it, you are not going to understand it, so please do take the time to look at the video. That is just the nature of trying to convey a lot of information on a small screen.

[Damien Blenkinsopp]: Yeah, and so what are your plans for that? Right now the correlations are between data of the Fitbit data and the Withings scale. What are the main areas people are correlating?

[Ronda Collier]: And the map my fitness, to measure how many mets your workouts are as well – just adding more, first we are going to stay where we are right now and get customer feedback on this. Once again, it is a lot of information crammed into one tiny screen, so we want to get that right first and find out what is useful to the customers and then do an iteration there and then just start adding more of the popular tracking devices.

[Damien Blenkinsopp]: Yeah and it sounds like you are going to learn as you go because you don’t know what is going to correlate either. And eventually patterns are going to pop out so it is going to be more interesting to integrate with some devices versus others.

[Ronda Collier]: That’s right, and one of our favorite scenarios is with the athletes that have been training using Sweetbeat and measuring all these things with let’s say blood pressure, weight, you name it, for a year and then they have Iron Man coming up. What we want to do is provide them with meaningful information of what they were doing that consistently got them into the most rested and ready state.

[Damien Blenkinsopp]: Yeah, like you were saying if they have six months of data or whatever that would be pretty amazing.

[Ronda Collier]: Yeah, and then they can go back and create this is what I was doing that consistently gets me to where I want to be the morning of the race, and so this is what I am going to do.

[Damien Blenkinsopp]: Whose idea is this? I don’t think anyone else is doing this yet. Obviously this is where people have been talking that things should go in terms of correlation.

[Ronda Collier]: This was our idea and oddly enough this came from an app challenge that we were going to do with Qualcomm Life. And Qualcomm Life collects data from so many different devices and so we were just going how can we show the value of the Qualcomm Life platform? And so that is what really led us to do this at the timing that we did it. So we are very grateful to Qualcomm LIfe for having that app challenge when they did because it really pushed us to get this together. So we really are the first people creating useful information besides just a dashboard with charts for all this data that everyone is collecting.

[Damien Blenkinsopp]: Yeah, and it will be interesting to see what kind of experiments they try to run and what correlations they can come up with. So how many users do you have using the Sweetbeat versus the new one? It has been out since May?

[Ronda Collier]: The new one has only been out since May so we have under 1,000 on Sweetbeat Life and tens of thousands on Sweetbeat.

[Damien Blenkinsopp]: I know you have got all this data – have you got any plans to try and sort through any of that? What are the most exciting things coming up next that you have ideas about? Or do you have ideas that you hope to do in the next two years?

[Ronda Collier]: I would have to kill you if I told you.

[Damien Blenkinsopp]: I thought it might be something like that.

[Ronda Collier]: We have a lot – that’s all of our secret road map. But we are doing some really cool stuff coming up and we are so excited, that is all I can say. And the health patch has really enabled this because it opens up a whole new market of people that frankly are not going to wear a chest app. They are just not going to put it on, so the patch really makes it more accessible. That allows us to create products for an audience beyond the Quantified Self hacker that will stick to the strap on or the athletes that already have straps.

[Damien Blenkinsopp]: How much does the patch cost?

[Ronda Collier]: So the starter kit is $199 and that comes with five patches and the electronic module.

[Damien Blenkinsopp]: So it is like $40 a patch, and they last – you said you used yours for -?

[Ronda Collier]: Well the replacement patches are $20, so a month or more depending on what you are doing with it .The price point is high because it is a brand new product, but that is going to be coming down as the volume ramps up, obviously.

[Damien Blenkinsopp]: It is brand new and I saw it.

[Ronda Collier]: It is brand spanking new. The only place you can get the health patch right now is through Sweetbeat, and we are the first app out with it. Consumers can expect that number to coming down in the years to come, like I said, as the volumes ramp.

[Damien Blenkinsopp]: Great, thank you very much. Just a couple of questions more about you and the way you use data in your life. What would be your number one recommendation to someone trying to use some form of data to make better decisions about their body’s health performance? What would be your number one recommendation?

[Ronda Collier]: Actually I think our correlation feature is our number one recommendation for me because it is giving you really useful information. HRV, for your listeners, should be measured along with your blood pressure, your weight, and your cholesterol because HRV perturbations are early indications to something that hasn’t shown up physically yet.

So if you are monitoring your HRV as you go through your life and you suddenly saw a drop, a consistent drop, then there is a problem. And then with the correlation feature you may be able to go back and see other aspects start to change with the lowering HRV. You can’t take one thing in isolation.

[Damien Blenkinsopp]: So you are using it as a discovery problem that you can’t see, because most health problems in our life take us by surprise.

[Ronda Collier]: Yeah, so I have the Withings scale and the blood pressure cuff and a Fitbit and I use iFitness.

[Damien Blenkinsopp]: So it is like risk management?

[Ronda Collier]: That is right, that is right, and learning what I can do. Sometimes, especially with weight loss, people are like, ‘I don’t know – I count calories and I do this and I do that. Why am I not losing weight?’ Then suddenly they will lose a couple of pounds and this will give some really useful feedback. I also want to mention on that vein that getting accurate calorie burn during the day – if you are really on a serious need and you need to lose 40 or 50 pounds, that is a long haul.

And 200 calories a day is a big deal when you are tracking, so getting an accurate calorie burn throughout the day is important. So really being more accurate, and Sweetwater health is really about more accurate feedback for the consumers and athletes.

[Damien Blenkinsopp]: Yeah, because there are a lot of apps out there and they are definitely not the same. I got the Mybasis watch and I think you know that compares unfavorably to some of the other trackers.

[Ronda Collier]: Yeah, we bought a Basis to check it out. And you have to wear it too tight on your wrist that it is not comfortable if you want heart rate. And it just doesn’t match my outfit.

[Damien Blenkinsopp]: Right, and just talking about the My Basis quickly, the reason you can’t do heart rate variability is that they are just not sampling quickly enough? Have you looked into it?

[Ronda Collier]: Any wrist face device, like [inaudible 01:00:52] use pulse oximetry, so what they are looking at are the capillaries in your skin as they expand and contract, so it is just very difficult to get very accurate beat times.

[Damien Blenkinsopp]: Right, so they are using averages to get the heart rate and they need way more accuracy to get to heart rate variability, which is more difficult than a heart rate. On My Basis if you start running around it starts losing track because your heart rate is moving, so it can’t even keep track of your heart rate.

[Ronda Collier]: Because it is motion and the pulse oximeters are very motion-sensitive because they are basically measuring capillaries and if you move your skin the capillaries are moving. And so Mio, just for those athletes, the Mio Alpha has done a terrific job of eliminating motion artifacts. You can actually use that one while you are running and still get an accurate heart rate.

[Damien Blenkinsopp]: A heart rate, but not heart rate variability.

[Ronda Collier]: No, and they want to do heart rate variability but they are also engineers and so they just know that they can’t.

[Damien Blenkinsopp]: They are struggling but potentially one day that technology might –

[Ronda Collier]: Potentially one day, yeah. If you can get the processing power without draining the battery in a watch it can be done.

[Damien Blenkinsopp]: You have probably told us some of this already. What data metrics do you track for your own body on a routine basis, like the things that you would keep in mind every month or every six months? What are the key five things that you think are most important for yourself?

[Ronda Collier]: I keep track of my HRV and I am aware of my blood pressure. I am also aware of my resting heart rate and I don’t know why, but I want to know. Mine actually drops low sometimes so I am worried on that end, it gets around 40 and I sort of want to keep an eye on that. I weigh myself, and weighing yourself every day is stupid, sorry. I weigh myself probably once every month or two and keep track of that.

You don’t want to – because pounds creep up and suddenly you are ten pounds overweight. And I track my steps because I work at home and you want to make sure you are moving your body. I exercise every day but man, if i don’t go out to the gym or go hike or do something like that –

[Damien Blenkinsopp]: Thank you very much for that. it is always interesting to hear what different people are focused on, especially when you are so involved in tracking yourself, so it is always interesting to hear what you focus on. Ronda, this has been an exceptional interview with tons of detailed information about how your app works and how you can use it. Thank you very much for your time today.

[Andrew Flatt]: The pleasure is mine, Damien. Thanks for having me.

[Damien Blenkinsopp]: Thanks. What I thought we would do to start with is jump into what is HRV a little bit – Heart Rate Variability – so that people who haven’t come across this before can have a rough understanding of what it is and where it was.

[Andrew Flatt]: Sure. So heart rate variability often gets confused with basic heart rate, which is measured in beats per minute. Heart rate variability differs by measuring the actual time difference between heartbeats.

So on an electrocardiogram we R-to-R (R-R) intervals and from breathing patterns there is variance between successive R-R intervals. And what heart rate variability is doing is capturing those changes between those heartbeats.

So it is a little bit more specific of a measurement but it is not dissimilar from basic heart rates, so people shouldn’t get too confused with it.

[Damien Blenkinsopp]: So could you give me a quick overview – what is heart rate variability, HRV, and how do you use it? What is it all about?

[Andrew Flatt]: So your resting heart rate is generally not consistent. We learn in a textbook that a heart beats approximately every 0.8 seconds for an average of 75 beats per minute. What that doesn’t factor in is the actual changes in heart rate, the subtle changes that, in response to respiration, where when you breathe in your heart rate actually speeds in a little bit and when you breathe out your heart rate will slow down. And that is normal.

That is called respiratory sinus arrhythmia. And essentially what heart rate variability is capturing is those subtle changes in heart rate in response to respiration. So heart rate in beats per minute is kind of giving you that average of how many beats there were, whereas the variability is telling you how much variation there was between the beats.

Now, there are various statistical procedures and so forth that we can assess variability. There is a standard deviation, there is the Rubian square, there are spectral analyses. So there are various parameters for heart rate variability but in a nutshell it is just measuring the variance and changes between the time interval between heartbeats.

[Damien Blenkinsopp]: Right, and you brought up a little bit of terminology there – it is R-R intervals, which is basically R means the top of the beat, the kind of spike of the beat that you kind of see on the electrocardiogram, so R-R just means the time in between beats, correct?

[Andrew Flatt]: Right, because they are such high peaks it is really easy to measure the interval between them so that is generally why the R-R intervals have been used.

[Damien Blenkinsopp]: Right, and just out of interest, why is it called an R? Why isn’t it called a beat?

[Andrew Flatt]: The peaks are just alphabetically named. There is the P, QRS complex, the T-wave, so – we just –

[Damien Blenkinsopp]: And the peak just happens to be the R, good. So I know that you have been using HRV in a bunch of areas to basically make better decisions, mostly about training. Could you talk about the different scenarios you have been looking at it with and where you find it most useful?

[Andrew Flatt]: Well, I think it just comes down to why I started measuring heart rate variability. I first learned about it just reading on some strength and condition forums, a website called [lead ips .com 00:03:22]. And there were some strength coaches talking about how they are using it with their athletes, so I kind of gained interest in it then.

But it wasn’t until I was preparing for a powerlifting competition and training was going really well. I was pushing it real hard and I was set to set some personal record at a lighter body weight when all of a sudden, I took a dive and I actually got a little bit of a cold. I took a few days off from it and I went back and hit the weights and things were just feeling real heavy.

And it was too close to competition for me to really fix things and I actually ended up pulling out of the meet and I was really disappointed. And I thought to myself there has got to be some kind of way that I can better manage my training and maybe kind of prevent this or see it coming a little bit better.

So that was kind of the motivation to actually purchase a heart rate variability device and start using it. So my original motivation was to guide my own training. I am involved in powerlifting so it was kind of a selfish motivation more so than working with athletes, but eventually that is kind of where it came to, where I would actually start using it with athletes.

I was training friends and colleagues and I would get them using it and look at their data. And that is kind of how things went from there.

[Damien Blenkinsopp]: So you obviously found it very useful, to have gone into an insight using this with other people now. So what kind of decisions do you make based on this? Is this is the only indicator you use? Is it the main indicator you use with your training program and deciding when to change up the variables?

[Andrew Flatt]: You know, when I first started using the device I was very skeptical at first. I didn’t know much about it other than what I read on the forms and what I actually did was for six months I used it and collected data, but I did not use it for any kind of decision making.

In fact, I really didn’t look at the trends or analyze anything until after about six months when I would kind of look at the trend and I would look at my training log and I would try to see what it was telling me in the first place. I think one of the biggest mistakes is people get a device and they think they know how to use it and then they want to start making decisions with it.

I think you almost want to do some kind of cross validation with it on yourself first and see what it is telling you in response to training or in response to different kind of life events – you get sick, you travel – what is it showing you? Is it meaningful? Can that drive better decision making?

And essentially, what I found was after six months of using it I would look back on it and after heavy training sessions I would see a decrease in my HRV score. Most noticeably I would see, after any kind of a new training stimulus, so being involved in powerlifting I wasn’t doing a whole lot of conditioning work but at the time I was doing my Masters, I was working with a whole bunch of other people.

In the weight room I was a grad assistant strength coach and they love to do conditioning on Wednesdays. So on Wednesday morning, we would go and run these stairs, and man, it was tough for me – being a power lifter and not running since I played football years before. And my HRV scores would just absolutely plummet after these sessions.

But after a few weeks I would notice smaller and smaller fluctuations in my scores and I was kind of reflecting the progressive adaptation for that training stimulus, and I thought that was kind of cool.

[Damien Blenkinsopp]: Right, so what kind of impacts do you see? So, once your score has plummeted, what does that mean the next day? Say you start the day and you track your HRV and your score has plummeted, what does that mean in terms of how you are going to be feeling? What does that mean in terms of how it is going to change the decisions you make that day?

[Andrew Flatt]: A low score can definitely be the result of a heavy training session. Unfortunately it is not that simple. One of the great things about HRV is also one of its downfalls, that it is a global marker of stressors, whether that is physical, mental, or chemical. So not always will you see a low score because of training, it can be brought on by other things. So you really need to be tracking other variables to really make a meaningful interpretation of what the data is telling you.

[Damien Blenkinsopp]: Right, so in the context of your training program, if nothing else changes it is kind of like that it then should be down to your training?

[Andrew Flatt]: Right, so I think one of the main things is are you an aerobic athlete? Are you an anaerobic athlete? Are you a team sport athlete? It depends on your training because what heart rate variability is, is it is a reflection of the cardiovascular autonomous nervous system. So for the most part, and especially within the research, it has predominantly been used with aerobic athletes and that is kind of who would most benefit from it.

I mean, resistance-training athletes, at this point it is all experimental to see what it is we are actually showing but it doesn’t necessarily reflect muscle soreness. It doesn’t necessarily reflect muscle damage or your neuromuscular abilities for that day, your CNS potential. It is a reflection of the cardiovascular autonomic nervous system, which is still a very important piece physiologically for being prepared for training.

So it is only one marker to consider the cardiovascular system is extremely important with the recovery process, with removing waste products, and so forth. So when the cardiovascular autonomic nervous system has kind of rebounded back to baseline levels or super-compensated to above, that would indicate that system is ready to go and it is more likely to be in a more adaptive state to any kind of physical stress.

[Damien Blenkinsopp]: Right, so you have mentioned that it is the autonomic nervous system and another thing that we often hear is that it is an indicator of vagal tone. What does that mean?

[Andrew Flatt]: So the autonomic nervous system, simply put, is divided into two branches – you have your sympathetic branch and your parasympathetic branch. The term ‘vagal’ is referring to the vagus nerve, which is essentially the parasympathetic branch of the autonomic nervous system.

You have parasympathetic innervation in the heart that essentially – in any kind of physiology class your professor will give you the car analogy, where if your foot is on the brake the car is not moving, and that is your rest and response. And the autonomic nervous system is taking care of all the things that we don’t consciously control – so our blood pressure, digestion, endocrine gland secretion, and so forth. And then when you take that foot off the brake you have that withdrawal of parasympathetic or vagal activity.

Then when you hit the accelerator all of a sudden you get that sympathetic output and that is going to actually increase heart rate and prepare you for any kind of stressful events, whether it is exercise or simple postural change from lying down to standing up. You have to pump blood to the brain so you don’t pass out and that is a sympathetic response.

[Damien Blenkinsopp]: Right, and another way I have heard it described it is that basically your parasympathetic is trying to balance your system so that the vagal tone is the ability for you to balance and respond to stressors around you. Is that another way you look at it, or is that not correct?

[Andrew Flatt]: Yeah, so essentially the sympathetic nervous system will be quite active during physical stress like exercise and then to recover from that is when your parasympathetic nervous system will help rebuild structures and repair the damage essentially that occurs during those stressful events.

So that is why measuring your parasympathetic activity on a day-to-day basis is a reasonably good indicator of your recovery status. If your body is still stressed from training and you have a higher sympathetic output or even just parasympathetic withdrawal, you know that your system may not be fully recovered.

Now, what I want to be clear is that it doesn’t mean that you can’t train if your HRV is a little bit low. And a lot of these apps, what I think people need to understand, is only measuring parasympathetic activity through a timed domain measured called RMSSD. So that does not give you any indication of sympathetic activity. It is purely vagally-mediated, so parasympathetic.

[Damien Blenkinsopp]: So just a couple of other terms that you hear quite a lot is LF, low frequency, and HF, high frequency. As I understand it they often say LF is the sympathetic stressor and HF is the parasympathetic relaxation. Is that true or is it more complex? Some of the apps track the LF and the HF as well, but some of them don’t.

[Andrew Flatt]: So the way you are talking about it, they are called spectral measures from frequency domain analysis. HF generally does indicated parasympathetic activity. LF actually would be indicative of both parasympathetic and sympathetic activity. So it is not as clear as we would like it to be, where HF is parasympathetic and LF is sympathetic and it gives you an indication of sympathovagal balance, they call it.

It isn’t that clear and one of the issues with the spectral measures that you are referring to is that in terms of their practicality and field settings, they require longer measurement durations for a valid assessment. These are less reliable markers on a day-to-day basis so it has kind of been recommended that RMSSD is the preferred parameter, especially for convenience and non-expert users in the field that just need a simple number that they can read and interpret real easily. The RMSSD value is preferred for that.

[Damien Blenkinsopp]: So is RMSSD the one that has the most research behind it?

[Andrew Flatt]: Well with RMSSD, the reason why it is preferred is that it is a more reliable marker. It is very easy to calculate. If you have R-R intervals you can actually calculate RMSSD in Excel – it’s a statistical measure, root mean square of successive R-R interval differences, that is what it stands for. It is consistent in paced or non-paced reading situations, where as HF and LF are going to be a lot more influenced by your breathing rate.

So, for in the field with athletes who may not be sticking to a certain respiratory rate or whatever, it is not going to affect your numbers as much. And lastly, I kind of got to it before, is it can be calculated in a relatively short time frame. In fact, you can get an RMSSD measure in ten seconds; however, that generally isn’t enough R-R intervals to capture a real window of that autonomic activity.

So actually part of our research was seeing what is the shortest timeframe we can measure HRV in with RMSSD and what we did was we found 60 seconds to be no different than a criterion measure, which has been established as five minutes. So we essentially randomly selected 60-second segments within a five-minute ECG and we found no differences. But when we looked at 30 seconds and 10 seconds there was less agreement with the five-minute measure. So our conclusions were that 60 seconds was probably enough time to get a valid HRV reading with RMSSD.

[Damien Blenkinsopp]: That’s great, that’s very short. A lot of the apps, you said, do a lot of the standard – I think it just comes from the research, which is five minutes for a recording. But a lot of the apps now are looking at like three minutes or something like that. What kind of variance do you see across the apps? Have you seen any apps that go as low as 60 seconds, making it a lot more convenient?

[Andrew Flatt]: Yeah, there are some apps – ithlete, for example, is an app that uses a 55-second test. There is another app call HRV4Training that uses – it actually allows you to select your test duration so there is a 60-second option. I believe there is a two-minute option, a three-minute option. And then I think there is a device called Tink that I believe is a 40 or 45-second test. I used that briefly. And the other apps tend to use a little bit longer.

Now, the longer measurement is certainly not a bad thing to get a bigger sample of R-R intervals for analysis. The issue comes down to is the athlete or the client – are you willing to do that every day? If it is two or three minutes, that can be a little bit long. Fifty-five seconds or one minute, that is generally not too bad. I find it more tolerable with the athletes I have used it with. Generally they can handle it, so it call comes down to preference, right?

[Damien Blenkinsopp]: Yeah, totally. So we talked a little bit about the apps. So I would like to dive into that because I know there are quite a few out there and there are a lot of them coming into the market now and HRV is just starting to become pretty popular. So basically you are going to have a device for tracking your heart rate and you are going to have an app to go with it. Which ones have you looked at and what are the tradeoffs and benefits of each? Have you got preferences and so on?

[Andrew Flatt]: So I first started out with the ithlete app. That was the one I read on the forums that people were talking about. In fact, I think it was the only one available at the time.

[Damien Blenkinsopp]: So when was this, by the way?

[Andrew Flatt]: This was 2011, early. I think around summer 2011 is when I actually bought it. So that specific device at the time required a heart rate strap and a little ECG transmitter/receiver device that you would actually plug into the headphone jack of your mobile phone. And again, it was a 55-second test and I have stuck with that device.

There are a few reasons why I have stuck with it, one being that it uses such short measurement duration. And especially now that I have looked at the data, I am quite confident that short of a duration is still going to give acceptable measures or more valid data. So I have stuck with that but I have used others. I have done some beta testing for some people and looked at some other apps. And at the end of the day you just want one that you are going to be able to use and that provides your data that is easy to interpret, nice visual trends, health, or whatever is more affordable for you.

There have been some advancements in technology that allow you to measure HRV without an ECG receiver. Now you can just use a Bluetooth heart rate strap with some of these devices. There was recently validated, a pulse wave finger sensor that ithlete is using that you can literally without any kind of heart rate strap you just plug your finger into this little finger sensor device that is plugged into the headphone jack and you can actually get your heart rate reading from the pulse at your fingertip.

[Damien Blenkinsopp]: How accurate do you think that is? Because I used one of those for something called Heart Math, which is using HRV but in a different area and that uses your ear. So it is collecting your pulse from your ear. But I find that every time I move in any little way that it is messing with the signal and it is not very clear. So do you find the finger sensor? Because it is using light, right? So it is pulsing light in to see what your heart rate is. Do you find that reliable?

[Andrew Flatt]: I think we have about 15 athletes where we looked at the pulse wave finger sensor and compared it to EKG. They were soccer players, male and female. We did supine and standing positions. And it was accurate. It was more accurate in the supine position but acceptable agreement also in the standing position. So we haven’t published that yet. We want to collect more data on it. But I am pretty confident in it based on the data that I have collected with it.

Now the pulse wave finger sensor device, that is not putting your finger over the camera lens – where the flash goes. That is not what we measure, just to be clear.

[Damien Blenkinsopp]: So if someone is getting one of these apps, what would be your suggestion? So all of them are using RMSSD, I’m assuming. I know the one I am using, Sweetwater HRV plus a Polar H7 strap, so the heart rate with the Bluetooth that you mentioned earlier for an iPhone 5. So that works fine for me and that was relatively cheap to get off and running with. So I know that Sweetwater, for example, they take RMSSD and they modify it a little bit. They put it on this 1-100 index. Do the other apps modify this? Are there compatibility problems later if you want to switch apps and you can’t compare your score?

[Andrew Flatt]: So Sweetwater, or the SweetBeat app, I have actually experimented with and that, from when I used it, was providing various HRV parameters. It was giving you the HF, the LF, RMSSD, SDNN – numerous parameters of HRV, which is great if you know what those mean and how to interpret them. But I generally tell people to look at the RMSSD.

I know when ithlete started using a modified RMSSD value what they essentially did was they logged transformed RMSSD and multiplied it by 20, and that gives you a figure on a 100-point scale. BioForce uses that value. I wasn’t aware that Sweetwater or that the SweetBeat device did or not. I thought it was a raw RMSSD value, but I could be wrong.

[Damien Blenkinsopp]: I actually spoke to them one time, so it is definitely a modified scale version of it.

[Andrew Flatt]: Okay, so then they probably use that value or something very similar. Now, not all apps use that value. For example, Omegawave has a smartphone app and they are using their own algorithm to come up with a daily readiness score, so they are factoring in HF, LF, the HF-LF ratio, RMSSD, so it is not one parameter that they use. So there is difference among the apps and what they interpret. So it is something you would probably want to look into.

[Damien Blenkinsopp]: Right, and you probably don’t want to switch around too much once you have settled on one.

[Andrew Flatt]: Right, you find an app that you like. What is most important for the end user is I think the visualization of the data and how they can view it so they can see what their kind is like, how it is responding to their training. One of the things I really appreciate about the ithlete app is that it allows you to input your training load score, so depending on what kind of training you are doing or how you choose to quantify your training load you have your RPE values and you can calculate tonnage for weightlifting or powerlifting.

You can do a trim value for endurance athletes or what have you. So you can input a training load value and then it also gives you the ability to track your cyclometrics, you perceived level of stress, sleep quality, muscle soreness, mood, your nutrition. There is a sliding scale for that you can kind of rate. So all of a sudden you have a device that isn’t just tracking your HRV but it is kind of monitoring several variables which really makes interpretation of your HRV trend more meaningful. I know BioForce has an online system where you can go on, input your data similar to the ithlete one.

I am not sure if you can do that from the app or not at this point but it is a very similar system. So that is another great product to look into. So when you are evaluating what app you want to use, you want to look at what additional features it has to offer because an HRV score by itself is less meaningful without all this other information. So the more information you have and that you can maybe attribute your changes and your trend to, the better off you are going to be.

[Damien Blenkinsopp]: Right, I know for me there have been a few times where there has been a huge crash and I have been wondering what happened. I didn’t have a big training session or anything yesterday, so it is definitely like this little investigation sometimes – why did my HRV crash? I know you have got some interesting stories about times that you have seen athletes or your own scores crash. What kind of things have you seen the influence where it crashes? Have there been any times where you really didn’t find any reason for it?

[Andrew Flatt]: I mean, if we are talking a substantial decrease in your score, usually it is pretty easy to attribute it to something. Sometimes it is these smaller deflections where you are like, you know, I am kind of surprised it is that low today. That may be harder to attribute to something specifically. But if you wake up with fever, you are going to have some real low scores and your heart rate is going to be high and you are going to have some low scores.

One of my coolest little anecdotes that I have with using an HRV app is when I got real sick a couple years ago over March break and HRV I was able to use to guide my training to where I could kind of start pushing it hard again and kind of get back to my normal routine.

For a week I had terrible symptoms. I had fever, I wasn’t able to train. My scores were really low. Once my symptoms kind of subsided and I wanted to get back into training, what I was seeing was from very moderate workouts, very low-intensity, something I would consider like a D-load type of workout, these were causing pretty substantial decreases in my HRV so I could see that my body was reacting to the training. But it was quite stressful, according to those scores.

So I would actually continue to train relatively light until my scores wouldn’t fluctuate so much and that is when I would actually start pushing harder again and I could see in my trend that it wasn’t as stressful. I wasn’t seeing as big of swings in my scores and I was kind of able to guide myself out of that situation where typically a meathead like me, I will just start pushing the weight as hard as I can as soon as I feel ready, which may not have necessarily been the best thing to do at that time.

[Damien Blenkinsopp]: Right, totally. I have been in similar situations myself. I know I had a score of 80 just recently and it crashed to about 50. I don’t know if that something you see often?

[Andrew Flatt]: Yeah, that’s a big drop. Were you able to attribute that to anything?

[Damien Blenkinsopp]: Yeah, I have been suffering from a chronic illness and it has something to do with that, so it is pretty serious. It is a pretty serious thing, it is not a typical thing. So in terms of someone a bit more normal, who is not dealing with medical issues or anything, what would a typical rash look like? Is it 20 points?

[Andrew Flatt]: Everyone is individual and unique. Every individual’s data needs to be taken in the context of what kind of training they are doing, how advanced they are, how trained they are. A more advanced endurance athlete, for example, will see smaller swings more than likely. They will recover faster.

You take an untrained individual and you put them through an intense workout, whether it is weights or conditioning, and they are going to see a big drop. That can last for 48 to maybe 72 hours. So every situation is unique and every individual really needs to take some time to collect some data and observe how their trend is evolving in response to their training because unfortunately you can’t just say that this means that for everyone, because that is just not the case.

And you really do have to maybe do some calculations with your data in Excel, looking at the weekly mean value. You look at the variance within that week and all that kind of analysis will give you a better indication of how you are responding to your training.

[Damien Blenkinsopp]: So of course, a lot of the other things that athletes look into when they are training are all sorts of lifestyle factors that could be affecting their recovery and how they are performing. I know that you have had many experiences with this and in one post you talked about travel and in another you talked about going home for was it Christmas or Thanksgiving? And seeing some stuff there.

What kind of situations have you seen – like another guy who went on Spring Break and he was partying a bit? What situations have you seen that could be said to be obvious, but what kind of things would you say to look at? Just typical things that you have seen affect it.

[Andrew Flatt]: Yeah, so your lifestyle absolutely will affect your HRV responses. For example, working with a soccer team, we put them through a hard week of training and we see pretty typical HRV responses and then half of them go out on Saturday night partying, maybe having a couple of drinks, I don’t know. And the other half maybe stays at home, gets to bed at a reasonable hour, and you can definitely kind of predict who was out that night based on that.

Now, you definitely would need to do a little bit more investigation. You can’t just look at a score and say, ‘This person did this.’ But it does give you some kind of indication that maybe you have to look into what is going on. Was it the night before a game? How are your athletes behaving?

Not necessarily a tool to spy on anyone or anything, but it kind of will lead to some questions. Why isn’t this person recovering? Why are their scores low? Are they getting sick? Are they staying up too late? Are they not getting enough sleep? Sleep is definitely one factor that will affect your score. Alcohol – if you are out drinking you are definitely going to see some lower scores the next day.

Like I said before, with illness your scores will definitely drop from that. In my experience any time I have gotten a cold or especially a fever, the score has dropped. Now you were referring to some of my older posts where I talk about I actually went home to visit some family that I get to see maybe once or twice a year. And I actually had really high scores the next day. Is that the reason why they were high? I don’t know, that is just speculation.

But anything that you perceive to be very restful, whether that is sauna, you get a book and read outside, get some sun – something that you perceive to be restful and relaxation is generally going to promote some of that parasympathetic activity and that restoration that we want to get. So I think it depends on the individual and their own personality for what they perceive to be regenerating and relaxing.

[Damien Blenkinsopp]: Well certainly sometimes I will take a specific day off and say okay, I am going to recover this day because I need to because my HRV is down. And it definitely pushes the score up, I have seen that many times. So like you say, the relaxation could be different for different people. But it definitely seems to impact the score if you take a day off and forget the work and all the other stressors. I don’t know if you have seen examples of work stress figure into this?

[Andrew Flatt]: I have seen some studies. I am not as interested in that so I don’t pay too much attention, but there is definitely a stressful lifestyle, whether that is from work, you can have money problems. These are all things that can affect your autonomic nervous system. So it can be apparent in your HRV score. One thing I found is just within the literature but also through trial and error, that some light aerobic work has a stimulatory effect on parasympathetic activity. So some active recovery can really help get people’s scores up.

In fact, just a few weeks ago I was going through kind of a work capacity phase where I was just trying to get in better shape, bring up my aerobic fitness a little bit, so after my resistance training sessions I was doing 10 to 15 minutes on the bike, on off days I was doing 20 minutes on the treadmill or 10 minutes on the treadmill and 10 minutes on the roller, just trying to increase my fitness a little bit. And I have actually never seen anything like it in my trend before.

I wasn’t seeing any really big swings from day to day, even after a heavy resistance training session with five sets of five with 80% plus. Normally that would result in a lower score the next day but it appeared that these smaller aerobic sessions really attenuated those swings day to day so I was seeing very little variance between my scores for that two-week period, but then as soon as I stopped keeping up with that it went back to my old-fashioned hard workout and you see a lower score and it takes a day or two to come back up.

So it is interesting how much of an effect just light aerobic exercise has on stimulating that parasympathetic activity. There is definitely a threshold where too much or too intense and it will have the opposite effect, but a reasonably late session for not too long generally has a stimulatory effect and you will see a bump in your HRV 24 hours later or so.

[Damien Blenkinsopp]: So are you saying that is something that is going to help people? Or is this just modulating the HRV but it is not going to impact your actual recovery? So it is just modifying the number but it is kind of hiding the fact that your HRV would have gone down?

[Andrew Flatt]: Well, I think again it comes back down to what your training goals are. Now after a heavy squat session and I do some cardio, some light aerobic work after, and I don’t see a drop in my HRV, that doesn’t mean I am going to be able to go squat heavy again necessarily. It is just saying that my cardiovascular autonomic nervous system has rebounded back to baseline level, so that system may be ready to go again. So again it comes down to context.

If you are more of an endurance athlete it would probably be more of a marker of when you are ready to train again, but with resistance training there is muscular damage. That isn’t necessarily reflected in your HRV. There is just not enough data yet to show that an HRV score is related to any kind of nervous system potential for strength scores or power or anything like that.

[Damien Blenkinsopp]: That is interesting because one of the things you mentioned was that when you are doing something new, some kind of new activity, some type of new training, that you see your score crash down in particular in those situations. Is that – do you think it is because of neuromuscular or metabolic adaptation that has to take place there? What do you think that is down to?

[Andrew Flatt]: Probably a combination of everything. You have introduced a novel stimulus that your body hasn’t necessarily adapted to yet or in a long time so it is just harder to recover from. I don’t have the answer for that. It hasn’t really been, at least I haven’t seen anything to explain why – that is just how it is. A novel stimulus, whether it is conditioning, resistance training – if you do a drastic change in your volume or intensity, from what I have seen it is going to cause a lower score than typical. But with persistence and that new training modality or those methods you will see that progressive adaptation and you will see smaller swings after the body kind of adapts. It gets more familiar with it. There is probably a better scientific explanation, I just don’t have it for you right now.

[Damien Blenkinsopp]: Great, so I want to talk about recording – how you record it, what kind of numbers you want to make sure you get, frequency, and so on. But just before that, how about baseline? Can you increase your baseline over time? Or are we just looking kind of like at the dips and the highs and trying to keep it in the highs more and slacking off when we have more of the dips? Or are we able to actually influence this and in a way build more resilience over time?

[Andrew Flatt]: Your lifestyle is going to change, your training is going to change, your training frequency. If you are a competitive athlete that you have different seasons, different times, that is all going to affect your HRV because your training is going to change. You are not going to always be doing the same type of training. You might be doing less aerobic work in a different phase and that aerobic work is really what stimulates those higher HRV scores.

So if you are doing less aerobic work you are going to see lower scores. So you do have to take whatever your baseline is – you have to take it into context for that training phase and your new training goal, so you absolutely have to have an evolving baseline. A lot of the apps will use a rolling 7-day average but generally at the start of a phase you look at your first week, you look at the average, you look at the variance within that week.

A simple value to use is called the coefficient of variation. It is just the standard deviation divided by the mean times 100, and that gives you a percent value of the variance, and see how it evolves from there.

[Damien Blenkinsopp]: So what do you use the COV for?

[Andrew Flatt]: So the Coefficient of Variation is where you have a weekly mean value, which is just the average of a 7-day period. That average doesn’t necessarily indicate or reflect how much fluctuation existed between those scores on a day-to-day basis, right?

So we want some kind of value or figure similar to a standard deviation of how much variance there was because let’s just say your average between two weeks is no different, but you have much more fluctuation in one week than the other – well, that could be indicative of some positive adaptation or I have a case study that we did with a cross country endurance athlete that should be published in one of the next editions of Australian Strength and Conditioning.

We actually found that his CV value, the coefficient of variation, was much more related to his endurance performance than his weekly mean value. And we get into possible explanations of why in the paper but the variance is important.

[Damien Blenkinsopp]: So you want less variance, which means that your system is dealing with the different stressors and it changes more easily?

[Andrew Flatt]: I don’t think – I think it is a matter of maybe when you want that. If you are seeing big fluctuations in your scores that is not a bad thing. That is your body adapting and adjusting to the training. But that probably means that you are not in the best state to compete at your best or to perform at your best because your body is adapting and it is going through the stress and recovery phases.

But all of a sudden you have been doing that training for a while and you see less fluctuation in your scores and there is maybe less – it is not the same amount of stress as your body initially perceived it as and had you recover from. You may be in a situation where your performance – you may be at a higher level of performance.

[Damien Blenkinsopp]: Yeah, it sounds like COV low variance could mean that you have adapted to whatever stimulus you are giving yourself, and that could be lifestyle or it could be training. And in another situation if it is pretty high it could mean that something different is going on and your body is adapting to it.

If it has got high variance it could be a good thing if you are going through these training sessions. It is showing that your body is going through that adaptation, does that makes sense?

[Andrew Flatt]: Absolutely. And one thing I need to point out is I started using the COV value after reading a case study by Daniel Plews and Martin Buchheit and all those guys that are the experts in this area. And what they found with the CV was in an overtrained, high-level endurance athlete I believe the CV was related with the progression of overtraining.

So when you are looking at any kind of value, whether it is the mean or the CV, you really need to look at the training load. You need to look at their perceived levels of fatigue and stress to really give more meaning to that value. So again, a high HRV score or an increasing trend can also be indicative of overtraining and mostly in endurance athletes. So you kind of have to look at these other factors.

The HRV scores alone aren’t going to tell you much without all this other information. So the CV, whether it is good or bad or whether we want it or not depends entirely on the context of that training and what is going on with the athlete and how far we are from competition, so there is no such thing as we want this, maybe in certain phases we want this, but it is all relative to the individual and to the training, so everything needs to be factored in.

[Damien Blenkinsopp]: If you take two athletes or perhaps an athlete and a non-athlete and you compare their HRVs, their 7-day average right and getting their baseline, are they going to be different? Is the athlete’s going to be higher? Is that something like going back to your baseline, is that something you want to be higher or you should be trying to get higher over time. Is it possible?

[Andrew Flatt]: I mean, the average person, just for the cardio-protective benefits of having a higher parasympathetic activity at rest definitely generally higher HRV is a good thing. If you take a team of athletes and you have them monitor their HRV, you are going to get different scores and a group of female soccer players that I work with over this past season, their average scores range from the low-70s up to a couple of girls that were pushing 100.

There is a genetic factor here. There is lifestyle, there is fitness. All these things come into play and you can maybe generalize that an endurance athlete who has a very low resting heart rate is going to have higher HRV, which can be in the 90s plus anaerobic athletes can be between the 70s and high 80s, depending on their fitness level.

So you could maybe say that this would be where the average would be for this type of athlete, but in my experience everyone has kind of have their own trend and their own response to training – similar responses in terms of the fluctuations in following a heavy training day and whatnot. But you are not going to get a team of soccer players with everyone’s score at 90 with similar changes, everyone is different. And you should plan accordingly for that.

[Damien Blenkinsopp]: Right, so for someone in the 60s, is that okay? Or someone in their 50s?

[Andrew Flatt]: Well, I mean I would ask if that is being measured in a supine, lying down position or if that is a standing value, because that obviously will make a difference.

[Damien Blenkinsopp]: Let’s get into that then, because I know you take both readings, correct?

[Andrew Flatt]: Well, I have experimented with both. I have been sticking with standing – I had been doing it standing since day one but I did an experiment for a little bit and actually at different time points I experimented with supine readings as well. So you want to get into –

[Damien Blenkinsopp]: So I mean, supine just for the guys listening – that just means you are lying down? So you are taking readings when you are still in both situations, right?

[Andrew Flatt]: Correct.

[Damien Blenkinsopp]: So we are getting into sort of recording methodology here. How do we go about actually taking these readings and when would you do it to get reasonable results? I take it, for instance, every morning when I wake up and I will take the lying down one and then I will stand up and take that. I have to let it rest for a little while, so I will stand up for about a minute and then I will take the reading.

So you can tell me if that is like correct or not. I seem to get relatively stable readings. How would you go about it now? What kind of things have you discovered that are good and bad and help to get and what kind of things do you need to avoid?

[Andrew Flatt]: Well, it’s interesting. The general guidelines are a supine measurement where you record the last five minutes of a ten-minute segment, so you essentially have what I often call a stabilization period where you let your heart rate adjust to that position.

So that is generally a five-minute period followed by a five-minute recording. You know, with the research that I have been doing at Auburn University with Dr. Michael Esko is trying to investigate shorter, more convenient HRV recording procedures because one, we want to do research with these smartphone apps but we weren’t entirely sure if we were going to be able to publish anything without any kind of validated shorter measurement procedures that we could say, ‘You know what? We did a shorter measurement recording. We had a shorter stabilization period.

But that is not necessarily a problem because it is not really showing any differences to these accepted standard measurement procedures. So as I kind of mentioned before we found that 60 seconds was a suitable duration for an RMSSD measurement. We have a new paper that is currently in review where we looked at how long does this stabilization period need to be, at least in a supine position?

So we looked at a standard measurement – five minutes following a five-minute stabilization period. And we just looked at if each individual minute – you know, minute one, minute two, three, four, and five – were those values any different to the five to ten-minute segment? I am not able to reveal the results but I am pretty confident that we can get away with a shorter stabilization period, much shorter than what is traditionally recommended. And we are just looking at capturing a resting measure and we are not using this for clinical diagnosis or anything like that, right?

So in healthy populations in athletes where we just kind of want to get a general indication of their heart rate variability that day and we don’t need a whole ten-minute procedure.

[Damien Blenkinsopp]: So what is the statistical variance we are talking about between yours and the five-minute one? Is that 5% difference?

[Andrew Flatt]: Are we talking about the stabilization or the 60 seconds?

[Damien Blenkinsopp]: Yeah, if you do your shorter version. Which is one minute and one minute?

[Andrew Flatt]: Let’s just say that you use a one-minute stabilization period and then a one-minute test. I mean, you are trying to get me to get into the results, which I shouldn’t do until it gets published.

[Damien Blenkinsopp]: Just a rough idea. You said it is okay, right? Don’t give me a statistic yet.

[Andrew Flatt]: Let me putting it this way, it would be trivial. That’s the term we use with that statistic called the effect size, which is telling us how practically meaningful the difference is. The shorter stabilization period as opposed to the traditional one, you would probably see trivial differences.

I could tell you within the literature a five-minute HRV recording has been used following only a one-minute stabilization period and that has been used in elite endurance athletes and the data was still providing very meaningful information pertaining to training status so again, a shorter stabilization period of one minute has been used so I would say to go ahead and use the one-minute stabilization period.

[Damien Blenkinsopp]: So it sounds like it is reasonable to do a one-minute stabilization and a one-minute – depending on the app they do different times or automatically of course, but you think that would be okay for some guys at home who want to use this for training and so on?

[Andrew Flatt]: I mean absolutely. With the athletes I work with and with myself and then with the data that we collected and looked at, the one minute is not very different from the five-minute value. So yeah, I am quite confident in that shorter measurement with RMSSD, specifically.

[Damien Blenkinsopp]: Great, so what other things – are you still taking the lying down, the supine, and the standing – and the one we have just spoken about, the one minute, one minute, is that just fine for both of them?

[Andrew Flatt]: Yeah, after a postural change what happens is in the supine position your heart doesn’t need to work as hard to pump blood to the brain. Then you stand up all of a sudden you have receptors that are going to detect changes in blood pressure and this happens real quickly, but essentially your heart rate is going to shoot up real high immediately following a postural change.

And then it actually takes longer than a minute to actually stabilize, but in the research one minute following that postural change is when they will start recording HRV in the standing position. Going back to why I like the standing measurement, it is simply because what’s happening is you are introducing a small stressor to the body that it needs adapt to. It is called orthostatic stress, when you stand and put that little challenge on the heart where it has to react to the postural change and then you essentially are evaluating how your heart is responding to that.

If your heart rate variability is very low after you have given your heart rate time to stabilize, that may be a better indication of how your body is going to respond to physical stress that day. That is kind of a working theory. And that is nothing new. I am not sure if you are familiar with what is called the Rusko test, where you start by measuring the heart rate lying down and then you measure it following a postural change at different times, and you are trying to see what the changes are between those. So it is not a new concept and certainly nothing that I can take any kind of credit for.

But I did experiment with taking supine and standing measures and seeing how it related to my previous day training. This kind of unequalled one experiment – I have always found that the standing position provided a better reflection of my perceived level of recovery with yesterday’s training. That is not a very scientific method and I didn’t take any blood markers or anything like that but just from visualizing the trend I see that the standing position looks how it should, based on how it is feeling and what training was like the previous day. So I have pretty much stuck with that.

[Damien Blenkinsopp]: Okay, so now do you use just the standing or do you use both?

[Andrew Flatt]: Yeah, my preferred position is seated or standing. I do standing just because it is practical. You wake up, you go pee, you are already standing. I use the finger sensor now, so I plug in the finger sensor and I do my measurement right there in the bathroom. It is just easy.

The seated position would also be similar to provided that. You are obviously going to have to sit up and there is going to be that little orthostatic, that seated up, more vertical position challenge. So the seated position is probably – I wouldn’t think it would provide significantly different in terms of at least the trend. The number value might be different but the trend would probably be the same.

[Damien Blenkinsopp]: Do you see more variance and slightly lower numbers for standing versus supine, or lying down?

[Andrew Flatt]: Absolutely. The supine values are going to be much higher. I have data on the soccer team I have been working with. I had them do supine and standing measures because that is a question I have always been very interested in – what is the better position?

Some preliminary analysis on the data – I think what we’re seeing is that without getting too much into the results I think supine and standing may be potentially indicating some different information where supine may be related a little bit more to fitness and standing may be more related to the acute changes in response to previous day’s training.

Again, that is very preliminary and we have still got a lot of analysis to do but from that data that is kind of what I am seeing. From my personal experience –

[Damien Blenkinsopp]: So what you are saying is that lying down is kind of like your baseline and standing is what has been going on the last week in terms of what you have been up to and exposed to in terms of stressors?

[Andrew Flatt]: Possibly. It is hard to draw any kind of conclusion. But in the supine position in very fit athletes there have been issues of parasympathetic saturation, but all of a sudden you sit up or you stand up and you kind of eliminate that issue. So I know in a recent paper by Stanley Peak and Martin Buchheit where it was in sports medicine and they reviewed the literature on parasympathetic reactivation after exercise. And one of their recommendations was to measure in a seated position.

I would definitely recommend anyone, especially exceptionally fit athletes – any endurance athletes or some really fit athletes like soccer players, rugby, or what have you – with really low resting heart rates. I would definitely do either a seated or a standing position. For less fit individuals with higher resting heart rates, the supine position may be fine. That is a gut instinct and I don’t necessarily have the kind of data to support that. So take that how you want to.

[Damien Blenkinsopp]: Okay, a few of the other things – just to make sure there are no other confounding variables coming in here – do you have to make sure this is at the same time of day, or is that irrelevant?

[Andrew Flatt]: Actually yes, I meant to get into some of this stuff. You definitely want to be consistent with your measurement procedures. One of the best recommendations is you have to remain as motionless as possible. It is funny, you collect ECG data on a bunch of athletes and you are reviewing it and you see some funny things and you are like, ‘Man, what were they doing in there?’ And one athlete had a bit of a cold at the time and we could see her sneezes in R-R interval trend.

On the tachygram we could see when she sneezed. We could see when athletes moved positions or adjusted their position. This all is going to affect your heart rate. I looked at an ECG trend when the investigator walks into the ECG room, or the lab, and just that startles the subject or it might not startle them but it does provoke a heart rate response and all that can affect your heart rate variability information.

So you want to be as undisturbed as possible. You want to limit any kind of noises. You want to limit anything that can be distracting. You obviously don’t want to necessarily check your emails or messages first thing before you do it because that creates an anxiety based on work-related issues or anything really.

So you definitely just want to wake up, do your business in the bathroom, empty your bladder, and do your measurement, whether you do it seated or standing or if you choose to go lay down again. Or if you choose to just do your measurement right in bed after you wake up, you know. Consistency is the most important, definitely limiting the noises, like I was saying.

Time of day is a research question that we have and that is something we want to answer. There is definitely going to be circadian rhythm effect so if you do a measurement at 7 a.m. it is definitely going to be different by noon. But is there a difference between a 7 a.m., a 9 a.m., or if you are within a reasonable time?

We have been asked by some professional NFL teams if they can bring their athletes into the workout facility, have them lie down on a training table, and do their HRV then, as long as they control for all the other variables. My assumption is that it is not going to be the same information you are getting from a waking measure, but how different is it and can we still get some meaningful data from that? I don’t know – that is something we definitely want to look into.

[Damien Blenkinsopp]: So the whole thing about doing this first thing in the morning is it manages to eliminate a lot of potential confounding variables like what is going on in your environment, what you have been doing in the morning, anxiety, and all these other things.

[Andrew Flatt]: Yeah, and apart from sleep it is going to be your most rested state, right? So that is the ideal time to do it.

[Damien Blenkinsopp]: So some of these apps also correct for things like arrhythmias, errors, artifacts, ectopic beats, and a bunch of things which are kind of noise. Would some of them, like I know the Polar kind of automatically does that. I am guessing that some of the others do. Does this eliminate these kind of things we are talking about to any extent or not?

[Andrew Flatt]: Yeah, because we did a cross-validation with the ithlete device and we looked into how it goes about interpreting the data. And actually that device particularly has thresholds for R-R intervals where basically the average highest range for an R-R interval versus the lowest range, if you get a series of R-R intervals that kind of exceed that threshold, either above or below it, it is going to correct for it with the adjacent normal cycle.

So a lot of these apps will have built-in irregular beat detection systems. Again, whether it is the R-R interval that is way longer than average or way shorter than average, it will essentially pretty much red flag that as an irregular beat or an artifact or what have you, and correct for it. And that is a limitation of a shorter measurement.

If you are doing a 55-second test and if you experience a couple of ectopic beats, generally within a one-minute period you should be experiencing more than one. But the shorter measurement duration, that is a shorter series of R-R intervals, and there is more room for error in that situation. But like I said there is that irregular beat detection function. When we have compared and I think we had 25 athletes where we compared it to ECG and it was accurate, and that small sample of people didn’t have as many issues.

[Damien Blenkinsopp]: Right, great. So is there anything else in terms of recording that you have to be careful of to make sure the data is useful and current and so on?

[Andrew Flatt]: I think the key is that you want to be able to do this every day and you want to do it consistently for meaningful data analysis and the key is to just make sure you do it and you are consistent in your environment and where you are consistent in your position.

You don’t want to stand one day and do it seated the next day and then supine. If you want to experiment, when you do a measurement save it in your preferred position and just log your other position measurement. You don’t want to save it so that it affects your trend line by any means.

So the key is being consistent in your position, being persistent if you choose to do the paced breathing. Some of these apps provide paced breathing. A lot of them will give you 7.5 breaths per minute, which was kind of the mean breathing frequency of a group of endurance athletes.

That is kind of where that value came from. Just be consistent and don’t do paced breathing one day and then not the other. It shouldn’t have too much of an effect with RMSSD but you do want to be as reliable as possible with your procedures. So either do spontaneous or paced breathing, pick one or the other and stick to it. Stick to the same position.

I am not going to like, I don’t necessarily measure at the same time every day. I mean, my lifestyle changes and I will be able to sleep in on certain days. I might have to be up super early one day and I do it when I wake up. That’s just the way life is, right?

Some people take it pretty seriously and they wake up at the same time every day and that is great. That would probably be more reliable but you have got to be reasonable.

[Damien Blenkinsopp]: Great, so what I do, for example, is I track it every single morning and I am looking for either acute drops, like big changes to take notice of. Otherwise, I am kind of looking mostly at the seven-day average. How do you approach this. Ideally I want my seven-day average to go up over time so that I feel like I am getting somewhere with things. How do you look at it? What is most important? Are you looking mostly at the seven-day average? Are you looking at the day-by-day? What are you using most in your actual decisions?

[Andrew Flatt]: Well, I like to look at everything. I like to see the acute change of what happened between today and yesterday. I do not generally at this point in time use a daily change to be a huge determining factor in my training, specifically because I am more of a resistance-training athlete.

I am involved in powerlifting, so an HRV score isn’t necessarily indicating if I am going to be stronger or anything like that. But I do take a look at it and I see and I always like to compare it to what happened the previous day. What I like to do is look at the weekly average and the variation of the previous seek, just to see how that corresponds to my training plan. If I had a higher-volume week where I was trying to create some fatigue, I would expect to see a lower average and maybe some more variation and go from there.

[Damien Blenkinsopp]: But if you didn’t you might say, ‘Okay, well I have been undertraining and I want to push a little bit harder this week.’ Is that the case?

[Andrew Flatt]: Yeah, I mean you can use that to guide how you may structure your next training cycle. Again, it really does depend on what kind of athlete you are. But for resistance-training purposes, I just do a lot of personal experiments.

I went through a phase where I was using the acute changes to guide my daily training, so rather than taking a – I would work three weeks harder and deload every fourth week. I stopped doing that for a bit where I would just reduce training loads on a day with a low HRV score, should that happen on a training day.

Training like that was fine and I made reasonable progress. I didn’t find that not deloading was an issue. Every fourth week by just taking off a day here and there or reducing loads. That was fine.

The issue is if you really want to make any kind of marked improvements you are going to have to do some overload training. And if you are doing overload training you are going to accumulate some stress. And you are probably going to see a decreasing trend in your HRV and that is generally not a huge issue. You just want to be mindful that you are starting to accumulate some fatigue and how long you want to persist with that. You want to pay attention to soft tissue issues. Are you getting a lot of inflammation? I would get some tendonitis in my elbows and so forth. So you use it as a guide but you take it with other parameters as well, like I was saying before.

Again, an endurance athlete would be a little bit different. I would actually probably use HRV – the acute changes. I would probably use that a little bit more to influence my daily training just because it has been shown that HRV-guided training with endurance athletes, based on your parasympathetic activity, you may be in a more favorable position for training for endurance exercise. So again it all comes down to what kind of athlete you are, what kind of adaptations you are trying to create.

[Damien Blenkinsopp]: Yeah, great. So looking at potential alternative metrics, another thing that people use a lot is resting heart rate. Is that something you would use as well or do you find HRV better? Is it ever worth taking both and looking at them in conjunction or do you think – what have done? Or do you have any experience with that, at resting heart rate?

[Andrew Flatt]: Well I think that resting heart rate is a little bit more crude of a measure. That is – now, although it is a little bit more prudent it can still be very effective. In fact, if you look at your RMSSD trend against your heart rate trend it will generally be a nice inverse relationship between them where they will kind of mirror each other. I personally don’t monitor both. I mean, if you don’t have an HRV device I would definitely do heart rate. I mean, that is something you could do by just measuring your pulse every morning. In my experience I just use the HRV value. What I want to do with the data we collected in the soccer team is see if the heart rate variability provided more meaningful information than basic resting heart rate alone. Do we even need heart rate variability? Even though it can be more specific of a measure, is it necessary? I don’t think that people need to dismiss heart rate and think that it’s not useful because it absolutely is. There has been good data on it and again, your heart rate variability trend with RMSSD isn’t going to be too dissimilar from your resting heart rate trend, it is just kind of inversely mirrored, you know?

[Damien Blenkinsopp]: Actually a couple of things, confounders I forgot to look at but I think are important. Our age and our gender, do they influence?

[Andrew Flatt]: Absolutely. What you will find as individuals approach middle age or they start to get a little bit older there is going to be a natural decrease in parasympathetic activity; however, that can be changed with training. So if you are doing regular aerobic work you can mitigate those decreases and have reasonably high HRV on a regular basis; however, I would assume that would change if you should stop keeping up with that kind of training, but absolutely. Generally what you will see is older individuals will have lower resting heart rate variability. Females tend to have – if you have two sedentary individuals the female will generally tend to have higher – that is not always the case.

In our data we looked at 20 endurance athletes – 10 males, 10 females. Their resting heart rate variability was not statistically significantly different so we measured them and compared them as a group rather than by gender. So if you are endurance trained you are going to have higher heart rate variability generally, whether you are male or female. But when you remove the training factor females will generally have a higher resting heart rate variability versus males – but again, that is not always the case, just generally.

[Damien Blenkinsopp]: I would like to talk a little bit about where this is all potentially going. In the future are we going to be able to do different things with HRV? Because I do know that it is getting more popular and there are more apps and devices coming out. What do you see happening with HRV over the next five years? Do you see it getting more sophisticated? Are a lot more people using it in different areas? What do you see?

[Andrew Flatt]: Well definitely in the clinical setting with regards to cardiac rehab guiding training of individuals who have had cardiac events and so forth, I am not as interested in the clinical side but that is kind of where a lot of this came from and started. So there is going to be a lot more usage of HRV in those situations, especially when we have validated mobile technology where you can acquire a resting score in a reasonably short period of time. I see it growing there.

One way that I see it being included in athlete is with reduced requirement, a lower frequency of measuring. So for example there is a recent paper that showed that less frequent measures of only 3 times per week was suitably reflective of the weekly mean value. So it didn’t necessarily need the seven-day value. You can get away with three when you are looking at the average.

One thing we are looking at with our data in the soccer team is how few days can we measure HRV where the mean value and the coefficient of variation are no different. So if we get more data on that and we start to realize that we don’t need to measure HRV every day if you are looking at the means and the CV. It becomes more practical and they are affordable. It was previously cost-prohibitive to measure HRV. You needed either an ECG or an expensive device. You needed an experienced and qualified technician to operate the device or the machine and then interpret it. Now within two minutes or less you can get an HRV score. An athlete can take it home and figure it out. It is real easy to do interpretation. Again, with the visualization and these other factors it is becoming a lot easier to use. So it is becoming more feasible for people and it is more affordable. So I can see it being definitely more widespread in sports, especially for any endurance athletes or soccer teams that currently aren’t using it. There are definitely plenty. But I think the more evidence that comes the more likely they will be to use it. Even the fact that we can now acquire HRV with a finger sensor makes it a lot more practical for an athlete to wake up and do the measurement.

If you think about it, a one-minute test is not that hard. But you would be surprised how many athletes can’t seem to do it every day. So reducing the measurement requirements to fewer days per week and making it easier to acquire the data, that is just going to increase the usage of it, I believe. It will at least increase the research where we will have more data to see if it is even worthwhile using in a soccer team or in a football team, and whatnot.

There are other areas where HRV is being used in the biofeedback where you are adjusting your heart rate, trying to increase your HRV prior to – there have been studies looking at baseball batting, golfing to see if it affects how accurate they are with their putts and so forth. That is not an area I am involved in by any means but that is where it is used.

[Damien Blenkinsopp]: Right, and I would say that some people have been connecting that to the flow stake, which they say is the high-performance stake. So the idea was that a higher HRV would mean that you are accessing your flow and you are more in a flow state than having a lower HRV. So I think that is some of the thing around that. I don’t know if you have seen that?

[Andrew Flatt]: Yeah, I have looked at some papers. My interest has always been in a resting measure and how it relates to performance and fatigue and so forth. But that research is progressing so who knows where that is going to evolve. But again, it is just a matter of having more published data to show that this is how it can be used. We are pretty clear that it is pretty effective but how practical can it be in the applied setting with a team of athletes and so forth is the next question.

[Damien Blenkinsopp]: So where is a lot of the research on this and which journals do you find it in? Are they in some specific journals or is it sort of scattered around? Have you seen it increasing over time?

[Andrew Flatt]: There has definitely been an increase in the amount of research on heart rate variability for athlete monitoring purposes and so forth. Just to name a few journals you are looking at International Journal of Sports Physiology and Performance.

There have been some in the European Journal of Applied Physiology. Every month there are one or two of these papers in a lot of these sports and science journals every month that pertain to heart rate variability. Journal of Sports Sciences, European Journal of Sports Science, Journal of Strength and Conditioning Research, so yeah – I kind of go through these every month and see what has been recently published. You can get on Twitter and follow a lot of these researchers and interact with them and sometimes they will give a heads up on what is coming and you can discuss it with them. Attending conferences, you can kind of see what research is upcoming, what is being done.

In fact, that is how I got into all of this. I attended the National Strength and Conditioning Association – their national conference in 2012. And that is where I met my colleague, who I have been working with for the last year or two, Dr. Michael Esko. He was presenting a poster on HRV and he was the only on there doing any HRV research. He was living in Alabama, I was living in Toronto. We hooked up and the next thing I knew I was moving to Alabama and we started doing research together.

[Damien Blenkinsopp]: Great, so who else might this be – you may have already answered this. I know you mentioned a few names, but who besides yourself would you recommend to follow to learn more about HRV and these biometrics?

[Andrew Flatt]: Well definitely Martin Buchheit. You can find him on Twitter. Daniel Plews, who worked with Dr. Martin Buchheit. Jamie Stanley, another guy who has been producing some great HRV research. Fabio Nakamora, Joel Jamieson, who kind of runs the BioForce system and the 8 weeks out website.

The ithlete has a blog where they discuss HRV research and maybe they have an endurance athlete that posts a training log. I try and post some data and some new research here and there. So on any of those social media sources like Facebook or Twitter you could generally find some of these individuals.

[Damien Blenkinsopp]: Great, there are a lot of good references there. So of course there is your blog, which is HRVtraining.com.

[Andrew Flatt]: Yeah, I try and update it every once in a while. Things get busy so I am not as religious with it as I used to be. But the whole purpose of that was to just share data and there wasn’t much talked about it and I wanted there to be.

So that is kind of where it has started and now it has evolved to I will discuss some of our new research projects and post some new research. But it kind of was started with just posting data and then trying to analyze it and leaving it open for discussion.

So if you are interested in looking at some previous trends of my HRV or HRVs of athletes, where we discuss and analyze the data or try to come up with a meaningful explanation or some research review and you can check out the sites. I should warn you that a lot of the older posts, I kind of reread some of them recently, and they make me cringe.

[Damien Blenkinsopp]: Isn’t that always the way?

[Andrew Flatt]: Take it with a grain of salt when you read the older posts. I have learned a lot since I started and I have learned a tremendous amount. So just be aware that some of the other posts may not be a current reflection of my thought process these days.

[Damien Blenkinsopp]: Of course. Coming back to more of a general view in terms of you personally, what would be your top recommendation to someone trying to make better decisions about their body’s health or performance with data?

[Andrew Flatt]: You need to select what monitoring variables you are going to monitor and you need to be consistent with them. And you need to do a lot of trial and error. You need to almost separate yourself from the data, collect the data, analyze it later with your training lots, and see what it is telling you. If a training variable isn’t meaningful, if it is not – if you can’t figure out why you are measuring it or what it is telling you, then you probably don’t need to do it.

You want something – so, for example, with me and the resistance training I am continually experimenting with HRV. There is just not a lot of data in resistance training and how you may be able to use HRV as a tool to guide your training. So I am consistently just experimenting with it.

But it is pretty clear in the research that perceived levels of training load, RPE values, perceived levels of stress, fatigue, muscle soreness – those things are worth tracking because they do correlate with other markers of fatigue and stress. They are just noninvasive. They are easy to monitor and you go with it.

I can’t tell you not to monitor certain things because it is fun. It is fun to collect data, it is fun to experiment. But generally if you are just in it to try and improve performance, you want to pick the variables that are the most meaningful to you, that are the most supported, and you need to be consistent with it.

[Damien Blenkinsopp]: What other data metrics, biometrics, do you track for your body on a routine basis besides HRV?

[Andrew Flatt]: Well I do, again, the perceived levels of fatigue, muscle soreness, and all that through the app. I will do training load and every now and then I will calculate my tonnage, where I will multiply the weight I have used by the amount of sets and reps and so forth and see how that relates to my session rating of perceived exertion.

If RPE better relates to HRV or if the tonnage value does – I don’t do that all the time. It is time-consuming to do those calculations. But regularly I do my RPE for my workout. I will do my perceived levels of fatigue and muscle soreness and so forth. And generally there is a comment section so I will usually make a note or two of something that happened the previous day.

If I was out and had a few drinks with some friends I will make a note that I had a few drinks. If I am traveling, when my training structure changes, things like that – I will make note of it. And I do keep a training log where I write down all my workouts and so forth. So there are plenty others that you can do.

[Damien Blenkinsopp]: So it sounds like you have a little diary related to stressors and health in general.

[Andrew Flatt]: Yeah, and again that is all stored right on the smartphone app that I use. The training log in my gym bag is just a little notebook where I log my workouts. I was going through a phase where I was going through a reaction time test and a tap test, again, with two different smartphone applications. Honestly, I was doing it at a time where I was less familiar with certain statistical analyses and I probably really didn’t know how to analyze the data very well, but it is definitely something I have been interested in.

There is some data to support that psychomotor speed assessed through a reaction time test can be related to fatigue and overtraining. So there is a smartphone app. I believe it is free. And essentially the screen will prompt you to react to a light changing on the app. So as soon as the light turns green, you tap it, and then there is an unknown time interval where it will then prompt you to tap it again over a series of five taps. And then it will give you kind of the mean value of your reaction time.

And I think the data is pretty cool, that I have read, and that supports it. I haven’t really seen any kind of longitudinal data where it has been done every day with athletes, so that is actually something I would actually like to include in a future study along with HRV and some other measures, this reaction time.

[Damien Blenkinsopp]: Yeah, great. There are a few of those apps and I know that some of them are free because I downloaded and played around with them myself. But like you I haven’t really gotten into it. I played around with it once or twice. So thanks for all this stuff, Andrew. This is very detailed and we have really done the topic of HRV justice, really tackling it from every area. So thank you very much for your detailed explanations on everything.

[Andrew Flatt]: Oh, it is my pleasure.