WHOOP Podcast - Daily Tips and Tricks to Boost Your HRV with Emily Capodilupo

Episode Date: September 13, 2023

On this week’s episode, WHOOP VP of Performance Science, Principal Scientist, Kristen Holmes is joined by SVP of Data Science & Research Emily Capodilupo to talk about all things Heart Rate Variability. HRV is one of the key signs of fitness and how well your body is ready to perform on any given day. Kristen and Emily will discuss what HRV is (2:15), how WHOOP measures HRV (5:15), adaptive behaviors to help HRV rebound (11:45), how HRV is a personalized metric (17:40), menstruation and pregnancy impacting HRV (21:12), HRV and sleep (27:30), the WHOOP Core4 Challenge (33:47), and listener questions on HRV (49:15).Support the showFollow WHOOP: www.whoop.com Trial WHOOP for Free Instagram TikTok YouTube X Facebook LinkedIn Follow Will Ahmed: Instagram X LinkedIn Follow Kristen Holmes: Instagram LinkedIn Follow Emily Capodilupo: LinkedIn

Hello, folks. Welcome back to the WOOP podcast. I'm your host, Will Ahmed, founder and CEO of WOOP, and we are on a mission to unlock human performance. We're diving right in this week's episode featuring WOOP VP of Performance Science, Kristen Holmes, and SVP of Data Science and Research, Emily Capulubo, and they are talking all things, heart rate variability. that is HRV. HRV is one of the key signs of fitness and how well your body is ready to perform on any given day. Kristen and Emily discuss what HRV is and how we measure it,

the link between HRV and the autonomic nervous system, how HRV is a highly personalized piece of data. You talk about how a good HRV is relative to the person, how HRV is impacted by menstruation, in pregnancy, ways to boost your HRV, WOOP member data from the Core 4 challenge, which just concluded, and some listener questions around HRV. This is a great all things HRV podcast. Remind you, if you're thinking about joining WOOP, you can visit our website and sign up for free. That's right, free 30 days on WOOP to the full WOOP experience. That is at WOOP.com.

New members can use the code Will W-I-L-L, get a $60, credit on WOOP accessories. If you have a question, what's the answer on the podcast? Email us, podcast to woof.com. Call us 508-443-4952. Here are Kristen Holmes and Emily Capulupo. So Hari Variability is one of the most asked about metrics that we have in the platform. And today, Emily and I are going to just go as deep as humanly possible on all things, Harvey Variability. Excited to dive into this with you, Kristen. I know, same. This is going to be fun.

Okay, so we're definitely getting into kind of the tactical side in terms of, okay, what can we actually do to improve heart rate variability? But before we dig into that, let's just set the stage, very simply, what is heart rate variability? High level, it's exactly what it sounds like. It's how variable your heart rate is. Not everybody realizes this, but when we talk a lot about, you know, oh, your heart rate's 60 or your heart rate's 120, it's actually not beating perfectly even. like a metronome, it's beating a little bit faster, a little bit slower each beat, and the variability or the amount that that timing changes from one beat to the next can be quantified, and we call that heart rate variability. The reason why heart rate variability is important is not because it's good or bad for your heart rate itself to move,

but that the cause of that movement is the movement of your autonomic nervous system. Your autonomic nervous system sends signals to increase your heart rate, and it sends signals to decrease your heart rate. And the increased signals come from your sympathetic or your fight and flight side, and the decrease signals come from the parasympathetic, that's the rest and digest side.

And so when both of those sides are getting their voice heard, so to speak, we see that dynamic play out, and your heart getting, go up, go down, go up, go down type signals from the two branches of the autonomic nervous system, and that nice balance of both sides being heard manifests in a nice jumpy little heart rate and high heart rate variability, and that's what we like to see. When we see low heart rate variability, it means one side is dominating the other, and we're not getting both of those voices heard. And so maybe, almost always, it's the sympathetic side dominating. It's that fight or flight go-up side that's

winning. And the parasympathetic rest digest side is being silenced as a result of that. And so our body is becoming only sensitive to half of our autonomic nervous systems inputs. And so we ignore those inputs. And so we don't meet some of those needs. And so we get out of balance as a result. And so you can think of heart rate variability. It's just one place where this plays out. It also plays out in like your eyes, you know, dilating, constricting. And And, you know, kidney function, all these other places, heart rate variability is just one place where that sympathetic parasympathetic activity is really, really simple and straightforward and non-invasive to measure.

So it's the one we choose to measure, but we care about it because of what it tells us about the nervous system. Perfect. So it's a function of the heart, but it originates not on a nervous system. Totally. Okay. And, you know, I think what you said is really important that it's a metric that gives us a nice overall picture of how your health is trending. So talk a little bit more about, you know,

how do we use this marker on the WOOP platform to give you a sense of how you're adapting? And what are some of the things that can impact how, whether we're adapting in a functional way or a maladaptive way? Yeah, a lot to unpack. Yeah, we have two big questions. Great big questions, though. Let's do it. So Woop measures your heart rate variability. continuously, but the heart rate variability that we report to you as part of the recovery score is an aggregate from the period in which you are sleeping. And so every morning you wake up and we show you as part of the recovery breakdown here is your heart rate variability.

What you want to see is that when you're at rest, in this case sleeping, your body can get into a state in which it's responding to both sides of that autonomic nervous system, the sympathetic and the parasympathetic. If you can't get into that balance, it's often because there's some demand on your body that is causing you to become sympathetic dominant. And a great example of this is like if you're sick, our sympathetic nervous system goes into overdrive

to rub up our immune system and fight that off. And that's important. We want it to do that. That's the desired response to fight the infection. But as a result, we're not, you said, listening to the parasympathetic side. And in not listening to the parasympathetic side, all of its agenda is being ignored. And so if you stay in that state for too long, there tend to be, like, different health consequences. You're not going to feel good.

It also means that if you are sympathetic dominant, your body is actively engaged in something. In the case that we just mentioned, fighting an infection revving up here, immune system. And so therefore those resources are not available to go to other activities. And so if you want to think about this from like a performance angle, right, like I need to put a bunch of resources into my legs to run quickly. If I'm putting those resources into revving up my immune system, they are not available to my legs. And so I can only run so fast, which is why if you're fighting a cold or something

or you've been sick, you go work out and just you feel heavy and draggy and not good, and it's because you literally cannot, like, put that oomph behind it. So that's why, like, you will feel less good on days when your HRV is low, because that is a sign that your body is doing something else. To back up a little bit to the other part of your question, you know, how do we think about HRV as showing us if things are adaptive or not? If I have a great workout, the goal of my great workout is to create a signal for my body that says, you know, I am not fit enough for the demands of my life. And our bodies respond to that by building muscle or expanding lung capacity, all kinds of different adaptive changes.

And so acutely, like right after that workout, I actually might see my HRV go down because I'm responding to the exercise stimulus. by building my muscles and your body heard you, which is a real positive thing. Yeah, no, it's a really positive thing. And I think, like, you know, if I wake up, I have a great HRV, I go do a great workout, I want to see that my HRV has gone down. And if it doesn't, that might be a sign that, you know, I didn't do something that, like, signals this need for an adaptive change. You didn't really overreach enough to have your body say, oh, yeah, okay, that meant something

to my body. Totally. And that doesn't mean that it wasn't. useless. There's other reasons to work out other than, like, I'm not trying to build muscle necessarily every single day. Different people have different goals. But if you do have this sort of adaptive response, you'll see your HRV come down as your body rushes in to build back stronger. But what you want to see then is that, like, then the next day, after you've had your rest recovery day, your HRV comes back. And there's this phenomenon called supercompensation,

which is your HRV will be at one level, it will go down in response to the training stimulus, and then it bounces back to an even higher level because now I am more fit. And you can look at the trends in your HRV of like, if I push, and I can push two, three days in a row, this doesn't always like one day, one day, one day, but if I push, I will see my HRV go down.

If I back off, my HRV needs to come back up, And if I'm getting the balance of overreaching to rest correct, when I back off properly, I will not only bounce back, but I will bounce back to a higher baseline. And so you can see if you track your HRV day after day after day or in whoops case, night after night after night, and you follow these trends in a way that Woop makes it so easy to do, you can see that are the different things that I'm doing in my life, laddering up to like getting this benefit of super compensation where I'm, you know, yes, I'm having this adaptive challenge, but I bounce back higher. Am I trending in that right direction? Or is it

stagnating or decreasing over time? If you do nothing as you age, we see the HRV declines over time. So it will naturally decline and you have to be actively engaged in adaptive behaviors in order to get it to stay confident or go up. Right. Let's talk a little bit about some of those adaptive behaviors because I think, you know, so many folks on our platform are interested in improving their heart rate variability because they know heart rate, you know,

an on our nervous system that's more responsive to the demands of the heart is healthier, right? And is going to allow us to be more functional and in our own environments. So when we think about some of the behaviors, so you talked about, you give a beautiful example of this kind of, of super compensation period of time and then there's you know and that might be for some people it's going to be three or four days of kind of a a workout where they're functionally overreaching and then there's this back off period right so as your hearty variability starts to decline and you maybe kind of get into that lower range of yellow that might be a time to kind of back off a

little bit and try to rebound now what behaviors are going to help promote that rebound versus behaviors that actually might kill that rebound. Because I think that's where people go wrong when they're trying to get fitter, right? They do all the hard work in the gym and then they ruin it by like kind of doing behaviors that are going to counteract all that hard work that they just did. Yeah, I think that was one of the things that I learned first when I came to whoop was just how much an athlete is made outside of the gym and how much like I think even people who have the best coaches money can buy are just botching it in the other 20 hours and it's when

you think about it it's not crazy right that like the 20 22 hours outside of the gym matter right it's not it's a small fraction of your day that you're actually training even for professionals it's not the majority of their time so it makes sense that the rest of it matters and I think it gets such a tiny fraction of the attention so I'm glad we're going to bring some attention to this Yeah. We opened by talking about the example of being sick, right? That's an example where your body's doing something. Your HRV's low because you're diverting all these resources to your immune system.

Well, it's very real. It will resolve itself because as soon as you stop needing to fight an infection, all those resources become available and we see HRV balance out again and increase. There are all kinds of different things that sort of gobble up these resources, some of which are reversible on very quick time scale. So when you think about something like hydration, right, we know that HRV is going to be depressed if you're dehydrated in a pretty dose-dependent way,

the more dehydrated, the more depressed. Drink a glass of water or two or three if you're dehydrated, and that's going to bounce immediately up. So you can go from having a low HRV to a high one in, you know, minutes. And so there's a lot of behaviors that you have, a lot of pretty granular acute control over that can impact your HRV and therefore, you know, these adaptive responses. So eating well, staying hydrated, managing stress. The timing of eating is, I think we're seeing really important. Timing of eating, that's more on the like day-to-day scale

for sure. We see that time-restricted eating has a huge impact on HRV. But even just like if I eat a nourishing meal that makes me feel good and meets my nutritional needs I'm going to see later in the day an HRV benefit versus if I eat a whole bunch of heavy junk that doesn't really satisfy me. The flip side is a lot of the obvious, right? Like if, and we see this all the time like athletes will work out and then go get beers. And like, you know, if you drink, not only does that put your body in a state where you're severely stressing it out, But you're also putting it in a state where it cannot respond to the exercise stimulus and get fitter. So you almost like waste that input.

Yeah. So you do all the work to work out. And then you see like less of a fitness game because there's this acute period in which that stimulus to build muscle and all of that is present. And it'll just dissipate without being met if you don't put your body in a state where it can engage in those building behaviors. Yeah, like restorative behavior. So principally, I think it's safe to say that, you know, as you're considering a behavior, you can kind of think about, all right, is this behavior, whatever it is I'm going to do? Is this going to deplete resources or divert resources or add to resources?

And I think that you can kind of think your body, think about your body in that context. It, I think, kind of helps you frame your choices a little bit more proactively if your goal is to, in fact, get fitter and make gains and improve your HRV. Yeah. And I think that that point is really important because I think sometimes people can think of whoop as being like really intense all the time. Right. And I don't think that there is no room for making decisions that deplete resources. I think a balanced life is a beautiful thing. But we want people to understand like if you just had a really tough workout, they don't ruin that, right? Or at least don't ruin it without realizing that's what you're doing. Because if it was just for the the fun of, like, playing a game with your friends of pick up basketball and you don't care, like, that's a decision you can make. But I think most people don't realize that they're making that decision. It's just you should realize that if you follow that up with all these, quote-unquote, like, bad behaviors or things that deplete resources, you will get a smaller fitness gain from that. And over time, we'll have a longer path to reaching whatever fitness

goals you might have, versus if you follow that up in a way that, you know, nourishes your body in every sense of nourishing your body. So getting enough sleep or keeping stress low. Putting your body in a place where it can take on those anabolic tasks and it put those resources behind gaining your fitness. And so, yeah, it's just important to realize that the fitness gain that you get is not solely determined by the exercise that you do. The exercise sets a maximum, but what you do over the next couple hours

determines if you get none of that or all of that. So that, yeah, it's just, it puts you on a potential scale, but you still have to do a whole bunch to go realize that potential. Perfect. Folks on our platform love to compare HRV. Let's just discuss why R.A. variability is a very personalized metric. And then I think, I'd love to, this is a question that I get a lot. You know, when they first come on to the platform,

they've got this, you know, and after the whoop has calibrated, they arrive at a baseline. You know, why is that baseline different than a friend who came on at the same time? So we can talk a little bit about just prior behaviors potentially that influence it, but there is obviously this kind of genetic component to it that I want for you to speak to. Yeah, it's a complicated question. We know in general that people who are more fit, people who have lower resting heart rates, tend to have higher heart rate variability, and the opposite is true. We know that in general people who are younger tend to have higher heart rate variability,

and people who are older tend to have slightly lower heart rate variability. That said, this is like one of the stats that has the most exceptions, like wide, wide variability. I've seen people who are professional athletes that do not have particularly impressive-looking HRV, even if they're young, even if objectively what they are achieving in the fitness world is incredible. So the correlation to fitness, while the trend absolutely exists, is very, very noisy. And we don't really know why. Presumably there's genetic components like there's anything else. How this happens to be manifesting in your heart rate, heart size. We do know that all kinds.

kinds of things, like there are medication and environmental interactions with HRV that could be interfering with our signal. There's a lot of things that can create artifacts in HRV, so change your heart rate variability without changing your autonomic nervous system underneath that. There are certain extreme examples, like if you have a cardiac arrhythmia that makes the reading of HRV somewhat invalidated, so it gets a little bit complicated, but that's a relatively rare state. But for the most part, it's like, you know, it's like, why? Why do two siblings that have the exact same parents and genetic potential end up six inches, you know, in height different from each other?

It's not that one had a less healthy anything or a better anything. It's just there's randomness. We've seen with resting heart rate, there tends to be a much tighter correlation to performance. Like the better runners really do have lower resting heart rates. HRV is just a lot noisier than that. And the best we can really do is say we don't super know. why. But we also know that it doesn't matter and that's why we talk about baseline a lot. Because within an individual, you know, whether you tend to be higher or lower for whatever

reason, it means a lot when your HRV goes up or your HRV goes down. And so even though the absolute number doesn't mean a ton, it's still extremely useful as an individual training tool. And so once you've established your baseline, something that whoop makes very easy by doing it automatically every single night and having a clean apples to apples comparison by doing it under those clean recording conditions every night, you can trust that if my HRV is trending higher, you know, this week's average is higher than last weeks, this month is higher than last months, whatever it is, I must have done something or something has happened such that, you know, I'm seeing this adaptive benefit. And so

without caring what your baseline is, it's very, very meaningful. that baseline shifting up or down. So it's still an incredibly useful metric. Let's talk about sex differences just very briefly. Women who have a natural cycle are going to experience cardiac profile is going to change across the menstrual cycle with kind of in concert with the rise and fall of hormones. So maybe just talk a little bit about what women can expect on the platform in terms of heart rate variability. I'm so glad that you're asking this question because during the follicular phase, which is the first half of your menstrual cycle,

so from menstruation to ovulation, roughly the first 14 days, although that does vary from person to person, you are going to have higher heart rate variability. You will respond better to training, recover more easily. Generally, certainly lots of exceptions as there are with everything. And an important caveat is this is for individuals who are, naturally cycling, so not using hormonal birth control, which because of the hormones changes this pattern quite a lot. But if you are not on a hormonal form of birth control,

what you see in the follicular phase, those first 14-ish days, is higher heart rate variability and all of the benefits that come with that. And then declines around ovulation, roughly the midpoint of your cycle. And then the ludial phase, which is from ovulation to menstruation, again, roughly 14 days, sometimes a little longer, you will see lower heart rate variability. And it's such an important thing for those who are naturally cycling to be aware of because you might accidentally read into it that like, oh, what's going on? Like, did I do something? That's better.

Do I am I doing something wrong? And so it's really helpful to know that this is a very common and very natural response to the fluctuations in your hormone. So, A, don't read into it, you didn't do anything necessarily wrong or right, right, when it goes up all of a sudden in your follicular phase. And it's also really helpful because you can program around this. Many people find that if they plan their tougher workouts during the follicular phase and the kind of back-off recovery stuff, endurance workout, lots of zone two training.

More technical work. Technical work, yeah, in the luteal phase, that they will make gains faster because they're working with their hormones and with their body versus if you try to do the opposite, so you're out of phase with what your body wants to do. And so by, and what's nice about it is for many people,

that cycle is super predictable, at least like, you know, within a few days. And so you can plan, like, I'm going to go on this trip and do, you know, hike this tall mountain or you know what I'm going to do it here instead of two weeks later because it'll be easier for me or you know when you're picking which marathon you want to run like you know this one versus that one if they're two weeks off you might have very different performance and if it's not always possible to you know schedule your financial cycle phase at least you can

plan around it right so this might take me a little bit longer I might need more water we sweat more more easily during different phases. And so we tend to get dehydrated more easily during our lidial phase. So we need more water. So it's like a really simple example of something where it's like, okay, no, not only is exercise going to be harder, but like I might want to be fueling for that exercise or supporting my body for that exercise a little bit differently.

So I'm going to pack extra water from doing it. Electrolites can be a super helpful during the medial phase. Yeah, totally. I'm glad we talked about the menstrual cycle because it's so important to so many people. but there are a lot of things that are like this, right? In pregnancy, you also see different changes in HRV. And pregnancy, you know, you just had a baby.

It was a while ago now, but Aria, we're born in January. So talk a little bit about just the fluctuations in your, you know, cardiac measures, you know, over the course of the pregnancy. You know, just what we've seen in the research and, you know, just spend a minute on this. I think it's really fascinating. Yeah, we've written two papers on this now, but it's almost scary if I hadn't done the research to know what to expect. But pretty much from the jump, your resting heart rate's going up, your HRV's going down, and it happens pretty quickly. It's, like, pretty dramatic, and it doesn't stop.

Like, my HRV, I think, went from average, like, in the 80s to averaging in, like, the 30s over the course of my pregnancy. It was a lot, and my heart rate went off like. 15 feet per minute. The crazy thing though is that literally like the first reading after you deliver it just super compensation right. It bounced back so far the other way and you know whoop was saying like oh you have like 400% increase in it's like I've never had such good values and it's exactly what we've been talking about right I can't imagine anything diverting resources more than a full-term baby, right? And all of a sudden you take that challenge or you,

I'm not going to say burden, I love my baby, but that physiological burden off of your plate and your body's like woo! Yeah. And it's actually like when you think about it, it's like such a beautiful physiological system because you feel like so light

and like there's this nice rebound moment and you're about to do the hardest thing you've ever done. Take care of a human. Just like not sleep and take care of a brand new human. So you need it, but it's pretty incredible. So you will see like this steady decline in HRV, steady increase in resting heart rate. But we do see that once the baby is delivered, that those metrics not only bounce back, but you have this super compensation effect that lasts for months.

And, you know, if you resume training once you're cleared to do so, you can maintain that. which is pretty incredible too. Yeah. The body is just unbelievable. Yeah. And how it functions. Okay. I think people expect there to be a very linear relationship

between hearty variability and sleep, performance. So let's talk a little bit about what is HRV actually correlated with. So if we're kind of to look at the literature and kind of look at our data, where do we see the strongest relationships in terms of hearty variability and sleep? Oh, yeah. That's a fun question. I think one thing people don't always appreciate is that our sleep performance score is really focused on did you get enough sleep?

Right. Sufficiency. Yeah. And that's a very different question from, is your body restored? And that's why we have a recovery score and a sleep score. You need both. They're telling you different things. Did you get enough sleep is really a commentary mostly on your behavior.

Sort of did you do the thing that we told you to do that you need. bed to like optimally yeah and then like have your environment enough in the right place that like the time in bed actually was like sleep right um i think the like extreme example that i like to give that helps people understand this like think back to the last time you were really sick like you can sleep for 16 hours and still be exhausted and still feel like crap yeah right so just because you've got enough sleep and in that case where you're sick and you sleep for 16 hours you very much could have gotten plenty of sleep, right? 100% sleep performance.

Your HRV is still going to be terrible. You're not going to have bounce back. We almost always see like the opposite case, right? Like where if you don't get any sleep, your HRV is going to be bad. But just because you did get a lot of sleep, in no way means that your HRV is going to be good. And I think like anybody who's ever seen, slept for a while and still woke up feeling crummy, should understand that. Like, sleep is the

behavior that gives you a very good chance at having HRV, right? You're not going to have great HRV without doing pretty well, at least, on sleep. So it's sort of necessary but not sufficient. And all these other things, like what was going on in your body, you know, or are you properly hydrated? Are you super stressed? Are you fighting anything? Are you fueled properly? All of is going to be captured in HRV, and that's why it's such a beautiful metric. You know, it's responsive to so many different things. So anything that's really going to drive sleep quality does tend to drive HRV. So when you have that really awesome night of sleep and you wake up just feeling incredible,

you probably do have a good HRV. And so things like sleep consistency and healthy sleep behavior, sleep hygiene, all of those things are definitely correlated. The correlation to sleep performance itself is weak because sleep performance is just one of so many dimensions that get into, am I restored and rest? Right, right. So basically we think about, all right, if we really want to try to improve our capacity to adapt, improve our hurry variability, it's going to start with, you mentioned it,

sleep consistency. Yeah. Right. And we just completed some research around us, which is really, exciting. We can kind of see an actual drop-off in your heart rate variability for kind of every minute of variability after 45 minutes. If you think about your, you know, when you go to bed and when you wake up, and if you're, if that variability is extended beyond 45 minutes, you'll start to see a deleterious effect or a negative effect on your hearty variability,

which is really interesting. And we know that sleep consistency drives quality of sleep and quality of sleep is also associated with a higher hearty variability. So one of the behaviors people can engage in to kind of back into improving adaptive response would be stabilizing sleep wait time. And that's probably like one of the bigger behaviors, right? Would you say in terms of if you can nail that, there's probably a lot of other behaviors that come along with that that are positive? Yeah.

One of the big things that happens when you align your bedtime, wake time, and improve your sleep consistency is that you become predictable to your body. And when you're predictable to your body, it can anticipate sleep is coming, wake is coming. And this actually doesn't just improve your sleep. It improves so many different aspects of your life. Like to get weird for a second, because people don't like talking about this, but you will digest food better if your circadian rhythm is aligned. And so you're less likely to get constipated.

And like, so you're going to process food, get more nutrients out of it, like have it move through the way it's supposed to move through. And, you know, you will feel tired when you're supposed to feel tired. You will maintain energy when, you know, in the evening when you're supposed to maintain energy, there is this wake maintenance effect that comes in. And so you'll feel energetic and present up until it's bedtime, at which point you will feel sleepy. And hormonally, you will be ready to transition into sleep. So you tend to see shorter sleep latencies, it's faster time to fall asleep. You stay asleep because, again, like, hormonally, we're ready for sleep. Your hormone levels are going to sustain that sleep.

And then you wake up and you feel present and awake when you wake up, not groggy. And, like, you want to roll over and sleep for two more hours. So you wake up and you feel ready to do the day. And everything is functioning better all day long. And so it's this funny behavior that's like it feels like it's just about sleep. there are huge benefits to sleep for doing it, but it's actually huge benefits to systemically, like your circadian rhythm affects everything,

and you see them systemically all throughout the day. Yeah, yeah. When you think about circadian dysrhythmia and its impact on fertility, its impact on metabolic dysfunction, its impact on your mood and alertness, like it's just, it's crazy how powerful it is. And I think when you're feeling alert during the day and feeling sleepy at night at a base level,

like that's really what we're kind of striving for. Yeah, because then you feel good. Exactly. And you have the energy to do things that you need to do. And there's nothing more frustrating than like laying in bed and not being able to fall asleep. Right. And then you start to stress that like you're going to be tired tomorrow. And that stress makes it even harder to fall asleep when you spiral.

Yeah. Totally. So throughout the month of August, our members got to take part. in the core for a challenge. So it was basically four simple activities that would help boost their heart variability, optimize their circadian rhythms, and restore focus. We had a cool kind of happy aside

is that people, this really did increase journal engagement, which was neat. People were really logging these behaviors, which was awesome. And it gave us the ability to then kind of show on an individual level and a group level, you know, what were the changes in, you know, heart rate and heart rate variability over the course of this challenge.

And we identified breathwork, morning set light, and intermittent fasting in Zone 2 cardio is kind of the top four that we felt like could move the needle the most. And these were also kind of a lower barrier to entry, you know, because they're democratically available to everyone. So we wanted to make sure people had access. But maybe talk a little bit about breathwork and its connection to heart rate variability. Why is it such a powerful kind of heart rate, you know, variability boosting activity? breathwork is kind of this like manual override for your autonomic nervous system when you breathe

slowly and in a controlled way your heart rate is going to change to match that breath work because when we inhale so we fill our lungs with oxygen we will preferentially like increase our heart rate to get blood to rush past the oxygen-filled lungs so that the blood is passing your lungs when they're full of the good stuff. Then when you breathe out, our heart rate slows down because the blood that passes by the lungs while your lungs are empty, they never really get empty, so empty is kind of a cheater word. But when they're less full, right, we'll get less oxygen. And so we want more blood going when they're full, less blood when they're empty. And so this is actually called respiratory sinus arrhythmia. It's the phenomenon of your respiratory rate

in a lot of ways contributing to your heart rate. So if you don't think about breathing, we will automatically adjust our respiratory rate up and down based on the oxygen demands of our body. So if you're more active, you'll breathe more in order to get more oxygen. But It's this funny behavior in that, like, most of the time, it's fully automatic, but when we choose to, we can override that, right? And so if we take over and we slow it down, we slow down our heart rates quite a lot, and we start to create that heart rate variability through the respiratory rate variability. And it kind of, yeah, it's this like manual power reset moment. And we see that when you come out of even just like a minute, two minutes, short periods of these intentional slow breathing, your heart rate variability is higher. And this is, and all of the good things that come with that, right?

You tend to feel less stressed, a little bit more focused. And it's, you know, particularly great behavior to do at night because it can help you fall. asleep. Because what's happening a lot, the way our autonomic nervous system works is when one side, you know, we were talking earlier about sympathetic and parasympathetic, when one side is having a strong input, it's not only having a strong input, but it's blocking the other one. And so when I'm being loud, I'm like actively making you quiet. And when you do this manual override, it's just this one moment where you like let some of those parasympathetic signals get through. And that's why it's so powerful.

It's like, stop blocking, you know, the little guy, let him get his stuff in. And so we have this moment of rebalance and in listening to all of these inputs that had been ignored. And when those get pent up, it's really powerful to like let that side of your autonomic nervous system get hurt. Yeah. Yeah, I think when we consider, you know, one of the HRV kind of crushers, it's definitely negative stress accumulation. And breathing breathwork is a way to basically interrupt stress in a very proactive way so you don't get this accumulation. Because invariably, when you allow that stress to accumulate, it can become chronic, right? And that's when we see burnout and low energy and it start to disrupt our sleep and our mood.

And so just this like very simple, intentional kind of breathwork sessions throughout the day can have a huge impact. And we saw that in the data, which is neat. Yeah. Morning sunlight, you know, this is tied to kind of the whole circadian rhythms thing, so we talked extensively about sleep-wake time. And in order for that melatonin to kind of be released, we need darkness. But I think what people don't realize is that we also need a lot of sunlight early in the morning. You know, as soon as we wake up, essentially, we want to get as much light, natural light as possible. Maybe just talk about the relationship between this, you know, between cortisol and melatonin and kind of how they bookend the way.

the day. Yeah. So it's just the same way that we need darkness to produce melatonin. We need not darkness to not produce. So you can think about sunlight as shutting that off, which is why we don't want all the artificial light exposure at night because it shuts off melatonin production. Well, now that I'm done sleeping and I want to be awake, I do want to shut that off and cut off whatever's left. It also is a very powerful signal to your circadian. rhythm to your brain that like it is daytime I want to be engaged in day so it helps to center the circadian rhythm it tells your brain yeah it's go time so it helps with alertness and so it's a powerful signal to help yeah center or circadian rhythm and keep it in line with your

environment yeah and you talked earlier about just the anticipation like your body's anticipating and we want to make sure that we're feeding our body the cues that they're that they're that they want to get at the right times. Right, and confirming what it thinks it's going on. Yeah, yeah, because I think when we talk about your resources, right, like you don't want to make your body work harder than it needs to, right? And these are the circadian behaviors why I love them is that they are relatively simple to kind of do for the most part, for most people, but it kind of creates this baseline

kind of homeostasis, you know, that like, and your body's not having to like work hard, to get to homeostasis. You're kind of helping it. Yeah, because one of two things happens if you don't set your body up to anticipate things correctly. Either it'll like over-prepare, which is a waste of resources and kind of like be ready for everything, which is like a high alert, wasteful state. Or it'll say, I don't know what's coming, so I'll wait to figure it out, in which case you don't prepare for anything. And when we see that with sleep, we're like, you have no melatonin production going into like getting into bed because you're trying to sleep but a weird time when your body's not anticipating it,

it's going to take like two hours for that to build up. So when you anticipate it, you actually start producing melatonin two hours before your body thinks it's going to move it. If you wait to say like, okay, I'm in bed. Like, I'd like some melatonin now, please. Or it's going to take a while to build that up, during which time you're going to roll around, you're going to get frustrated.

That frustration is going to suppress it. Bad things happen. And so you want to put your body in a position where it can guess and guess correctly and then get a positive feedback loop on I just guessed correctly. And you like super briefly mentioned this a couple minutes ago, but like this is why your circadian rhythm is like such a 24-7 thing because it's not just that I want to anticipate sleep, but I also want to anticipate meal time, right? Because if a meal comes when I'm anticipating it, I'm ready with insulin. If it comes when I'm not anticipating it, when I have a larger spike in my blood sugar while I like wait for the insulin response to happen.

And then you get that sugar crash, right, and all these different things that's like not great for your metabolic health. But if my body knows, like, I get food in this window to jump ahead, to intermittent fasting or time-restricted eating being, you know, the third of our four behaviors, if my body knows when something is going to happen and it can rely on that, it can be ready for it. And so we see that it's not that eating at 10 o'clock is bad. It's like eating when your body was like thinking that I'm not getting any more food tonight. And so it was like, you know, doing other things. doing other things or, you know, releasing sugar in anticipation of, like, being in on-reserve mode

instead of on new inputs coming in mode, right? Like, then you have to adjust on the fly and just think of it. I mean, it's no different than, like, at work, right? Like, if you just get something random, like, slapped on your desk in the morning, like, it's a lot less, like, smooth, right? It's like, okay, I know what I'm doing today, I have my agenda, I'm doing it. You know, our bodies are exactly the same way. And so anything you can do to be predictable is going to make it easier.

And so it is much less work to like do something that feels like it's the same thing. Right. Totally. And we definitely see in the data, you know, individuals who, you know, talk about internet fasting obviously is, you know, really picking this consolidated window where you're eating all of your calories. And then you have a very, you know, kind of, you have defined kind of fasting window. and there can be lots of different iterations on kind of when you're eating and when you're fasting. But I think long story short, as it relates to hearty variability, we do see that when folks report

eating meals within two to three hours of bedtime, we see an impact on hearty variability next day. So there is, I think, this competition that's happening when you're actively trying to digest your food whilst also trying to sleep. So they do seem to compete with one another in some way that impacts hearty variability. Yeah, and I think this goes back to the conversation we were having earlier around, like, understanding how what you're doing affects things. Like, if you're super hungry at 10 o'clock at night, you know, because for whatever reason, you missed dinner, by all means, like, go eat. And I think, like, it's not necessarily the goal, and it's not possible for most people to do this perfectly day after day after day. It's probably worse for you to, like, go to bed starving than it is to go to bed.

having eaten a late meal, like in terms of your HRV, but also just broadly. No question. But if you have the opportunity to control this and, like, can both stop eating, you know, on a reasonable time and not therefore be starving at night, that is better than just, like, it is worth understanding the consequence of having that exact same meal two or three hours later. It's metabolically different. The way that it interacts with sleep is different. So this isn't to say like this is bad and, you know, if your work schedule or whatever only gives you certain opportunities, by all means, please don't starve. But, you know, when you have

control and, you know, are motivated to get those benefits, this is something that oftentimes is an easy, relatively easy one to manipulate and does have a meaningful benefit. So when you can do it make sense to do it. Cool. Zone 2 cardio was the final behavior. We see really nice relationships between getting in this zone, you know, for 160 to 200 minutes per week seem to have a meaningful impact on recovery. So what's kind of happening physiologically during Zone 2 and And why is this such an effective recovery modality that promotes heart of variability? Zone 2 is this beautiful level of exercise intensity where it doesn't super fatigue you, it doesn't wear you out, it doesn't put a tremendous amount of recovery burden on you, but it does flush the system out,

you get all the fun endorphins of exercise, you get a good stretch. you get, you know, your heart rate up, which is good for you. You get the benefit of it coming down and the relaxing effect after that. And so what we see is that it's, it almost like shouldn't count as exercise. I mean, you're definitely being active and you might sweat and all those things. And I give everybody credit for any exercise that they all credit for. But its primary function is like, it is such an incredible recovery tool because you just, it's this like

release things that need to be released yeah I mean it's impact on mitochondria yeah on some turnover like it seems to have some real yeah because it's enough to like wake the system up right so you get like the mitochondrial activation you get it's good for your body to like use your full range of motion

and range of function so you know you breathe deeply you fill those lungs right you get your heart rate up a little bit but not enough to create a recovery burden. So when you do, we're talking about like those higher zones, zone four and five, and you create that training stimulus. That's great because it has this fitness adaptive effect. But you do have to have like the hit to then adapt to.

This is nice because you get a lot of those benefits of like exercising your range of function without incurring a recovery burden. Yeah. And we definitely saw that people who track zone two showed a greater percentage increase in hearty variability compared to those who didn't. Right, because it's all the benefits of exercise without the recovery burden, so you just get the boost instead of the like dip then boost. For sure.

And we absolutely acknowledge that there could be other health and lifestyle factors that wouldn't into that change. But it definitely shows that members who are more diligent about tracking and were conscious of their zone two, efforts throughout August saw the benefit in their heart rate variability. It's worth mentioning that this is the beauty of our journal feature that like, you know, you mentioned like, oh, there could have been other things going on. That's what the journal will help you tease apart. So you can go in and try these things for yourself.

I think that's even more important. We did this study to have a fun challenge and to raise awareness of four relatively simple, free behaviors that you can engage in to boost your HRV. But in order to really understand what these things are going to do for you, you need to go journal about them, try them out, see what it does to your HRV because different people are going to respond in different ways.

and the only way to know what's going to work best for you is to try it. Yeah. And just for people who want to, the raw change at a group level was 0.3 milliseconds, which is, you know, which is the smallest, you know, kind of meets a threshold of smallest worthwhile change, which is just cool. Yeah, and it's small, but there's a tremendous amount of variability, right? Exactly. And so knowing if you're going to be one of the people this is game-changing for

or one of the people that this is just kind of nice for, you have to play with the journal, find out. Totally. Love that. This is kind of like an incredible story. And I, you know, we talk about the, you know, the physiological implications, or we talk about how, you know, taxing our physiology is going to have an impact on heart variability. We mentioned stress briefly and its impact on heart rate variability. But I think this question that Melissa has really does show that, you know, it's not just a physiological kind of monitoring device.

You know, I mean, a heart rate variability is such a great proxy for our emotional. psychological state as well. Melissa says that she's had her loop for almost four years and her hearty variability has been very stable, usually in the mid to high 50s. For the last five months, my average hearty variability is between 54 and 58. Prior to mid-August, my hearty variability had never gone above 100. In mid-August, I did a four-day intensive therapy retreat to address some extreme anxiety as a result of the trauma she'd had been experiencing. Within days of this, her heart rate variability began spiking above 100. And once it even got to 270.

Over the last two weeks, my average hearty variability has been 111. My question is, have you seen any research on the impact of HRV after intensive therapy experience or other emotional psychological changes? And the answer is yes. There's some really good literature showing changes in heart variability

after therapeutic intervention. So there's no question that hearty variability is a wonderful indicator of, you know, how you're managing your psychological state. And there's, of course, this interplay between the psychology and the physiology that's very, very difficult to tease apart. But I think understanding that it's not just how you train, how you eat, how you sleep, that impacts your hearty variability. It's very much how you're managing your emotional and kind of psychological landscape.

Yeah. And, I mean, it's so incredible to see that Melissa had this amazing response. I think one thing that's... interesting that she calls out is that her HRV improved immediately even though she says she did not feel better immediately and I think that that's we've seen this over and over again where HRV kind of responds and like before we realize we responded it's like this leading indicator and you think that you know if the therapy worked and my HRV is responding like why don't I feel better we see this a lot even just with like talk therapy right like people go to

therapist and their recovery scores are terrible the next day and it's because they're like mulling over and like processing but then like you know over time of like adding therapy right their HRV goes up which is interesting too so like there's all these different patterns where it's like so cool that the HRVs like oh I know you did something good and and I'm releasing something I'm processing it and you'll catch up to this being good in a moment you know and I just wish her the best and hope that she continues to feel better and, you know, work through that. Yeah, just really appreciate her sharing this, you know. Honor, asked a question about the impact of pain, medication, sleep medication, anxiety

medication, and the answer is yes. All of those things are going to artificially push around heart variability. Yeah. So just to be aware of that. Yeah, and I think it's a great question because it's really complicated. First of all, pain medication is so many different things, right? There's opiates, there's all kinds of natural stuff. There's so many different things.

There's also just pain is going to decrease your HRV because we will have a strong sympathetic activation to being uncomfortable. And so just the removal of pain, you know, even if you did it totally non-medically, like if you hypnotized me or I don't know what you do, right, what you would expect removing pain to increase your HRV. One thing to be aware of as we talk about medications and, you know, anything, pain, sleep, anxiety totally falls into this.

There are medications that can increase your HRV and increase it in a way that's an artifact. So it's a way of saying, like, you didn't get fitter by taking this medication. It is impacting and creating noise, yeah, artificial response on your autonomic nervous system because it is interacting with your autonomic nervous system. So any medication that's going to activate your parisic. sympathetic side with benzos, which are used for anxiety and sleep, might increase your HRV. It does not mean that it is better for you. It might be appropriate for you to be taking it, but I wouldn't read into that, like, oh, I got more fit by taking this med. It is an artifact

of the medication. So it's, you know, we've talked a lot about like monitoring your baseline and all of that. It's worth being aware how different medications can shift your baseline in a way that doesn't mean, like, I am fitter or less fit. Right. And you think about it from the perspective of autonomic health, it might not necessarily be improving your autonomic nervous system health. Yeah. All right.

How do you obsess over HRV? You know, to me, what's so beautiful about HRV is it's this all-cause indicator of what's going on. And so it's this speedy, quick view of, like, is the sum total of what's going on in my body moving things in the direction that I want or moving things in a direction that maybe I should do something about? And to have that, like, quick, again, relative to my baseline, but quick view of things are going well, things aren't going well, is really helpful and can let me know, like, you know, keep doing what you're doing. or take a moment, reflect, go look, dig into what's changed, and think about, you know, how you want to move forward. It was so fun chatting. It was so fun chatting with you. It was one of my favorite topics.

I know. I know. You have done such groundbreaking work, frankly, in this area. You too. This was your challenge. Well, just generally, I mean, gosh, over the course of the last 10 years, really. It's funny because I know when I joined Louvre seven years ago, I know. You had already been working on this for a few years. And, you know, I was using HRV in my environment, you know, and just to see how it's become kind of part of, like, people know what hearty variability is now. Like, I just think about, you know, seven to ten years ago, like, literally just a handful of humans even knew what hearty variability is. And now it's like, it's kind of commonplace.

Yeah, it's so interesting. In my loop interview, which. was 10 and a half years ago. Will asked me if I knew what heart rate variability was, and he said that he thought it was going to be important. And, well, first of all, he could not have been more right. Wow. But nobody had heard of it, and it was so interesting, like in 2013, 2014, when we were talking to people about it,

and it was the core of our recovery score, we had to really fight to get people to understand that this was worth tracking, and now everybody appreciates it, But there's still so much to learn about, like, how do you control it, all those things. And it's cool because decades ago, it was used in these acute care settings. It's a great predictor of whether or not a preemie is going to survive for 30 days. It's a great indicator of survival after heart attack.

And it was used in these sort of niche medical situations and not kind of in the daily world. And I think that, you know, it's in a lot of ways that's like the story of where. right that you democratize this information you make it available to everybody you make it available continuously and things that used to sort of only be used in these really specific settings can have like tons of impact on everyday situations you know way more than people realized yeah big thank you to Kristen and Emily for giving all the insights and tips to boost HRV if you enjoyed this episode of the Wooke podcast please subscribe to the WooF podcast. Leave us a rating and a review. Check us out on social at Woop at Will Ahmed.

If you have a question, you notice the answer to the podcast. Email us, podcast at Woop.com. Call us 508-443-4952. You can join Woop for free. That's at Woop.com. New members use the code. Will get a $60 credit on WOOP accessories. Okay, that's a wrap, folks. Thank you all for listening. We'll catch you next week on the WOOP podcast. As always, stay healthy and stay in the green.