WHOOP Podcast - The Recovery Habits That Drive Performance: Why Training More Isn’t Always Better

Episode Date: July 15, 2026

Welcome back to the WHOOP Podcast’s Science of Human Performance Series! On this week’s episode, WHOOP Global Head of Human Performance and Principal Scientist, Dr. Kristen Holmes, sits down with WHOOP SVP of Research, Algorithms, and Data, Emily Capodilupo, to explore the science behind the WHOOP Recovery Score. Emily explains the progression of the recovery algorithm, from the company’s origin to the supporting research that supports it today. Dr. Holmes and Emily identify the key metrics, like heart rate variability, resting heart rate, and sleep performance, that impact your recovery the most. Each physiological signal tracked by WHOOP helps to predict your body’s readiness to adapt to the stressors of the day, boosting injury prevention, immune health, and decision-making. This episode is your essential guide to improving and understanding your recovery. (00:00) Recovery 101: How WHOOP Looks At Recovery(00:58) The Origin of The WHOOP Recovery Score(01:32) What Is The Overtraining Curve?(05:08) Adaptive versus Maladaptive Stress(07:49) Balancing Strain and Recovery (08:18) Recovery for Everyone(10:48) How Recovery Improves Sleep, Immunity, and Mood(15:44) HRV: How Recovery Impacts The Nervous System(21:04) Why Your Recovery Is Low(28:45) Why Recovery Matters For Performance(29:53) The Relationship Between Sleep and Recovery(31:50) Treating Recovery as a Lifestyle(33:21) Strain Coach Explained(40:26) Is A Solid Recovery Routine The Secret To Muscle Growth? (47:07) How Your Recovery Is Measured(49:52) The Correlation Between Recovery, HRV, and Mental HealthSupport the showFollow WHOOP:Sign up for WHOOP Advanced LabsTrial WHOOP for Freewww.whoop.comInstagramTikTokYouTubeXFacebookLinkedInFollow Will Ahmed:InstagramXLinkedInFollow Kristen Holmes:InstagramLinkedInFollow Emily Capodilupo:LinkedIn 

This was like one of my very favorite aha moments was it was a professional athlete and he and his wife were both on WOOP and they noticed that when their recovery scores were red that they were snapping at each other. And so they implemented this like very sweet marriage saving protocol around like if either of them were read, they would be more mindful of giving each other space. And he actually wrote to us after a couple weeks. He was like, whoop saved my marriage. And what I loved about this story was just like it again, it was like not what the recovery score was at all built for, but it makes a ton of sense that like, Like when our bodies are depleted, these little things that, you know, in a ideal world, you forget to say good morning nicely to me or you just, you roll it off and you're like, you're more forgiving.

And if somebody says something a little bit weird, you're likely to sort of think before you respond. But when you're exhausted and depleted, we get into this very like reactive instinct-driven mode where we're snappier. We don't give people the benefit of the down and all these things. And so what we've seen actually is we have loads of like Fortune 100 CEOs who use whoop and like cancel important meetings if their recovery scores are read because they don't make good decisions. And like there's so many different ways where if your body is in a state where you can be adaptive, where you like have control over all of your faculties and all these things, when a stressor hits you, your ability to like show up in the way that you want to and are going to be proud of is just much higher than if you're very, very, very. depleted. Welcome, Emily. So excited to be back with you, Kristen. We are going to do a recovery 101. Just to give folks a baseline understanding of what recovery is, why it matters, why they should

care, and just some ways to think about recovery detractors versus promoters, and usually the detractor, you know, the opposite of the detractors of the promoters, but not in every case. But just so folks understand, I think, the utility of recovery because I don't think that's immediately obvious, you know, to everyone. And, you know, I think we both have had our own kind of history and evolution with this, you know, what is really one of the core pillars of the WOOP experience. So why don't you give our listeners just a tiny bit of history on Woop Recovery and then we'll get into defining exactly what it is. Before I do that, I just want to jump in and say that recovery always has had like a really special place in my heart because I joined.

Woop a little over 13 years ago, and the recovery score was the first algorithm. I ever wrote it was Woop's first algorithm. And you said one of the core, but actually in some ways, recovery was our entire reason for being. And then everything else was like what we needed in order to do recovery. But it is like our company origin story was this idea of recovery, right? Like how do we measure it? How do we understand it? Super briefly, for those who aren't familiar, the motivation for starting whoop, which it's helpful to understand because it very much influenced how we thought about recovery, was our founder, CEO, was captain of the Harvard Squash team when he was an undergraduate, and he had this really, I think, confusing experience around overtraining.

And the entire time that he was overtraining, he was getting praised for, you know, working so hard and doing so much. And meanwhile, watched himself get less and less good at his sport and was just very confused because you almost have this story your entire life of like the more you do, the more you're rewarded, right? And that shows up in so many elements of our lives. But with athletics and sports, there's this actually at the far end, this almost you-shaped or end-shaped curve. It's a point of diminishing return. Diminishing returns for sure, right, where actually you start to do too much. And instead of getting better, instead of getting rewarded, you start to get punished and get worse. So the idea behind recovery is how can we help you understand where you are

on this curve? Are you in a place where if I keep going, if I do more, I will be rewarded and have this like kind of, you know, up into the right linear relationship? Am I at this sort of plateauing place where if I do more, nothing will change? And I actually have I crested that curve and gone over that hill where actually if I keep doing more, I'm going to get worse and worse and worse. And that's the absolute worst place to be, right? Nobody wants to be working hard to like lose money or lose fitness. Right. So how do we help somebody understand when they wake up in the morning where they are, what their body's capable of. And really early on, we partnered with the Corey Stringer Institute at Yukon. The PI, Doug Kasa, was really obsessed with this idea of understanding when athletes are not safe to compete,

not safe to keep training. We worked with their soccer and track and field teams and collected a lot of data. We also were deeply inspired by the research of people like Martin Bouchette and Daniel Ploos who had, Andrew Flatt, who had come before us and done a lot of the research around how do you look at morning heart rate and heart rate variability and predict performance. And then even research from loads of other people looking at things like how to sleep relate to performance, how does even nutrition relate to recovery and all these different things. And we ended up modeling a lot of the literature that was out there and putting together the first version of the recovery score. And what's cool is like our current recovery score 14 and 13 years later is actually like

70, 80 percent similar to that original one. We have evolved it both as the product evolved and as the science and our understanding of the space has evolved. But we got a lot of it right back then because it turns out that resting heart rate and heart rate variability in particular and then sleep, both. although a lot of that information is also contained within heart rate and heart rate variability. Are really powerful predictors of the state globally of your autonomic nervous system, and therefore a great measure of whether or not your body is ready to,

the language we use is action of training stimulus. And so what that means is if you give it the sort of stimulus of a workout or of training, is your body in a place where it can turn that stimulus into a fitness gain or not? And what happens is when your body is in a state where it's like ready to receive that, that means that in response to this stressor, it can improve, right? It can take that and it can build muscle stronger. It can adapt in a functional way. Yeah, it's positive adaptation. When your body's not actually capable of it, but you still apply that same stressor, all you get is the damage.

Because the thing that people don't always realize is that like the exact same stressor can be adaptive or maladaptive, having nothing to do with the same stressor. the stressors, but based on like sort of its size relative to your capacity to receive it. And so if you are in a place where your body's able to receive it, you'll get fitter, you'll build muscle, build bone, build sort of endurance, build grit, right? If instead it's this horrible thing, right, that you're not able to receive, you still get the damage of the workout where, you know, you get these like micro tears in your muscles, micro, like fractures in your bones, right? And instead of building back stronger, your body just goes like, well, you get no credit for that work. You get no credit, right? And instead,

you still have this damage. And so if the next day, instead of building back stronger, which mostly happens overnight in response to the workout, you're sort of just layering on top, like that's when you start to see things like stress fractures, right? It's these like little fractures that happen every single time, all of us, you know, go for a long run. It's just that the adaptive response to those is increased bone mineral density and the maladaptive response is just break a little and then break a little more and then break it. And then eventually it's a true fracture that, you know, can show up on an x-ray. And now all of a sudden, you know, you're benched for however many weeks. And so you want to know where you're, what state your body is

actually in so that, and not saying that everybody needs to like max out capacity every day, but like you certainly don't want to go past that. And the tricky thing is, is it's a moving target. So it's not like I can go take, you know, some convenient blood test or, you know, scan or whatever and get told like, your capacity is this and just use that number for the rest of forever, right? It's changing every day. It's even changing within the day. And so you need more dynamic real-time measures of like what can Krista handle today? What can Emily handle this afternoon, right?

Those kinds of things. And it turns out that like measuring your autonomic nervous system is a great signal that we can tap into to say, okay, this is what we can handle. And then, of course, this is not our episode about the strain score, but to just sort of paint the complete picture, the idea behind strain is if we can measure how much you're capable of today, we also wanted to have a real-time measure of how close you are to that limit. And so the idea behind strain was to give this companion metric of if we say today you can handle up to some number, we want you to be able to say, and I'm 10% of the way there, 20% of the way, or all the way there. So it's the idea behind strain. Yeah, you mentioned kind of safe to training compete. And I just wanted to like,

you know, punch into that a little bit because I think that's, there's, I think in order to make fitness gains, of course, and in order to, I think, feel good about your life. Like, you don't want to be sick. You don't want to be injured, right? And that's where I think this recovery metric is wildly useful. And I saw this, you know, I was a double sport athlete, you know, and I put it in the U.S. team and then I coached for 13 years. And, you know, I saw this dynamic play out all the time, right, in terms of the overtraining, right? More is better, right? When, in fact, more is just more, right? It's definitely not always better by default. So understanding how an individual, not just an athlete, but just an individual is responding

and adapting to the load that is being put on them is an incredible source of insight. And when I was coaching, I was really, and this is one of the things that drew me to whoop. You know, my very short origin story, you know, is we were thinking really intentionally about recovery in a way that I think was, you know, quite novel at the time, right? And it's one of the reasons why my teams were so. successful is we were safe to compete and train relative to our competitors. Now, were we getting it perfectly right? No, right? We didn't have a lot of these type of data over the span of the entire 13 years, but once we started getting these data, we became much more informed. And, you know, one of the

reasons why I left Princeton to go to Woop was this promise of recovery to help foster not just human performance, but health and longevity, you know, and we've kind of seen this beautiful arc, you know, where we've seen, wow, this idea that recovery is reserved for the elite athlete is really not the story, right? And certainly not where our story at Whoop is going to end, but recovery is actually for everyone. So maybe use that as a way to kind of talk about this next. And I think this was the really cool moment for me where I realized that like Whoop wasn't just going to be cool product, but was, like, deeply onto something. Totally.

We've been talking a lot about safe to train and athletes and all of that kind of stuff. And unapologetically, that's our origin story. We were originally a product for elite and professional athletes, and that DNA very much, like, still guides a lot of what we do. But at the same time, there was this incredible paper that had come out in 2011 by Dr. Sherry Ma at Stanford, and she had this very intentional sleep and recovery protocol. with the Stanford men's basketball team. And one of the unexpected outcomes of this, like,

hyper-intentional recovery thing that she did was she noted that they didn't have a single, like, athlete out sick the whole season or something. It was like they had no missed games due to, like, no colds or whatever. I forget exactly what the language was, and that that was remarkable and noticeably different from other seasons. And that actually makes a ton of sense that, like, you know, when we talk about this ability to essentially, receive a stressful stimulus and the difference between a stressor making you stronger or weaker,

right? A infectious agent is also an example. It's not just a workout, right? Our immune systems get stronger every time we fight off bugs. And for those of us who are not immunocompromised, we're getting exposed to, you know, illness-causing pathogens every single day that we just, you know, you get infected and you fight it off without ever realizing you're sick and then your immune system gets stronger. And eventually we know that like people who are sleep deprived, people who are like not productively stressed, people who aren't

eating well, the same controlled exposure to let's say a cold or a flu virus results in illness. So like symptomatic sort of progression of the disease far more often. And so what was cool is like our recovery scores also predict sort of whether or not you're going to get. seasonal colds, you know, even in people who are definitely exposed to them. We also noticed this was like one of my very favorite aha moments was actually it was a professional athlete and he and his wife were both on whoop and they noticed that when their recovery scores were red that they were snapping at each other. And so they implemented this like very sweet marriage saving protocol around like if either of them were red, they would be more mindful of

giving each other space. And he actually wrote to us after a couple weeks and he was like, whoop saved my marriage. And what I loved about this story was just like, again, it was like not what the recovery score was at all built for, but it makes a ton of sense that like when our bodies are depleted, these little things that, you know, in a ideal world, you forget to say good morning nicely to me or you just, you roll it off and you're like, you're more forgiving.

And if somebody says something a little bit weird, you're likely to sort of think before you respond. But when you're exhausted and depleted, we get into this very like reactive instinct-driven mode where we're snappier and we don't give people the benefit of the doubt and all these things. And so what we've seen actually is we have loads of like Fortune 100 CEOs who use whoop and like cancel important meetings if their recovery scores are read because they don't make good decisions. And like there's so many different ways where if your body is in a state where you can be adaptive, where you like have control over all of your faculties and all these things, when a stressor hits you, your ability to, like, show up in the way that you want to and are going to be proud of is just much higher than if you're very, very depleted. And so you have both

the very physical thing of like, are you more likely to just start accumulating a stress fracture in the case of sports? But you also have these sort of harder to pinpoint things like, you know, are you going to do like the moral equivalent of stress fractures in your relationship? So are you doing the moral equivalent of like stress fractures to your immune system? And so then all of a sudden it's going to show up in all these other ways. And so the thing that for me has been so cool about their recovery scores, we've only ever fit it intentionally to this like athletic performance injury prevention metric. But then when we go and validate it, you know, it predicts reaction times.

It predicts like. I was talking efficiency, exit bat velocity, exit ball velocity, well, that's all the sports stuff. Yeah, yeah, yeah. You know, it's been, you know, validated in sport after sport injuries and during 5K training programs and different things like that, but then like workplace satisfaction. And mental capacity to handle the demands of work is precisely tied to autonomic nervous system functioning. Which for those who aren't familiar is exactly what heart rate variability or HRV is measuring.

And is an input into our recovery score. Which is the most significant input into the recovery score. So heart rate variability, it's a little bit, if you're not familiar with it, it sounds like it's about heart rate. But what we're actually looking at is the variability or the change. from the length between successive heartbeats. So a lot of people, if you're not familiar, might think that when your doctor takes your heart rate and says, okay, your heart rate's 70 beats per minute,

that it's almost like a metronome beating evenly, and that's actually very much not the case, which is why we tend to measure heart rate, you know, in a doctor's office over the course of, say, 30 seconds or something like that, and then you average the sort of average beat-to-beat interval over that time to get what gets reported as your heart rate. but it turns out that the amount of time variability from beat to beat is caused by your autonomic

nervous system activity. And so the more balanced, they say your nervous system is between the two competing branches, the sympathetic and the parasympathetic, the more variable it is. And that means like sort of the more capacity your body has to respond to changes in your environment as needed. I want to go back to something you said because I think it's really important. And you did a beautiful synthesis of just what happens when you're kind of consecutively under recovered, right? Like you're basically taxing the system, taxing the system with no reprieve, right? And that's, I think, precisely the utility of recovery.

It allows you to course correct, right? It gives you some insight into, wow, okay, I'm not actually adapting in a functional way. Therefore, maybe I need to extend my sleep slightly and just get back into stable sleep, wake time. I need to maybe pull back on my alcohol. or, you know, whatever the, it will get into recovery detractors. But, you know, just kind of like course correct my behaviors a little bit so I can get back on track, right?

And without this insight, one could argue, you can end up going down this slippery slope without course correcting. Or maybe you course correct a couple weeks. And now you're really in a situation where you're in a hole. And getting back to where you need to be is much more of a climb than if you had recognized that within a couple days and course corrected and got yourself back. on track. So I think that's where I find, and that's what we see, certainly see in the data, is that individuals who kind of make recovery a way of being in the world, right, and really

mapping this kind of stress and rest in a proactive way, far better in all the ways that you described in terms of illness prevention, injury prevention, right? Like when you look at things like markers like bone density and, you know, advanced labs, you know, biomarkers, right? Like, when you are proactively managing your stress and your rest, the world kind of is oyster in some ways. Yeah, and I think one of the things that you were kind of getting at that's so important to highlight is that often by the time you're consciously aware that you're under recovered, you've gone really far. And what's so powerful about measuring heart rate variability, whether it's with whoop or anything else,

is that it can pick up on these little subtle things, kind of pre-symptimimatically. if you want to, can you use that language where we can help you course correct before you have consequences of under recovery so that you don't have to reach consequences of under recovery. And so that was really the idea was just two pieces. One, we wanted this objective third party because so many, again, back to sort of the athlete origin story, high performance athletes have so much motivation and drive sort of grit. that they're actually very good at ignoring their body saying to stop. Yeah, pushing through.

And that is often celebrated. And it is important to a degree. I don't think anybody becomes an Olympic athlete without pushing through. So you have to build those skills. And often their coaches push too, right? And that's their job. And so having this objective third party to be like, wait up, when neither side are going to say like, let's do nothing this week and just, you know,

was very helpful. And then the other piece was truly we can tell you something before even somebody who's highly in tune with their body might consciously be aware that something's going on. Yeah. And I think for folks who, you know, might, are on the platform, you might find themselves not recovering and maybe are not sure why. It's not entirely obvious to whoop coach and just ask, you know, and you'll probably get some really interesting insight about maybe the type of structure.

drain you're taking on, you know, the duration, the intensity. There might be some insights specifically about your sleep that you might not be thinking about, right? That we know, you know, sleep quality has a really big impact on heart rate variability, which is also, and they're both kind of inputs into the recovery score, so it's a little confounded. But it's all related, you know, and you might, you know, an insight might surface that you can, you know, correct to get you back on track. Yeah. So let's like double click on that. And what are a couple of the things that might cause you to be struggling with recovery. And so one of the first things that I always look at with somebody who's had a bunch of red

recoveries in a row where it is feeling under recovered is, you know, have you increased your training load? That's going to be kind of an obvious one, especially if you increased it by a lot. We've definitely seen people, you know, that they have their New Year's resolution and they're ready to go hard and they jump in, you know, feet first into the deep. And, you know, while I respect the motivation and all of that, you know, some of that could be adaptive, right? If you're noticing your recovery's low, but you're feeling good, and especially if it's only been a few days, that can be okay. That could just be your body saying, whoa, something's

different. But if you kind of feel like, wow, you know, I haven't really, that's not me, but why has my recovery been down for a couple of days? You want to think about stress that you might not be as aware of, right? A workout stress or tends to be kind of obvious, but, you know, are you experiencing any kind of emotional stress from work, from relationships, anything like that. Any kind of decrease in sleep quality is a place I tend to look for really quickly. Stress in the form of changes to your environment that can be maladaptive. This can be allergy season for those who suffer. Air quality is a huge one for a lot of people.

Even just like when it gets hot out, if you, you know, don't heavily climate control your bedroom, if it's just a couple degrees warmer, that can make it a lot harder to thermoregulate. We actually see sleep stress goes up. And so people don't recover as well. Similarly, just given that it's the middle of the summer right now, it can be easy when it gets warmer to not increase your hydration levels. And so dehydration can cause poor recovery. And the other thing, especially as so many of our members are reporting, taking GLP ones,

you do want to think about nutrition. You know, with people on GLP ones, it could just be easy as you're eating less to become micronutrient deprived. If you're dieting without the use of any kind of medication, you also run the same risk, although you tend to go slower. And so the risk is somewhat mitigated by that. But you do want to be really thoughtful around, you know, are you getting enough protein, especially if you're cutting calories to make sure that you're not just cutting everything equally,

but cutting junk more than the really important stuff. So are you getting enough protein? Are you getting enough iron? Are you getting enough? Yeah. And, you know, to kind of shout out one of my favorite features on Woo, if this sounds like maybe you where you're like, oh, my, My diet has changed.

If you, like, would give a new name to your diet, like, you've recently become a vegetarian or you're trying paleo, or even if you're trying to do a diet that, quote, unquote, is healthier. But, like, if you're going all in on the Mediterranean, if you've, like, meaningfully changed your diet, it is really worth thinking about, like, could I accidentally have removed a nutrient group that's helpful? One that can be sneaky also is even salt, right? Like, electrolytes have a lot to do with, you know, your ability to retain. water. And so like if you cut out a bunch of salty foods and your body just like was expecting more salt for its fluid balance, all of a sudden you might actually become a little bit dehydrated and not realize it because salt helps us retain water. And dehydration will immediately. Totally tanking recovery. Yeah. Totally tanking recovery. So to shout out one of my favorite favorite

features, you know, that can be a really good moment to think about doing an advanced lab's blood test. Because it will tell you, is there anything clinical going on or subclinical? that might explain why I'm having trouble recovery. So if you can't pinpoint like, oh, yeah, it's my sleep. Oh, yeah, it's because, you know, I went from zero weight training to one rep max deadlifting every single day, which I do not recommend. But if you did that, like, you know, you don't need to run for blood work. That's probably the reason. But if you can't kind of point to this temporary thing explains this, and I, you know,

I know everything will be fine, but you're kind of wondering, what's going on? And is there something I need to pay attention to? this blood work will give you a lot of those answers and make it much easier for you to quickly correct it because the great news about some of these like micronutrient deficiencies is while they can be really nasty and unpleasant to deal with they are so easy to fix for the most part you know there are certainly more extreme absorption issues and things that can point to bigger problems but if it's just you've changed your diet a little bit maybe it's seasonal eating and so some food group you didn't realize you've kind of eliminated your best source of iron or your

best source of whatever, and there's sort of no other underlying issue, you start supplementing or you add those foods back in, and all of a sudden you'll notice you feel more like yourself and recovery scores bounce back. Altitude is also a big one. Yeah, that's definitely, meaningfully change. We'll definitely tank your recovery until your body adapts, and again, hopefully something you would know about yourself that you've changed altitude. And so my general advice is do not get worried if you notice really bad recovery scores, but also expect them. So if you're going, you know, skiing or just traveling or whatever and you know you're going to be in a higher altitude, you really want to think about doing recovery promoting behaviors and potentially

depending on how much you need to perform, whether that's in sports or life at this higher altitude, giving yourself a day or two to acclimate. Yeah. Especially if you have had trouble acclimating the past. That's a really good point. I was talking to Frari this morning. You know, we were doing our debrief and looking at their data and then kind of planning for Q4 where they have just a lot of the most intensive kind of,

it's the back third of their season is the most intense and is going to be extraordinarily demanding. And this middle third is really where they're staying mostly on their home time zone. So travel obviously is a huge disruptor, sleep wake, inconsistency, a huge disruptor. One of the things that I'm noticing with Ferrari, which I think is very much amplified given the fact that just the demands of their work, the demands of the travel, you know, there's the whole thing kind of, I think, magnifies recovery, right?

And one of the things that we're seeing is that when you're creating buffer in the system, in your downtime and when you're away from your craft, when you are really dialed in, you know, and this is kind of the cross that I think folks in these type of high stakes, high stress environments bear is they kind of have to be perfect in their downtime. It's the reality, right? So when you get to race day, which is basically four red recoveries in a row, it's usually at least 50% yellow and the other 50% of red. So two and two for some folks.

For the individuals that have buffer, it's yellow and then it gets to red, right? And then what's interesting is they bounce back better post-race, the individuals who have more buffer in the system. So that is, are more primed, more recovered going into the stressor. So that's another way to think about it. we might we don't all work for f1 we don't all have these high stakes high stress environments but if you're going into a patch of time where you know you know maybe where it's going to be highly stressful maybe it's a patch of travel or whatever it might be build that buffer in the system you

know really try to manage your recovery as proactively as possible and i would make the argument that that's again once you get accustomed to it it becomes a way of being in the world so when life does pop up your child gets sick or injured or you have a mom or dad who gets sick. You have that buffer so you can go into it and not crush yourself, you know, as you navigate maybe a hard time, if that makes sense. Yeah. Yeah, and that's actually something we've seen on several different timescales. That's really interesting in our data. Like we published a paper back in 2020 and we looked at sleep patterns prior to the COVID pandemic.

Love this baby. And whether, and then we looked at. at basically like acute mental health events six weeks post-pandemic. Even if in the first six weeks of the pandemic, you know, you showed a lot of signs of being stressed and had highly disrupted sleep. Six months of sleep prior to the pandemic was an incredibly strong predictor of whether or not you had an acute mental health event six weeks in. And what was fascinating to us was it almost didn't matter how many like signs of stress you showed during those first six weeks. What

mattered was like what was your baseline when you got hit with this stressor. And what was interesting is we weren't looking at people who got COVID. We were specifically looking at like the stress around social distancing and your life getting shut down and all of that. So in people who still were not sick, but we're very much, you know, sort of looking at like the zip codes where there was high COVID burden. And so it was scary and you were locked down and all those things. And it was so cool and powerful to see that if you are disciplined when life is going well, you build up this resilience and protectiveness that even if your life falls apart a little bit, you fare way better and can kind of weather that disruption, even if you are very much disrupted, far better than

if you're already kind of depleted going into that exact same stressor. And so, you know, I think about that a lot, especially because it's tempting when I have nothing to do this weekend. So, and I don't need to perform tomorrow so I can like go and stay up later, like go and like do these things. And it's not that we should not enjoy life because of course we should. But if you take those opportunities to to sort of stay the course and build resilience, like you truly are pocketing that for, you know, whatever life throws your way. I love that. And the paper that you brought up and hopefully we link to it in the description, but prior sleep weight behavior predicts mental health during the COVID-19 pandemic, I think is the rough title of the paper,

but it's a beautiful piece of work that you and Seisler and others collaborated on. But I think this idea, and to me that's the most important, from my perspective, the most important takeaway about recovery is this idea that it's not just a weak thing or a month thing. It's just literally a way of being in the world, right? And I know just in my own life, this idea of recovery has changed the trajectory, of my life, you know, in terms of my ability to be available for the people and things that I care about consistently, you know, and I think that's the promise of recovery, right, is being

able to consistently show up for the people and things that we care about in our lives, you know. So Emily, as the creator of this incredible metric, I thank you, you know, for, I think, changing not only my life, but a lot of people's lives, you know, and it's absolutely incredible. So to close it out, if someone ignored everything else, just followed recovery daily, how much fitter actually would they get? And we have some data around this. So we actually have some fascinating data around this and it's actually, it's a little bit different than what you might expect. So we have a lot of anecdotes, which is actually not what we built any of these things for. But there's the recovery score. And then when you say like following recovery, every morning

based on your recovery score and based on your menstrual cycle phase if you're a naturally cycling woman, you will get a recommendation through a feature called strain coach, which is basically what an appropriate amount of strain would be or maximally appropriate, which is based on that idea that we were talking about at the beginning of this conversation that there's sort of a limit up to which point you will get a functional adaptation. After that, you will get sort of no continued ROI, and then eventually if you keep going, you will get negative ROI. that is a bit of an oversimplification because there are definitely elements of training that are a little bit more nuanced. For example, in the military, one of the things that like the Navy will do to you in part of like seal training is like they make you drown.

And like part of why they drown everybody is because you actually have longer than you think before you lose consciousness. and it is critical to being able to do that job, to not panic, and to know how long you take, right? And so, like, there is an exercise that all seals go through, which is, like, where they will drown you to the point of losing and conscious, and then they will arrive you. And you're fine. It's all, like, medically supervised. But, like, that is an example of, like, is that good for you? No. Is that probably really life-saving and important in that context?

Yeah. So, like, there are definitely situations where it probably makes sense to, like, know you can push your limits and to, like, go to the absolutely. limit and do things that are sort of in some other dimensions bad for you. And that can make sense. So let's put all of that stuff aside. But in the sort of normal, like, am I going to get fitter from this training stimulus? There's a sort of, yes, the more you do, the more fit you will get, up to a point. And then eventually you get these like sort of, it starts to make you less fit and less healthy if you keep going. So we were like, how can we help people know, like what that limit is based on where they are today? And that's our strain, a coach number. And so you get this,

this strain target for the day. Woop has this fun feature. If you're on a four or five adetto product where it buzzed when you hit your strain target, it's very fun when you get that little haptic notification. And you can stop immediately. No. But you just get your celebratory moment.

And there's definitely some buffer around it. Yeah, of course. We did a study seven years ago called Project PR. And what we did was we took a bunch of people at various training levels and we broke them into two demographically matched groups, a control group that did a 5K training program. We worked with two former Olympic athletes, but created a static plan that everybody was going to follow. In our interventional group, which was, like I said, training experience-wise and everything demographically an identical group, they had that same plan, but if they woke up with a yellow

recovery score, they reduced their training by a certain amount. and if they woke up with a red recovery score, they didn't train at all. At the beginning of the study and before they were divided into groups, everybody did a sort of baseline 5K race, and then I think it was a 12-week training protocol, and then they did another 5K. And so you might imagine that because the control group that just followed the plan as written,

did the prescribed training amount regardless of their recovery score, but the interventional group did at most what was prescribed, basically if they were green, but if they were yellow and red, did meaningfully less, that intervention group trained a lot less. They had about a third last total training volume. What was fascinating was that there was no difference between the groups in terms of the improvement to their 5Ks. What was even more interesting is that that control group that didn't reduce their training had much higher rates of injury and lots of dropout because of those injuries. Right.

So what was so fascinating to see was basically this validation of a recovery metric that when you keep training beyond what your body is capable of, you might finish the miles. But your body can't translate that into getting fitter. And so this control group did a lot more training. They spent a lot more time, objectively worked much harder. And they had not only nothing to show for it, but actually a lot of injuries because of it. this control group or the interventional group that did as much as sort of their body was capable of and rested when their body said it wasn't. And by the way, we didn't tell them anything in terms of like they weren't specifically instructed to try to have green days. Right.

They were like if they drank, if they did whatever, like if the red was totally their fault, it didn't matter. But like they had to respect it. And we did, of course, this whole group was wearing whoop during the time. So we also were able to confirm that they followed the protocol as. programmed, yeah, as directed. And we thought that the primary difference we would see is differences in the gains. What was so interesting was that there was no difference and that like this injury rate, which was a sort of secondary outcome of the study, was so dramatically different.

And so to answer your question about like how much fitter do you get, you could look at the fact that that control group had so many injuries and, like, therefore, are probably benched for a while and, like, lose fitness in that moment as, and also just knowing the importance of consistency for fitness. Like, it's really hard when you're trying to be consistent to look at a red day, maybe when you had, you know, plans to go to the gym and, like, give yourself permission, you know, not to quit, but to respect that red recovery and to rest. But it's powerful to know there's not a lot good that's going to come from this. You are not going to hit your goals by essentially throwing a stimulus at a body that is not

in a state where it can convert that stimulus. And I think that's like the new mental model that people need to internalize. That it's not like every time I curl this bicep, my muscles going a little bigger, a little bigger, a little bigger, right? It doesn't work that way. It's actually, it's getting smaller and broken down and sad, but it creates this basically like chemical signal to my body, like this bicep, needs to grow. And then during slow wave sleep at night, if I am capable of it, I will produce

growth hormone. Which is the mother of all recovery. I will produce growth hormone. And because there's all these signals that say, wow, this bicep is not strong enough. Like it was really struggling today, right? That's the stimulus or the signal that I created while curling. Then at night, it will grow stronger. But I have to be nutritionally and like sleep wise and all these things in a state where my body can produce that growth hormone, mobilize the resources, right? So protein needs to be on board, all these things, and stick them here, and then I wake up with the bigger bicep.

Right. And so it's like you do have to, like, line up all of those little ducks. The training stimulus is absolutely critical, but like what follows and that ability to mobilize those resources and have them on board equally important. And so if that's just not true, right, I'm nutritionally depleted, I'm exhausted,

I'm not having good quality sleep, all I'm doing is, you know, forcing the muscle breakdown, down as I curl that weight. And then at best, I'll, like, kind of heal the muscle, but not really, like, grow it back. And so I don't come back the next day with stronger muscles. And so I think that's, like, what's super cool. We have seen some anecdotes from members who have used whoop in a little of, like, an off-label way and done things like, you know, in the spirit of weight loss, just been like, I am going to hit this recovery or the strain score every single day, no matter what. And they,

they use strain coach and they hit that number. And they just find that very, very motivated. and those people, anecdotally, we haven't properly studied this, like, report really great results. And I think it's more... Well, this will go into peer review. Yeah, you have... You have the data. You have a proper study coming.

We've had a ton of anecdotes over the years of people doing this just kind of end of one with themselves. But I think it's fair to say that we have analyzed the data, you know, properly and we will submit for review in a week or so, you know, so we've been preparing that manuscript. But I think what's phenomenal is that these aren't random... number generators. Yeah. I think that that's, you know, just to build on these anecdotes that you just shared,

you know, when people listen to strain coach, they do, and they indicate that they want to lose weight. They do, in fact, lose more weight than the individuals who are not listening to strain coach, right? So, again, you know, this is, it's all, you know, correlative, you know, but I think it's exciting in that, you know, this could potentially be a path, especially for folks who have never really done a lot of training, right, in a kind of a programmed attentional way, this could just be a great way to start, right?

As you listen to strain, which is based on your capacity, right, to get back to recovery, based on what what Woop says you can safely take on, right? And when you listen to that, you do get, you do get bitter, you know? Yeah, and can we talk about weight loss just for a second? Yeah, of course. It's actually really interesting. I think a lot of us have internalized or been told this, like, really unhelpful oversimplification of like weight loss is like just a story of calories in minus calories out, right?

When your body feels safe to let go of weight, it will let go of weight. And when your body doesn't feel safe to let go of weight in a calorie deficit, it goes into a low power mode. And so like part of why it doesn't surprise me at all that we've had these anecdotes and now you're soon to come out proper study on the subject is that like the story of like calories in minus calories out is so, so much more complicated than these little, like, you know, food tracking apps will lead you to believe because when you are over-training and your body is experiencing the calorie deficit as this, like, major stressor, we start to shut down, right? And that's when you start to see things like women lose their periods. And you actually get like bloated and like super low energy. And then you move less.

And then, of course, your calorie expenditure goes down, you know, and all the like time around that, you're metabolic rate drops all these horrible things versus like if you're, sort of, of taking care of your body and not over training, but going up to like what your body's capable of. It's almost like safer to let go of your fat isn't an energy store. It is a survival mechanism. Right. It is really, really important. And so our body does not like to give away our fat. You know, you have to be careful that like you're losing weight at a rate that your body's going to sort of allow that to happen versus essentially try and like fight back. To survive. Yeah. And so, you know, not training past what your body is capable of resulting in faster weight loss.

It doesn't surprise me at all. And I think mechanistically makes an enormous amount of sense. And it's something that, you know, I think is, again, like not at all what the recovery score was built for, but it's just so fascinating to see yet another example of something that it just naturally extends to. And I think that's the beauty of it being so deeply rooted in this concept of heart rate variability and therefore autonomic nervous system balance, which is it's just this like powerful global metric of your body's state. And so it just like dictates all these other things.

And whether it's, you know, reaction timing or like patients with other humans. Right, right. Or yes, like free throw percentage and all that kind of stuff. But then also like whether or not you're going to get injured. And of course, like whether or not you're going to be successful with weight loss. And so it's really, really powerful metric. And it's just been such a privilege and a fun journey over the last 13 years to watch. this thing that we very much built in an athletic lab at, you know, D1 Athletic University

for athletes, just be like, oh, and it can do this. And it's just like, I don't know, I wonder when we're going to find out what it can't do. I know. But it's been, for me personally, just like a fascinating metric to track. Yeah, I hope that everybody else is getting as much value at it as we are. Well, that was a beautiful framing, I think, a round weight loss. So thank you for that. I think that would be helpful for a lot of people who are trying to think through this

very, I think, kind of blood instrument of calories and calories out, you know, where there's not a lot of nuanced discussion, you know, with I think nutrition, exercise physiologists in particular. We obviously talked a lot about heart rate variability, which is the most heavily weighted input to the recovery score. There's also three other metrics as well that we incorporate resting heart rate, respiratory rate, and sleep performance. Do you just want to talk very briefly about why you've included those? And we could say, we could sign off. Sure. Most significant inputs are heart rate variability, heart rate, so measured during sleep, your sleep performance, and then your respiratory rate, which we actually added during the pandemic when we noticed

that your respiratory rate was a pre-symptom onset useful indicator of COVID-19 infections. That element has actually been updated, so we also do give a little bit of weight. We have replaced respiratory rate a couple years ago with a illness prediction model that also is including. So it's just slightly more robust. It's a little bit more robust. So there's some other stuff in there now. So not just lower track respiratory infections, but actually a broader category of illness.

Yeah. And so it's using metrics like your skin temp and stuff like that, although those are relatively less important in the model overall and really only kick in if the model thinks you are sick. Basically, we had this incredible data from our early partnership with the Corey Stringer Institute on these sort of objective markers of recovery. And then we had all these downstream targets of what we were. trying to predict. So that exit velocity, you know, free throw percentage, and then of course

all the project PR data. And so we're able to use that data and in aggregate kind of almost like reverse engineer with our inputs to the recovery score. What changes to the recovery score would have enabled us to predict these outcomes that we care about better? Because we have so many diverse outcomes that we've looked at, the more diverse outcomes we look at, whether it's, you know, ball exit or bat exit velocity all the way down to like likelihood of you know acute mental health during the pandemic all these different things based on sort of which ones you wait more or less you can end up with slightly different versions of the recovery score kind of emerging in that process and so we've partnered with our product team to think about what is actually the version that like makes the

most sense in the whoop context but like I said earlier you know it's it's 80% undefed changed from the algorithm that we wrote back in 2013. And so, you know, those core, core elements really have held up, which is pretty incredible to see. You mentioned acute mental health outcomes or events. So this might be just a good time to make sure listeners understand that heart variability and recovery is not just a predictor of your training stimulus and, you know, but it's also a very much a psychological mirror as well. So you can think of it as kind of a psychophysiological mirror, hearty variability. And we have this beautiful story from Reddit that I always bring up because I think it just is, number one, like I just am grateful that this individual posted it. But, you know,

he had really suffered a pretty, you know, deep depression and sought therapy. And basically, he posted his six-month trajectory of his HRV over the course of, you know, the six months of therapy. And it was just this really beautiful steady climb, you know, where I think he maybe started out at 30 and I think he ended maybe around 70, you know, was the post. And I think that is a, and this is very well documented in the literature. There's lots of evidence, you know, linking heart variability. And so just so folks understand, you know, if you do have, you know, a lot of of psychological distress or there's something going on from mental health perspective that will be reflected in your heart rate variability. So it's not just this kind of physical response,

but it's also very much psychological as well. It's very well said. And it's also fascinating to see that there are so many stories like that. Even before people admitted to themselves maybe that they were very stressed, they're seeing it in their data. And we've had people, we actually had one example really early on at Loop where one of the athletic teams that had bought Loop, the coach was like, you know, kept emailing us. Like, this isn't working. It's like one of my best athletes. And it said she's like the least recovered of everybody. What's going on. And like kept sending us these messages. I think you were. Yes. I think I was sending them those messages. You're probably the one dealing with these emails. But it was just like this one athlete

like could not recover. And the coach was like really frustrated with us. She was a swimmer. Yeah. Do you want to finish the story? Yeah. I mean I, well, no, no, keep going. It turned out that she had this horrible thing happening in her family, and she was just insanely stressed about her mother's health. Oh, yes. This was her mother's breast cancer diagnosis. Yeah, yeah, yeah. And just the way that that was showing up in the data,

I think that was the first time we'd seen something like that where she hadn't shared that with her team or her coach yet, and the coach was seeing this in her whoop data. And first was like, your product is wrong. We're like, I don't think that's our product. And then she went to the athlete and was basically like what's going on and enabled them to have this conversation that probably needed to happen because this athlete needed to be loved on a little bit.

Just like the power of that information and like how it can show up in all these unexpected ways. Yeah, yeah. There's this, that specific one. I was thinking of the swimmer, but that specific one was actually a volleyball player. But yeah, it was just a very interesting. It was the Christmas break and things happened over break. And yeah, and this athlete was really thriving beforehand and then was faced with this, you know, terminal diagnosis that her mother received.

Yeah, it just, it gives me chills and, like, you know, makes me emotional think about it, you know, but because it was just such a daunting time for that athlete. But I think, you know, a lot of folks, I think for this athlete in particular, like, had never really confronted anything like that in her life. And she just didn't know how to talk about it. She just felt like, you know, she didn't want to, like, reveal, you know, this to the team, you know, but clearly the data showed that she was suffering, you know. And I think what this enabled is just a conversation, you know, that,

And I think the support that she really did need ultimately, you know. And I think also, like, it might not have been safe for her to continue to train the way that she had been before. And so hopefully not just enabled sort of the external support in the conversation and all those things, but actually for, you know, for the environment to be changed, you know, to support that. Right. And just the recognition that these changes in an autonomic nervous system functioning, you know, are not just about how you're moving your body, you know. And I think that that was a really powerful lesson. And I think for us, you know, too, to be like, wow, this can manifest so acutely, you know,

in the armory system and how we can actually measure it, you know. And that was like one of the more inspiring moments, I think, of just seeing the data in action and seeing that intervention take place and seeing and observing how that program rallied around the student got her to a better place. You know, it was just like, it was really a, yeah, it was really cool. Lymley, thanks for the discussion today. Thank you for having me. I get emotional about wood recovery.

But yeah, it's been an incredible journey. And thank you again for all of your efforts and collaborations, I guess, over the years, you know. Me too. Yeah.