We continue our recovery month with interviewing Chris Schneider. A PhD student in Athlete monitoring & heart rate measures. Chris has contributed to several scientific papers relating to this topic including his leading author contributions in the paper 'Heart rate monitoring in team sports - A conceptual framework for contextualizing heart rate measures for training and recovery prescription'. I chat with Chris about the relevance of heart rate for the recreational runner and where the current science sits on its accuracy. We then dive into factors that can influence your heart rate and when you should be cautious with interpreting this data to make smarter training decisions. Finally, Chris shares his views on the practical implications of heart rate monitoring for the recreational runner, whether it be during exercise, or during recovery. This episode ties in well with our last episode interviewing Simon Wegerif on Heart rate variability and the clinical relevance of its data. Click here to find Chris Schneider on Twitter If you would like to support the podcast, participate in Q&As & access bonus material sign up for $5 per month at our patreon page For Brodie's running blogs, podcast episodes and online courses visit our Run Smarter Website To follow the podcast joint the facebook group Becoming a smarter runner To find Brodie's running information on instagram @runsmarterseries
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On today's episode, Heart Rate Data Insights with Chris Schneider. Welcome to the Run Smarter podcast. The podcast helping you overcome your current and future running injuries by educating and transforming you into a healthier, stronger, smarter runner. If you're like me, running is life. But more often than not, injuries disrupt this lifestyle. And once you are injured, you're looking for answers and met with bad advice and conflicting messages circulating the running community. The world shouldn't be like this. You deserve to run injury free and have access to the right information. That's why I've made it my mission to bring clarity and control to every runner. My name is Brodie Sharp, I am a physiotherapist, a former chronic injury sufferer, and your podcast host. I am excited that you have found this podcast and by default, become the Run Smarter Scholar. So let's work together to overcome your injury, restore your confidence, and start spreading the right information back into your running community. So let's begin today's lesson. Continue this recovery month in particular we've got part two of heart rate week and I hope you enjoyed the episode with Simon Wagerith talking about heart rate variability. This one is going to be focused just on the heart rate side of things even though Chris Schneider is very well versed in heart rate variability we do delve into it a little bit but by way of bio Chris Schneider is a sports scientist in Germany. He is a PhD student in athlete monitoring and heart rate measures, has contributed to several literature publications on these topics, and is the lead author on several papers that are relating to heart rate measures for training and recovery prescription. A great guest to have on, right? This one is a great interview. Chris Schneider is very like softly spoken. I did. have a few issues with his microphone. I did enhance a lot of his audio wavelengths when I did my editing. So apologies if you do notice a bit of inconsistency when it comes to the sound volume. I think it turned out really well. And as long as it's not too soft that you can't hear, I think it's pretty good. The content is fantastic. Chris is quite softly spoken. And he told me at the end of the interview he was actually quite worried about his English. And I thought it was absolutely perfect. A lot of the stuff I say doesn't make sense, but he was very meticulous with how he was talking. He was very calculated with what he was saying, very scientifically driven. Um, he has this particular view, even though he's done a lot of papers on this. It's a very unbiased view around heart rate for monitoring athletes. And it's not this like real flashy sexy content that everyone wants where you get a guru on and they say this is the be all end all these are all the magic benefits it'll have this is all the amazing effects. In reality when it comes to science and what we can say based on the data that is available apparently well it's not really that flashy and sexy it is very raw it's very honest it's very up to date and I know. a lot of runners or some runners, they're not too interested in heart rate. Maybe this interview isn't really for them. Others are really constantly monitoring their heart rate and wanting to know what their heart rate is like outside of running, inside of running, after running. And this would be right up your alley. So we definitely start off talking about the negative. I won't say negatives. I'll say more of the inconsistencies of heart rate and what you should be very cautious of what you should be wary of. interpreting your heart rate data. And then we sneak in some positives at the end. So enjoy this conversation. Next week we have Shona Halston, who is a very well-recognized professional when it comes to recovery. She has been featured on several podcasts, books, articles, and her wisdom and expertise is she's almost like the guru when it comes to recovery. around the world. So we speak to Shona and then we have also next week, Christy Ashwandon, who is the author of the book Good to Go, subtitle, How to Eat, Sleep and Rest Like a Champion. These two are going to be like this one-two punch in terms of recovery. You're going to love those next two. That is for everyone. So I'm excited to bring you that, but let's dive into heart rate for now. So without further ado, let's bring on Chris Schneider. Thanks for having me, Brody. You're very welcome. If you, we might just start off with, uh, introducing yourself and your academic backgrounds and how you found yourself into this, um, specific research topic. Well, um, I grew up really countryside. Um, like we had five to 500, 400 to 500 inhabitants in our village. So really, really small. And then. was got interested in training and sports science and then moved in the city to study sports science. Did my bachelor's and master's there. And afterwards I got lucky to start a PhD on ethnic monitoring using heart rate measures. And yeah, meanwhile, I also tried to work as a coach in between. I grew up as a basketball player. So therefore basketball was my initial starting point. And then... got into the strength and conditioning more and more interested and also, um, become coached there until up to semi-professional basketball level. And, uh, now I'm working at a university and also at a sports medicine Institute. And yeah, that's basically my background. Cool. And coming from a basketball background myself as I wish you had that common interest. That's nice. Uh, your paper that, uh, you directed me to heart rate monitoring in team sports, heart rate measures for training and recovery prescription. It's a very interesting title. What were you aiming to get out of this topic? What were you trying to learn? What were you trying to achieve? So maybe I have to go one step back before we start with the actual topic because like the entire PhD was implemented in a big recovery project that my boss was working on with a couple of other colleagues. And therefore, heart rate measures is like one tool of the many tools that could be used to track recovery and recovery processes was always one option. And therefore, I got into the heart rate measures. And because we are also working a lot with team and game sports and record sports, that was always like the overall aim because we're Most of the subjects, most of the teams we are working with were always team sport athletes. And the question was in the beginning, OK, what does actually the literature say at the moment? I was reading around a bit. And most of the time, the authors concluded, OK, there might be some value in heart rate or heart rate variability measures in game sports or even in other sports. But at the same time, you need to contextualize all the information. You need additional measures. You need to. consider the training content and so on and so far. And the original idea was that I sit down, read a lot of papers, and summarize how could we actually do the multivariate monitoring or the multidimensional monitoring. And that was the original background. So I tried to find some of the suggestions and hopefully some of the solutions that others are suggesting that might be useful to work with these measures. And I tried to, yeah. outline this a little bit in the paper. That was the original aim. Okay. And if you were allocated to the heart rate variables, what were your other colleagues, what were they delving into? So we had a huge part of, basically we did almost everything. Like there were a couple of review papers before and because we were funded to work with elite sports, elite sports in Germany, basically. The big question is, okay, at the end, we have some good evidence for that physiological processes of different recovery interventions will work and so on and so forth. And therefore we could see like blood measures change, subjective measures change, but at the end, will it also always impact performance as well? So therefore we did several studies with different training contexts. where we did all of the different measures, lots of blood measures and performance measures, sports specific or training specific performance measures, non-invasive measures like heart rate, tensiomyography. And we also developed the big research group, which was a big research group at the time, also developed a questionnaire. Michael Kellman did that. And all of these measures in different training contexts and always with the main background. does performance change as well in response to recovery, in response to overload? And that was the main setup. And then we looked which measures were sensitive to fatigue and recovery changes in a different training contexts. Yeah, I think as we get, I think we'll delve further into that throughout the interview. And I think we might come to a nice, well, probably not a nice conclusion, but like a nice plain English of where we're currently at. And- conscious of the fact that a lot of the listeners are recreational runners that might not have a massive like scientific background in understanding a lot of the how a study is actually designed and you know, all the technical jargon that goes along with it. So I guess based on your current research and what you have found, what can heart rate currently tell us as a measurement of data for when we're exercising and also. when we're resting, are there any conclusions currently of what we can, what useful measures we can use it for? I think we cannot take it down to the measurement like as the main outcome, because the heart rate measures are really much dependent on when you measure them, on the which context and on which situation. And then also what it tells us changes dramatically. So basically, if we're talking about resting measures, for example, the first thing that you do in the morning, the typical resting heart rate, or nowadays with all the applications and so on, heart rate variability, is something different than if you're doing autostatic tests where you have some active standing up, for example, after a lying period, or when you are looking at heart rate measures during exercise, at the beginning of exercise, for example, how quickly does heart rate change and adapt at the beginning of when you start from resting to exercising, then how's the heart rate during exercise? How high is it? How low is it? And how quickly can heart rate recover afterwards? And all of these different things, all of these different situations with the same measures, like some measures of heart rate, exercise heart rate, resting heart rate, and variability, then they tell us probably different things and also impacted by different. influencing factors. So basically, a really, really broad suggestion, which is mainly focused on a really great review by Martin Bouchette from 2014, is like resting measures is probably more related to the overall state, like overall recovery state, for example, or overall fatigue state. But it does not necessarily tell you how well you are able to cope with exercise stress. because responses may differ then. And when we then look at exercise heart rate, for example, we have a really standardized workload. We just do an easy jog as a warm up. We have a submaximal test when we talk about team and game sports. And then we just look at the standardized exercise about what is the heart rate at this. Most of the time, we think of this like relative intensity. For example, I have at 12 kilometers per hour. 80% of my maximum heart rate. And therefore, my relative intensity is something like 80% of maximum heart rate. So we can think of this like individual relative intensity. And also, it's really well associated, at least under steady state exercise, with energy expenditure, for example. And in contrast to resting measures, it's typically less associated with fatigue or recovery. That's at least the main idea, like exercise measures. are typically suggested to be a little bit more stable and a little bit more associated with actual aerobic fitness, but less associated with recovery. And then again, looking at the kinetic of heart rate changes, like the changes in heart rate at the beginning of exercise, how quickly is the acceleration, and how quickly is the recovery. Then again, there's the idea, OK, we may be able to see how good is the autonomic nervous system responding to these changes in workloads. And therefore our good is recovery and fatigue again. That's at least the basic idea. Okay. So you're to exercise more fitness, put it into rest, more fatigue and recovery. That's the idea. So if you were to measure your heart rate, just over a couple of days, continuously, there's a couple of measurements. One could be how quickly you're recovering after exercise, like how quickly your heart rate goes back down to kind of baseline resting heart rate. how quickly it adapts once you start exercising, what the sudden change is like in exercise or response to exercise. And then you're looking at certain intensities or how like when you're working at certain intensities, how close your heart rate is getting to max heart rate or how I guess submaximal it is at different levels. And as you're monitoring these through the rest period, through the exercise period, you can start to use it as a piece to the puzzle to depending on or to predict or to have as a bit of information of what your body's doing, how healthy you are, how quickly you're responding, the accuracies of that heart rate, like how well we should rely on that data is another question. But the fact that we're using that measurement as a piece of the puzzle can be helpful. Is that what you're saying? Yeah, I think so. But we like Again, we have to be really aware that when we are putting this heart rate measure in different situations, it may tell us something different. Yeah, definitely. Okay, also, I was I was previously talking about fitness. I mean, we always talk about endurance or aerobic fitness. And when talking about heart rate measures and fatigue and recovery, I think it's also important that we mainly can take or make conclusions about the, again, aerobic systems or autonomic nervous systems, like heart rate and heart rate variability would probably, at least from my opinion, never tell us anything about muscle stitches or how we feel. We have to be aware that our body, our recovery, our fatigue can happen on different levels, on different physiological or psychological systems. And heart rate and heart rate variability are always just one. of the puzzle, even when we're looking at the complex, um, phenomenas like fatigue and recovery. I mean, fatigue for a runner is something entirely different compared to fatigue in a team sport athlete or for weightlifter. At least in many cases, it would be different. In some cases it could be the same. And so we need to be aware that we are talking sometimes about different things, although we're using the same terms like recovery. Okay. When it comes to exercising. I know the topic, the theme of this month is around recovery and a lot of people don't like complete rest. They, they sometimes have a recovery day where they exercise at a really relatively low intensity. Uh, can we use heart rate for that? If we measure like their max heart rate and say they want to keep their exercise intensity below or at a certain amount, can we use heart rate and say, look, I don't want to. have my heart go above 140 beats per minute during this exercise. Is there some level of accuracy to that? Oh yeah, definitely. I mean, that was at least from what I know at the original starting point with measuring heart rate, looking how intense this exercise and therefore always coming back to what's actually happening with energy distribution. Are we working on our fats or are we still, are we already fueling a lot of carbohydrates and therefore how high is the intensity. I mean, this is really, really a good construct in general that works quite well for acute training prescription or just not over pacing during practice. But at the same time, we have lots of influencing factors. So it could be different if you're just looking at the numbers blindly, because we have many situations where this is not as good. overall really good association between intensity and heart rate changes. But if we are aware of some general situations, I think we can work with this quite nicely. I mean, the other thing is looking at your pace, but pace, depending on the, um, on the terrain that you're running at could also be difficult. And heart rate is at least partly suggested as also being reflective of the overall stress, like if it's harder, um, if it's warmer outside. heart rate is higher, but then again, it could also be, or it's quite plausible that the overall stress on your body is higher. So therefore, this higher exercise heart rate may even be a good indicator of the actual stress that you had. So I think this is a really good approach to not overpace, at least in general. But there are, again, also some situations, for example, it could be difficult, especially in endurance, in recovery blocks. weeks because I mean, when we talk about training camps, for example, where you are doing really high training volumes, there's also the quite common phenomenon that heart rate drops, the more and more you work and the more you fatigue throughout the high volumes, some situations and some factors that limit your heart rate to go up to the common values and therefore sub maximum heart rate will drop with fatigue. in overload with high volumes at low intensity. And also maximum heart rate will drop. And therefore, when you usually have a low, an easy run at 130 beats per minute, for example, and when you're then at some kind of overreaching due to really high volumes at low intensity, then even being below 130 could be an overload because your entire system is breaking you down. And then maybe 120 or 110 would be the sufficient stimulus to still keep you at low intensity at a low recovery run, you have to be aware of these phenomena. And I think an extremely good and practical approach is always at the same time look at how do you actually perceive the exercise? How hard does it feel at the moment? If your heart rate tells you something but it still feels tough, something has to be wrong. And this is probably the best indicator to validate what your heart rate is telling you. And this is what all the papers say. You need at least to contextualize exercise measures. with your perceived exertion, basically RPE, or just like hard, easy, moderate. And that's also in most of the studies, the only possibility when we can differentiate between heart rate is low because we get fitter or heart rate is low because we are overreaching. Yeah. And you're saying there- It's easier, it feels hard. And when you over train and the heart rate drops, you're saying that's quite common with like elite athletes or top performing athletes working at a really high volume? Not necessarily. And I maybe need to clarify myself. It's basically not over training. It's more like the overreaching states of when we talk about a short, short amount of times when we only have performance decrease or really high fatigue for a couple of days, a couple of, or maybe one or two weeks. So basically this is the situation what I'm talking about. It's better called overreaching. And this could also happen to the recreational runner. So for example, I was also working and supporting some recreational triathletes for several years now when they are at Mallorca in Spain and their training camps for two weeks and all of them over pace. And probably all of them will have a sudden heart rate decrease. during exercise at the same intensities, at the same wattage when they are on the bikes, at the same speed when you're running, because they are training at. amount of training after coming off the winter break and so therefore even for recreational runners, for fitness athletes, this can happen quite easily if you are at a training camp situation, for example. So you don't even have to be an elite athlete to be aware of this phenomenon and to face these problems probably. Okay, you did briefly talk about other factors that might affect heart rate. and some other factors outside of exercise that might produce some inaccuracies. When it comes to, I guess, resting heart rate, well, I guess resting and exercise heart rate, what are some common situations or common factors that might influence heart rate that we don't necessarily think about? What we don't think about, that's obviously something different between people. What's really clear is caffeine. Caffeine or really strong black tea, green tea, it will have an increase in heart rate. I would assume, but I'm not actually sure what the research says there, that intensities don't really change that much, but just the heart rate is higher. So therefore, this is probably considered and inaccuracy. At the same time, we often have, even in other situations, that nutrition can really influence the way that we work during exercise, like the amount of carbohydrates and fats that we actually fuel during exercise. So I would also suggest, or I would also assume, that caffeine intake will have an effect on how much fats and carbohydrates we burn. And therefore, maybe it again, gives us good information about what actually happens during training. But I'm not really sure about that. So caffeine is definitely one thing. Stress could be another thing, which, again, then could be that it actually is also a larger physical stress at the end. Temperature, sometimes it doesn't really feel that strong, but it could be even stronger. And this definitely influences your heart rate. during exercise and also things like okay when it's cold outside and maybe it's not that cold maybe the wind is not there and you are having too many clothes um wearing three throughout the runs maybe you have some kind of i don't know how you call it uh overheat and therefore your heart rate is increasingly high um and you are not able to run your pace anymore so this could also be a problematic situation but i think um A really important thing is also acute training influences, acute stress influences, like physical stress. And this is probably not so much on our minds. I personally observed only or saw only some more recent studies that also address this. So for example, if we are having really high intensity training, the next day, probably your heart rate is lower. Breast and heart rate, but also exercise heart rate. because we have acutely after high intensive training, quite often an increase in plasma volume. So therefore, even at the same intensity, we have more plasma volume. Therefore, heart rate will drop during exercise. And this is something that we observe very often. People feel fatigue, but they are due to high intensity training, there's increase in plasma volume and blood volume, therefore. And therefore, heart rate drops. And if we then have. a short period of recovery where the body can restore all the processes and the blood volume and the plasma volume comes back to normal state, then heart rate will increase although we are recovered. And then the original idea, okay, lower heart rates are good, are entirely reversed. This is also something that's not that often discussed, I think, because I think like the what is happening during training. Most of the time they look pre-post and they are not monitoring each single training day, each single training session. And therefore the short-term effects of something like high intensity to low intensity are not that often described in the literature. And this is something that we really have to be aware of sometimes and we observed this in a, in a elite badminton group a couple of years ago, every time or really, really often. At the end of the week, at the end of the training week, and they are game sport athletes, so they're working really high intensity, several hours a day, at the end of the week, exercise heart rate was lower, although they were fatigued. After the weekend, heart rate went up again. So entirely the opposite way of what we actually think. Usually, we think lower heart rates are good, higher heart rates are bad. But the short-term effects could be the entire different way. And when you say that there's a low heart rate after they've had that massive exercise week, are you saying that it's lower than their normal baseline heart rate? Yeah. Okay. And if you are to measure, because I think the theory being that once your heart rate returns to its normal steady state at rest, that we can say, oh, well, we're we're meant to, um, meant to guess that the body has recovered from the training session and, uh, the weekly exercise intensities, can there be false positives with measuring that like, can someone exercise once they've exercised the next day, their heart rate, their resting heart rate has returned back to baseline. Can we accurate accurately say that the body's recovered or can there be some situations where that is actually a false positive? They are definitely false positives because of several reasons. What I mentioned before is we also observe this in exercise heart rate, just to make that clear again. But also, especially with resting heart rates, I think there are even more influencing factors that we need to consider. And... Like everyone who measured resting heart rate or resting heart rate variability for several days, for several weeks, knows how large the fluctuations can be. Although we often think that there are not really big differences between days. But I mean, the good and the bad thing is under resting conditions, we typically get we try to get an insight with the resting heart rate measures into our the stages of our autonomic nervous system. Like basically, the way the parasympathetic and sympathetic nervous system work together, but mainly the heart rate variability measures or the heart rate measures are directly impacted by the parasympathetic. That's the basic idea. But the autonomic nervous system, as probably most of us know, is influenced by almost everything. Like if we are having bad thoughts, this could be some kind of. psychological stress, and therefore heart rate at the moment could be higher or lower. If you are coughing, if the temperature's a little bit colder, if you are standing up one hour later, if the night was bad, if you drank too much, because also then you can change your plasma volume quite rapidly, or the temperature within your body if it's cold water. The exercise before. the way you measure your heart rate, because sometimes we talk about really short amounts of times in resting heart rate. So at least what we observe, we have quite a substantial amount of variation from day to day when we talk about resting measures, even if we try to control the situations as good as possible. And then the big question is, is this actually something that should be considered a change in actual state, in something like recovery or fatigue? Or is this something that really just imitates the different situation, and therefore we should not overcall the changes that dramatically? I think the biggest consensus is it's really difficult just from a single resting measure to say, OK, this day should be entirely different. The changes need to be dramatic, basically, because we have quite huge changes from day to day, even under normal conditions. And to really call just from a single resting measure, OK, now we definitely need to change today. Therefore, you need to see really big changes. Otherwise, all of these different influencing factors, all of these different factors have an impact on our autonomic nervous system. Autonomic nervous system is really sensitive to all the changes, and it adapts all the time. And therefore, also, heart rate measures will dramatically change in different situations. You can also change your heart rate, and especially heart rate variability, with breathing a little differently, having a different breathing pace, breathing faster or slower or more in depth, less in depth. And your heart rate will automatically change within seconds. Okay. I think we should be a little bit careful to overcall on a single measurement. Yeah. I think when you're talking about one reading, like one snapshot, one moment in time where you're taking this heart rate, the, the amount of what you're saying is the amount of variation. is way too much, there's way too many inaccuracies for you to interpret what's happening at that, that moment in time, because things like temperature, breath rate, all that kind of thing will influence your current heart rate in terms of maybe taking an average over a certain period of time is, would that help with accuracy? Yeah, definitely. Um, but at the same time, you have to be aware that then you're looking at like something like the, the actual current state where you're working at, like something, the level that you're just currently working at, it still could be that on a given day, you actually are really less recovered, or more fatigued, or something like this. This could be the case. But in many situations, we actually don't really know about that. So what I always would do at the one On the one hand, when it's about daily changes in training, try to consider more information, more than just one. It's not always just heart rate. It's also, I had a bad sleep. I don't feel that good. Or usually, yesterday I did a training. And I know in 90% of the times when I do this training, like for example, when I go for a really easy recovery run, and my heart rate usually is less than 90%. comes up after this or comes down or whatever, and then it's largely different this time, that's the first indicator of making things differently. Like you really have to be aware of what is actually usually your responses. And if the response is quite consistent in the past and it's different right now, that's also a good indicator of doing something different. And also if more or several measurements and your perception, your feelings. guide you in a different direction. I would never consider just one information. Always go with that. And if we're looking at, if we try to average heart rates, resting heart rates, for example, to get a more accurate idea, but then again, we are not looking at daily responses. Then we're looking at longer, moderate changes over time. So for example, when looking at training adaptations, I would always use at least a one week average, for example. But then. a one week average is never sensitive to acute changes because it averages all the changes out. I do know cause, uh, I monitor my heart rate overnight and I'll know that my training can be like consistent and I'm not training for anything at the moment. So not pushing through high intensities, but I will notice that over the course of a night in some instances, my heart rate will be elevated to a greater extent throughout the night compared to. all these other nights and sometimes I can pinpoint it. Sometimes I can say it was either like a hot night or like, I'm not used to drinking a lot of alcohol, but I'll have like a couple of beers before bed or some type of food that, um, that's not in my regular sort of routine. I think, Oh, maybe that's it. Uh, but if my heart rate is elevated overnight, more so than all other nights, should I be aware of my training intensity? Should I be aware of like, is that heart rate? potentially influencing my ability to recover afterwards? Should I take an easy day? Is there any, in your opinion, is there any way to, any suggestions? Yeah, definitely. I think you worded this quite nicely. I think you should be aware, but actually changing the entire practice just because your resting measure is different, I would rather suddenly do that. Okay. Maybe even if like, really slept bad or the heart rate measures is really bad, then I would actually change the training at that day, but everything else or the other situations I usually would be aware during practice. And if some things even don't turn out that well during practice, I would be really, like I would then turn intensity down during practice or don't make it that long or something like this. But I think they are, it's really good. good opportunity to overcall and have false positives. So I would rather not be so data focused all the time. I mean, it could be interesting and informative to inform your decisions, but I would not guide the decisions solely on just for measure. Be aware if there's an outlier, but most of the time I would still do the training and see how it's going. And even there are good situations where sometimes you even perform better. Although your resting measures were crap, maybe there were some weird situation that you didn't consider. And afterwards, you had a really good morning and you had a really good breakfast, and then your run turns out way better than usually. And even you recover quite nicely. And this could happen. And I think we should not resist our opportunities, our potential just by some single measure. We shouldn't be over-reliant on these things. They could inform. If I observe a really interesting phenomenon over and over again, that tells me something. But even if it's one instance, I would probably be, um, yeah. I wouldn't over call. And like you said several times already, it's one piece of the puzzle. You can't just rely on this measurement because of the inaccuracies. But if you're measuring over time and you're relatively consistent, same stress levels, temperature, all that kind of thing. then maybe it could tell you something. Maybe the accuracy is a little bit, well, maybe it's a little bit more accurate if you know your body really well and you're measuring over a long period of time, but still, even then, it's still one piece of the puzzle that we need to make sure that we're not over reliant on that one measure. Which takes me into my next point, and it kind of illustrates, I interviewed Dr. Izzy Smith a couple of episodes ago, and she was on the same line as you. She said sometimes, relying too much on one measure or like relying on your heart rate. Um, what being way too involved in that measurement can sometimes have its problems in itself. And perhaps looking at how you're feeling and these subjective measures can be very well, even more useful and more accurate. Because if you look at your heart rate, it's more elevated than usual, then that can trigger like a stress response in itself, just physically looking at your measurement and relying on your measurement can. start to influence that again. And I did look at a 2015 systematic review just before we jumped on this episode and it looked at the subjective self-reported measures. So how someone feels and like answering certain questions themselves almost trumps objective measures when it comes to athletic wellbeing. And I did bring up this conversation with you before we started recording. You seem to be On the same opinion as that as kind of almost merging the two and maybe having or understanding the accuracies and the importance of self reported measuring and how you actually feel in a day, how stiff your muscles are, how well recovered you feel. Um, what can you say about that? Um, that's, that's a really good point. And from a practical perspective, like how I go with my own training, how I worked with all the athletes that I work with before. It's always extremely important about how people feel, how they perceive themselves, have they a good understanding and perception of what is actually happening, are they progressing? So definitely that's a really, really important point. And at the same time, I also, especially with recreational athletes or with at the moment, I also have more contact to clients, to patients. And it's also quite easily possible, if you are not exercising for a long time, that you lose your good perception. Really often, the way you perceive your intensity, what you're doing, are you over training in the way of doing just too much, doing too little? I think we have really often a quite good feeling about that. But we can lose that if we are just not exercising or if we have a really bad lifestyle. And therefore, there are some situations where we can also help getting back to the good feeling just by calibrating our perceptions with objective measures. So there's also lots of situations where you go out for a run, think like, oh, this is hard. You can look at your heart rate and think, maybe it's not that hard. Maybe it was just like, I was still that stressed. I'm not using my running technique as I used to use it before. And it also can help you the other way around to get like a reverse biofeedback, for example. Or it could also help you to understand how different behaviors react on your physiological responses. It's also when just talking about practical aspects, it can help you get a better feeling, get a better... individual control of what is actually happening in the training process. At the same time, I also think it's quite obvious, at least from my perspective, why this meta-analysis or review found these effects as suggested. I mean, even when we go to the physician and we have some blood measures, they typically have some reference values. And some of the time, when you consult a physician over and over again and you have a really high value or really high or really low heart rate, for example. My wife has a really low heart rate all the time. In the beginning, at the first consultation, they always say, yeah, your heart rate is really low. Maybe we should consider this, that you not have any problems. But if they know she has these low values over and over again, and this also happens with blood values, and they know, okay, this may be an individual level and we need to take this into consideration. And this is also what's happening in studies. So people have their individual responses. People react to potentially standardized exercise differently because the exercise is not really standardized in the studies. And what every athlete can tell you after demanding and after an overreaching period of training is that they will feel fatigue. So every measure that requires athletes or patients or subjects to report if they are feeling fatigued after intensive training. I mean, this is almost a non-brainer. Everyone would say, yeah, it was demanding when you have higher training loads than usually. And so therefore, it's quite obvious that in study contexts where it's a really short and overseable amount of time, that such measures will be extremely accurate, because everyone knows what's happening. You can't blind the training load. And therefore, everyone will be able to realize what's happening and say that they are fatigued. But physiological measures and objective measures are not that easy. It doesn't really mean that they are like the big question is, are they really less accurate or are they telling us a different story? So for example, if I am having a runner that is used to really high altitude, or no, not altitude, really high elevation. and we are doing an overload training with high elevation, or maybe has a really specific running technique that he doesn't bother elevation, then probably a blood measure that will indicate blood damage will not respond with this athlete because he actually doesn't have blood muscle damage. And therefore, when we look at objective measures, responses can differ because people can differ, but everyone will say they are fatigued. And I think this is also something that we should have in our minds. When we talk about studies like this, it's also like they, I think, are a bit oversimplifying the real situations. But again, it shows how difficult it could be to rely on objective measures. I think that's really good. But even with blood measures, most of the time you have to understand your individual variability, your individual baseline, your individual level to even work with such objective lab-based measures, like blood measures like CK, for example. And this is also something that we have to consider when interpreting these results. And sorry, the last point is when we talk about self-reported measures, and I tried this in different settings and different athletes, I monitored a basketball team where I also was a strength and conditioning coach for over 2 and 1 half years. And we did weekly monitoring. And after half a year, people were really annoyed by just filling out the questionnaires over and over again, especially when they are not that big changes in team sports, for example, on a daily basis based on these measures. And therefore, when we really look at the implied setting and at the long term, is it feasible to have daily subjective measures with an app, with a questionnaire, for example, to use this really good accuracy that is found in the studies? But it's difficult, at least with elite athletes, to get valid recordings. over and over again without having something like the fatigue of not wanting to respond anymore to this questionnaires. And this is something that we also have to keep in mind. We did an interview around heart rate variability in a previous episode and tended to, well, what we learned from that is kind of the heart rate variability, if it's quite elevated means that the sympathetic parasympathetic are a little bit more in sync. and it can relate to things like stress, to things like sleep, to things like exercise, changes in like maybe some foods are disagreeing with you, like certain internal processes and it seems that heart rate variability was some sort of measurement to predict what the body's doing with the in sync of the sympathetic parasympathetic nervous system. What's your that measurement. This is extremely difficult because on the one hand, I think we have extremely good situations and extremely good experiences and also case studies documented that quite impressively show that there's some kind of information in there and that what we actually think about and how we believe that an autonomic nervous system works on a different situation, it imitates this quite nicely. At the same time, I think we have a really substantial issue in the studies, because most of the time, we can't actually measure how the autonomic nervous system actually works. Like, to do that, we need to stick a needle in our nervous system and see how active is the parasympathetic and sympathetic systems. Like, we have to get really invasive to actually measure what is happening. And really often, we just assume to know what is happening. And this is the first issue. There are obviously some physiological experiments also in the animal model or in different animal models that allow us a quite good extrapolation of what we think actually happens. But in a specific situation, when I'm changing my diet and heart rate drops or heart rate variability increases or the other way around, whatever, the question always is, was it due to this specific intervention or was it due to another factor that changed it? that changed, and I'm not aware of that. The good thing is, if we think about resting measures of heart rate and heart rate variability as something like a global indicator, because it could be one of these different aspects that may have a negative effect on the way that I'm currently recovering, then that might be a good indicator. But at the end, we never know where it's coming from, because it could be A, it could be B, it could be C, it could be D. And this is the big problem. This is also really difficult because at the end, it's extremely and therefore I'm not a good physiologist to understand this quite well enough. I think we don't have good study models to control for such a complex situation. We know everything influences the autonomic nervous system, but how can we go the other way around and understand, OK, if I have a change in the measure, what is actually the reason for it? How can I then manipulate the different circumstances? And I think this is really a big, big difficulty where there are also lots and lots of questions and where we don't know actually at the moment, is it accurate? Or not? Is it measurement error? Is it noise that we are observing? Or is it some signal that is important, but I don't know where the signal is coming from? And. As at least as far as I know, we did not solve this question so far. So if we think of this, OK, this might be one indicator that something is wrong and that I'm then at a mental state of being aware and thinking about what's actually happening. Is there something that I could or should adjust in my life to just stay on my road for achieving my goals? Then that's good. But it's really. like the door is really open for over reliance and for over simplification, I think. So it's, I think there's quite, it's quite easy to overcall heart rate measures. Okay. Let me throw this question at you then. If a recreational runner came to you and said, Chris, I've been running, I'm training for a marathon, maybe my first marathon, and I... I've got this heart rate device or this, um, this sensor that's measuring my heart rate, heart rate variability, a couple of other things. I do understand that it's, I do understand the inaccuracies of it. I do understand there's one piece of the puzzle and I will be following my, um, self-reported, how I'm feeling to, as like a P another piece of the puzzle to judge my training. Would you still recommend that they monitor heart rate and monitor the heart rate variability, knowing everything that we've covered today? I think especially with endurance based sport, I would almost always give it a try. Like if I have the time, just give it a try. It's like really inexpensive. It's really easy to do. You have to try to standardize it a little bit, but if you make it your routine, it's extremely easy. Try to see if it's... giving you interesting information, like if it matches the overall framework, the overall changes that are actually happening during training. Does it imitate your long-term changes? And also, do you see really replicatable short-term changes? Then you could use it. There are lots of situations where it doesn't work. I have a colleague who's doing Iron Man's for a long time. The amounts of training he did and the changes that he not saw were extreme. Like even pre-imposed Ironman, he didn't see any substantial changes for him. It didn't work. For other athletes, it works extremely well. So just give it a try. It's not a lot of effort and see if the information is helping you. I mean, it's also you could play around with different situations. There's some suggestions that you should do something like an autostatic test. supine period, and then you have a standing up period. We also look at how does the heart rate respond in the standing up maneuver in a change, and how high is your heart rate during standing. If you are really well-trained endurance athlete, lots of the time, your resting heart rate and your parasympathetic and the supine position is so strong that you actually lose all the sensitivity that this measure can get, and then you have to go to a sitting... recording or to a standing recording to still see any changes due to training, for example. But there are lots of situations, like if the measure doesn't work, you can try different situations and then it may work or you start with standing or seated measures right away. So definitely try that. And also, like I personally would always, especially in endurance-based sports, collect heart rate during practice. This is so easy. Even if you don't like the chest straps, you nowadays have the optical sensors. And especially if we are talking about things that are not necessarily at the watch, but for example, like the sensors that are more upwards to the arm, the things, the data that I saw and the studies that I saw and the experiences I have myself, they are quite well for just getting the overall impression. But it's really easy. You don't have to do an additional measure. And I mean, what every runner that I talked with mentioned when monitoring their heart rates during training over a longer period, even if the training is not standardized, you usually see like you get fitter, heart rate at the same pace get lower over the long term. Like just observing the overall trends, even in completely unstandardized condition, gives you some information and great strength. You can do this in every single session. Sometimes you're doing two runs a day or you have several sessions per week. And if you then find some situations, for example, you always have a short distance in the beginning where you run every time the same thing with the same pace, you could use the first five to 10 minutes with the heart rate and see, okay, this over time doesn't change. It's really easy to get a really good impression. over the many, many measurements that you have to see where you actually going. Yeah. I think, when you're talking about trends, I think that's a really nice way to put it. Because from what we described, it looks like the shorter term you go and the more like, if you rely on data, that's like in the moment or like if the timeframe is really short, it seems to be. It's very, very hard to accurately interpret. Whereas if you're looking at very trends over time or reproducible trends over time, then that's where you can start to learn more about your body and tend to hone in on some accuracy. Some things that I've learned when I'm doing like really short, fast. Triathlon races is my heart rate will be elevated for three days, three to four days afterwards. And that's totally like. out of the norm for me, for my heart rate to be so elevated, but it always happens every time that I race. And it's always three or four days that takes my heart rate to drop back down. And so you're almost being your own little scientists, just gathering data and the first time it would have happened during that race, I would have just taken it as a bit of information, but then if it's reproducible every single time and it's kind of predictable in a way as you start to measure over. this might not be just for races. It might be during trainings. It might be during times of the week. It might be, um, just something that is a variable that is reproducible over a period of time. Then you can start to learn more about your body. And I think a lot of the times, oh, well, this conversation, a lot of it is quite realistic. We're focused a lot on the negative sides and the inaccuracies and the different variations in heart rate. But I think we can come to some sort of conclusion around the importance of objective measures as just a little bit of piece of the puzzle, but it does need to follow some sort of trend and you don't really necessarily need to focus on the numbers. We need to focus on yes, the numbers, but also how you're feeling, how the, um, do you feel recovered? Do you feel like you've got fatigue or do you feel like you're underperforming? Do you feel like you have muscle soreness? These are all really, oh, well, they're, they're very, very important. You can't just rely on the numbers to accurately interpret things. Would you agree with that, everything that was said? Yeah, totally. I think this is the best opportunity. It's like, it gives you an extremely easy tool. And if you then have, look for the situations, you can investigate on yourself with a new training. I mean, like good trainers, good coaches are working the same way as scientists do. They figure out situations, they try to understand what's actually happening. They do it over and over again. Every day is a small experiment and it's a small investigation, small study. And that's, I think the biggest opportunity and the biggest thing that we can learn with all the different variables, measures, and so on and so far. It could help us to learn something about our body to then focus on our body and get the performance out of it. Yeah. I think we've fallen into it. Yeah, I think the theme of this topic has concluded very nicely. And Chris, if anyone wants to learn more about you and your papers or anything else, if they have any questions, is there any social media accounts or handles to something that people can go to? Yeah, like if you want to, probably the best place is Twitter, I think. I need to look my handle up. That's okay. I've got it here. Oh, so I can, I can easily just include the Twitter link in the show notes. So that if people interested, they just click on that and it takes you straight there. So I'll include that definitely. So Twitter's the best. Yeah, definitely. So like just to get a conversation starting. That's that's the easiest part. And they are. quite a lot of Christoph Schneiders in Germany. So it's difficult to just Google the name, but if you look at for sports science or if you find it through Twitter, you are really easy to find like the other profiles. If you want to look at some papers or if you want to find my email address and so on. And yeah, always happy to chat. And that's probably the easiest way. Great. Yeah. Fantastic. Yeah. I want to thank you for coming on. I want to thank you for kind of like a real, real unbiased view on the data. I think I find a lot of researchers when they are really invested in a certain topic, they tend to, um, start to slowly mold their bias in a certain direction. And you seem to be totally level-headed and totally like, um, yeah, unbiased towards these sort of certain topics. And it's left us with a really informative topic and a real, like we've been really informed around heart rate and how to, how to practically start using it. And I think. In a lot of these topics, there's no one answer. You can't say like the evidence doesn't show that we can hone in on a certain way to use it, but if we're fully aware of now our current understanding around heart rate and how to measure it, what the inaccuracies are, I think that's a really nice step and we're not misleading people to rely on too many different things and lead them astray. So I want to thank you for coming on, sharing your knowledge and yeah, this has been really informative. Yeah, thank you very much. 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