Podcast, Science and Physiology

HRV and applied sports science with Jamie Stanley, PhD | EP#308

 October 18, 2021

By  Bernardo Gonçalves


Jamie Stanley - That Triathlon Show

Jamie Stanley, PhD, is a sports physiologist with the South Australian Sports Institute. Jamie did his PhD thesis on the topic of Heart Rate Variability (HRV), but in his applied sports science role today he has a wide breadth of performance and recovery optimisation expertise, and we tap into that expertise on a number of interesting applied sports science questions in today's interview.

In this Episode you'll learn about:

  • The responsibilities and day-to-day work of Jamie in his role as sports scientist supporting athletes and coaches
  • How to use HRV to monitor training adaptations
  • Looking at medium and long-term HRV trends rather than daily values
  • Tools of the trade: recommendations for tools with which to measure HRV and analyse the data
  • Tracking resting heart rate, sleep duration, and sleep quality
  • Lab and field testing - who should use what kind of testing, and when?
  • Best practices for monitoring training load
  • How to find your individual physiological limiters, and when to work on strengths vs. weaknesses
  • Continuous blood glucose monitoring

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Jamie's background

03:57 - 

  • I am Jamie Stanley, and I am a sports physiologist. I currently work with hour record holding, Olympic, Paralympic and Commonwealth champion athletes. (in swimming and track and road cycling)
  • I work in the Australian Science Sports Institute (an institute within the Australian High-Performance Sporting Network). And they allow me to work with the Australian Cycling Team.
  • I started as a triathlete myself. I wanted to go to the Olympics and be a professional athlete. My genetics were not at that level, but that made me find ways to train smarter. I wanted to do the best I could with the genetics I have.
  • I got into Sports Science. My PhD was on Heart Rate Variability (HRV) for monitoring training adaptations. And then, I worked my way to be a sports scientist.

Jamie's role as a sports scientist

05:37 -

  • On a day-to-day basis, my role is quite varied. It revolves around engaging with athletes and their coaches. We discuss training, the response to the workouts. And we manage to find ways to apply the science in future training plans.  
  • As part of that, every week, I have meetings with the coaches I work with. And they explain the sessions they have in their minds for each athlete. We discuss the objectives of the training. The goal is to define what coaches to the athletes.
  • There are two common themes I discuss with coaches often. 
  • The number one question I ask them is why. That is not trying to nitpick every session. But you want to understand the overall objective of every session and why coaches prescribe it at that moment. I want to see how the sessions will complement each other to provide that outcome.
  • It is that sort of discussion we have. We do not do it to critique but to refine what we have.
  • The second thing is around how the athlete is responding to training up to that point. We need to understand if he is doing too much, and we need to pull things back. In the elite and amateur sport levels, there is a biased to do more. Therefore, I always like to pull it back and ask if we are doing too much. I focus more on the minimal effective dose.

HRV to monitor training adaptations

09:19 -

  • In 2009, I was looking for a topic I could do my PhD. That is where I got to learn about HRV and how to access recovery from training stress.
  • Through my PhD journey and my time working the last twelve years, I have grown my knowledge and the use of HRV as a tool to access how well athletes are responding to training.
  • The power in HRV is in the long cumulative assessment. You do not want to rely on just one value (daily value). Its power shows itself when you have months and years of data. (within the context of the athletes training or other factor in their life)
  • The first thing to do is trying to look for patterns of the data over the long term. If you have the training history, you can get more context from the coach (whether it is a high or moderate load).
  • And then, you look, in combination with that, at the pattern in heart rate and HRV over time. It is Marco Altini who has done many good blogs explaining the different trends you might see. It gives much information based on the work that Dan Plews has done over the years.
  • As a starting point, I would be looking at whether there are the classic indicators of a response to a training load. So, if you have a two-week training block, you look at heart rate and HRV response at the beginning of that block. This analysis allows accessing whether there is a sympathetic response. As the training block progresses, you might see a parasympathetic dominance as the athlete begins to cope with that load.
  • And toward the end of the block, fatigue starts to set in. So, you might see a pattern that is reflective of an increase in sympathetic response again.
  • For me, we look at red flags to try to start conversations.
  • If the coach has planned a period of sustained high workload, you use the HRV data to evaluate whether the athlete is accumulating fatigue earlier in the block. Or they might cope well with the training block, which you might extend the work a little more.
  • It is another tool in the toolbox you can use in combination with the feedback from the athlete and objective measurements or visualising the athlete in what they are doing.
  • It adds another layer of context in how they are responding or adapting. 

Connection between the autonomic system and performance

15:02 -

  • The Flight or Fight mechanism is your sympathetic response. So, your body is mobilising all its resources because it is preparing for a "battle". In another analogy, it is preparing to run away from something that is trying to eat us.
  • The parasympathetic system is the opposite of that. It links to rest or recovery state.
  • Therefore, as you go through different phases in training, your body is in a dynamic state of flux. You either are tipping towards a sympathetic dominance, where the body is under increased stress. Or it might tend to a more parasympathetic state, where the body has become accustomed to that level of stress.
  • From a training status, your body is tipping from a sympathetic to a parasympathetic state. On top of that, there might exist other stresses in your life that influence the autonomic system.
  • It is where the value of using HRV is. It provides that extra assessment to a more holistic view of how an athlete is going.

Jamie's methodology to evaluate HRV

17:50 -

  • The research on HRV is the basis of my methodology.
  • I use a sixty-day rolling average as the baseline. Above or below that value is your natural range of variation (square of the small worthwhile change).
  • Then, you look at the variation in the seven-day rolling average predominantly and how it relates to your typical values (above or below the baseline).
  • We also look at the daily value to see if it is substantially away from the base.
  • But it is primarily seeing what the seven-day moving average is doing relative to the natural range.

Tools and applications to monitor HRV

19:27 - 

  • I do use HRV4Training. In my day-to-day work, I built a spreadsheet and doing my system.
  • As a scientist, I like to know how the analysis work. And there are some sultanates in HRV apps versus the way I assess things. 
  • But the overall concepts align. 
  • For the general public, the apps to use come down to two things. Make sure you have an accurate measurement. It can be a chest strap, phones camera or ring. On top, the ease of use. The value in HRV is a long term assessment. Getting consistent data is crucial. Therefore, you have to find a device that is going to enhance compliance. 
  • Finally, you have to look at how platforms evaluate the data. Each app can do it in different ways. Some are better than others.
  • EliteHRV, Ithlete and HRV4Training are the most prominent HRV platforms out there. 
  • The wearable industry is growing massively with devices that measure HRV heart rate and sleeping patterns. They make their assessment. Moreover, they allow this data to go to these other platforms.
  • You could sync your Ouraring data to HRV4Training if you wanted to use that analysis methodology.

How and when to meaure HRV

23:02 -

  • It all comes down to consistency in your measuring protocol. 
  • There is enough evidence to show that a one-minute morning measure is sufficient to apply filters to have a clean dataset.
  • The limitation to do a waking resting morning sample is that you are exposed to various stimuli as soon as you wake up. The noise outside, birds, your partner, the stress of the day influence your state when you do that measurement. But that is the whole point. You want to capture your condition at that moment.
  • Therefore, there is solid proof that we can use this method to evaluate HRV long term. And I operated this way for five or six years.
  • In the beginning, I was using the chest strap.
  • Now, because of the convenience, I use a device that measures it overnight. (you are not awake, and you are not prone to the different stimulus that is going on)
  • Having the data for the entire night is better because, statistically, you have a larger sample to use.
  • You notice that if you do a one-morning sample for a year and then move to an overnight reading, the values will be slightly different. But it is all about building that longitudinal history.

Is resting heart rate an important factor to look at?

25:56 -

  • There are two points. In terms of the trend analysis, the combination of heart rate and HRV is crucial to decide what physiological state you are in at the moment.
  • Changes in resting heart rate are less susceptible to acute stresses. But they show up the larger ones.
  • If you are coming down with a sickness, you might see a higher resting heart rate (five to ten beats above the baseline). But more subtle changes that can accumulate over time might not be evident.

Sleep tracking devices

27:30 -

  • Sleep is the most powerful tool for recovery. Therefore, if you can measure it, I think that is a positive. 
  • With so many devices available, it is crucial to understand what they measure and their accuracy. 
  • If you are trying to make a decision, you want to do it based on good data.
  • I am interested in this space and the relationship between your sleep duration, quality, and how that relates to your adaptive state in training.
  • Sleep quality is a feature that the current devices cannot measure with accuracy. If you go to a sleep lab, it takes an experienced sleep technician a few hours to assess what phase of sleep you are in at a determined moment.
  • It is more about the sleep duration what most products are tracking accurately now.
  • It is always biased with every subjective measurement. Sport psychologists are very focused on and how you form the question. It is because it can influence the response the athlete gives. And the answer you get is not the one for the question you are trying to ask.
  • I still think there is value in subjective data, particularly if you have a longitudinal history of it. It is not looking at changes in a day. It is about the patterns we might find, the same way you would look at heart rate and HRV.

Practical takeaways messages from HRV, heart rate and sleep tracking

31:48 -

  • I think they are practical tools. The availability and ease of use of products out there now is something I wish I had before.
  • You need to be aware of the potential limitations of each device. In that way, the data you look at is at a level of accuracy you are comfortable with, especially to make prime decisions on training.
  • The HRV and sleep tracking are good tools to better inform you of your physiological state and your response to training. But it is not only your training you need to concentrate on but also your life stresses. Is work taking a toll? Are your relationships stressful? It is that holistic space tracking these things is beneficial.

Lab and field testing

33:44 -

  • You should have some feedback mechanism to understand how the training is affecting an athlete. 
  • But you have to be clear on the purpose of the test. And you should know its limitations. It applies to both lab and field-based testing.
  • Not everyone can have access to lab tests whenever they like. But, if you are an amateur athlete, lab tests can provide crucial information on, particularly aspects of physiology. You cannot get these with field testing.
  • If you want to understand your fuel utilisation to prepare your nutrition for racing, doing a lab test with gas analysis will give insights on the topic.
  • If you want to see how well you are progressing in training, field testing is an alternative.
  • (e.g. Standardise main sets you do each month in swimming or using the power meter on the bike)
  • However, you need to understand what you want to measure to choose which methodology is better.
  • When you start working with an athlete, it is fundamental to characterise their physiology. You want to understand their strengths and weaknesses and how they relate to the event demands.
  • If you have access to their training history, you can look at their power duration curve and evaluate how that progressed over time.
  • On top of that, you might want to know their aerobic capacity, so you do a lab test. On another point, you want to see how economical they are running. Therefore you do some lab testing. With this, you can work with the coach on the proper training.
  • Lab testing necessity will depend on the goals of each athlete. If the athlete is interested in understanding their body and works with a knowledgeable coach, there is value in knowing your body's capacities.
  • On the other hand, if you cannot use that information, lab testing is not a worthy investment. From my point of view, I like to understand at the highest level what is going on in the athlete's body.
  • Lab testing might give you interesting information. In some cases, you can use that data to prescribe training zones. But, I would not look at lab test data in isolation either. Even if I did a lab test every month, I would still use the training data as a reference. And then analyse it with the lab test data.
  • Lab testing is not vital to set training zones. With the multitude of devices you can use, you can get that information from field base data.

Muscle fibre typology and strength

50:10 -

  • With this limited database we have, we eliminate fast-twist fibres reason for higher peak power.
  • If the torque development, at fifty milliseconds, correlated with W', fibre typology would be a significant determinant for W'.
  • It was with an indirect measure that you took fibre type out of the equation.
  • The only difference between slow and fast twist muscle fibres is the time you exert force. If you have the same muscle cross-section for type I and type II fibres, the force production will be the same if you take out time.
  • And that is why it correlates with W'. You do not need to do it quickly (spin as fast as you can).
  • Having said that, if you have fast twist fibres, you will be a higher W' compared to your critical power. But that is not the reason we did this study.
  • You cannot exert W' in a minute. Therefore, as it dragged out, fast twist fibres lost their peak edge.
  • We cannot prove that individuals with more muscle mass have a higher proportion of type II fibres. (with this study)
  • In studies I have done, many top-class sprinters have less fast twist fibres than people might think. 
  • Let's assume sprinting is fatigue-free. Power comes from torque over crank revolution times velocity. (force times the angular speed) It is the same for every sport with linear movement.
  • Cycling is one of the only sports where you can change your cadence aggressively. The stronger you are and the less fast twist fibres you have, you can gear up and press against it. Whereas, if you have more fast twist fibres or a better pedaller, you can gear down and have the same speed.
  • In cycling, you can almost mask your type I/II ratio. You can evaluate the type I/II ratio if you do a max cadence test or a torque cadence test.
  • What this study states is it is not fast twist fibres the principal determinant for W'. But we cannot say for sure W' is not dependant on muscle typology.
  • The sprinters' max cadences are not different from road endurance cyclists. What separates them is the max torque production.
  • Their performances depend on the type of gear you have.

Monitoring training load

40:23 -

  • Most triathletes are familiar with TSS (Training Stress Score), acute and chronic training load. They are useful metrics because they provide a reference point.
  • If you want to quantify training, you might consider other aspects apart from volume and intensity. (number of steps when running and the magnitude of each one. The reason is that running is an impact sport. Therefore it is crucial to know the load you put in your body)
  • There is also intention when doing a gym session, and all these factors impact the body. 
  • Your body will react differently to different workouts with the same TSS.
  • What I do is quantify the training planned and completed. We first on basic things: volume, intensity or duration. With this, we break them down into training zones. 
  • You have your heart rate training zones which are very robust. In Australia, we use five-zone models. And we apply the same for power and speed.
  • We quantify time in zones at a more macro level. Therefore, we analyse then how the training correlates with research (polarised versus pyramidal training model).
  • After, we might go on more specific things regarding the training you are doing. If you are working on speed, you might quantify power above critical power, for example.
  • With the training structured, you look at the response from the athlete. You can have the best thought training plan, but if the athlete progression is not the desired, it will not bring a good outcome.
  • In conclusion, it is crucial to understand both the training proposed and the athlete response to it. And various load markers can help you guide your planning.
  • As long as you are aware of the limitations, the TSS model is a good reference point.

Workout prescription

47:12 -

  • I like to prescribe sessions based on all metrics (internal and external).
  • I plan workouts in different ways in different periods so that the athlete does not rely on any piece of data.
  • It makes the athletes more aware of their bodies and how they are executing a session.
  • After the off-season, you tend to see high heart rates in athletes for a determined power or pace. Therefore, I prefer to prescribe based on an internal load because the speed will be lower than regular.
  • Mentally, the workout is better because the athlete is not thinking about the power he is putting.
  • Therefore, being aware of the different ways you can prescribe training is a crucial tool you should use.
  • When athletes are doing cross training (modalities they are not used to), I prescribe sessions based on RPE. For example, swimmers who do some run or bike based training do not have any concept of running or cycling paces. RPE in those situations is a handy tool to use.

Finding individual physiological limiters

50:22 -

  • What I do is asking the athlete what their favourite and less favourite workouts are.
  • Athletes will tend to enjoy the sessions they are better and feel stronger. And they will avoid the ones where they are not so good or dislike.
  • At a basic level, this is what I do when I first meet a new athlete.
  • Based on their answers, we might work on the limitations according to their specific event.
  • To train for a specific event, you need to understand what it takes to perform such events. Then, you want to know what the athlete characteristics are. The goal is to compare their level of performance relative to that of the event.
  • With the information, you decide if you work on their weaknesses or their strengths. The choice will depend on the time you have until the event and the performance requirements.
  • If their weakness is a crucial performance requirement, you have to address that weakness. 
  • If you have a long preparation period, you focus on the weaknesses earlier on. As you get close to competition, you start tapping into the athlete's strengths, and their confidence will come up.
  • How much volume and intensity you do come down to the event demands and the athlete characteristics.
  • If you are training for an Ironman, volume is fundamental because you want to survive the day. If you come down to an Olympic distance triathlon, you need to use more of the other energy systems. Thus, you might need more intensity.
  • Deciding what sorts of volume and intensity are enough is tricky. You have to guide by the athlete's history and their response to training.
  • For example, I wish I had more time. My weakness was swimming, and I should have invested more time there. My biggest weeks were 20 to 25 hours, but this was the most I could sustain without losing quality.
  • If you are in a state where you cannot perform as prescribed, it means you are overdoing it.

Continuous blood glucose monitoring

57:53 -

  • I have not used any of these devices. I have seen some posts and data out there.
  • My first question is about what information it provides and its use case. And more importantly, we should ask if these devices are accurate.
  • If you have an inaccurate device, you are wasting your time.
  • I have read one paper recently that makes me biased on not using these devices more. Accuracy seems to decline after you consume carbohydrates.
  • Therefore, at the moment, they are not at a level where they are useful. For this reason, I have not invested more time in them at this stage.
  • I am not discarding how important fueling properly and monitoring is during training or competition. 

Top tips for endurance athletes

1:00:40 -

  • Number one: Consistency is crucial. You need to be as consistent as possible in training. Do not be sucked into doing big blocks or one-off sessions because it feels good at the time. Ultimately, it is consistent training that will lead you to better results. And if your training plan does not allow that, you need to take a look at it.
  • Number two: for the amateurs, triathlon is just one component of your life. You have work, family and other obligations which add stress to your body. If you chasing a particular event, you need to get your life stress under control over that period. (try to reduce them as much as possible)
  • Number three: make sure you are having fun. If you are not having fun, there is no point in doing it. 

General questions

1:02:14 -

What would you tell yourself ten years ago if you could? 

As an endurance athlete, I wish I had more exposure to strength and power physiology. Many of the sports I work in now focus on power endurance efforts (four minutes or less). Now, I appreciate how having the strength and speed characteristics in your development can benefit endurance events. I would have tried doing more structure strength training. (hill running or hill efforts on the bike, not only about gym sessions)

What is one thing within coaching or training you are now learning/curious about or fascinated by and why?In elite sports, there are athletes already training a lot. In many cases, you cannot add anything else to the training program. For me, I am trying to find ways to get more of the training they do. It could mean also doing less volume and getting the same responses. Therefore, I have been interested in external environmental conditions (heat and hypoxia) to potentiate some of the adaptations you get from a training session. I would use it for the development of the athlete and not only focus on specific race preparation.

Rapid fire questions

1:05:55 -

What is your favourite book, blog or resource?
Science and Application of High Intensity Interval Training: Solutions to the Programming Puzzle

What is an important habit that benefited athletically, professionally or personally?
"Actions speak louder than words" - I like to do something than tell someone to do something.

Who is someone you have looked up to or who has inspired you?
My dad who was a marathoner and a scientist (leader in his particular field)


Bernardo Gonçalves

Bernardo is a Portuguese elite cyclist and co-founder of SpeedEdge Performance, a company focused on optimising cycling and triathlon performance. He writes the shownotes for That Triathlon Show, and also produces social media content for each new episode.

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