How to use HRV to measure and manage Total Load with Simon Wegerif | EP#162

Simon Wegerif is the founder of ithlete, a company that creates sensors and apps related to heart rate variability (HRV). He discusses how triathletes and endurance athletes can use HRV to measure and manage total load - the sum of various different kinds of stress on the body, including mental and physical. 

• What is total load, and how is it relevant for triathlon training?
• What is the relation between HRV and total load?
• How do we know how much we can or should train, given all the stressors in our lives outside of training?
• Does stress really equal stress, no matter the source of that stress?
• How can age-group triathletes practically use HRV to measure and manage total load?

0:41  -

• Simon is the founder of ithete who create apps and sensor products for measuring heart rate variability (HRV) and other similar things. 
• Simon is also a competitive cyclist and has also previously competed in triathlons. 

5:00 -

• Total load is the idea that in addition to the stress from your workout, other factors impact your bodies ability to train and perform.
  
  These may include sleep and mental stress,
• Many athletes often don't realise that factors such as work stress and travel impact their ability to train, and subsequently to perform well. 
• In early 2016 the international Olympic committee put together a team to assess evidence that high total loads in sport were leading to high rates of injury and illness. 
  
  It resulted in a comprehensive two-part paper on identifying and managing total load.
• They concluded that measurement is important, particularly assessing both internal and external load.
  
  External load is the stress that you apply - e.g. an hour at your threshold, which gives a TSS of 100. 
  
  Internal load is the stress the results in the body from applying that load. 
• The relationship between internal and external load is not constant, and depends on a number of environmental factors such as psychological stress, travel, illness etc. 
• The difficulty is quantifying other stressors such as environmental stress. 
  
  Ways of measuring these factors are improving, such as sleep measurements and diet prescriptions and compliance. 
• The internal load is the concept that the bodies response to external stressors is intricate and complex, and varies over time. 

9:18 -

• What we saw in the early years producing an HRV app is that users would not find a perfect relation between changes in the external load and dips in the HRV. 
• This turns out to be a good thing as HRV turns out to be a holistic and comprehensive measure of internal load and resilience. 
  
  The amount your HRV changes after an external load is applied depends on you individually at that point in time.
• The smaller the change in the HRV for a given external load means you are more resilient. 
  
  You can build this resilience as well. 
• One of the best examples of building resilience would be long slow distance training.
  
  Having a good aerobic base increases your HRV, showing your resilience has improved.​
• The greater your bodies adaptations to training, the most robust you become to future training. 

11:36 - 

• This can be done if you record HRV every morning at the same time, and also record other lifestyle factors diligently and honestly.
  
  These may include adherence to a prescribed diet, stress management, sleep quantity and quality, muscle soreness, mood and fatigue.
• Stress is the imbalance between a set of environmental circumstances (e.g. high pressure deadlines/late train/argument) and the internal response. 
  
  Your internal response will depend on your resilience, your mental attitude and values etc. 
• Once you've recorded these factors you can chart them all simultaneously to visually identify trends. 
  
  Increasingly we can utilise machine learning to do this for us. If HRV changes and we have been recording holistic factors well, we can assess the likely contributors. 
• We do this in ithlete Pro using a feature called Simon Says. 
  
  This is a knowledge based system that tracks all those variables and tries to identify the most likely relationship between them.
  
  It gives this back in the form of simple to understand text. 
• There tends to be quite a tight relationship between stress management reducing ability to sleep effectively.
  
  When we have poor sleep we tend to make bad food choices. Your body doesn't know what stress it's under, it just knows when under stress you need more glucose and glycogen to perform fight or flight reactions. 

18:50 - 

• In professional team environments they tend to use salivary cortisol measures and blood markers of inflammation.
  
  In anecdotal reports I've had working with these clubs, they regard HRV as the most sensitive measure. 
• Ideally we'd want to measure HRV, blood glucose and adrenal family hormones if we could do it in a non-invasive way.
• However, I don't think enough work has been done to identify whether HRV is the most sensitive. 
• It is quite likely to be sensitive because it originates in the brain stem and is part of the basic wiring of the body in changing its state and altering factors such as inflammation, sensitivity to main and mobilisation of resources. 

20:35 - 

• There are three things that are useful to consider:
  ​
  1) The day to day changes in HRV
  2) The HRV baseline
  3) The acute to chronic training load ratio
• HRV is a sensitive metric, which comes with the downside that it varies day to day. 
  ​
  It's pretty desirable to have a 7-day rolling average or baseline. 
• Trends in the baseline have been shown in research to be pretty to indicators of when the stress is becoming cumulative, and there's a bigger chance of non-functional overreaching. 
• As endurance athletes, we don't want to overreach non-functionally as it takes a long time to recover from and will be unpleasant in the meantime. 
  ​
  When you did yourself into a hole, once you've recovered you don't actually gain anything. There is no successful adaptation. 
• The day to day variation in HRV still has value - if you're starting to become unwell you will notice a big change in one day without any aparant explanation. 
  ​
  This is what AI can do - it can show when other variables are not able to explain the change in HRV, which may mean you are becoming unwell. 
  ​
  In a football club this would lead to separating the player from normal training, adding rest and giving vitamin supplements to try and minimise the pending illness. 
• I've had many stories from users about how ithelete as been useful in detecting pending viral illnesses, especially serious ones. 
• There's a concept in sports science called the smallest worthwhile change, which is an idea put forward by Will Hopkins, an NZ statistician. 
  ​
  It proposes that if you repeat athletic performances or any biological measure, there will be some noise and then there will be a threshold where it starts to become significant: the smallest worthwhile change. 
  
  It's usually something along the lines of 0.5 times the standard deviation of a recent set of measurements. 
• Non-functional overreaching would be a negative change in your HRV baseline. 
  ​
  There is also a percentage change in baseline that can be used a threshold to indicate when you are reaching this point. 
• For the acute to chronic training load ratio, there is good work being done by Tim Gabbett in Australia. 
  ​
  They are looking at a 7-day versus a 28-day baseline of training loads, and the ratio between the most recent week, and the average of the past 4-6 weeks. 
  ​
  If that exceeds 1.2, there is an increase likelihood of soft tissue and muscoskeletal injuries, and over 1.5 there's a pretty high chance of that.
  
  Values below 0.8 (a fast decrease in training load) are also likely to cause problems once training is resumed as the body becomes de-conditioned to the training stress that it was accustomed to previously.  

• ithlete website
• Heart Rate Variability (HRV) for triathletes with Dan Plews | EP#42
• Applications and Insights in 2018 and Beyond with Marco Altini | EP#144
• Non-functional overreaching with Cyril Schmit | EP#159
• Periodisation Theory: Confronting an Inconvenient Truth with John Kiely | EP#148

Connect with Simon Wegerif

Connect with host Mikael Eriksson

Hi! I'm your host Mikael,

I am a full-time triathlon coach and an ambitious age-group triathlete. My goal is podium at the Finnish national championships within the next few years.

I first started the website Scientific Triathlon in autumn 2015 as a passion project to share my learnings with a larger triathlon audience. Later on, in early 2017 I started the podcast That Triathlon Show. 

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