On Heart Rate Variability (HRV), training load and subjective metrics

Blog post by Marco Altini

Part 4 of our Ultimate Guide to Heart Rate Variability is all about common misconceptions (full post coming soon). In this post, I am covering an important misconception on HRV and subjective data. 

Misconception 7: HRV is less useful than subjective data to capture how an athlete responds to training

This misconception is mostly deriving from a paper that a few years back stated that subjective metrics are better than objective ones in monitoring athlete training response. 

But let’s look at what was actually analyzed in the paper.

The authors looked at how training load related to both subjective and objective metrics, hence according to the paper, the reference to determine if a metric is a valid metric, is how it correlates to training load. 
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In my opinion, the whole assumption that you should find the metric that “correlates the most” with training load, makes very little sense. Why? Because you are already measuring training load, so what is the point of having another metric that gives you the exact same information? Well, none. By definition, if a metric is perfectly correlated to training load, then it is a useless metric, as it does not add any information to the training and recovery equation (but ironically, it would have been interpreted by the study as the best metric).

I’ve already discussed before how the notion that increased load should trigger a reduction in HRV is very simplistic. As a matter of fact, we have seen we can have stable or increased HRV when increasing load (a sign of positive adaptation) as well as reduced HRV with low load because of other stressors (travel, work, etc.). HRV tells you how you are responding and coping with stress, and you can use that information as part of your decision-making process (you can find many case studies here). 

Finally, don’t get me wrong, it is fairly obvious that subjective metrics are also extremely important. This is why we include a questionnaire after the measurement so that you can take a minute to pause, and self-assess how you are feeling subjectively, a key part of the process.

A smart coach, educator or athlete, understands that training load, HRV, and subjective metrics all provide important information that needs to be integrated daily, to decide the better course of action. 

There is no winner between objective and subjective metrics, they all serve a purpose. ​Isn't that obvious?