11 Feb Heart Rate Variability For Athletes
In recent years, the fitness world has been slowly adopting the trend of measuring heart rate variability (HRV) as a means of assessing an athlete’s readiness to train and overall recovery. But what is it? Is it actually useful? And how do we measure HRV? Let’s discuss…
Heart rate variability is a measurement of the variation that naturally occurs between individual heartbeats. While you’ve probably never considered this, when we measure an individual’s heart rate in beats per minute we are getting a larger picture of their heart’s status. HRV is looking at the smaller details.
This beat-to-beat variation gives us a measurement of autonomic nervous system activity. In other words, it gives us a snapshot into pain, inflammation, and recovery of the human body as a whole. Higher variability (the beats are less regular) indicates less stress and better recovery. Less variability in HRV means the body is stressed and the nervous system is ramped up.
We won’t dive deeper into the science here but this data can give us some great insight into an athlete’s current status and readiness to train.
Declines in HRV may indicate sickness, overtraining, emotional/psychological stressors are high, etc. I’ve repeatedly seen my HRV drop in the days preceding getting sick, after poor sleep, the morning after drinking 2+ beers, or after several strenuous days of training.
In athletes we can use this data to try and get ahead of issues arising. If we see a decline in HRV maybe we cut down training volume, implement various recovery strategies, and simply check in on the emotional status of the individual.
While there has been a lot of research published on HRV, I’ll be focusing on one study with CrossFit athletes (since that’s the biggest population following my work).
In “Heart Rate Variability is a Moderating Factor in the Workload-Injury Relationship of Competitive CrossFit™ Athletes” researchers followed six competitive CrossFitters over a 16 week period and were able to find a relationship between changes in HRV, training volume, and overuse injuries. Note: see my previous article discussing monitoring training volume if you aren’t already very familiar with the subjects of acute to chronic workload ratios and maximal recoverable volume.
In the study they found that the risk of overuse problems was increased when HRV declined alongside of spikes in training volume. On the flip side, when HRV was normal or high, spikes in higher workloads were well tolerated.
They concluded that “Monitoring HRV trends alongside workloads may provide useful information on an athlete’s emerging global pattern to loading. HRV monitoring may therefore be used by practitioners to adjust and individualize training load prescriptions, in order to minimize overuse injury risk.”
WHO SHOULD TRACK THEIR HRV
While this research is very cool and can be a great way to help athletes perform optimally and stay healthy, I don’t think it is necessary for everyone to track. There are a few people I do regularly suggest it to:
- High level athletes needing to perform optimally.
- Recreational fitness athletes that I have seen for multiple overuse injuries in a relatively short period of time (giving them data about their recovery and when pushing hard isn’t the right thing to do).
- Athletes that I know aren’t sleeping enough (the Whoop app discussed below is best for this).
- Recreational fitness athletes that are likely training close to or above their MRV (maximal recoverable volume). For example, a mom of 3 that works a full time job coaches twice a week, and does a combination of CrossFit with extra weightlifting and gymnastics work.
How Do We Measure HRV?
There are a number of available options for measuring heart rate variability I’ll discuss what I believe to be the best two currently available.
HRV4Training is an easy and inexpensive way to measure HRV. This app can be downloaded for $10 and uses a smart phone’s camera to measure HRV once per day. Users then input data on their sleep quality, energy, and previous day’s training.
This allows the app to come up with general measures of readiness to train and will give a number of read outs like the image to the right and can also be sent to an individual’s coach for team tracking.
I used HRR4Training for a while and enjoyed it but eventually wanted to get a more data accurate measurement of my training and recovery so switched to using Whoop which has become very popular in the CrossFit world (full disclosure I was given a 6 month membership for free by Whoop).
Whoop is a wearable band than an athlete leaves on 24/7 (it comes with a removable battery charger so that it never has to be taken off) and captures 100 different pieces of information every second!! The data collected includes HRV, resting heart rate, body temperature, and an accelerometer. Compared to HRV4Training that measures HRV only once per day this is a big jump up in how much information you can get.
Based on these data points and some subjective input from the user, Whoop calculates your daily strain level, a recovery score, sleep performance, and more. It can even suggest how much sleep you need to recovery from your day based on how well you need to perform the following day.
THIS ARTICLE from Whoop outlines a lot of the features of whoop as well as shares high level CrossFitter Sam Dancer’s data during the 2017 CrossFit season that ultimately lead to an injury due to training load vs. recovery imbalance.
Whoop is significantly more comprehensive but requires a 6-month membership to join at $30/month so it is also more expensive. For the average athlete, HRV4Training gets the job done. But for someone wanting more information on their body’s status or needing things like sleep suggestions, Whoop is the winner.
If you consider buying Whoop, my affiliate discount code “barbellphysio” will give you one month free in your initial 6-month membership (and help me continue to put out articles like this).