What's Cool In Road Cycling

How To Use Heart Rate Variability As Your Training Guide

The digital era has arrived in many different aspects of our lives. Heart rate variability has become a sexy new measure – how might it help your daily training?

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Most of us love cycling and pushing our limits yet aren’t paid to ride, so we need to balance a multitude of other factors & stressors in our personal lives. Not allowing yourself to recover adequately can actually impede your ability to get better by sacrificing the quality of your HIIT sessions, or the volume of your riding. Therefore, further understanding how our body is recovering – not only from cycling, but from other life stressors – might help improve the quality of our training.

One of the newest proposed tools in monitoring recovery is heart rate variability (HRV), which can give us insights into our autonomous nervous system. This is done by looking at the beat-to-beat variations in the timing of your heart rate. Contrary to what most people might think, our hearts do not beat rhythmically like a metronome. The miniscule differences in duration between beats are collectively known as heart rate variability. Although it has been suggested that having a “higher” HRV score is generally better, it is important to note up front that the absolute value is not of major concern, but rather the recent trends in HRV, relative to your baseline scores. Things like stress, lack of sleep, alcohol, etc. tend to manifest in decreased HRV scores and imply reduced readiness to train.

How do you measure HRV?

HRV is becoming more popular in the scientific community, which I find fascinating since HRV is becoming more accessible for “weekend warrior” athletes, since it can be measured by most Bluetooth heart rate monitors and a smartphone app. Personally, I use the Elite HRV app, which allows me to measure my daily morning HRV, as well as input additional data to put the reading into context, such as exercise, sleep quality/quantity, stress levels & mood, as well as personal tags. The reading itself takes just 90 s, which I measure in a standing position first thing in the morning after waking up and using the washroom.

After taking my measurement, I can adjust my plan for the day using Xert’s Freshness Feedback Slider to adjust the intensity of recommended workouts. If my HRV returns a green/optimal value in the Elite HRV app, I can feel good knowing that my body is prepared for a harder day on the bike. However, if my HRV score ends up in Elite’s Yellow Zone, I am sure to pick an easier endurance ride (<70% FTP). And if I end up with a Red HRV score, I’ll consider a very light active recovery ride (~50% FTP) or taking a day off entirely.

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Does HRV-guided Training Work?

A research group from Miguel Hernandez University wanted to investigate the efficacy of a daily, HRV-guided training program against a traditional pre-planned training program.

17 cyclists participated in the study. After a 4-week standardized baseline period, half of the athletes would follow 8 weeks of a pre-defined training program (TRAD), while the other half would follow 8 weeks of a novel HRV-guided program (HRV-G). The traditional group followed a more typical training program, which included 3 weeks of building intensity, followed by a recovery week. A typical 4-week block for these athletes is outlined below:

The HRV-G group was assigned training based on their HRV scores and following a decision-making schema as displayed below:

Interestingly, the researchers found that the HRV-G group spent significantly less time training at a moderate intensity (called Zone 2 in Dr. Seiler’s 3-zone intensity model). The HRV-G group also spent more time training at low intensity (Seiler’s Zone 1), though it did not reach statistical significance. Finally, there were no differences spend in the time at high intensity (Seiler’s Zone 3). So, looking at all that evidence together, the HRV-G group was slightly more polarized than the TRAD group, by reducing training time in the “sweet-spot” intensity range.

Following the training intervention, the researchers found that both groups did improve in response to their training programs. However, the athletes guided by HRV saw greater increases in Maximal Aerobic Power (as indicated by the last 1 min average power on a ramp test), Power at VT2 (FTP), and 40 min TT Power. The authors suggested that the increased changes in fitness might be caused by optimized prescription of High Intensity training when HRV indicated athletes were ready/prepared for it, as well as reduced time training at moderate intensities.

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Practical Applications & Key Takeaway

We saw that training guided by HRV was shown to be more effective than following a traditional training program with respect to increases in Max Aerobic Power, FTP, and average power on a 40 min TT. By starting to record your own HRV, you can make daily adjustments to your training to optimize your recovery and complete HIIT sessions only when your body is ready.

However, remember that HRV and other recovery measures are simply data to guide your decisions, and you shouldn’t simply be a reactive robot to it. It’s equally if not more important to be aware of your own sensations and feeling, in the same way that you shouldn’t become a slave to power numbers.

In my upcoming article next month, we’ll continue on the topic of HRV-guided training and see how it stacks up against other commonly prescribed workout programs found in the research literature.

Thanks for reading and train smart!

References

Javaloyes A, Sarabia JM, Lamberts RP, Moya-Ramon M. Training Prescription Guided by Heart Rate Variability in Cycling. Int J Sports Physiol Perform. 2018 May 29:1-28.

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