Triathletes religiously track Heart Rate (HR). As they should. It’s a great stress metric. It monitors the stress load a body is used to handling as well as what load it can take during strenuous training.
Unfortunately, relying on your resting heart rate isn’t the most accurate way to know if you’ve recovered from your previous workout. But take heart (literally) because there’s a relatively new heart-related metric in endurance training.
It’s Heart Rate Variability (HRV). And, simply stated, if you're not using it yet, you will be.
The Importance of Heart Rate Variability
HRV offers a window into the “flexibility of our nervous system” which can be used to guide an optimal triathlon training program. As triathletes well know, recovery is every much a part of an optimized training process as the actual work-out miles themselves. If the body can’t recover, it can’t grow, replenish itself, and improve.
Today we have more products than ever geared towards recovery, from compression socks to electrical muscle stimulation. Recovery is a key component of a triathlon training plan. Most athletes know that getting enough rest after exercise is essential to high-level performance, but many are guessing as to how to do this correctly and know whether or not they have fully recovered from the previous workout.
The Science of Heart Rate Variability
HRV refers to the fact that your HR does not have a consistent "thump" like you think. The time between each beat actually varies and a very quick HRV meter can pick this up. HRV goes beyond the basic HR beats per minute and looks at how the beats behave within that minute.
Our Autonomic Nervous System (ANS) is a control system our body uses to regulate functions such as our heart and respiratory rate and has two main branches that play an important role in our HRV:
- Parasympathetic System (PS): When we "rest and digest" we’re said to be in our PS. Although it seems a bit illogical, this is when HRV is more variable within a minute. It's ready to adapt and respond.
- Sympathetic System (S): When we impose stress, whether physical or emotional, our "fight or flight" kicks in and it leads to a lower HRV (less variable). This is our S.
HRV is a measurement of the continuous interplay or "tug of war" between the PS and S influences on our HR. It gives us important information about the “flexibility” of our autonomic nervous system.
In general, a higher HRV represents a more flexible ANS. A more flexible ANS means your body is more able to respond to internal and external stimuli. This allows for faster reactions and more adaptability. A lower HRV represents a less flexible ANS that is less able to respond to stimuli change.
Applying Heart Rate Variability to Training
So how is HRV useful in training? If we wake up fatigued and have a choice to train more or train less, half of us train more and half of us train less. In many of these cases, we should in fact be doing the exact opposite.
HRV enables triathletes to track this recovery and eliminate guesswork, being confident in what level of training is most appropriate for that day.
All in all, HRV is a great metric of an athlete's ability to respond to both physical and emotional stress and provides a window into one's capacity to perform physically at maximal levels.
TriDot Takeaway: Monitoring your heart rate is good. Monitoring your heart rate variability is even better as a reliable and more comprehensive metric for gauging recovery.
Talk with TriDot: How interested are you in this new metric and do you plan on taking advantage of it?
B.J. Leeper is Director, Health and Sports Performance Medicine for TriDot, a big data and biometrics-based triathlon training science that uses patents pending algorithms to consistently improve triathlon performance in up to 30% less training time.