It is widely known by exercise scientists and runners that our bodies recover and adapt to training during our rest periods. Exercise is a form of stress.
If we give our bodies adequate rest time and nutrients, we adapt to this stress and become stronger and faster with improved endurance. If we train too much and rest too little, we compromise our training efforts.
But how can you measure this? Every type of stress can have an impact on your body. You have to consider exercise stress, mental stress, emotional stress, sleep quality, sleep quantity, and nutritional status.
With so many variables to consider, I had given up years ago on trying to quantify recovery from exercise. I learned to rely on how I felt. But there is a problem with that approach.
Sometimes your body feels great when it’s in a state of increased stress. Adrenalin is a stress hormone, and it can feel really good! This is a survival mechanism.
Then I found a simple way to quantify how my body was handling all the various stressors of life:
HRV (Heart Rate Variability)
Heart Rate Variability is a way to measure the impact of all the various life stressors. Since the heart rate is governed by the central nervous system, precise monitoring and measurement gives us a gauge of how stressed our system is.
This is a measurement of the time interval between heart beats and how much variation there is over a specific time period. So if your heart rate is 60 bpm, it is rare that your heart will be beating exactly once per second.
It is more likely that your heart will beat once and then 1.1 second later beat again. And then 0.9 seconds later, it will beat again. The measurement of this variation is called heart rate variability.
Low HRV (heart rate variability) means that the sympathetic branch of the central nervous system is more active. The sympathetic branch is responsible for the stress response commonly known as “fight or flight”.
High HRV (heart rate variability) means that the parasympathetic branch is more active. The parasympathetic branch is responsible for the relaxation response commonly referred to as “rest and digest”.
How to Use HRV Measurement
Modern innovations in smart phones and heart rate monitors have made it possible to do it yourself. There are several apps available. Here is the one I use.
Each morning after measuring, it gives you a readout like this:
As you can see, when your HRV drops, it will prompt you to ease up on your workout. I usually will do some form of active recovery such as walking, slow running, tai chi, or yoga on those days.
Interview: Andrew Flatt on HRV
Beyond Training, Ben Greenfield
Nick Ortego is a health coach specializing in biohacking for runners. He integrates modern methods with the ancient wisdom of yoga to help runners get the most out of every aspect of life. He is the owner of N 2 Action, a wellness studio in Baton Rouge, Louisiana, offering personal training, health coaching, yoga, and fascial stretch therapy.