Heart Rate Variability

When you exercise, you provide your body with a stressful shock, interrupting its homeostasis. Afterward, your body recovers and adapts to handle more next time. Your body’s energy, muscular, and cardiovascular systems rebuild themselves to be stronger in order to handle a heavier workload next time.

Exercise—especially high intensity training—can put your body in a stressed state for hours or even days after completed activity. The rate of recovery is determined by quality of sleep, diet, and how accustomed your body is to the level of activity it endured. During exercise, the body’s flight or fight response kicks in; the sympathetic branch of the nervous system becomes more active. As the body recovers, the parasympathetic branch rises back to a level higher than it started before exercise. This branch of the nervous system is responsible for the “rest-and-digest” activities when the body is at rest.

Heart Rate Variability (HRV) tracking is a great way to observe the parasympathetic branch as it controls the body’s recovery. While HRV was originally used in the space program, anyone with a heart rate monitor (like an Apple Watch, Fitbit, or MyZone belt) can check their recovery.

Heart Rate Variability is the variation in heart rate that occurs when our body is at rest. High variability is a good indication of recovery. Low variability indicates a higher level of stress. This is because when that flight or fight response kicks in, your body changes its heart beat to become very steady. If you are tracking your HRV, you should be monitoring your heart rate at the same time of day and comparing results to your baseline.

Monitoring your HRV is a good way to help determine your training regimen. Exercising when your body is unstressed is far less likely to result in overuse injury. HRV allows you to see when and how quickly your body recovers so you can plan what to jump into next! But it’s not all about the gym. Other sources of stress, sleep, diet, and overall lifestyle can all impact your HRV. If you want to see results, recovery is just as important as all the work you put in. Tracking your HRV is a great way to insure your allowing your body adequate time to get stronger!