One of the newest innovations in sports tracking is the heart rate variability (HRV) measurement.
HRV measures the constant variations (in milliseconds) between each beat of your heart. The variations can decipher whether you’re fatigued, beginning to get ill, or recovering well. HRV tends to notice these influences before your resting heart rate is affected.
To use HRV, you need a sports tracking device and the most popular options are an Oura Ring, Whoop band, or specific Garmin and Polar wearable devices. These devices need a few days of tracking on you, to create a baseline that sets benchmarks for future reference.
HRV tends to be tracked during your sleep, taking into account your day’s training load. A high HRV number would mean you are recovering well, where a low HRV number could suggest you’re overtraining or your body is under more stress than usual.
Using HRV when training can be a good deciding factor as to when you should take an extra recovery day or schedule in a more intense session if your HRV is high. Sleep plays a major factor in your HRV with most of the devices giving you accurate sleep data as well as setting sleep targets (yep, you should be training in your sleep too) and parenting your bedtime schedule.
It’s not quite as simple as a high number being good and a low number worse. According to Oura a high HRV is, "generally positive, there are situations where low HRV is necessary and even desirable." During extreme training sessions, "low HRV is a reflection of your fight-or-flight system appropriately dominating to get your heart rate up for activity. Your HRV will rebound afterwards, as your rest-and-digest system takes over to help you recover."
Many of the contemporary tracking devices appear to be exceptionally accurate in tracking both HRV and heart rate. Studies have shown that the data output of these devices is close to that of an ECG.
HRV isn’t an immediate requirement if you’re are a novice rider. But for those looking to get the most out of their training, it’s certainly an added benefit. One that can help you decipher why some days you have good legs and some days, for no reason, your legs are just dead.