Heart Rate Variability (HRV) Tracking Devices

THIS ARTICLE IS A DRAFT

We all know about heart rate: the number of beats your heart makes in a minute. However, a new measure called heart rate variability (HRV) is quickly becoming an essential metric for athletes. The latest Apple Watch measures it, and I predict that more mainstream wearables like Fitbit will soon offer products that do as well.

HRV is a measure of the beat-to-beat fluctuations in your heart rate and can indicate the state of your autonomic nervous system – the unconscious system that regulates heart rate, digestion, respiratory rate, urination, sexual arousal, and other bodily functions.

Less variation between heart beats (a lower HRV score) is an indication that your nervous system is in a sympathetic or "fight-or-flight" mode. While more variability (a higher HRV) indicates that your body is in a parasympathetic "rest-and-digest" mode.

Why measure HRV

HRV is being used to determine how stressed your nervous system is. This can help determine if you're getting sick or need to rest more after that hard workout day.

One study hypothesizes that HRV indicates early metabolic disturbances that may be responsible for further development of disease. source A study has also shown that a measure of heart rate failure has been associated with a lower HRV score. source

Devices to measure HRV

  • WHOOP Strap – See our review of the WHOOP strap. While not perfect, this is a high-end device worn on the wrist that measures HRV and sleep stages extremely well.
  • Oura Ring – This is a cleverly-designed device that looks like a normal ring. You wear it at night to measure your sleep stages and HRV. I found the ring to be uncomfortable at night, but this device is popular in the biohacking community.
  • Apple Watch – There have been doubts about the sensitivity of the Apple Watch, but at least one study has indicated that the device is a reliable source of HRV. source
  • Inner Balance – This company produces a device that clips onto the ear and is sensitive enough to measure high and low frequency HRV. It comes bundled with its own mobile app.
  • EliteHRV CorSense – This company started with a popular mobile app and has since moved into manufacturing their own device. The CorSense can be worn on the finger and looks like a pulse oximeter you might wear at a hospital. It is sensitive enough to measure high and low frequency HRV. This device is unique in that it can be used with a variety of mobile apps.