What’s Apple Watch HRV Tracking¬†

The Apple Watch, ever since its inception, has always focused on not just being a communication tool, but a personal health device. One of its key health-tracking features, particularly from the Series 4 onwards, is the Heart Rate Variability (HRV) measurement. This tool has far-reaching implications in predicting and maintaining a user’s overall health and wellness.


What is HRV?

HRV stands for Heart Rate Variability, a measure of the variation in time between each heartbeat. This variation is controlled by a primitive part of the nervous system called the autonomic nervous system (ANS). It works continuously, adjusting the heart rate based on the body’s stress levels and needs.

Interestingly, a higher HRV (more variability between beats) is usually a sign of a healthy, well-functioning heart. For instance, during a moment of high physical or emotional stress, the ANS may decrease HRV to make the heartbeat more consistent and predictable. On the contrary, during a relaxed state, the ANS might increase HRV, allowing for more variability between beats.

How does the Apple Watch Track HRV?

Apple Watch uses a method called photoplethysmography to measure your HRV. This involves using the built-in sensor on the underside of the watch that flashes green LED lights hundreds of times per second onto the skin. By measuring the amount of light reflected back, it can calculate the rate at which the heart is beating and the variability between these beats.