Heart rate variability (HRV) is the variation in the time between two consecutive heartbeats over a specific period. Doctors may use HRV as an indicator for certain aspects of a person’s health, ...

Micro-fluctuations in the time between heartbeats are proving a helpful indicator of mental health, stress levels and exercise capacity. They could even provide insight into how well you are ageing.

Fitness trackers and smart watches are widely popular wearable devices that measure several types of health metrics, including step count, calories burned, sleep quality, Vo2 max and heart rate. As a ...