What is heart rate variability (HRV)? As popular as the metaphor may be, a healthy heart doesn’t beat as regularly as a metronome. In fact, it changes its rhythm with each beat. Heart rate variability ...

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 ...

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.