Heart Rate Variability
The time between heartbeats varies slightly, even when the average Heart Rate is constant. For example, a Heart Rate of 60 BPM is an average of one beat per second. However the actual time between heartbeats could vary so that some beats occur after 0.8 seconds, and some after 1.2 seconds. Generally, heart rate variability is greatest at rest and the variability declines as the heart rate rises. Heart rate variability is linked to aerobic fitness, with the fittest individuals having the greatest variability, and this can be used to predict V̇O2max. Some Running Watches can display heart rate variability.
- Heart rate variability and physical exercise. Current ... [Herz. 2006] - PubMed - NCBI http://www.ncbi.nlm.nih.gov/pubmed/17036185