Understanding Heart Rate Variability

Fourth Frontier

Last Update vor 7 Tagen

Heart Rate Variability is a measure of the variation of time in between each of your heart rates.


Heart Rate Variability is a good measure of the Autonomic Nervous System which consists of the Parasympathetic system (A neural system that promotes rest and recovery) and our Sympathetic system (Our fight-or-flight system). A higher HRV indicates that your Parasympathetic system is more active whereas lower HRV values may occur due to stress, fatigue, and illness.


Activities like relaxation, yoga, meditation, and moderate exercise training can lead to increased HRV over time, which is a positive indicator of good heart health.


When measured continuously, most individuals have HRV values between 0-100, where higher values are better. It is normal for HRV to vary during the day depending on the time of measurement. When continuously monitoring HRV, it is normal for HRV to be minimal during exercise, and reach its highest value during deep sleep.


Average HRV, when measured at rest, is a good day-to-day indicator of how stress, illness, training and relaxation is affecting your autonomic nervous system. Average HRV values are known to reduce as you age.

Variation in Average HRV by Age, Gender and Time of Measurement

The shaded contours are 1 SD ranges for measurements taken from 0600 hrs to 0700 hrs

(Natarajan A, Pantelopoulos A, Emir-Farinas H, Natarajan P. Heart rate variability with photoplethysmography in 8 million individuals: a cross-sectional study. Lancet Digit Health. 2020 Dec;2(12):e650-e657. doi: 10.1016/S2589-7500(20)30246-6. Epub 2020 Nov 23. PMID: 33328029)


Frontier X2 Measure of Heart Rate Variability


We use a standard method of calculation called RMSSD which stands for Root Mean Square of Successive Differences ( between heartbeats). This means that we first calculate each successive time difference between heartbeats in ms. Then, each of the values is squared and the result is averaged before the square root of the total is calculated over a 20s session.


In the example below, the HRV by RMSSD is calculated to be 57.2


For any further clarifications or questions, please reach out to us at support@fourthfrontier.com

Was this article helpful?

14 out of 15 liked this article

Still need help? Message Us