Measuring Heart Rate Variability – R-R Recording

Heart rate varies with every heartbeat. Heart rate variability (HRV) is the timing between beats, also known as R-R intervals.

An average heart rate of 60 beats per minute (bpm) does not mean that the interval between successive heartbeats would be exactly 1.0 sec, instead they may fluctuate/vary from 0.5 sec up to 2.0 sec.

HRV is affected by aerobic fitness and is generally large at rest for a well conditioned heart. Other factors that affect HRV are age, genetics, body position, time of day, and health status. During exercise, HRV decreases as heart rate and exercise intensity increase. HRV also decreases during periods of mental stress.

HRV is regulated by the autonomic nervous system. Parasympathetic activity decreases heart rate and increases HRV, whereas sympathetic activity increases heart rate and decreases HRV.

HRV is used in the OwnZone®, OwnIndex®, and in OwnOptimizer™ features. It can also be monitored on its own using the RS800. If your HRV changes at a given running pace and heart rate, this may indicate a change in your training load and stress.

Variation in milliseconds between each heartbeat.

RS800 shows SD1 timing in real-time

SD1 is the mean time difference between maximum & minimum heart beat intervals.

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Polar RS 800 SD manual Measuring Heart Rate Variability R-R Recording