What are R-R intervals?
Heart rate variability (HRV) is NOT heart rate. Heart rate is just your average number of heartbeats, while HRV is the tiny difference BETWEEN each heartbeat.
HRV is a powerful biomarker that has helped millions to:
- Improve training and recovery
- Get fitter, faster, and stronger
- Get healthier and address chronic disease
- Manage stress
- And much more!
Key to the power of HRV is its deep connection to your nervous system, which controls and responds to many important body processes, like:
- Vision, hearing, and smell
- Sexual function
- and more
This connection requires tracking small changes (milliseconds) in the intervals between successive heartbeats (Fig 1), also called "RR intervals". This is different from heart rate, which just averages the number of beats per minute.
Fig 1: Heart rate variability
To measure HRV, you must have a compatible heart rate monitor that can accurately sense RR intervals. Many monitors do not meet this standard because:
- They were not designed with HRV in mind, and do not have the required accuracy. Most wrist-wearables (watches, etc) fall into this category.
- They record RR-intervals but artificially "smooth", average or alter them before transmitting to us. Our app tries to alert you when this happens with a reading.
For example, most wristbands and watches have difficulty sorting through the "noise" of an HRV reading because of all the complicated tissue in your wrist that surrounds your arteries.