Your HRV number is not the point
In 1,175 healthy adults, mean rMSSD was 27.3ms with a standard deviation of 22.2ms. The spread between people is why HRV charts tell you so little.
In a study of 1,175 adults free of cardiovascular disease, mean rMSSD was 27.3 milliseconds with a standard deviation of 22.2 milliseconds. When the spread between healthy people is almost as large as the average, a comparison chart stops being useful. Your own trend is the measurement that carries information.
What is a normal HRV range?
The most cited reference values come from O’Neal and colleagues, published in the Journal of Electrocardiology in 2016, drawn from 1,175 participants free of cardiovascular disease in the Multi-Ethnic Study of Atherosclerosis, mean age 59. Mean SDNN was 24.1 milliseconds (median 20.8) and mean rMSSD was 27.3 milliseconds (median 22.0), reported with sex- and ethnicity-specific cutoffs.
The standard deviations are the interesting part. At 22.2 milliseconds around a mean of 27.3, two equally healthy people can differ by a factor of several and both sit comfortably within the normal range. Genetics, age, sex, measurement method and recording length all move the number before behaviour gets a look in.
This is why HRV values from different devices are not comparable, and why a chart that tells you the average for your age bracket answers a question you were not really asking.
What does HRV actually predict?
It predicts outcomes at the population level, and it does so reliably. When those reference cutoffs were applied to a larger MESA cohort of 6,332 participants followed for a median 11 years, people in the borderline abnormal and abnormal categories had higher rates of cardiovascular disease and all-cause mortality. HRV reflects autonomic nervous system balance, largely the parasympathetic activity that shows up as beat-to-beat variation in timing, and that balance responds to a lot of things.
The practically useful signal is directional. HRV is suppressed within hours by alcohol, late heavy meals, poor sleep, acute illness and training load that exceeds recovery capacity. It rises with aerobic fitness over months. A 20% drop from your own two-week average tells you something. A number 20% below the population mean for your age mostly tells you about the population. What actually moves it is a separate question from what a good value looks like.
These are observational findings, so lower HRV is associated with worse outcomes rather than shown to cause them.
The bottom line
- In 1,175 healthy adults, mean rMSSD was 27.3ms with a standard deviation of 22.2ms, so healthy values span a very wide range.
- Applied to a larger cohort followed for a median 11 years, lower HRV was associated with higher cardiovascular disease and all-cause mortality.
- Deviation from your own rolling baseline carries more information than your position on an age chart.
Frequently asked questions
- What is a good HRV for my age?
- There is no single good value. In a 1,175-person reference cohort, mean rMSSD was 27.3ms with a standard deviation of 22.2ms, meaning healthy people vary enormously. Age charts describe population averages and cannot establish whether a given individual’s value is appropriate for them.
- Why does my HRV change so much day to day?
- Heart rate variability responds quickly to alcohol, late meals, sleep quality, illness onset, heat and training load. Day-to-day swings are expected. This is why most analyses use a rolling average over one to two weeks rather than reading a single night in isolation.
Sources
- O'Neal, W.T., Chen, L.Y., Nazarian, S. and Soliman, E.Z., 2016. Reference Ranges for Short-Term Heart Rate Variability Measures in Individuals Free of Cardiovascular Disease: The Multi-Ethnic Study of Atherosclerosis (MESA). Journal of Electrocardiology, 49(5), 686 to 690.
- Umetani, K., Singer, D.H., McCraty, R. and Atkinson, M., 1998. Twenty-four hour time domain heart rate variability and heart rate: relations to age and gender over nine decades. Journal of the American College of Cardiology.