Physicians' Academy for Cardiovascular Education

Large resting heart rate variability between individuals, but small variability within individuals

Inter- and intraindividual variability in daily resting heart rate and its associations with age, sex, sleep, BMI, and time of year: Retrospective, longitudinal cohort study of 92,457 adults

Literature - Quer G, Gouda P, Galarnyk M et al., - PLoS ONE 2020, 15(2):e0227709, doi: 10.1371/journal.pone.0227709

Introduction and methods

Several studies have found that changes in individual heart rate (HR) measurements over a prolonged period of time are associated with CV outcomes [1-4]. Longitudinal, individual HR data that are obtained daily in normal living conditions over long periods may therefore provide more information than a single HR measurement. Commercial wearable devices often contain sensors that can measure HR continuously. The accuracy of these sensors is similar to that of standard ECG monitoring, especially at rest [5-7]. The aim of this study was to evaluate the inter- and intraindividual variability in resting HR (RHR) using data from wearable devices.

This retrospective observational cohort study collected data from 92,457 individuals that used a wearable device for a minimum of 35 weeks, for at least 2 days per week, and at least 20 hours per day. The average age was 45.8 ± 14.4 years, 63% were women, average BMI was 28.4 ± 5.8 kg/m². The RHR measured by the wearable device is expected to be representative of the true value of RHR that would be measured in a supine position immediately after waking and before getting out of bed. The association of individual mean RHR, as well as RHR variability, with age, BMI, and average time sleep (measured by the device) was analyzed. Furthermore, RHR variability between individuals and long- and short-term changes in an individual’s daily RHR were studied.

Main results


This retrospective observational study investigated the inter- and intraindividual variability in daily RHR and found that the average RHR varies widely between individuals (as much as 70 bpm). Within individuals, RHR was more consistent over time. A prospective study will be necessary to investigate whether information about daily RHR can be of value for the early detection of important physiological changes in individuals.


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