While it is widely recognized that a person’s normal resting heart rate is fairly consistent over time, a new research study suggests otherwise. According to an analysis of the largest dataset of daily resting heart rate ever collected, the findings suggest that normal heart rate may vary from others’ by up to 70 beats per minute.
Giorgio Quer of the Scripps Research Translational Institute (SRTI) in La Jolla, California, and colleagues presented this finding in the open-access journal PLOS ONE on February 5, 2020 as part of an upcoming PLOS Collection on Digital Health Technology.
A routine visit to your doctor usually consists of taking a measurement of your resting heart rate, but such measurements are rarely actionable unless they deviate significantly from a “normal” range established by population-level studies. SRTI researchers say that wearables that track heart rate now provide an opportunity to continuously monitor a person’s heart rate over time, and identify normal resting heart rates at the individual level.
In the largest study of its kind to date, Quer and colleagues retrospectively analyzed de-identified heart rate data from wearables worn for a median of 320 days by 92,457 people from across the U.S. During this study, nearly 33 million days’ worth of heart rate data were collected in total by the researchers who used the collected data to examine variations in resting heart rate for individuals over time, as well as between individuals with different characteristics.
Differing Heart Rates
The study’s analysis revealed that one person’s mean daily resting heart rate may differ by up to 70 beats per minute from another person’s normal rate. The researchers note, taken together, age, sex, body mass index (BMI), and average daily sleep duration accounted for less than 10 percent of the observed variation between individuals.
Quer’s research team observed also a small seasonal trend in the resting heart rate, with slightly higher values observed in January and slightly lower values in July. They also found that some individuals may occasionally experience brief periods when their resting heart rate differs by 10 or more beats per minute from their normal range.
The researchers say that their findings suggest the potential value of further research to investigate whether tracking a person’s daily resting heart rate.