What a rising resting heart rate tells you

Resting heart rate is the cheapest longitudinal biomarker you own. In a 5,262-person study, its drift from baseline flagged infection days before symptoms.

By Hydra Editorial

Resting heart rate is the cheapest longitudinal biomarker most people own, and the clinically normal range is so wide that the absolute number rarely says much. The drift says more. In a 5,262-person study, sustained elevation above personal baseline flagged infection a median of four days before symptoms.

What is a normal resting heart rate?

The American Heart Association puts the normal adult resting range at 60 to 100 beats per minute, a 40-beat window that includes both a sedentary office worker and an endurance athlete. Trained adults frequently sit in the 40s. That is not an abnormality, it is a larger stroke volume doing the same work with fewer beats.

Because the range is so wide, a single reading tells you very little about an individual. What resting heart rate does well is behave consistently within a person. Measured the same way each night, it settles into a narrow personal band, and departures from that band are informative in a way that comparison against the population band is not.

What makes resting heart rate rise?

Several things, most of them ordinary. Alcohol, late meals, heat, dehydration, poor sleep, psychological stress, altitude and training load that exceeds recovery all raise it, usually for a night or two.

Infection is the case with the best published evidence. In a Stanford study of 5,262 participants published in Nature Biomedical Engineering, a real-time algorithm watching for sustained elevation in resting heart rate relative to each person’s own baseline would have detected 63% of confirmed COVID-19 cases before symptoms appeared, with a median lead time of four days.

The pattern that carried information was not a threshold. It was a sustained departure from an individual baseline, which is only detectable if that baseline has been measured continuously for long enough to know what it is. That is the wider case for pre-symptomatic detection, and resting heart rate is the metric it rests on.

The bottom line

  • The normal adult range of 60 to 100 bpm is wide enough that a single reading says little about an individual.
  • Resting heart rate is stable within a person, which makes deviation from a personal baseline the informative signal.
  • In a 5,262-person cohort, sustained elevation above baseline preceded COVID-19 symptoms by a median of four days.

Frequently asked questions

What is a good resting heart rate by age?
The standard adult range is 60 to 100 beats per minute and does not change dramatically with age in healthy people. Trained adults often sit below 60. Because the healthy range is so wide, the more useful measure is how your own resting heart rate is trending over weeks.
Why has my resting heart rate gone up?
Common causes include alcohol, poor or short sleep, late heavy meals, heat, dehydration, psychological stress, altitude and training load exceeding recovery. Infection also raises it, often before other symptoms appear. A sustained rise over several days is more meaningful than a single elevated night.

Sources

  1. Mishra, T., Wang, M., Metwally, A.A. et al., 2020. Pre-symptomatic detection of COVID-19 from smartwatch data. Nature Biomedical Engineering, 4, 1208 to 1220.
  2. American Heart Association, 2024. All About Heart Rate (Pulse). American Heart Association.
  3. Mount Sinai Health System, 2021. Wearable Devices Can Detect COVID-19 Symptoms and Predict Diagnosis: the Warrior Watch Study. Mount Sinai, press release.
Hydra Editorial

Hydra's editorial team. We write from primary research and cite every study we rely on, with its year and journal. We quantify claims wherever the evidence allows and state plainly where it does not: where a finding rests on a small or single trial, we say so in the text rather than in a footnote.