Resting Heart Rate (RHR)

Resting heart rate (RHR), the number of heartbeats per minute while at rest, is one of the oldest and most accessible cardiovascular biomarkers, requiring nothing more than a pulse count or a basic wearable sensor. The claim: a higher resting heart rate independently predicts greater all-cause and cardiovascular mortality risk, and this holds true both for a person's baseline level and for how their heart rate changes over time.

The original Framingham Heart Study, following 5,070 subjects free of cardiovascular disease at baseline for 30 years, found death rates increased progressively with higher antecedent heart rate in both sexes at all ages [1]. A more recent analysis combining a 53,322-person cohort found individuals with RHR of 80 bpm or higher had a 66% higher all-cause mortality hazard (HR 1.66, 95% CI 1.45-1.89) and an 87% higher cardiovascular mortality hazard (HR 1.87, 95% CI 1.52-2.30) compared with those under 60 bpm, with a significant positive linear trend across RHR categories; low RHR remained protective regardless of cardiorespiratory fitness level, though unfit individuals with high RHR carried the single greatest risk (HR 2.21 for all-cause mortality) [2]. A 2024 analysis spanning the Paris Prospective Study I and the Framingham Heart Study found that subjects with resting heart rate above 90 bpm had an average lifespan of 70.3 years compared with 79.3 years for those under 60 bpm, a 9-year difference (hazard ratio per 10-bpm difference 1.25, 95% CI 1.21-1.30, p<0.0001), and that increases in resting heart rate over a 5- to 8-year period independently predicted higher mortality risk even after adjusting for the starting heart rate itself (HR per 10-bpm increase over time: 1.20 in Paris Prospective Study I men; 1.13 in Framingham men; 1.09 in Framingham women) [3].

How to measure it: manual pulse count for 30-60 seconds upon waking, before rising from bed, is the traditional approximation of true resting heart rate; clinical measurement uses a resting ECG or pulse oximetry after several minutes seated quietly [4]. Consumer wearables estimate RHR continuously overnight using photoplethysmography, generally correlating well with manual counts though subject to some device-specific variability [5].

How to intervene on it: aerobic exercise training is the best-established intervention for lowering resting heart rate, since improved cardiovascular fitness increases stroke volume and allows the heart to pump the same cardiac output at a lower rate; beta-blocker medications also lower heart rate pharmacologically but are prescribed for specific cardiac conditions rather than as a general longevity intervention, since artificially lowering heart rate with medication in the absence of a cardiac indication has not been shown to replicate the mortality benefit seen with fitness-driven RHR reduction.

Critics note that resting heart rate is confounded by caffeine, stress, sleep quality, medication use, and illness at the time of measurement, so single readings, especially from consumer wearables, can be misleading without accounting for context [5]. The mortality association, while consistent at the population level, is partly a proxy for underlying cardiorespiratory fitness and autonomic health rather than a directly independent causal risk factor [6].

The plain takeaway: resting heart rate is an extremely low-cost, highly accessible biomarker with decades of consistent evidence linking higher values, and increases over time, to higher mortality risk, and unlike many other biomarkers can be meaningfully lowered through a well-established, side-effect-free intervention: sustained aerobic exercise.