Resting Heart Rate (RHR)

What it is

The number of heartbeats per minute at rest, ideally measured first thing in the morning before getting out of bed. Modern measurement is dominated by wearables (smartwatches, smart rings, chest straps) that track nightly RHR continuously.

Why it matters

Meta-analyses across millions of person-years show a roughly linear relationship between RHR above ~60 bpm and all-cause mortality — each 10 bpm increase corresponds to roughly 9% higher mortality risk.

Reference ranges

• Endurance athletes: 40–55 bpm.
• Fit recreationally-active adults: 55–65 bpm.
• Average adults: 60–75 bpm.
• Sedentary / deconditioned: 75–90 bpm.

Persistent RHR >90 in adults warrants clinical evaluation (hyperthyroidism, anaemia, anxiety, beta-agonist medications, cardiac arrhythmia, sleep apnoea).

Caveats

• Athletic bradycardia is normal; very low RHR with symptoms (dizziness, syncope) needs evaluation.
• Beta-blockers mask RHR.
• Acute illness, dehydration, stress, alcohol, poor sleep all elevate it.

What lowers RHR (chronically)

• Endurance exercise is by far the strongest modifier.
• Weight loss, smoking cessation.
• Improved sleep, reduced alcohol.

Related entries

HRV, VO2max, Exercise.