Resting heart rate — the slow signal and the daily one

Resting heart rate is how few beats your heart needs at rest. It carries two different stories at once, on two different timescales.

The slow story is fitness. As aerobic fitness improves, your heart moves more blood per beat, so it needs fewer beats — resting HR drifts down over months of consistent training. That drift is real progress, and it is the reason your "normal" is a moving target rather than a fixed number.

The daily story is recovery. Against your own recent normal, an elevated morning reading — often a handful of beats is enough to notice — points at something your body is dealing with: an unabsorbed hard session, a short night, alcohol, dehydration, heat, travel, or the start of an illness. Illness in particular often shows here a day before you feel it.

As with HRV, the absolute number is individual. Trained endurance runners commonly sit in the 40s or 50s, but plenty of fit people sit higher and plenty of untrained people sit low. There is no threshold that means "healthy" or "fit", so Runsei never compares you with a population — only with your own established normal, a 30-day median that excludes the most recent week so recent training cannot redefine it.

Resting HR is the most robust of the recovery signals — less noisy day to day than HRV — which is why an elevated resting HR *and* a suppressed HRV together is the pattern worth acting on.