Heart Rate Variability isn't just for elite athletes anymore. If you have an iPhone, you already have everything you need to start tracking your recovery — starting today.
Heart-rate variability sounds technical, but the idea is simple: a healthy, well-recovered nervous system produces slightly uneven gaps between heartbeats, and that variation is a useful daily signal. Pulse Rate measures it from your iPhone camera and explains what it means. This beginner’s guide starts from zero.
The variation between heartbeats — your nervous system's report card.
Two metrics, one number. Why Pulse shows both — and which to watch.
Training-impulse: your weekly training load, in one chart.
HRV measures the millisecond variation between consecutive heartbeats. Higher variability signals your nervous system is in a well-recovered, adaptable state. Lower variability signals fatigue or stress.
HRV only becomes useful once you have a personal baseline to compare against. Commit to 14 consecutive morning readings before drawing any conclusions. Pulse Rate builds your baseline automatically.
An HRV of 40ms might reflect excellent recovery for one person and poor recovery for another. What matters is whether YOUR number is trending up, flat, or down relative to YOUR baseline.
On mornings when HRV is well above your baseline, your body is ready for a challenging effort. On low-HRV mornings, prioritize easier movement, extra sleep, and stress management.
The same chart that lives on your iPhone's Progress screen — rebuilt so you know what you're looking at.
Outstanding score. Your key heart metrics are above normal.
Most healthy adults fall within this range.
Not necessarily alarming — but worth monitoring.
If this persists, please consult a healthcare professional.
TRIMP = duration × intensity. A 60-minute easy run scores about 70 TRIMP. A 30-minute interval session scores 110. Pulse adds them up daily and tells you when your week is too light, just right, or about to overcook you.
HRV is the variation in time between consecutive heartbeats. Counter-intuitively, more variation usually means better recovery and a more adaptable nervous system, while a flat, low HRV can signal stress or fatigue.
Higher is generally healthier, but HRV is deeply individual — it varies with age, fitness and genetics. The useful comparison is your own trend over time, not someone else’s number.
Place your fingertip over the rear camera and flash and stay still for 60 seconds. Pulse uses photoplethysmography to read the beat-to-beat intervals and calculate your RMSSD and SDNN.
Give it one to two weeks of consistent morning readings. A single day tells you little; the trend across many days is where the signal lives.
You've already got the hardware — your iPhone. Pulse does the rest.
Free to download · Core tracking always free · iOS 15+