Every watch hands you the same zones off the same age formula. RunEasy runs one guided test that measures your actual zone 2 — from your voice — then coaches you silently from your own band.
Requires Apple Watch with watchOS 10 or later
Almost every heart rate zone you have ever been given traces back to 220 − age. That estimate misses individual maximum heart rate by roughly ±10–12 bpm, and by considerably more at the tails. Two runners the same age can have genuinely different thresholds — and receive identical zones.
The error compounds, because zone 2 is a band derived from that single wrong number. A 15 bpm miss at the top displaces the whole band.
A real calibration result. The formula's band starts 12 bpm too low — so its bottom half is barely training, while its ceiling sits above the point where this runner's speech actually broke down.
If holding "zone 2" forces you to walk, the likely problem is your zones, not your fitness. That is the single most common symptom of a miscalibrated band, and it makes people quit aerobic training just as it starts working.
Zone 2's real boundary is your first ventilatory threshold — the effort past which breathing demand becomes impossible to suppress and you can no longer speak in full sentences. That is a thing you can observe directly, which is exactly what the talk test has been used for in clinical exercise prescription for decades.
RunEasy automates it into a single guided run.
The whole thing takes about 20 minutes, once. Running and cycling calibrate separately, because they are genuinely different physiological measurements — calibrating one never overwrites the other.
After calibration, RunEasy stops talking. Ordinary runs are coached silently from your own band: the display colour tells you where you are, and a distinct haptic tells you to ease off. Turn the Digital Crown to enlarge whichever metric you care about.
An occasional voice check-in re-verifies the zone as your fitness changes, and the app nudges you to recalibrate every few weeks — because a measured zone is only accurate until you get fitter.
Every response is scored against a resting recording of your own voice, so the assessment is relative to you rather than to a population.
| Dimension | Weight | What it detects |
|---|---|---|
| Respiratory fragmentation | 30% | Words per unbroken phrase and total breath count — the most direct read on ventilatory threshold |
| Breath pattern | 20% | Whether breaths land at clause boundaries or force in mid-phrase; audible gasping |
| Speech fluency | 20% | Response completeness, gap variability, overall speech rate |
| Vocal strain | 15% | Pitch elevation, jitter, and volume fading across a phrase as lungs empty |
| Signal quality | 10% | How cleanly the voice was captured — wind and traffic trigger an automatic retry |
| Temporal stability | 5% | Whether speech held steady or deteriorated across the sample |
A personal HR and pace band per activity, with a confidence rating and formula comparison.
Colour and haptics from your own band. No chatter unless you ask for it.
Metrics stacked like Apple's Workout app — turn the crown to enlarge one.
Dictate how a run felt on your watch; your iPhone transcribes it into the workout.
Workouts save with GPS route maps, distance and calories.
Separately calibrated, with the right metrics and US units for each.
Talk test audio is analysed on your watch and discarded. It is never written to storage and never transmitted.
We wrote a thorough, independent guide to zone 2 training and the talk test — what the zone physiologically is, why "zone 2" confusingly means two opposite things depending on who's talking, how to run a talk test yourself with no equipment at all, and the mistakes that quietly undo the training.