Heart rate now reaches your iPhone the moment the watch reads it, so the phone no longer shows "No signal" while your watch is reading you fine. When the watch's sensor briefly loses your pulse (common on a rower or with weights, where your grip flexes the wrist), the watch and the treadmill screen now say "Finding pulse", so you know to snug the band rather than wonder about the connection.

New: how recovered are you. • A Recovery card at the top of History reads the overnight heart-rate variability your Apple Watch already records and places last night against your own last four weeks: about your usual, above it, below it, or well below. It says what commonly causes a dip and that it is a signal, not a diagnosis. • The milliseconds are there for those who want them, behind "The numbers". Opt-in, compared with your own readings only, and nothing leaves your iPhone. • When your training load has been climbing while your recovery signal is below usual, the card says so in one sentence. • Uses the newer RMSSD measure on iOS 27 once it has a month of its own readings, and the SDNN your watch has recorded for years before that.

Built for iOS 27 and watchOS 27. Still runs on iOS 17 and watchOS 10. • Your zones travel with your workouts. From iOS 27 the Health app works out time in each heart-rate zone by itself. In The Zone now tells Health which zones you actually trained on, so the split in Health matches your summary. • Health's zones, if you'd rather. Settings › Zones shows whether your zones match the ones in Apple Health, names any zone that starts at a different heart rate, and lets you switch to Health's with one tap (and back). • Training Plans. Six zone-based interval sessions built on your own zones, sent to the watch's Workout app. • A note under each finished workout, written on your iPhone (Apple Intelligence where available), only ever restating what the numbers already say. • Honest about short history: if Health shares less than four weeks of workouts, the training-load card says so. • The Lock Screen workout banner now also appears in the Apple Watch Smart Stack, and the Dynamic Island shows your zone colour in landscape when the number won't fit. • Weekly Zone Mix in iOS 27's extra-large widget size. • Ready for wider screens, and a note on how watchOS 27 treats a paired chest strap.