Train by heart rate,
not guesswork.
Effort is easy to misjudge. You set out for an easy run and finish it tired; you plan a hard session and coast. In The Zone shows which of five training zones you're actually in — live, while it still matters.
For iPhone and Apple Watch. Requires iOS 17 and watchOS 10.
A glance, not a stare
Prop your phone on the treadmill and the whole screen becomes your zone's colour. Green means easy. Red means you're deep in it. You can read your effort out of the corner of your eye, without breaking stride to squint at a number.
Turn the phone sideways and the number roughly doubles in width — the difference between readable and not, at running distance.
Your watch does the work
Live heart rate comes from an Apple Watch workout session, so readings are immediate rather than minutes stale. An iPhone alone genuinely cannot do this — Health data syncs from the watch on a schedule the system controls, and no app can hurry it.
Set a target zone and your watch taps your wrist when you drift out: one pattern for working too hard, another for easing off, and a gentle confirmation when you're back. You can hold a zone without looking at anything at all.
Built for indoors as well as out
Treadmill, elliptical, bike and rower are first-class here, not an afterthought — which is more than most running apps manage.
Outdoor runs, walks, rides and hikes record a route map coloured by the zone you were in. You can see the hill where you tipped into threshold and the stretch where you finally settled. Other apps show terrain, or pace. None of them show what your heart was actually doing.
Know if you're doing too much
Training load weighs your time by intensity — twenty minutes at threshold costs five times twenty easy ones — and compares this week against your recent average. It answers the question a total-time figure never can.
The comparison is withheld until there's enough history for it to mean something. A verdict based on three days would be noise dressed as insight.
Your data stays yours
Your heart rate, workouts and routes live on your devices and in Apple Health. The only thing that ever leaves is a single number — your weekly minutes — and only if you choose to use the Game Center leaderboard. Read the full privacy policy.
In The Zone is a training aid, not a medical device. Heart rate zones are estimates. If something feels wrong while exercising, stop and speak to a doctor.