Does PEAKVO2 have color-coded workout phases?

Yes. PEAKVO2 shows every phase full screen in its own color, warm-up, work, and recovery each look different, so a glance tells you exactly where you are in the session without reading text. The phase changes automatically and taps your wrist at each switch.

Does PEAKVO2 show your heart rate during intervals?

Yes. Your live heart rate is shown on screen during the workout, so you can see whether you are hitting the target zone for each interval. On Apple Watch the heart rate is read from the wrist sensor in real time.

Does PEAKVO2 have a yearly activity heatmap?

Yes. The Activity tab shows a year-in-review heatmap of your training frequency, along with your VO2 max trend over time, your streak, and totals, so you can see consistency and progress at a glance.

Does PEAKVO2 sync with Apple Health, and can it see workouts from other apps?

Yes. PEAKVO2 works with Apple Health: your interval sessions are saved as Health workouts with heart rate and activity data, and because Apple Health aggregates everything, workouts logged by your other fitness apps and your Apple Watch appear alongside your PEAKVO2 training.

Does PEAKVO2 have built-in calculators?

Yes. The app includes built-in calculators, including a heart rate ratio estimate of VO2 max and heart rate training zones. The website adds free browser calculators for VO2 max, max heart rate, and zone 2.

How many workout protocols does PEAKVO2 track?

16 ready-to-run workouts: Norwegian 4x4, Tabata, HIIT 30/30, REHIT 2x20, Norwegian 3x3, Marten's 6x3, hill, track, and fartlek intervals, and more, plus a custom workout builder. Each has built-in warm-up, work, recovery, and cool-down phases, and the app tracks all of them in one place.

PEAKVO2 Features: What the Interval Training App Does

Q: Does PEAKVO2 show workout progress on the lock screen?

Yes. A Live Activity shows your current phase, round, and countdown on the iPhone lock screen and Dynamic Island, so you can check the session without opening the app.

By Cristian Serb · Updated August 12, 2026

Athlete using a fitness app on a phone and Apple Watch

Run these workouts on your iPhone, or hands-free on Apple Watch. Get PEAKVO2

Everything PEAKVO2 does, in one place: 16 guided interval protocols, full-screen color-coded phases with your live heart rate, hands-free training on Apple Watch, lock-screen Live Activities, Apple Health sync, a yearly activity heatmap with your VO2 max trend, and built-in calculators. It is a training app, not a testing service.

Full-Screen Color-Coded Phases, With Live Heart Rate

Every phase of a workout fills the screen in its own color, so a glance tells you whether you are in warm-up, work, or recovery without reading anything. The app moves between phases automatically and taps your wrist at each switch, and your live heart rate is shown on screen so you can tell whether you are hitting the target zone for the interval.

PEAKVO2 work phase full screen in red with a large countdown and interval count

PEAKVO2 Live Activity on the iPhone lock screen showing the HIIT 30/30 warm-up phase and countdown

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16 Guided Protocols in One App

PEAKVO2 tracks 16 built-in interval workouts: the Norwegian 4x4, Tabata, HIIT 30/30, REHIT 2x20, Norwegian 3x3, Marten's 6x3, hill, track, and fartlek intervals, and more. Each runs itself with warm-up, work, recovery, and cool-down phases built in, so you pick one and start rather than programming intervals by hand.

PEAKVO2 interval workout list showing REHIT, Tabata, Norwegian 4x4, HIIT 30/30 and more protocols

A Yearly Activity Heatmap and Your VO2 Max Trend

The Activity tab is where progress shows up: a year-in-review heatmap of how often you trained, your VO2 max trend over time, your streak, and your totals. It answers the two questions that matter, are you consistent, and is the number moving.

PEAKVO2 Activity tab showing a yearly activity heatmap, VO2 max trend, streak, and training totals

Apple Watch, Live Activities, and Apple Health

Workouts run natively on Apple Watch with no phone needed, and a Live Activity puts your current phase and countdown on the iPhone lock screen and Dynamic Island. PEAKVO2 works with Apple Health, so your sessions are saved as Health workouts with heart rate and activity, and because Health aggregates everything, the training you log in other apps and on your watch sits alongside your PEAKVO2 sessions. For more on the wrist experience, see the Apple Watch interval training app page.

Built-In Calculators

The app includes built-in calculators, including a heart rate ratio estimate of VO2 max and your heart rate training zones. On the website, you can also use the free VO2 max calculator, max heart rate calculator, and zone 2 heart rate calculator.

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Cristian Serb

I'm the developer of PEAKVO2. I built it because I was doing the Norwegian 4x4 myself and wanted the timing handled on my wrist so I could just train. I took my own VO2 max from about 41 to 51 with it. PEAKVO2 on the App Store.