Your Personal
4×4 Interval Coach

Train smarter with real-time heart rate monitoring, live coaching feedback, and detailed workout analytics. The scientifically proven 4×4 interval protocol — right on your iPhone.

See It in Action Contact Us
4×4 Treadmill app home screen showing a runner on a treadmill ready to start a workout

Why 4×4 Treadmill?

Everything you need for effective high-intensity interval training

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4×4 Interval Protocol

Based on the scientifically proven Norwegian 4×4 method: 4 intervals of 4 minutes at high intensity with active recovery periods. Customizable warmup, interval, and recovery durations.

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Real-Time Heart Rate

Connect your Bluetooth heart rate sensor or Apple Watch. See your heart rate in real time with color-coded zone indicators so you always know if you're in the right intensity.

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Live Coaching

Get real-time feedback during your workout. The app tells you to pick up pace when your heart rate is too low, or to slow down when you're pushing too hard.

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Execution Score

After each workout, get a score from 0 to 100 based on your intensity, consistency, and recovery. Track your progress and see how your performance improves over time.

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Detailed Analytics

View heart rate charts, per-interval breakdowns, distance, duration, and VO₂max estimates. Every workout is stored so you can review your training history.

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Fully Customizable

Adjust warmup duration, interval length, recovery time, treadmill speed, and incline. Set your max heart rate manually or use the built-in calculator. Supports English and Norwegian.

How It Works

A complete 4×4 session in three simple steps

1

Set Up

Connect your heart rate sensor, configure your warmup and interval durations, and set your target heart rate zones.

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2

Train

Hit Start and follow the guided workout. The app coaches you through warmup, four high-intensity intervals with recovery, and cooldown.

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3

Review

See your Execution Score, heart rate charts, and per-interval breakdown. Track your progress over days, weeks, and months.

See It in Action

A clean, intuitive design that keeps you focused on your workout

Home screen — Ready to train with start workout button

Ready to Train

Active workout screen with timer, speed and incline controls

Active Workout

Activities overview with weekly stats and workout history

Activity History

Workout detail with metrics and execution score

Workout Details

Heart rate chart with interval breakdown

HR Chart & Intervals

Settings screen for language, appearance, sensors, and durations

Settings

Workout complete screen showing Well Done message

Workout Complete

Send Us Feedback

We'd love to hear from you. Help us make 4×4 Treadmill even better.