Ramp4x4: VO2 Max Trainer

Train your VO2 max with guided Norwegian 4x4 interval workouts. Ramp4x4 handles the timer, heart-rate guidance and coaching so you can focus on the effort.

Four 4-minute hard intervals. Three-minute active recoveries. Warmup and cooldown included. Start the classic workout for free on iPhone or Apple Watch.

KNOW WHAT TO DO NEXT
See your next session, recent workouts and cardio fitness in one clear Today view. Follow a structured 8-week plan with Ramp4x4+, progressing through Build, Overload, Peak and Taper.

STAY WITH YOUR TARGET
See whether your heart rate is below, within or above your target. Follow interval countdowns, voice cues and haptics without constantly watching the clock. Apple Watch is optional: use a compatible Bluetooth heart-rate monitor, supported heart-rate earbuds on iOS 26 or later, or Timer Only on iPhone.

TRAIN WHERE YOU LIKE
Run outdoors, use a treadmill, ride a bike, or train on a rower, elliptical, stair climber or SkiErg. Run a workout directly from Apple Watch, even when your iPhone is unavailable.

MAKE EVERY INTERVAL COUNT
Review completed intervals and your latest workout summary. Ramp4x4+ adds full workout history, interval breakdowns, time in target, heart-rate recovery and workout-quality insights to help you understand each session.

FOLLOW YOUR CARDIO FITNESS
See your latest available VO2 max estimate from Apple Health. Ramp4x4+ adds available Cardio Fitness history and workout trends. Ramp4x4 displays Apple Health estimates; it does not directly measure VO2 max or guarantee improvement. Indoor workouts do not generate Apple Watch Cardio Fitness estimates, and a new estimate is not guaranteed after every outdoor workout.

START FREE
- Unlimited classic Norwegian 4x4 workouts
- iPhone and Apple Watch workout guidance
- Standard voice cues, haptics and interval countdowns
- Apple Health workout saving with permission
- Your latest workout summary and available Cardio Fitness estimate

GO FURTHER WITH RAMP4X4+
- Complete 8-week training plan
- Full workout history and detailed interval analysis
- Available VO2 max history and workout trends
- Custom interval, recovery and warmup presets
- Advanced heart-rate alert and coaching settings

Ramp4x4+ is an optional auto-renewing monthly or annual subscription. Price and duration are shown before purchase. Manage or cancel your subscription in your Apple account settings.

No account or login required. Heart-rate features require a supported source. Apple Health features require permission and available data. Supported heart-rate earbuds require compatible hardware and iOS. Ramp4x4 provides general fitness guidance, not medical advice. Build up gradually and speak with a clinician before high-intensity exercise if you have a health concern.

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