Ramp4x4: the easiest way to run Norwegian 4x4 VO2 max intervals
Ramp4x4 is a free iPhone and Apple Watch app built for one job: running the Norwegian 4x4 VO2 max workout cleanly. It is not a generic fitness app you have to bend into shape. It knows the protocol, knows your heart-rate zones, and sets up all nine phases so you can tap start and just train.
What Ramp4x4 does
The Norwegian 4x4 is simple on paper and awkward in practice: a 10-minute warmup, four 4-minute hard intervals at 85 to 95% max HR, 3-minute active recoveries, and a cooldown. Ramp4x4 turns that whole sequence into one tap and then coaches you through every phase so you never have to manage a timer mid-effort.
- One-tap Norwegian 4x4. The full session is built for you: 10-minute warmup, four 4-minute hard intervals at 85 to 95% max HR, 3-minute active recoveries, and a cooldown.
- Live heart-rate zone coaching. Your current heart rate against the target zone, so you can pace each interval instead of guessing.
- Haptics and voice cues. A wrist tap and a spoken prompt at every phase change, so you feel "push" and "ease off" without staring at the screen.
- Big countdowns. A large, glanceable timer for the phase you are in, readable while you are working hard.
- iPhone live mirroring. Follow the same session on your iPhone, with a Live Activity in the Dynamic Island.
- Post-workout summary and shareable card. Total time, Avg HR, Peak HR, Time above 90% max HR, and your heart-rate curve over the whole workout.
- VO2 max trend estimate. See how your fitness is moving across a training block.
- Apple Health sync. Workouts are written to Apple Health so the rest of your data stays in one place.
- External chest-strap support. Pair a Bluetooth chest strap for faster, more accurate interval heart rate.
Free vs Premium
Ramp4x4 is free, and the free app is enough to actually do the workout well. You get the full one-tap Norwegian 4x4, live heart-rate zone coaching, haptics and voice cues at every phase change, big countdowns, iPhone live mirroring with a Live Activity, your post-workout summary with a shareable card, Apple Health sync, and external chest-strap support.
An optional Premium subscription is for people who want to train this seriously over time. Premium adds your full workout history, VO2 max trends across a training block, the detailed quality-score breakdown of each session, custom presets, a multi-week plan, and smart, adaptive ramp modes that adjust as your fitness changes.
Why Ramp4x4 instead of Apple Fitness or a generic timer
Apple Fitness and generic HIIT timers can run a 4x4 if you build it yourself, but they are not aware of the workout. They do not know your heart-rate zones, they make you program nine phases by hand, and their alerts are not tuned to "push now" versus "ease off now." Ramp4x4 is built around this one workout: it knows your zones, sets up all nine phases in one tap, and cues every transition with haptics and a voice prompt.
It is also not trying to replace your wider fitness setup. Ramp4x4 complements Apple Health, writing every workout there so your VO2 max, heart rate, and activity all stay in one place. You get a focused tool for the hard session and keep the rest of your ecosystem intact.
Learn the Norwegian 4x4
Run your first Norwegian 4x4 today
Ramp4x4 is a free, guided Norwegian 4x4 timer for iPhone and Apple Watch. It calculates your target zones, sets up the whole session in one tap, cues every phase with haptics and voice, and tracks your progress so you can keep your eyes up and just train.
Frequently asked questions
Is Ramp4x4 free?
Yes. Ramp4x4 is a free iPhone and Apple Watch app. You can run the full guided Norwegian 4x4 workout, get heart-rate zone coaching, haptics, voice cues, and your post-workout summary at no cost. An optional Premium subscription adds full history, VO2 max trends, the detailed quality-score breakdown, custom presets, a multi-week plan, and smart adaptive ramp modes.
Do I need an Apple Watch?
Ramp4x4 is Apple Watch-first, and a paired Apple Watch runs the workout with live heart rate, haptics, and phase cues on your wrist. You can also follow along on iPhone with live mirroring, big countdowns, and a Live Activity in the Dynamic Island.
What is the Norwegian 4x4?
The Norwegian 4x4 is a VO2 max interval workout: a 10-minute warmup, then four 4-minute hard intervals at 85 to 95% max HR with 3-minute active recoveries between them, finished with a cooldown. It is one of the most studied ways to raise your VO2 max. See the full Norwegian 4x4 guide for the protocol and the science.