Norwegian 4x4 Timer for VO2 Max Intervals

Ramp4x4 is a guided Norwegian 4x4 timer for iPhone and Apple Watch. It sets up the warmup, four hard intervals, recoveries, and cooldown in one tap, then cues every phase with haptics, voice, and live heart-rate targets so you can focus on the effort instead of the clock.

What a Norwegian 4x4 timer runs

The structure never changes, which is exactly why it suits a dedicated timer. One session is:

• 10-minute warmup at an easy, conversational effort.
• Four 4-minute hard intervals at 85 to 95% of max heart rate.
• Three 3-minute active recoveries between the intervals, at 60 to 70%.
• A short cooldown of 3 to 5 minutes.

Warmup Hard interval (4 min) Recovery (3 min) Cooldown

Try the 4x4 interval flow

Run a short, sped-up demo of the Norwegian 4x4 structure: warmup, four hard intervals, active recoveries, and cooldown. The demo uses simulated heart rate so you can see how Ramp4x4 guides each phase. In the app, your Apple Watch provides live heart-rate data, haptics, and workout cues.

Heart rate shown here is simulated for demonstration only. In the app, your real heart rate comes from Apple Watch.

Why generic timers are annoying for 4x4s

You can run a 4x4 with a stopwatch, a treadmill timer, or a generic HIIT app. The friction is in the setup and the babysitting:

• You have to program nine phases by hand every time, or count them in your head.
• A generic countdown does not know your heart-rate target, so you are also doing zone math mid-warmup.
• During the hard minutes you end up staring at a screen to catch the next phase change, exactly when you least want to.
• Miss a beep and you drift past the interval or cut a recovery short.

Why a dedicated 4x4 timer helps

Because the Norwegian 4x4 has one fixed structure, a purpose-built timer can take all of that off your plate:

• One-tap setup of the warmup, four intervals, recoveries, and cooldown.
• Target heart-rate zones calculated for you, so the timer knows what "hard" means for your body.
• Phase changes you feel, not just see, so you are not glued to a screen.
• Live heart-rate feedback as a pacing guide through each interval.
• A clean summary afterward, plus history and VO2 max trends over your training block.

On Apple Watch: haptics and phase changes

Ramp4x4 is Apple Watch-first. The watch keeps the current phase, a big countdown, and your live heart-rate zone on your wrist, and it taps you with haptics at every phase change so you know to push or ease off without looking. That matters most during the hard intervals, when reading a screen is the last thing you want to do. There is a dedicated walkthrough on the Apple Watch Norwegian 4x4 timer page.

Live heart-rate target feedback

The timer is wired to your heart-rate zones, so it shows your live heart rate against the 85 to 95% target during work and the 60 to 70% range on recovery. Heart rate is a guide, not a pass-or-fail line: it lags at the start of each interval, so the app helps you pace and watch the trend rather than chase a single beat. You can set your zones first with the Norwegian 4x4 heart-rate calculator.

Your summary and share card

After the session, Ramp4x4 shows a clean recap with your Total time, Avg HR, Peak HR, Time above 90% max HR, and distance, plus a heart-rate curve over the whole workout. The shareable card uses the same numbers, so the recap you see in the app is the one you can post.

What the workout looks like

Keep going

Timer FAQ