What is the Norwegian 4×4?
The Norwegian 4×4 is an interval workout developed by researchers at the Norwegian University of Science and Technology (NTNU) in Trondheim: four intervals of four minutes at high intensity, each followed by three minutes of active recovery. Studies from the group, such as Helgerud and colleagues (2007), found it improved maximal oxygen uptake (VO2max) more than steady running at moderate intensity.
How hard should the intervals be?
| Part | Effort | How it feels |
|---|---|---|
| Hard, 4 min | About 85–95% of max heart rate | Breathing hard, only a few words at a time. The last minute is tough but doable. |
| Easy, 3 min | About 60–70% of max heart rate | Easy jog or brisk walk. Keep moving. |
You don’t need a heart rate monitor. If you could hold the pace for much longer than four minutes, go a little harder; if you can’t finish the fourth interval, start the first one easier.
How to do the 4×4
- Warm up for 10 minutes at an easy pace, with a few short pick-ups towards the end.
- Run four hard intervals of 4 minutes. Uphill running or a treadmill on an incline is easier on the legs and makes it simple to reach high heart rate.
- Recover actively for 3 minutes between intervals.
- Cool down for 5–10 minutes.
The 4×4 works just as well on a bike, rowing machine, ski erg or as fast uphill walking. One or two sessions a week, alongside easier training, is plenty for most people.
Frequently asked questions
Can beginners do the Norwegian 4×4?
Yes. Start with two or three intervals instead of four, and use uphill walking or cycling if running at high intensity is new to you. Check with a doctor first if you have a heart condition.
Do I need a heart rate monitor?
No. Use breathing and effort: in the hard intervals you should only manage a few words at a time, and in the recovery you should be able to talk.
Can I do the 4×4 on a treadmill?
Yes. Many people find a treadmill at a 4–8% incline the easiest way to reach the right intensity without running very fast.
Why four minutes?
It takes a minute or two for your heart rate to climb, so four-minute intervals give you a few minutes at high intensity in each one.
Run the 4×4 without looking at your watch
TruTimer's Norwegian 4×4 template (Pro) includes the 10-minute warm-up and calls out “Hard” and “Easy” at every change, so you can run with your phone in your pocket. It works offline, with no account.
