Raising it

How do I do the Norwegian 4x4?

By GyroscopeUpdated November 14, 20267 sources

Warm up, then go 4 minutes at 90 to 95 percent of your max heart rate and 3 minutes easy, four times. Three sessions a week for 8 weeks raised VO2 max 7.2 percent in the trial that made it famous.

The name makes it sound like an elite program from a Scandinavian training camp. It came from a university lab in Trondheim, and the version that ran longest was done by people in their 70s. You can do it walking up a hill, on a bike or on a rowing machine, and the whole thing takes about 40 minutes.

We’d make it the one or two hard sessions in your week, on top of steady cardio. In head-to-head trials it raised VO2 max more than the same work done at a steady pace, and it fits in a lunch hour.

The session

1. Warm up for about 10 minutes, easy. Generation 100, the Trondheim study in older adults, used a 10-minute warm-up.
2. Go hard for 4 minutes at 90 to 95 percent of your max heart rate. On the 6 to 20 effort scale it’s about 16, breathing hard, a few words at a time.
3. Ease off for 3 minutes at about 70 percent of max. Jog or walk, and keep moving.
4. Repeat until you’ve done four hard blocks. That’s 28 minutes.
5. Cool down for about 5 minutes.

Each hard block is about the length of a song.

Your numbers

The max comes from a formula built on 18,712 people. A study of 3,320 Norwegians with verified max tests found a person’s real max sits within about 11 beats of the best formula only about 2 times in 3, so if you know your measured max, use it. These are typical ranges, and the Gyroscope app personalizes yours. The timer below runs the session with beeps and your own band.

The trial

In 2007, researchers at the Norwegian University of Science and Technology split 40 healthy, moderately trained men into four groups. All did the same total work three times a week for eight weeks. One ran steady at 70 percent of max heart rate, one at 85 percent, one did 15-second sprints, and one did the 4x4.

The 4x4 group went from 55.5 to 60.4 ml/kg/min, up 7.2 percent. The 15-second group rose 5.5 percent. The two steady groups didn’t improve significantly. The heart’s output per beat rose about 10 percent after the intervals, which is where the gain came from.

Those men were already fit, around the 80th to 90th percentile for men in their 20s. Across 28 trials in a wider range of people, intervals beat steady training by about 1.2 points on average, so expect a smaller edge if you’re starting from the couch, where steady training works well too.

Who should hold off

If exercise brings chest pain, fainting or unusual breathlessness, or you have heart, metabolic or kidney disease, see a doctor before hard sessions. If you’ve been inactive, build up with a few weeks of brisk walking first. On a beta blocker, use the effort scale instead of beats (see heart rate zones on a beta blocker).