NORWEGIAN 4X4
The Norwegian 4x4 workout: four hard minutes, four times
The Norwegian 4x4 is four hard efforts of 4 minutes with 3 minutes of easy recovery between them, plus a warm-up and a cool-down. The hard efforts run at 90 to 95 percent of your maximum heart rate. In a 2007 study of 40 men over 8 weeks, runners who trained this way raised their VO2max by 7.2 percent, more than runners who did the same total work at lower intensities. The full session takes about 40 minutes on a road, a treadmill or an erg.
What the Norwegian 4x4 is
The Norwegian 4x4 is an interval session built from four efforts of 4 minutes each. Between efforts you jog or move at an easy pace for 3 minutes. A warm-up comes first and a cool-down closes the session, which brings it to about 40 minutes.
The hard efforts target 90 to 95 percent of your maximum heart rate, the highest rate your heart reaches in an all-out effort. VO2max is the most oxygen your body can use in a minute, the top of your aerobic engine, and this session is built to train it. By the end of each effort your breathing should be heavy.
A Norwegian 4x4 from Complete’s workout library
This is the Norwegian 4×4 (VO2max Run), a session in Complete’s workout library. It takes about 40 minutes. Effort 9 out of 10 means hard: your breathing turns heavy late in each effort. Pace the first effort so the last one is still strong, and aim to reach 90 to 95 percent of your maximum heart rate by the end of each effort. An A-skip is a quick skipping drill that primes the legs for fast running.
If you are new, jog the full 3 minutes of recovery every time. The aim is time spent near your maximum heart rate. If you are experienced, hold the same pace across all four efforts and run them on a treadmill at a 5 to 8 percent incline.
| Block | What you do |
|---|---|
| Warm-up | World’s Greatest Stretch (a lunge with a twist that opens the hips and upper back): 1 set of 4 reps per side. A-Skip: 20 meters. Run: 10 minutes at effort 3 out of 10. |
| Main: 4 rounds, 3 minutes of easy jogging between rounds | Run: 4 minutes at effort 9 out of 10. |
| Cool-down | Run: 5 minutes at effort 2 out of 10. |
The same session on an erg
If running is hard on your legs, the library has the same session on an erg, the Erg Engine 4×4. Use the erg of your choice, such as a rower, and stay on the same machine for the whole session. It also takes about 40 minutes.
Pace the first effort so the last one still holds the split. A split is your time for each 500 meters on a rower. If you are new, keep the effort hard but repeatable, about 8 out of 10, and take the full 3 minutes of recovery. If you are experienced, hold a tighter split window across all four efforts and shorten the recovery to 2 minutes 30 seconds.
| Block | What you do |
|---|---|
| Warm-up | Erg of your choice: 5 minutes at effort 4 out of 10, an easy-to-moderate ramp until you break a light sweat. |
| Main: 4 rounds, 3 minutes of recovery between rounds | Erg: 4 minutes at effort 9 out of 10. |
| Cool-down | Erg: 5 minutes at effort 2 out of 10. |
What the research found
The best-known study of the protocol, published in 2007, came from researchers at the Norwegian University of Science and Technology in Trondheim. It put 40 healthy, moderately trained men into four groups for 8 weeks of running, 3 days a week. All four groups did the same total work.
One group ran long and slow at 70 percent of maximum heart rate. One ran at the lactate threshold, 85 percent. One ran 15 seconds hard and 15 seconds easy. One ran the 4x4, with 4 minutes at 90 to 95 percent and 3 minutes of active recovery at 70 percent.
Both interval groups raised VO2max more than the long slow and threshold groups. The 4x4 group rose 7.2 percent and the 15/15 group 5.5 percent. Stroke volume, the amount of blood the heart pumps per beat, rose about 10 percent after interval training, and the authors link the VO2max change to it.
The limits are plain. All 40 runners were men, all were moderately trained, and they trained 3 days a week for 8 weeks. The study cannot tell you what one 4x4 a week does for you.
A pooled review gives a wider picture. It combined 37 interval training studies of 334 healthy adults under 45, 120 of them women, who were sedentary or recreationally active. They trained at least 3 days a week for 6 to 13 weeks. VO2max rose by an average of 0.51 litres of oxygen per minute (95 percent confidence interval 0.43 to 0.60). The nine studies with longer intervals showed larger gains, about 0.8 to 0.9 litres per minute.
How to pace the four efforts
Start the first effort at a pace you can hold for all four minutes. Complete’s library note for this session says even efforts beat a fast fade, so the fourth effort should match the first.
If you do not know your maximum heart rate, go by effort: 9 out of 10, with heavy breathing by the end of each effort. Complete sets your zones from your own heart data. If you have workouts in Apple Health, it analyses them during onboarding. Our guide to personal heart rate zones explains how.
How often to run it, and who should wait
The runners in the study did the 4x4 three days a week. Our advice is to start with one a week on a fresh day, keep the rest of the week easy or on strength work, and add a second when you recover well. Our concurrent training guide covers how hard runs and lifting fit in one week.
Hard intervals ask a lot of your heart and legs. If you have a heart condition, are coming back after a long break or are not sure, talk to a doctor first and start with the beginner version.
How Complete fits
Complete starts from your long-term goals: build muscle, lose fat, improve cardio, get stronger, general health or become an athlete. A 4x4 is one way to work on the goal of improving your cardio. Every workout that reaches Apple Health counts toward your score and your daily recommendation, in any sport. You can also log it in the app.
Complete is free to download, and logging and sharing your workouts on it stay free.
Frequently asked questions
What is the Norwegian 4x4 workout?
It is an interval session of four efforts of 4 minutes at 90 to 95 percent of your maximum heart rate, with 3 minutes of easy recovery between them, plus a warm-up and a cool-down. The whole session takes about 40 minutes.
Does the Norwegian 4x4 work?
A 2007 study divided 40 men into four running groups for 8 weeks. The group that ran the 4x4 three days a week raised its VO2max by 7.2 percent, more than the groups that did the same total work at lower intensities. A pooled review of 37 interval training studies found an average rise of 0.51 litres of oxygen per minute. Both measured weeks of regular training.
How often should I do a Norwegian 4x4?
Our advice is once a week to start, on a fresh day, with the rest of the week easy or on strength work. The study that made the protocol known had runners do it three days a week for 8 weeks.
What heart rate should I hit in a 4x4?
Aim for 90 to 95 percent of your maximum heart rate by the end of each 4-minute effort. If you do not know your maximum, go by effort: 9 out of 10, with heavy breathing by the end of each effort.
Can I do the Norwegian 4x4 on a rower?
Yes. Complete’s library has the same session on the erg of your choice, such as a rower, called the Erg Engine 4×4. The shape is the same: four efforts of 4 minutes at effort 9 out of 10 with 3 minutes of recovery.
Does the Norwegian 4x4 count in Complete?
Yes. Complete counts every workout that reaches Apple Health toward your score and your daily recommendation, in any sport. You can also log it in the app.