Norwegian 4×4 interval timer
The Norwegian 4×4 is four rounds of four minutes at a hard, steady pace, each followed by three minutes of easy walking or jogging. It was developed by researchers in Trondheim, Norway, and is one of the best-studied interval workouts.
Start the timerTreadmill settings
| Step | Time | Speed | Incline |
|---|---|---|---|
| Warm-up | 90s | 5–6 km/h3–3.5 mph | 0% |
| Warm-up | 90s | 7.5–9 km/h4.5–5.5 mph | 1% |
| Run | 4:00 | 10–13 km/h6–8 mph | 2% |
| Walk | 3:00 | 5–6 km/h3–3.5 mph | 0% |
Rounds: 4
Why it works
Four-minute efforts at 85–95% of your maximum heart rate push your heart and lungs to adapt, raising your VO₂max, one of the strongest markers of long-term health and endurance. Research links it to better heart health and fitness at any age.
Who it's for
Intermediate runners and fitness-focused walkers who want a big aerobic boost. The hard pace should be tough but steady, not a sprint.
Questions
How hard should the 4-minute intervals be?
Hard enough that you can only say a few words at a time, around 85–95% of your max heart rate. You should be able to hold the same pace for all four minutes.
Can I walk instead of run?
Yes. On a steep incline, a fast walk can reach the same heart rate. Raise the incline instead of the speed.
How often should I do the 4×4?
Once or twice a week, alongside easier sessions, is typical in the research programs.
Warm up with 5 minutes of easy walking or jogging first. Stop if you feel dizzy, faint or unwell. If you have a health condition, check with a doctor before starting hard exercise.