The Norwegian 4x4 Workout, Set to Your Heart Rate

The Norwegian 4x4 only works if the hard minutes are hard enough, and the usual 220-minus-your-age formula can miss your real max by as much as 40 beats. NTNU, the Trondheim lab behind the Norwegian 4x4 workout, uses its own formula, so find your age in the table, note your two numbers, and go.

The whole session takes 40 minutes with the warm-up. NTNU says two or three a week will build your fitness, and one a week will hold it.

The Norwegian 4x4 workout, minute by minute

Norwegian 4x4 heart rate zones by age

NTNU uses this formula to estimate your max heart rate:

211 - 0.64 x your age

The formula comes from the measured max heart rates of 3,320 Norwegian adults, and it's typically within about 11 beats a minute of your real max, though some people are further off.

NTNU says 220 minus your age gets less accurate from about 30 and can miss by as much as 40 beats. You may also see 208 - 0.7 x age, which comes from a 2001 US study. NTNU doesn't use it.

A better number: test your max

NTNU's self-test: warm up until you sweat. Do two 4-minute intervals that leave you very short of breath, with 3 minutes of walking between. Start a third, and after 2 minutes go as hard as you can until you can't continue. The highest heart rate you see is your max.

If you take beta-blockers, they lower your max heart rate. Test it rather than using a formula.

How to pace each 4-minute interval

• Go out at a hard pace from the first interval. Your heart rate takes about 2 minutes to catch up.
• Minutes 3 and 4 should sit at 85-95%.
• If you can't finish the 4 minutes, you started too hard.
• Aim to feel about the same after each interval, and to finish feeling you could do a fifth.
• No monitor? You should be too out of breath to hold a conversation. On the 6-20 Borg scale, that's 16 or higher.
• In the 3 minutes between, keep moving. Walk or jog slowly so your heart rate drops to about 70%.

4 ways to do the Norwegian 4x4

Same protocol, different machine. Pick the one you can push hardest on without thinking about technique.

The 7-week Norwegian 4x4 plan for beginners

How often to do the Norwegian 4x4

NTNU says 2 to 3 sessions a week to build fitness, and about one a week to keep it. Its own programmes mix the 4x4 with easy hikes and steady 20-45 minute sessions.

Does the Norwegian 4x4 work? What the research found

• Healthy young men (Helgerud 2007): 8 weeks of 4x4, three times a week, raised VO2max by 7.2%. Long easy runs and threshold runs did not significantly change it.
• Heart failure after a heart attack (Wisløff 2007): 12 weeks of 4x4 raised peak oxygen uptake by 46%, against 14% with moderate training. A larger trial in 2017 (SMARTEX-HF, 261 patients) found 4x4 no better than moderate training. Half its interval group trained below the target.
• Older adults (Generation 100, 2020): 1,567 people aged 70-77 trained for five years. The 4x4 group had the biggest fitness gains and the best quality of life. 3.0% of them died during the study, against 4.7% of the control group, but that difference was not statistically significant.
• Ulrik Wisløff, who leads NTNU's group, said in 2024 that no study shows 4x4 makes you live longer than other exercise.

Check with a doctor before you start if

• you have coronary heart disease. NTNU reports good results, but each person needs an assessment and possibly a hospital exercise test.
• you have atrial fibrillation. NTNU says there's no clear answer yet.
• you take beta-blockers. Test your max heart rate.
• you feel chest pain or dizziness during a session. Stop.

Run it in sweatcue

Connect a heart-rate strap and sweatcue puts your live heart rate beside the target for every block. It tells you when each one starts and how long is left, so you can watch the hill instead of your watch.

More workout guides

Norwegian 4x4 FAQ

How do I calculate my Norwegian 4x4 heart rate?

Work out your max with 211 - 0.64 x your age, then take 85-95% for the hard blocks and 60-70% for the easy ones. The table above has it done for you.

How often should I do the Norwegian 4x4?

2 to 3 times a week to improve, once a week to maintain.

Do I need a heart-rate monitor?

It helps. Without one, use the talk test: in the hard blocks you shouldn't be able to hold a conversation.

Can I walk the 4x4?

Yes. Walk uphill on a hill or a steep treadmill. NTNU prefers it for beginners.

Is 1x4 enough?

It's a good start. In one small study it gave most of the 4x4's gain in inactive men.

What should I do in the 3-minute recovery?

Keep moving: walk or jog slowly so your heart rate settles around 70%.

Sources

1. NTNU CERG: Summer fitness (the 4x4 session)
2. NTNU CERG: 7-week training programme
3. NTNU CERG: Training advice
4. NTNU CERG: FAQ
5. NTNU CERG: Max heart rate calculator
6. NTNU CERG: 1x4 summer programme (Norwegian)
7. Nes et al. 2013, age-predicted max heart rate (Scand J Med Sci Sports)
8. Tanaka et al. 2001, 208 - 0.7 x age (J Am Coll Cardiol)
9. Helgerud et al. 2007, aerobic intervals and VO2max (Med Sci Sports Exerc)
10. Wisløff et al. 2007, intervals in heart failure (Circulation)
11. Ellingsen et al. 2017, SMARTEX-HF (PEDro record)
12. Tjønna et al. 2013, 1x4 vs 4x4 (PLoS One)
13. Stensvold et al. 2020, Generation 100 (BMJ)
14. Acala et al. 2020, 4x4 on a bike (IJERPH)
15. Norwegian SciTech News 2024: 4x4, popular and controversial