Norwegian 4x4 Workout: Protocol, Heart Rates, Frequency

The Norwegian 4x4 is 4 intervals of 4 minutes at 90-95% of your max heart rate. Between intervals, you recover for 3 minutes at about 70% of max heart rate. The main block takes 25 minutes. Done 1-3 times per week, it is one of the best-studied ways to raise VO2 max.

Key takeaways

• Structure: 4 × 4 minutes hard (90-95% HRmax), 3 minutes active recovery (~70% HRmax).
• In an 8-week study, the 4x4 group raised VO2 max by 7.2% (Helgerud et al. 2007).
• Most people should do it 1-2 times per week, with a hard cap of about 3.
• Any large-muscle cardio works: running, cycling, rowing, sleds or swimming.
• Beginners can start with fewer or shorter intervals and build up.

What is the Norwegian 4x4?

The protocol comes from Norwegian exercise researchers. The best-known study, Helgerud et al. (2007), compared four training methods with the same total work.

Forty healthy, moderately trained men trained 3 times per week for 8 weeks. The groups were:

• Long slow distance: Session Steady running at ~70% HRmax, VO2 max change Smaller gain
• Lactate threshold: Session Steady running at ~85% HRmax, VO2 max change Smaller gain
• 15/15 intervals: Session 15 s at 90-95% HRmax, 15 s at 70%, VO2 max change +5.5%
• 4x4 intervals: Session 4 min at 90-95% HRmax, 3 min at 70%, VO2 max change +7.2%

Both interval groups beat the steady groups. The 4x4 format gained the most. It became popular because it is simple to follow and needs only about 25 minutes of work.

Why does it matter? VO2 max is closely tied to long-term health. In about 122,000 patients, the least fit quarter had roughly 5 times the mortality of the fittest group (Mandsager et al. 2018).

How to do the Norwegian 4x4

Step 1: Find your target heart rates

Estimate max heart rate (HRmax) with the Tanaka formula, then work out the two targets:

HRmax = 208 - 0.7 × age Work intervals = 0.90 to 0.95 × HRmax Recovery = 0.70 × HRmax

Worked example for a 40-year-old:

HRmax = 208 - 0.7 × 40 = 180 bpm Work intervals = 162 to 171 bpm Recovery = 126 bpm

Predicted HRmax can be off by 10-12 bpm. If you can still say more than a few words in the last minute of an interval, push harder. See our guide to heart rate zones for more precise methods.

Step 2: Run the session

• Warm-up: Duration ~10 min, Intensity Easy, building gradually
• Interval 1: Duration 4 min, Intensity 90-95% HRmax
• Recovery: Duration 3 min, Intensity ~70% HRmax, keep moving
• Interval 2: Duration 4 min, Intensity 90-95% HRmax
• Recovery: Duration 3 min, Intensity ~70% HRmax
• Interval 3: Duration 4 min, Intensity 90-95% HRmax
• Recovery: Duration 3 min, Intensity ~70% HRmax
• Interval 4: Duration 4 min, Intensity 90-95% HRmax
• Cool-down: Duration 5-10 min, Intensity Easy

The main block is 4 × 4 + 3 × 3 = 25 minutes. With warm-up and cool-down, plan about 40-45 minutes.

Pacing tips:

• Judge the first minute of each interval by effort, then use heart rate to fine-tune.
• Start each interval controlled. You should finish the fourth one strong, not crawling.
• Keep recovery active. Walk, jog or spin easily rather than stopping.

A good warm-up raises body temperature before hard work. Our guide on how to warm up properly covers the principles.

Norwegian 4x4: how many times a week?

Start with once per week. Move to twice per week if you recover well. The study used 3 sessions per week, which is the upper end for most people who also lift.

High-intensity intervals are harder to recover from than steady cardio. A sensible ceiling is 1-3 interval sessions per week. Fill the other cardio days with easy zone 2 sessions.

This follows the pattern used by elite endurance athletes: about 80% of sessions easy and 20% hard (Seiler 2010). For general fitness, 2-3 easy sessions plus 1 hard session per week works well.

Norwegian 4x4 protocol for beginners

The full 4x4 is demanding. If you are new to hard cardio, build up over a few weeks:

• Weeks 1-2: 30-30s. Do 10 rounds of 30 seconds hard and 30 seconds easy.
• Weeks 3-4: 2 × 4 minutes at 85-90% HRmax, 3 minutes easy between.
• Weeks 5-6: 3 × 4 minutes, reaching 90% HRmax by the end of each interval.
• Week 7 onward: the full 4 × 4 at 90-95% HRmax.

Use a bike or rower at first. Low-impact modes reduce joint stress while your fitness catches up.

If you have heart disease, high blood pressure or other medical conditions, get medical clearance before maximal-effort intervals.

Norwegian 4x4 exercises: which mode is best?

Any activity that uses large muscle groups and lets you hold a high heart rate works.

• Running (uphill or treadmill incline): Pros Easy to reach 90-95% HRmax, Watch out for Most impact and muscle damage
• Stationary or outdoor bike: Pros Low impact, easy to control, Watch out for Needs enough resistance to reach the target
• Rowing machine: Pros Low impact, uses arms and legs, Watch out for Technique needed
• Sled push: Pros Low impact, little skill needed, Watch out for Needs space and equipment
• Swimming: Pros No impact, Watch out for Technique limits effort for weaker swimmers

Norwegian 4x4 running

Running is the original mode. On a treadmill, use an incline that lets you reach the target heart rate at a pace you can sustain for 4 minutes. Outdoors, a steady hill works well.

If you also lift, consider cycling instead. Running interferes more than cycling with lower-body strength gains, likely due to more impact and muscle damage (Wilson et al. 2012). Read more on combining cardio with lifting.

How to apply this

• Calculate your targets: 90-95% and 70% of 208 - 0.7 × age.
• Pick a mode you can push hard safely, such as a bike or incline treadmill.
• Start with the beginner progression if you are new to intervals.
• Schedule 1 session per week, away from heavy leg days.
• Add a second session after 3-4 weeks if you recover well.
• Keep 2-3 easy sessions per week for your aerobic base.
• Retest after 8 weeks. Read our guide to improving VO2 max for testing options.

FAQ

How do you do the Norwegian 4x4?

Warm up for about 10 minutes. Do 4 intervals of 4 minutes at 90-95% of your max heart rate, with 3 minutes of active recovery at about 70% between them. Cool down for 5-10 minutes.

How many times a week should you do the Norwegian 4x4?

Once or twice per week suits most people. The original study used 3 sessions per week for 8 weeks. Keep your other cardio easy so you can recover.

What is a Norwegian 4x4 protocol for beginners?

Build up gradually. Start with 30-30s, then 2 × 4 minutes, then 3 × 4 minutes, and reach the full 4 × 4 after about 6 weeks. A bike or rower is easier on the joints while you adapt.

Can I do the Norwegian 4x4 running?

Yes, running was the mode used in the original study. Use a hill or a treadmill incline so you can reach 90-95% of max heart rate. If leg strength is a priority, cycling causes less interference.

What exercises can I use for the Norwegian 4x4 workout?

Running, cycling, rowing, sled pushes and swimming all work. Choose a mode that uses large muscle groups and lets you hold a high heart rate for 4 minutes. Low-impact modes reduce joint stress.

Educational content, not medical advice.

Sources

• Helgerud J et al. 2007. Aerobic high-intensity intervals improve VO2max more than moderate training. Med Sci Sports Exerc. https://doi.org/10.1249/mss.0b013e3180304570
• Tanaka H, Monahan KD, Seals DR. 2001. Age-predicted maximal heart rate revisited. J Am Coll Cardiol. https://doi.org/10.1016/S0735-1097(00)01054-8
• Seiler S. 2010. What is best practice for training intensity and duration distribution in endurance athletes? Int J Sports Physiol Perform. https://doi.org/10.1123/ijspp.5.3.276
• Wilson JM et al. 2012. Concurrent training: a meta-analysis examining interference of aerobic and resistance exercises. J Strength Cond Res. https://doi.org/10.1519/JSC.0b013e31823a3e2d
• Mandsager K et al. 2018. Association of cardiorespiratory fitness with long-term mortality. JAMA Netw Open. https://doi.org/10.1001/jamanetworkopen.2018.3605

The Field Manual lists the 4x4 alongside Tabata, sprint intervals, 30-30s and threshold work, with the main effect of each. Its templates show where an interval day fits in a week that also includes strength training.