If you’re serious about improving your endurance, whether you’re a runner, cyclist, or just want better cardio fitness for overall health, there’s one method that’s backed by science, used by elite athletes, and surprisingly simple to follow — the Norwegian 4×4 workout.
Originally developed by exercise scientists at the Norwegian University of Science and Technology, the 4×4 interval method is designed to push your heart, lungs, and legs just hard enough to get real aerobic improvements without overtraining. It’s not a fad. It’s not a miracle hack. It’s just smart training that works — especially when your goal is to increase VO2 max.
Let’s break down exactly how to do it, why it works, and how you can use it in your own fitness routine, no matter your level.
What Is VO2 Max and Why Should You Care?
VO2 max is short for maximal oxygen uptake — basically, how much oxygen your body can use during intense exercise. It’s one of the best indicators of aerobic fitness and endurance capacity.
The higher your VO2 max:
- The longer and harder you can go before fatiguing
- The more efficient your heart and lungs become
- The better your cardiovascular health overall
Elite athletes have sky-high VO2 max levels, but anyone can train to improve it — and that’s where the Norwegian 4×4 method comes in.
What Is the Norwegian 4×4 Interval Method?
This training style involves four intervals of 4 minutes each at a high intensity, with 3-minute rest periods between them.
Here’s the basic structure:
- 10-minute warm-up at low to moderate pace
- 4 minutes at 85-95% of your max heart rate
- 3 minutes of active recovery (easy pace)
- Repeat the 4-minute effort and 3-minute rest 3 more times (total of 4 sets)
- Cool down for 5-10 minutes at an easy pace
You’re looking at a total session time of about 40-45 minutes, depending on your warm-up and cool down.
Why This Method Works
There’s a sweet spot in heart rate training where your body adapts most effectively to endurance stress. That’s usually around 85-95% of your max heart rate — not an all-out sprint, but uncomfortable enough to feel the burn.
This high-intensity zone helps:
- Boost mitochondrial density (your muscles’ energy factories)
- Improve cardiac output (your heart’s ability to pump blood)
- Increase oxygen delivery to working muscles
- Strengthen your lungs and expand aerobic capacity
The 4×4 intervals give you just enough time in this zone to stimulate these changes — while the rest periods keep you from burning out too quickly.
How to Calculate Your Training Zones
You’ll want to monitor your heart rate during this workout, so a chest strap or wrist-based heart rate monitor is useful. First, estimate your maximum heart rate:
Simple formula:
220 – your age = max heart rate
Then take 85-95% of that to find your target zone.
For example:
If you’re 35 years old:
Max HR = 220 – 35 = 185 bpm
Target zone = 85–95% = ~157 to 176 bpm
During the 4-minute intervals, aim to stay in that zone.
How Often Should You Do It?
Because this workout is intense, once or twice a week is plenty — especially if you’re pairing it with strength training or long-distance sessions.
Here’s a weekly layout for runners or cyclists:
- Monday: Easy recovery cardio
- Tuesday: 4×4 workout
- Wednesday: Strength training or rest
- Thursday: Tempo or steady-state cardio
- Friday: Rest
- Saturday: Long slow distance workout
- Sunday: Optional recovery session (walk, yoga, light jog)
Stick to this routine for 4 to 6 weeks and you’ll likely see noticeable gains in endurance and stamina.
Where Can You Do the 4×4 Workout?
This method is super flexible. You can do it almost anywhere as long as you can control your effort:
- On a treadmill
- On a bike (outdoors or stationary)
- On a rowing machine
- Running or cycling outdoors
- Even swimming (with longer rest if needed)
Just make sure your intensity during the intervals is consistent and repeatable.
Tips for Success
- Don’t go all out. The goal isn’t to hit 100% max effort. Stay in the 85–95% heart rate zone — you should be breathing hard but still in control.
- Stay consistent. It takes several weeks of regular interval training to boost your VO2 max noticeably.
- Track your progress. Use apps or a smartwatch to monitor your heart rate and pace.
- Hydrate well. These sessions demand a lot from your body — hydration will help performance and recovery.
- Cool down fully. Don’t skip the 5–10 minute post-workout cool down. This helps lower your heart rate gradually and reduces soreness.
What Results Can You Expect?
Studies on the Norwegian 4×4 method have shown impressive outcomes:
- VO2 max increases of up to 10-15% in just a few weeks
- Improved endurance for both recreational and elite athletes
- Better race times and faster recovery between workouts
Even if you’re not training for a marathon or race, the benefits translate to everyday life: better energy levels, lower blood pressure, stronger heart function, and increased physical resilience.
Sample 4×4 Treadmill Workout
Here’s how you might structure a session on the treadmill:
- Warm-up: 10 minutes jog or brisk walk
- 1st interval: 4 minutes at 7.5 to 9.5 speed (based on fitness level)
- Recovery: 3 minutes walk or light jog
- 2nd interval: Same speed or slight increase
- Recovery: 3 minutes
- 3rd interval: Try to maintain pace, keep heart rate in target zone
- Recovery: 3 minutes
- 4th interval: Push through, maintain breathing control
- Cool down: 5 to 10 minutes easy jog or walk
Adjust pace based on how your body feels and how your heart rate responds.
Who Should Try the 4×4 Workout?
This method works for:
- Runners looking to break a performance plateau
- Cyclists aiming to improve endurance and time trials
- Fitness enthusiasts wanting to improve heart health
- Anyone looking to get more done in less time
However, if you have any heart or respiratory conditions, check with your doctor before starting high-intensity interval workouts.
Final Thoughts
The Norwegian 4×4 method is simple, scalable, and incredibly effective. Whether you’re training for performance or just want to improve your heart and lung capacity, this workout format delivers results.
You don’t need to spend hours on the treadmill or bike to boost endurance. With just 45 minutes, one or two times a week, you can transform your VO2 max and feel more powerful in every workout.
So next time you hit the gym or the road, consider giving this science-backed method a shot. You might just surprise yourself with how strong your lungs — and your legs — can become.
