The scientifically-proven method used by elite athletes to boost VO2max by up to 10% in just 8 weeks.
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The Norwegian 4×4 protocol is a high-intensity interval training (HIIT) method developed by researchers at the Norwegian University of Science and Technology. It was originally designed to improve cardiovascular fitness in cardiac rehabilitation patients but has since been adopted by elite endurance athletes worldwide.
Multiple peer-reviewed studies have shown this protocol can increase VO2max (maximum oxygen uptake) by 10-15% over 8-12 weeks — more than traditional steady-state cardio.
Originally developed for cardiac patients, it's proven safe and effective for improving heart function, blood pressure, and overall cardiovascular health.
In just 25 minutes, 2-3 times per week, you can achieve better results than hours of traditional cardio training.
Works with any cardio activity: running, cycling, rowing, swimming, elliptical, or even walking uphill. Choose what works for you!
Start with light cardio to gradually increase your heart rate and prepare your body.
Work at 85-95% of your maximum heart rate. You should be breathing hard and unable to hold a conversation.
Reduce intensity to 60-70% max HR. Keep moving but allow your heart rate to come down.
Complete 4 work intervals with 3 recovery periods between them.
Finish with light activity and stretching to help your body recover.