✅ What is Norwegian 4x4?

Norwegian 4x4 is a high-intensity interval training (HIIT) protocol designed to increase VO2 max efficiently. Backed by scientific studies and used by elite endurance athletes, the structure is simple and effective:

? 5-minute warm-up
?‍♂️ 4 intervals of 4 minutes at 85–95% of your maximum heart rate
?‍♂️ 3-minute active recovery between intervals
? 5-minute cooldown

This 40-minute format has been shown to produce faster gains in cardiovascular fitness than steady-state cardio. It’s ideal for runners, cyclists, rowers, and anyone looking to improve endurance in less time.

✅ Why does it work?

VO2 max is the maximum amount of oxygen your body can use during intense exercise. Training close to your max heart rate with structured intervals forces your cardiovascular system to adapt. The Norwegian 4x4 method keeps you in the optimal training zone long enough to drive real improvement, but with rest periods that help you recover just enough to sustain intensity.

✅ Who endorses it?

Several respected voices in health and performance have publicly discussed or supported the Norwegian 4x4 protocol:

?‍⚕️ Dr. Rhonda Patrick – Biomedical researcher and health educator. She has compared Norwegian 4x4 to other interval protocols and highlighted its effectiveness for increasing VO2 max and overall cardiovascular fitness.
? Dr. Andrew Huberman – Neuroscientist and fitness advocate. He has highlighted Norwegian 4x4’s benefits for cardiovascular and cognitive performance, and its role in building mental resilience.
? Dr. Peter Attia – Leading expert on longevity. Attia emphasizes VO2 max as a key health marker and has praised this protocol for its measurable impact on cardiorespiratory fitness.
?️‍♂️ Dr. Iñigo San Millán – Exercise physiologist and Attia collaborator. San Millán supports the protocol’s efficiency in improving VO2 max and metabolic function.
These endorsements have increased awareness of the Norwegian 4x4 method across athletic, medical, and research communities. 2024 has become a breakout year for this training style.

✅ Why use this app?

This app gives you the exact structure you need—nothing more, nothing less:
⏱️ Built-in Norwegian 4x4 workout timer
⚙️ Adjustable phase durations
? Sound and vibration alerts
? Lock mode to prevent accidental taps
? Works with your favorite music or podcast app
Built for focused training. Simple design. Zero distractions.