Norwegian 4x4 Timer

Norwegian 4x4 Interval Training Timer The Norwegian 4x4 protocol is a highly effective high-intensity interval training method consisting of 4 rounds of 4-minute work intervals at 85-95% of maximum heart rate, separated by 3-minute active recovery periods at 60-70% max heart rate. Originally developed for running, this protocol has been scientifically proven to significantly improve VO2 max and cardiovascular fitness. However, it's incredibly versatile and can be adapted to various high-intensity exercises including: - Cycling - Swimming - Rowing - Kettlebell swings - Jump rope - Or any other cardio exercise you prefer Protocol Structure: - Warm-up: 10 minutes - 4 x (4 min high intensity + 3 min active recovery) - Cool-down: 5 minutes Target Heart Rate Zones: - High intensity intervals: 85-95% of max HR - Active recovery: 60-70% of max HR Use this timer to stay on track with your intervals and maximize your cardiovascular gains!