Norwegian 4x4 protocol

Topic

The Norwegian 4x4 protocol is a highly structured high-intensity interval training (HIIT) method designed to maximize aerobic capacity (VO2 max) and cardiovascular health. Developed by researchers Jan Helgerud and Jan Hoff at the Norwegian University of Science and Technology (NTNU), the workout consists of four high-intensity intervals lasting four minutes each at 85–95% of maximum heart rate, separated by three-minute active recovery periods.