The Norwegian 4x4 Protocol is a cutting-edge approach to exercise that can significantly boost your cardiovascular health and stamina. It consists of four intense 4-minute intervals at 90-95% of your maximum heart rate, each followed by a three-minute recovery period. This scientifically backed method is renowned for its efficiency in improving VO2 max and overall endurance. Norwegian 4x4 App is the perfect companion for anyone looking to implement the 4x4 training protocol into their routine.