Norwegian 4x4 Protocol

You can master the scientifically proven 4x4 interval training method using the official Norwegian 4x4 Protocol app. Available for both iOS and Android, this tool helps you improve your VO2 max and cardiovascular health through guided HIIT intervals. You can benefit from integrated heart rate tracking and precision timing to ensure you are training at the correct intensity. The app provides a structured way to follow the legendary 4x4 workout routine used by elite athletes and fitness enthusiasts worldwide.