Norwegian 4x4 Timer

Norwegian 4x4 Timer is a simple, free app to guide you through intervals for the Norwegian 4x4 Protocol. It can also be customized to adjust interval durations and number. Use it to amp up your cardio and VO2 Max. Whether it's running, rowing, jump rope, cycling, or other forms of cardio training, this is your trusted companion to know when to push yourself and when to rest in your interval workout.