Why the Norwegian 4×4 HIIT protocol provides flexibility when programming conditioning

The Norwegian 4×4 protocol is one of the most widely adopted formats of high-intensity interval training (HIIT) across endurance, team sport, and general populations.[1] Its appeal lies in its efficiency and simplicity: four four-minute intervals performed at high intensity interspersed with recovery periods. This format maximises the time the athlete spends near maximal oxygen uptake (VO2max). The protocol is often applied rigidly, with limited consideration of how coaches can manipulate its programming variables to target specific adaptations. The original Norwegian 4×4 model consisted of fo...