The Norwegian 4x4 Hiit workout is a favourite among athletes and actress Jessica Biel – here’s why it’s so beneficial

Lack of time is often the main reason people don’t exercise regularly. But a type of interval workout recently popularised by actress Jessica Biel could be the solution – with research showing it can improve fitness faster than traditional, steady-pace workouts, such as jogging or cycling.

The Norwegian 4x4 workout has traditionally been used by athletes. It’s a form of high-intensity interval training (Hiit) that involves four-minute sets of very intense cardio exercise, followed by three minutes of very light exercise.…

© La Conversation - lundi 12 janvier 2026