Norwegian 4x4

Four minutes near max heart rate, four times, beats steady-state cardio on VO2 max.

Also called Norwegian 4×4, 4x4 Interval Training, Aerobic Interval Training, 4x4 HIIT, Norwegian 4x4 Method, 4x4 Norwegian Protocol

Who it's forAny man whose cardio is an hour on the treadmill at one unchanging pace.

The item

Three squares: proven in human trials. Two: a strong signal. One: early human data. Striped: the trials disagree.

Emergency: call 911.

I am not a doctor. This is not medical advice. This is self-education. Talk to a physician who has your history before you change anything.