Calculate your Maximum Aerobic Function heart rate using Phil Maffetone's 180-Formula — the gold standard for building endurance.
Developed by Dr. Phil Maffetone, the 180-Formula identifies the heart rate at which you develop your aerobic system most efficiently — without triggering stress hormones or overtraining. Widely used by ultra endurance athletes including Mark Allen (6x Ironman World Champion) and many of Gene's athletes.