Boxing is an explosive, anaerobic sport. Anaerobic means to conduct an activity without oxygen.  The sport has been estimated as approximately 70-80% anaerobic and 20-30% aerobic. Anaerobic exercise, like boxing, stresses the muscles at a high intensity for short periods of time. In boxing, one must punch, slip, and block with split second movements and reactions. A boxer must be prepared to fight with intensity, round after round. The body must be conditioned to throw the same explosive punches in the last round that you started with in round one.