Aerobic fitness and aerobic endurance are two separate components of aerobic metabolism. Aerobic fitness, best measured by VO2max, is a measure of oxygen transport and utilization. Aerobic endurance is not measured in a VO2max test because it does not measure the ability of the muscle to perform prolonged work. Endurance fitness may be a complementary measurement to VO2max, providing additional information regarding the capacity of the muscle for long-term work. The muscle is the primary site where increases in mitochondrial enzymes improve aerobic endurance capacity. Aerobic endurance may be more closely related to health-related fitness than aerobic fitness. conditioning must be specific to the sport or activity, progressing from general aerobic fitness in the off-season to sport-specific aerobic fitness/endurance during the playing season. Aerobic fitness/endurance decreases rapidly with detraining. Adequate, aerobic fitness/ endurance specific to a particular sport may help prevent injury in terms of delaying fatigue and improving the strength of the tendons and ligaments. A properly initiated sport-specific aerobic conditioning program is essential for maximal performance to be reached in most any sport.