The objective of endurance training is to develop the energy production systems to meet the demands of activity for as long as they are required.

Aerobic Metabolism and Endurance
Most often it’s a combination of energy systems that supply the fuel needed for exercise, with the intensity and duration of the exercise determining which method gets used when. However, aerobic metabolism fuels most of the energy needed for long duration or endurance exercises.

Athletes continually strive to push their capacity to exercise harder and longer and increase their endurance. The factors that limit sustained high intensity efforts include fatigue and exhaustion. Sport training has been shown to modify and postpone the point at which this fatigue occurs.

VO2 Max and Aerobic Endurance
VO2 max or maximal oxygen uptake is one factor that can determine an athlete�s capacity to perform sustained exercise and is linked to aerobic endurance. VO2 max refers to the maximum amount of oxygen that an individual can utilize during maximal or exhaustive exercise. It is measured as milliliters of oxygen used in one minute per kilogram of body weight. It is generally considered the best indicator of cardiorespiratory endurance and aerobic fitness. Elite endurance athletes typically have a high VO2 max. And some studies indicate that it is largely due to genetics, although training has been shown to increase VO2 max up to 20 percent. A major goal of most endurance training programs is to increase this number.