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. 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.