VO2 max (also maximal oxygen consumption, maximal oxygen uptake, peak oxygen uptake or maximal aerobic capacity) is the maximum rate of oxygen consumption as measured during incremental exercise, most typically on a motorized treadmill or an adjustable indoor bike.

It is a key 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 intense or maximal exercise. It is measured as "milliliters of oxygen used in one minute per kilogram of body weight."

The best indicator of an athlete's cardiovascular fitness and aerobic endurance because theoretically, the more oxygen you can use during high-level exercise, the more energy you can produce. This is often the case with elite endurance athletes who typically have very high VO2 max values.