VO2 max
Also: VO2max, maximal oxygen uptake
In plain language
The maximum amount of oxygen your body can use during hard exercise — a key measure of cardiovascular fitness.
Technical definition
The maximal rate of oxygen consumption during incremental exercise, expressed in mL/kg/min, reflecting integrated cardiorespiratory and muscular capacity and a strong predictor of all-cause mortality.
VO2 max is considered one of the best single markers of aerobic fitness and is strongly associated with longevity. It can be improved substantially through endurance and interval training.