Definitions for "VO2 max"
The highest volume of oxygen a person can consume during exercise. Often used as a predictor of potential in endurance sports.
The maximum rate at which a given athlete can consume oxygen.  The higher an athlete's VO2 max, the faster he or she can run, swim, bike, etc. without accumulating excess lactic acid in the working muscles, which causes fatigue.
The maximum oxygen uptake; measured during exercise and expressed in kilograms per minute.