VO2 peak is the measurement of the volume of oxygen that the body can utilize during physical exertion. ShapeSense.com notes that an individual's VO2 peak can be increased with aerobic and interval exercise.
EXOS states that during a VO2 test, the subject performs physical activity, such as running on a treadmill, while the physician measures the concentration of oxygen and carbon dioxide of the subject's breath.
When the amount of oxygen utilized by the subject plateaus during the exercise test, VO2 peak is reached. VO2 is measured in milliliters of oxygen used per kilogram of body weight per minute. The VO2 of endurance athletes, such as cyclists, might reach measurements in the 70s, according to EXOS.