Ask The Experts: What is VO2 Max?


VO2 max is your body’s maximum rate of oxygen consumption. It is most commonly measured in mL of oxygen, per minute, per kg of body mass. It is measured during a maximal exercise test effort on a bike or treadmill. Oxygen is consumed by the lungs and then transferred to the bloodstream and muscles, where it reacts with ATP to produce cellular energy for activity.

There are a number of factors that may affect VO2 max: genes, age (declines with age), sex (men have higher), fitness, training types and loads, changes in altitude, action of the ventilatory muscles, cardiac output, pulmonary diffusion capacity, oxygen carrying capacity, and other peripheral limitations like muscle diffusion capacity, mitochondrial enzymes, and capillary density.

The test will give a number indicating one’s lungs ability to consume mL of oxygen per minute. The participant wears a mask attached to a machine that measures ventilatory oxygen and carbon dioxide concentration of the inhaled and exhaled air. They also wear a heart rate monitor. The athlete performs a graded exercise test, with the goal being maximal effort, and the athlete stops the test.

The results indicate maximal heart rate and oxygen consumption. A line indicating one’s anaerobic threshold is also shown on the result. This line represents the effort time at which the subject begins to produce lactate during exercise. This threshold can be modified/ delayed in onset with training at high intensity intervals.

Lastly from the results, we glean the heart rate ranges of the individual. This can be used to gauge current fitness (lower being preferable), prescribe exercise intensities, and see progress of those prescriptions over time.

Wendy Winn, PT, OCS Director

New York Custom Physical Therapy

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