What is Oxygen Consumption (VO₂)?
By Brent Gallagher

Energy is a must to sustain life. Our bodies use it to flex muscles, pump blood, maintain tissues and carry out numerous other functions. Adenosine triphosphate (ATP) is the form of energy that the body needs to complete each of these tasks. Think of ATP as gasoline from your cells. Because the body does not store ATP in large quantities, our bodies must continually make more. Although these are processes that can produce ATP without oxygen (O₂), these anaerobic systems are limited in their capacity to produce ATP. The greatest capacity to produce ATP is through the breakdown of carbohydrates, fats, and to some extent proteins. To make ATP from these nutrients, O₂ is required. Ultimately, oxygen-requiring – also known as aerobic – processes are necessary to sustain the body’s energy needs.

Oxygen Consumption Defined.

Oxygen consumption (VO₂) is the amount of oxygen taken in and used by the body per minute; thus, it is the rate of oxygen use.

Why Is It Important?

VO₂ reflects energy expenditure, meaning that measuring VO₂ provides an estimate of calories burned. Approximately 5 kcal of energy are expended for every liter of O₂ consumed. Thus, a person with a VO₂ of 1 L/min is burning 5 kcal each minute. As one exercises harder, VO₂ rises, meaning that energy expenditure is higher.

Information about VO₂ also can be useful for athletes. Economy tests examine the relationship between work performed and energy expenditure during exercise. Athletes who are able to move smoothly, without wasting energy, perform better.

Maximal VO₂ (VO₂Max) is another measurement that provides the maximal ability to perform high-intensity aerobic work. This value is strongly associated with performance and health.

VO₂ Metabolic Testing

By testing your VO₂ work capacity, you’ll be able to define the following:

• How many calories your body needs
• How hard you need to exercise
• How your body functions best
• How you can optimize your performance
• How to combine nutrition, exercise and the time you have available to reach your goals