Oxygen consumption is a measurement of how much oxygen the body uses per minute. A person’s maximal oxygen consumption ability, known as VO2 max or peak oxygen uptake, is one of the best ways to determine a person’s cardiovascular fitness level. Sports trainers use special laboratory machines to calculate VO2 max directly, but people at home can also estimate VO2 max using indirect methods, such as the 1.5-mile (2.4 m) run test.
An elite endurance athlete with a high fitness level can achieve a higher VO2 max. That means that they have a high maximum oxygen capacity, so they efficiently utilize more oxygen. Athletes can use their oxygen consumption data to measure improvement in aerobic levels, compute specific caloric needs, and determine the optimal heart rate for endurance training.
There are two ways to express oxygen consumption levels: in absolute terms as liters of oxygen per minute (L/min) or in relative terms as milliliters of oxygen per kilogram of body weight per minute (mL/kg/min). Oxygen consumption rates are typically higher in males than in females. Other factors that influence VO2 max include a person’s body composition, age, the altitude of the land, and the temperature of the environment.
People can increase their oxygen consumption by endurance training; thus, athletes can regularly measure their VO2 max level to check improvements in endurance ability. A nutritionist can use oxygen consumption details to accurately determine a person’s metabolic rate and caloric needs and recommend appropriate foods that meet an individual's energy requirements. Sports trainers also use VO2 max to design optimal endurance training programs. Athletes can improve on their aerobic ability if they consistently train at a certain percentage of their VO2 max, which corresponds with an optimal heart rate level that can be measured with a heart rate monitor during exercise.
Physiology laboratories typically have special equipment to directly and accurately measure oxygen consumption. An automated treadmill or stationary bicycle gradually increases the intensity of exercise until maximum aerobic ability, while a respiratory mask sends oxygen concentration data to a computer. There are also indirect tests that can predict a person’s VO2 max. A common indirect test is the 1.5-mile (2.4 m) run test. In this test, people record the amount of time it takes for them to run 1.5 miles (2.4 m) as fast as possible and identify their approximate VO2 max using a specific calculation that also incorporates age and body weight.