VO2 max

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VO₂ max (also maximal oxygen consumption, maximal oxygen uptake or aerobic capacity) is the maximum capacity of an individual's body to transport and utilize oxygen during incremental exercise, which reflects the physical fitness of the individual. The name is derived from V - volume per time, O₂ - oxygen, max - maximum.

VO₂ max is expressed either as an absolute rate in litres of oxygen per minute (l/min) or as a relative rate in millilitres of oxygen per kilogram of bodyweight per minute (ml/kg/min), the latter expression is often used to compare the performance of endurance sports athletes. A less size-biased measure is to divide by rather than mass.

Measuring VO₂ max

Accurately measuring VO₂ max involves a physical effort sufficient in duration and intensity to fully tax the aerobic energy system. In general clinical and athletic testing, this usually involves a graded exercise test (either on a treadmill or on a cycle ergometer) in which exercise intensity is progressively increased while measuring ventilation and oxygen and carbon dioxide concentration of the inhaled and exhaled air. VO₂ max is reached when oxygen consumption remains at steady state despite an increase in workload.

Fick Equation

VO₂ max is properly defined by the Fick Equation:

, when these values are obtained during an exertion at a maximal effort.

where Q is the cardiac output of the heart, CaO₂ is the arterial oxygen content, and CvO₂ is the venous oxygen content.

Cooper test

Kenneth H. Cooper conducted a study for the United States Air Force in the late 1960s. One of the results of this was the Cooper test in which the distance covered running in 12 minutes is measured. An approximate estimate for VO₂ max (in ml/min/kg) is:

where d₁₂ is distance (in metres) covered in 12 minutes. There are several other reliable tests and VO₂ max calculators to estimate VO₂ max.

VO₂ max Levels

“Maximal oxygen uptake (VO₂max) is widely accepted as the single best measure of cardiovascular fitness and maximal aerobic power. Absolute values of VO₂max are typically 40-60% higher in men than in women.”^[1] Clearly, then, VO₂max varies considerably in the population, with sex being a primary determining factor in this variability.

The average young untrained male will have a VO₂ max of approximately 3.5 litres/minute and 45 ml/kg/min.^[2] The average young untrained female will score a VO₂ max of approximately 2.0 litres/minute and 38 ml/kg/min.^{[citation needed]} These scores can improve with training and decrease with age, though the degree of trainability also varies very widely: conditioning may double VO₂max in some individuals, and will never improve it at all in others.^[3][4]

In sports where endurance is an important component in performance, such as cycling, rowing, cross-country skiing, swimming and running, world class athletes typically have high VO₂ maximums. World class male athletes, cyclists and cross-country skiers typically exceed 75 ml/kg/min and a rare few may exceed 85 ml/kg/min for men and 70 ml/kg/min for women.^{[citation needed]} Five time Tour de France winner Miguel Indurain is reported to have had a VO₂ max of 88.0 at his peak [1], while cross-country skier Bjørn Dæhlie measured at an astounding 96 ml/kg/min.^[5] Dæhlie's result was achieved out of season, and physiologist Erlend Hem who was responsible for the testing stated that he would not discount the possibility of the skier passing 100 ml/kg/min at his absolute peak. By comparison a competitive club athlete might achieve a VO₂ max of around 70 ml/kg/min.^[2] World class rowers are physically very large endurance athletes and typically do not score as high on a per weight basis, but often score exceptionally high in absolute terms. Male rowers typically score VO₂ maximums over 6 litres/minute, and some exceptional individuals have exceeded 8 l/min.

To put this into perspective, thoroughbred horses have a VO₂ max of around 180 ml/kg/min. Siberian dogs running in the Iditarod Trail Sled Dog Race sled race have VO₂ values as high as 240 ml/kg/min.^[6]

Estimation of VO₂ max

This section requires expansion with: examples of these methods.

Tests measuring VO₂ max can be dangerous, as any problems with the respiratory and cardiovascular systems will be greatly exacerbated. Indeed many organised VO₂ max tests require a medic to be present. Hence many protocols for estimating VO₂ max have been developed. These generally are similar to a VO₂ max test, but do not reach the maximum of the respiratory and cardiovascular systems and are called sub-maximal tests.

Uth—Sørensen—Overgaard—Pedersen estimation

Another estimate of VO₂max, based on maximum and resting heart rates, was created by a group of researchers from Denmark.^[7] It is given by:

This equation uses body mass in kilograms, maximum heart rate (HR_max) and resting heart rate (HR_rest) to estimate VO₂max expressed in ml/minute.

See also

• VVO2Max
• Training effect
• Anaerobic exercise
• Cardiorespiratory fitness
• Respirometry

References

External links

• VO₂ max Calculator - the Rockport Walking Test
• All About VO2max - Horses
• So What Exactly is VO2?
• Calculate your VO2max from your run distance