VO2 max

Dr Chelsey Dempsey and Dr Jennifer Brierley describe VO₂ max as the maximum capacity to transport and utilize oxygen during incremental exercise. (The derivation is V̇ - volume per time, O₂ - oxygen, max - maximum). It is also called maximal oxygen consumption or maximal oxygen uptake. It is also known as aerobic capacity, which reflects the physical fitness of a person.

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.

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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:

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

Cooper test

Dr. 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

VO₂ max varies considerably in the population. The average young untrained male will have a VO₂ max of approximately 3.5 litres/minute and 45 ml/kg/min.^[1] 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.^[2][3]

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 80 ml/kg/min and a rare few may exceed 90 ml/kg/min for men and 70 ml/kg/min for women. Three time Tour de France winner Greg LeMond is reported to have had a VO₂ max of 92.5 at his peak - one of the highest ever recorded, while cross-country skier Bjørn Dæhlie measured at an astounding 96 ml/kg/min.^[4] It should also be noted that Dæhlie's result was achieved out of season and that 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.^[1] 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/min/kg. Siberian dogs running in the Iditarod Trail Sled Dog Race sled race have VO₂ values as high as 240 ml/min/kg.^[5]

See also

• Training effect
• Anaerobic exercise
• Respirometry

References