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 ![\sqrt[3]{mass^2}](http://upload.wikimedia.org/math/0/2/8/02891800c8292e5f3024fd0e84f639b6.png)
rather than mass.
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[edit] 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.
[edit] 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.
[edit] 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.
[edit] 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] 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.[5] 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.[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]
[edit] Estimation of VO2 max
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.
[edit] See also
[edit] References
- ^ Thomas E. Hyde and Marianne S. Gengenbach, Conservative Management of Sports Injuries (2nd ed; Sudbury, Mass.: Jones & Bartlett, 2007), 845.
- ^ a b Geddes, Linda (2007-07-28). "Superhuman". New Scientist. pp. 35-41.
- ^ Bouchard, Claude; Ping An, Treva Rice, James S. Skinner, Jack H. Wilmore, Jacques Gagnon, Louis Perusse, Arthus S. Leon, D. C. Rao (September 1999). "Familial aggregation of VO(2max) response to exercise training: results from the HERITAGE Family Study". Journal of Applied Physiology 87 (3): 1003–1008. PMID 10484570. http://jap.physiology.org/cgi/content/abstract/87/3/1003?ijkey=189eebcbc5a461258da582b4aef41ebcf7bec51f&keytype2=tf_ipsecsha. Retrieved on 2007-07-17.
- ^ Kolata, Gina (February 12, 2002). "Why Some People Won't Be Fit Despite Exercise". The New York Times. http://query.nytimes.com/gst/fullpage.html?res=9406EEDE113CF931A25751C0A9649C8B63&sec=health. Retrieved on 2007-07-17.
- ^ Ski-VM 1997
- ^ Cornell Science News
