A pronghorn antelope may use oxygen three times faster than the fittest human
VO2 max measures how much oxygen your body can burn per minute at full effort. The highest human figure ever tested, 101.1 millilitres per kilogram per minute, belongs to the Norwegian triathlete Kristian Blummenfelt. Iditarod sled dogs have reached 240, and pronghorn antelopes are estimated at up to 300.
The name stacks three abbreviations. V stands for volume, and the dot above it marks a rate, following Newton's notation; the rest simply names the gas and the ceiling. It is usually scaled to body mass, though the numbers do not rise in a straight line with size, so comparing people or species of different bulk needs careful statistics. A related figure, VO2 peak, is the highest value reached in a given session and can only equal or fall below the true maximum; older fitness writing often confuses the two.
In a lab the test is graded: effort climbs on a treadmill or cycle ergometer while the oxygen and carbon dioxide in each breath are analysed. The classic definition from Hill and Lupton in 1923 is the point where oxygen use plateaus even as the workload keeps rising, though not everyone shows a clear plateau. Untrained people score 10 to 20 percent lower on a bike than on a treadmill, while trained cyclists can do as well or better on the bike. Because pushing to the limit is risky for people with heart or lung problems, estimates from lighter tests exist, such as Kenneth Cooper's 12-minute run, devised for the US Air Force in the late 1960s.
An average untrained healthy man scores roughly 35 to 40, a woman roughly 27 to 31. Elite male runners reach up to about 85. What limits the number is debated: delivery of oxygen by lungs, heart, blood and capillaries probably matters most in trained athletes, while untrained people may be limited by how fast their muscle cells use it. The hormone EPO can raise VO2 max substantially, which is why it has been banned since the 1990s and was at the centre of cycling's 1998 Festina affair.
In 2016 the American Heart Association urged doctors to treat cardiorespiratory fitness as a vital sign. A 2023 meta-analysis of observational studies linked each one-unit rise in estimated fitness, measured in metabolic equivalents, to 11 percent lower mortality, though cost means the test is still rarely used in routine clinics.
Source: VO2 max
