VO2 max is the maximum rate of oxygen consumption as measured during incremental exercise, most
typically on a motorized treadmill. Maximal oxygen consumption reflects the aerobic physical
fitness of the individual, and is an important determinant of their endurance capacity during
prolonged, sub-maximal exercise. The name is derived from V - volume, O2 - oxygen, max
- maximum. VO2 max is expressed either as an absolute
rate in litres of oxygen per minute or as a relative rate in millilitres of oxygen per
kilogram of body mass per minute). The latter expression is often used to compare the performance
of endurance sports athletes. However, VO2 max generally does not vary linearly with
body mass, either among individuals within a species or among species, so comparisons
of the performance capacities of individuals or species that differ in body size must be
done with appropriate statistical procedures, such as analysis of covariance.
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 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.
(CaO2 – CvO2) is also known as the arteriovenous oxygen difference.
Estimation of VO2 max Tests measuring VO2 max can be dangerous in
individuals who are not considered normal healthy subjects, as any problems with the
respiratory and cardiovascular systems will be greatly exacerbated in clinically ill patients.
Thus, many protocols for estimating VO2 max have been developed for those for whom a traditional
VO2 max test would be too risky. 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 VO2 max for humans, based
on maximum and resting heart rates, was created by a group of researchers from Denmark. It
is given by:
This equation uses maximum heart rate and resting heart rate to estimate VO2 max in
mL/(kg·min). 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. Based on the measured distance, an estimate of VO2 max [in mL/(kg·min)]
is:
where d12 is distance covered in 12 minutes. Multi-stage fitness test
There are several other reliable tests and VO2 max calculators to estimate VO2 max, most
notably the multi-stage fitness test, based on the research paper by Leger and Lambert,
"A Maximal Multi-Stage 20-m Shuttle Run Test to predict VO2 Max".
VO2 max levels “Maximal oxygen uptake is widely accepted
as the single best measure of cardiovascular fitness and maximal aerobic power. Absolute
values of VO2 max are typically 40-60% higher in men than in women.”
The average untrained healthy male will have a VO2 max of approximately 35–40 mL/(kg·min).
The average untrained healthy female will score a VO2 max of approximately 27–31 mL/(kg·min).
These scores can improve with training and decrease with age, though the degree of trainability
also varies very widely: conditioning may double VO2 max in some individuals, and will
never improve it in others. In one study, 10% of participants showed no benefit after
completing a 20 week conditioning program, although the other 90% of the test subjects
all showed substantial improvements in fitness to varying degree.
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 maxima. Elite male runners can consume up to 85 mL/(kg·min), and female elite runners
can consume about 77 mL/(kg·min). Five time Tour de France winner Miguel Indurain is reported
to have had a VO2 max of 88.0 at his peak, while cross-country skier Bjørn Dæhlie measured
at 96 mL/(kg·min). 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. Norwegian cyclist Oskar Svendsen
is thought to have recorded the highest VO2 max of 97.5 mL/(kg·min), a "sensational"
value in itself, made more remarkable by his young age. 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 have VO2 values as high as 240 mL/(kg·min).
The highest values in absolute terms for humans are often found in rowers, as their much greater
bulk makes up for a slightly lower VO2 max per kg. Elite oarsmen measured in 1984 had
VO2 max values of 6.1±0.6 L/min and oarswomen 4.1±0.4 L/min. Rowers are interested in both
absolute values of VO2 max and in lung capacity, and the fact that they are measured in similar
units means that the two are often confused. British rower Sir Matthew Pinsent is variously
reported to have had a VO2 of 7.5l/min or 8.5l/min, although the latter may represent
confusion with his lung capacity of 8.5 litres. New Zealand sculler Rob Waddell has one of
the highest absolute VO2 max levels ever tested. Factors affecting VO2 max
The factors affecting VO2 are often divided into supply and demand. Supply is the transport
of oxygen from the lungs to the mitochondria while demand is the rate at which the mitochondria
can reduce oxygen in the process of oxidative phosphorylation. Of these, the supply factor
is often considered to be the limiting one. However, it has also been argued that while
trained subjects probably are supply limited, untrained subjects can indeed have a demand
limitation. Tim Noakes, a professor of exercise and sports
science at the University of Cape Town, describes a number of factors that may affect VO2 max:
age, sex, fitness and training, changes in altitude, and action of the ventilatory muscles.
Noakes also asserts that VO2 max is a relatively poor predictor of performance in runners due
to variations in running economy and fatigue resistance during prolonged exercise.
Cardiac output, pulmonary diffusion capacity, oxygen carrying capacity, and other peripheral
limitations like muscle diffusion capacity, mitochondrial enzymes, and capillary density
are all examples of VO2 max determinants. The body works as a system. If one of these
factor is sub-par, then the whole system loses its normal capacity to function properly.
The drug erythropoietin can boost VO2 max by a significant amount in both humans and
other mammals. This makes EPO attractive to athletes in endurance sports, such as professional
cycling. By 1998 it had become widespread in cycling and led to the Festina affair as
well as being mentioned ubiquitously in the USADA 2012 report on the US Postal team. Greg
LeMond has suggested establishing a baseline for riders' VO2 to detect abnormal performance
increases. See also
Anaerobic exercise Arteriovenous oxygen difference
Cardiorespiratory fitness Comparative physiology
VDOT Oxygen pulse
Respirometry Training effect
vVO2max References
External links VO2 max Calculator - the Rockport Walking
Test All About VO2max - Horses
So What Exactly is VO2? Values by age, mL/(kg·min)