Max: How Fit Is An Athlete?
Max is a measure of how fit an athlete is: It expresses the volume
of oxygen a body consumes per minute.
Athletic performance is directly related to the amount of oxygen
supplied to the muscles. The supply of oxygen is dictated by how
often the heart beats, the volume of blood transported by every
beat and the amount of oxygen in that blood. It is also dependent
on how well the tissue or muscle extracts the oxygen (O2). So
if we could find the volume of blood pumped in one minute and
the difference between the amount of oxygen in arterial and venous
blood we would have all the data we need. The stroke volume is
usually measured in milliliters per beat. The cardiac output is
the product of stroke volume and heart rate and is measured in
milliliters per minute. Multiply this by the difference in oxygen
concentration and we have the liters of O2 processed per minute.
If we make these measurements when the athlete is working at his
or her maximum heart rate, we have VO2 Max.
A straight comparison of the absolute amount of oxygen that the
bodies of two different athletes can process is not quite fair.
A heavy weight athlete with the same values would not perform
as well as a lighter athlete. For most sports, including running,
VO2 Max is expressed as VO2/Kg - milliliters of O2 per minute
per kilogram of body weight. Cyclists tend to be measured strictly
in terms of liters of O2 per minute because body weight is less
important in that sport.
To measure VO2 Max directly an athlete has to be wired to a computer
and breathe into an apparatus that analyses exhaled air while
he runs on a tread mill. The equipment is expensive and the test
is not practical for most people. Strictly speaking, it is VO2
peak that is measured any way. It becomes too painful for anyone
but the highly motivated to reach the maximum.
If we measure a group of athletes directly and take them to the
maximum and then have them perform some simpler, submaximal test,
we can find an equation to extrapolate the indirect test's result
to a predicted VO2 Max value. There are some problems with this
- the test is not always accurate and max heart rate factors into
the equation. Because the subject isn't taken to the limit, a
theoretical maximum heart rate number must be used. A common estimate
is 220 - age. However, if you are interested in a rough measurement
to use as a base against which to measure your progress, then
indirect measurement is fine.
Other somewhat estimates for VO2 max are based on calculations
for a 1.5
mile run, 12
minute run, and Rockport
Fitness Walking Test, although these measurements are based
on population averages and are rough calculations.
Improving VO2 Max
You probably just realized that you can improve your VO2/Kg simply
by losing weight, assuming you lose fat and not muscle. Women
are at a slight disadvantage because they have a higher percentage
of essential body fat.
There is not much that can be done to increase max heart rate.
In fact it decreases with age. We can increase the cardiac output
by making the heart larger and stronger. This can be achieved
over the years through prolonged endurance training. A trained
athlete's resting heart rate is lower because it pumps more blood
per beat than an untrained person's does.
last parameter in the equation is the body's ability to extract
more oxygen out of the arterial blood. This is increased mainly
as a result of long, slow endurance runs. The aerobic capacity
of Type I fibres (slow-twitch muscle) is improved only after 1.5
This chart shows actual figures from a researcher's test at the
Science Centre in 1989. The subject's VO2/Kg peaked at 63.2 ml/minute/kg
after 13 minutes of progressively faster and steeper running on
a treadmill. The subject weighed 72.1 kg at the time. This means
the VO2 MAX was 4.6 liters/min. The test listed a lot of other
data, things like liters per breath and the
VCO2 (at STP) that are used during the calculation of VO2. A MET
is a metabolic equivalence unit. One MET is equal to 3.5 ml/kg/min
and is the amount of oxygen the body uses at rest.
The tables below list VO2/Kg in ml/min/kg for men and women in
a range of ages and levels of fitness.
Max Values for Men & Women
Here, expressed as VO2/Kg are some well-known athletes' statistics.
Whitlock: 52.8 (at 69 years)
Indirect VO2/Kg Test
Here is one indirect test you can do yourself. It is the Rockport
Fitness Walking Test (RFWT).
To perform the test, all you need is your weight and age and to
walk one mile. Before the walk, warm up with some stretching.
After the warm up, walk one mile as fast as possible and note
the time it took you. Immediately after finishing the mile, take
your pulse. The equation for estimating your VO2/Kg follows:
VO2 max (ml/kg/min) = 132.853 - 0.0769 (weight) - 0.3877 (age) +
6.3150 (sex) - 3.2649 (time) - 0.1565 (heart rate)
is in pounds.
Age is in years.
Sex: male = 1, female = 0.
Time is expressed in minutes and 100ths.
Heart Rate is in beats per minute, taken at the end of the walk.
Notice how gender adds a constant 6.3 to the male score.
A high VO2 Max alone does not make a super athlete. On competition
day, psychological factors are important. If it's a race, then
pacing and tactics are also critical. Depending on the sport,
mechanical efficiency and technique play a large role. If lactate
tolerance is low, then a super VO2 Max may not be advantageous.
Interval training can help. But as a measure of the efficiency
of the amazing heart / lung / muscle machine, it's the standard.
your VO2 Max
Articles on VO2 Max
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