Physical Education - How is VO2 max. measured?
How is VO2 max. measured?
In order to determine an athlete's true maximal aerobic capacity ,
exercise conditions must be created that maximally stress the blood
delivery capacity of the heart.
A physical test that meets this requirement must:
* employ at least 50% of the total muscle mass. Activities that meet this
requirement include running, cycling and rowing. The most common laboratory
method is the treadmill running test. A motorised treadmill with variable
speed and variable incline is employed
* be independent of strength, speed, body size and skill. The exception
to this rule is specialised tests for swimmers, rowers, skaters, etc.
* be of sufficient duration for cardiovascular responses to be maximised.
Generally, maximal tests using continuous exercise protocols are completed
in 6 to 12 minutes
* be performed by someone who is highly motivated! VO2 max. tests are
very tough, but are over quickly
If we use a treadmill test as an example, here is what will happen:
You will go to a good laboratory at a university fitness program or
hospital wellness centre. After a medical exam, and after being hooked up
to an ECG machine to monitor cardiac electrical activity, you might start
the test by walking on the treadmill at low speed and zero grade. If your
fitness level is quite high, the test might be initiated at a running
speed. Then - depending on the exact protocol - speed or inclination (or
both) of the treadmill will increase at regular intervals (30 seconds to 2
minutes). While running, you will be breathing through a 2-way valve
system. Air will come in from the room, but will be expired through sensors
that measure both volume and oxygen concentration.
Using these values and some mathematics, your oxygen uptake will be
calculated by a computer at each stage. With each increase in speed or
incline, more muscle mass will be employed at a greater intensity. Oxygen
consumption will increase linearly with increased workload. However, at
some point, an increase in intensity will not result in an increase in
oxygen consumption. This is the true indication of achieving VO2 max.
Exercise will cease soon after this point due to the rapid accumulation of
lactate that will have started several minutes before. Other indications of
VO2 max. are extreme hyperventilation, and a heart rate of very near 220,
minus age, that does not increase further with increased workload.
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