The
Science
In McArdle, Katch and Katch (1994) it is suggested
that three important factors determine endurance (aerobic) performance:
1. Maximal oxygen uptake (VO2max)
2. Lactate Threshold (OBLA)
3. Economy of effort
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VO2 Max
While
exercising aerobically a person operates at a certain VO2. VO2 is the
volume of oxygen being metabolized by the body at any one time. VO2 max
therefore is the maximum amount of oxygen that can be metabolized by
the body. This figure is a useful measure of aerobic fitness, and is
represented in milliliters of oxygen per minute (mls/min) or
milliliters per kilogram per minute (ml/kg/min). It reflects well, an
individual's ability to aerobically resynthesize ATP (the molecule
which supplies the body's cells with energy). In short, VO2 increases
as exercise intensity increases. The harder a person exercises, the
higher their volume of oxygen utilized (VO2).
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Anaerobic Threshold and Lactate Threshold
As the intensity of exercise increases and
oxygen supply to the
working muscles becomes inadequate, lactic acid is produced. This is
due to the muscles greater reliance on energy being produce
anaerobically (without oxygen). Anaerobic Threshold (AT) also described
as OBLA (Onset of Blood Lactate Accumulation) is the point at which
blood lactate is being produced faster than it can be remove. Lactic
acid accumulation in the muscles causes discomfort and at increasing
levels will eventually result in the activity being reduced or stopped.
AT is a good predictor of endurance
performance, often offering a
better indicator than VO2max. In a study that compared race-walking
velocity with AT, performance was predicted to within 0.6% of the
actual time!
AT in healthy untrained subjects occurs
around 55% of VO2 max
(69% of max heart rate). World class endurance athletes can have an AT
of 85-90% of their VO2 max (91-94% max heart rate)!
The other performance measure of Lactic Acid
production is the
Lactate Threshold (LT). This is the first workload producing a
sustained increase in Lactate above resting values, and can be used in
aerobic training zone calculations. |
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Economy of Effort
Economy of effort describes how much energy is
being wasted or
directed towards the activity. For example two physiologically
identical athletes may run at different speeds, while running at the
same heart rate. This is because the faster athlete has a more
economical running style than the slower athlete does. This principal
can be applied to all sports, for example smooth pedaling in cycling,
fluid swimming technique for swimmers and so on.
In conclusion, each of these areas can be tested and improved to
enhance aerobic performance. When combined with strength and power
testing, as well as strength and power training, will lead to a well
balanced athlete. |
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