Cycling efficiently means covering a maximum distance using
a given amount of energy. In a formula it can be expressed as
follows:
Efficiency = [physical effort/(energy used minus energy used
at zero Watt)] x 100
The five factors that determine the efficiency in order of importance
EFFICIENCY
The formula makes it is clear that efficiency can be increased
by increasing the physical effort and, at the same time, using
the same amount of energy, or by using less energy during a
given physical effort. The advantage of this formula is that
it takes into account the minimum amount of energy required
to move the legs (i.e., the energy required to cycle without
any resistance). In this way, the efficiency of the muscles
is accurately determined because the energy needed to keep the
body in motion is deducted from the total use of energy. How
is this formula applied? The use of energy can be measured in
a laboratory through the intake of oxygen. The intake of one
liter of oxygen (not air) equals the use of 5 kcal. In other
words, a given person first starts to cycle without any resistance
and afterwards with a certain resistance. In both cases, the
intake of oxygen is measured, after which the results are put
into the formula. Physical effort is expressed in Joule. In
order to convert Joule to kcal, the figure expressed in Joules
has to be divided by 4.19.
Another method to determine the efficiency is the cost function.
This is a mathematical expression which provides a description
of a certain physical effort by giving it a numerical value.
Or to put it more simply, the cost function describes the relative
efficiency of a movement with only one number. The determination
of this cost function is based on the moments in the joints
during the cycling movement. It is an established fact that
these moments correlate directly with the tension in the muscles.
Subsequently, the tension in the muscles is a criterion for
the efficiency of a contraction. If the sum of the moments in
the ankle, knee and hip is minimal, then the position in which
this is the case is the most efficient one.
The formula mentioned above, however, does not take into consideration
one important element which is inherent in sport, in general:
the aspect of competition. This implies that the distances are
covered at a relatively high speed or, alternatively, within
a certain time frame. When we introduce the time element into
the formula, we no longer speak of physical effort, but of power.
The best cyclist will be the one who burns the most calories
within a given time frame, thereby taking for granted that all
cyclists expand the same amount of energy at a certain speed.
In reality, this is not the case because not all cyclists adopt
an equally efficient position on the bicycle. So there are a
number of cyclists who use up more energy than others in order
to arrive at a certain speed.<
What are the factors on which efficiency depends when looking
at it from a biomechanical perspective? Gonzales and Hull (1989)
conducted a survey into this matter, and they came to the conclusion
that there are five factors that determine the efficiency in
cycling. In their research they also come to the conclusion
that these factors are interrelated. A logical result of this
conclusion is that these factors should be adjusted accordingly,
in order to arrive at an optimal combination. Hence the use
of the term multi-variable measuring method.