enced by the hormonal environment: important
factors include the catecholamines, insulin, corti-
costeroids, growth hormone, cyclic nucleotides
and others. Dietary influences on the metabolic
environment in the recovery phase will influence
the extent of recovery from training and
competition.
6 A varied diet is essential to provide all the
nutrients needed by that athlete in adequate
amounts, but other factors, including especially
those associated with the storage and prepara-
tion of foods, will affect the availability of these
nutrients from the diet.
7 The diet must be chosen to include foodstuffs
that will provide all of the essential nutrients, but
care must be taken to ensure that, during periods
when the athlete is training two or three times
per day, the meals are readily digested and
absorbed and do not result in gastrointestinal
disturbances.
8 Where there is a need to increase body mass,
usually in the form of lean tissue, and specifically
in the form of muscle, the diet must contain suffi-
cient protein and other nutrients to ensure that
the increased requirement is met. For athletes
competing in weight category sports, and for
others where a low body mass or a low body fat
content are important, there must be special
attention to the composition of the diet to ensure
that all nutritional requirements are met from the
restricted total energy intake.
9 The diet must be chosen to take account of the
individual physiological, metabolic and anthro-
pometric characteristics of the individual athlete,
and should consider the condition of the athlete’s
digestive system. It must also take personal
tastes and preferences into account.
Only if the diet is selected in the light of these
considerations is it possible to meet all of the
requirements imposed by training and competi-
tion and to optimize the athlete’s performance.
Strength training
Muscle, fat and bone are the three major struc-
tural components that determine the body shape
and size of the individual. Body build is to a large
degree genetically determined, as is the ability to
achieve success in sport. Specific types of physi-
cal training can modify the expression of the
individual’s genetic endowment, resulting in
changes in body composition. Weight training is
effective when the aim is to increase muscle
mass, whereas endurance training can alter
energy balance and reduce fat mass. An appro-
priate weight-training regimen, however, will
also be effective in reducing body fat content if
combined with a suitable diet.
There are several categories of strength exer-
cise that can be included in a weight training
programme: these include isometric (static) con-
tractions, which are not truly contractions, as the
muscle is not allowed to shorten during activa-
tion and the angle of the limb is fixed. Because of
stretching of the elastic components, however,
there will be some shortening of individual sar-
comeres. Isokinetic exercise involves shortening
of the muscle at a fixed velocity, and requires
special apparatus to keep the velocity of shorten-
ing constant while measuring the applied force.
Isotonic exercise, in which a constant load is
applied to the muscle is the type of training
most familiar to and popular with coaches and
athletes (Fahey 1986). The applied load may be
in the form of free weights or a resistance ma-
chine. Isotonic strength-training techniques may
include constant or variable load, and may
involve lengthening of the muscle (eccentric acti-
vation) as well as the more normal shortening
(concentric activation) when the load is applied.
Plyometric and speed loading techniques may
also be included in a strength programme.
It has been shown that greater increases in
strength can be achieved following a programme
of maximum-force concentric and eccentric acti-
vation than when concentric activation alone
is used (Fahey 1986). The available evidence
suggests that eccentric activity results in some
degree of damage to the muscle, involving dis-
ruption of the muscle membrane and possibly
also some disruption of the contractile compo-
nents, and the subsequent repair process seems
to be important for the increase in the size of
muscle fibres that results from a strength training