season, the physical condition of the athlete, pro-
gramme variation for both physiological and
psychological considerations and programme
objectives.
The principal adaptation of the athlete’s body
is the increase in size (commonly termed hyper-
trophy) of type II muscle cells. It is generally held
that no interchange takes place between type I
and type II fibres as the result of specific condi-
tioning programmes.
As the force development capability of a
muscle is directly related to its physiological
cross-section, the increase in size of the muscle
cells is the principal reason for increased force
development. The energy requirement for per-
formance of a 1 RM is quite small, as is the perfor-
mance of any bout of exercise from the 1 RM to a
20 RM. However, the total energy requirement of
performing multiple bouts of exercise for each of
a number of movements or exercises (e.g. 10) in a
daily workout is large. This deserves careful con-
sideration from the standpoint of the athlete’s
nutrition, both in terms of quantity and content.
In addition to the total energy balance and
accompanying maintenance of appropriate body
mass, consideration must be given to suitable
protein intake.
Adaptations of skeletal muscle
Muscle cells and the structure of an individual
14 nutrition and exercise
muscle, in general, respond in very different
ways to the unique exercise stimulus that is pro-
vided. The muscles respond to the acute stimulus
by providing the forces and power demanded by
such widely diverse performances as weight-
lifting, high jumping, 100-m sprinting and
running at marathon pace. Following a single
bout of exercise or a single day’s conditioning
session, however, the individual muscle fibres
and the total muscle recover to a physiological
state with little or no measurable change.
Repeated workouts over weeks and months
elicit adaptations, and these structural and
functional changes are highly specific to the
conditioning programme (i.e. the stimulus)
as appropriate to the competitive event for
which the athlete is preparing (Fig. 1.6). A high-
resistance (strength) programme which results
in significant muscle hypertrophy could be de-
trimental to distance running performance. A
conditioning programme for distance running
would definitely be detrimental to weightlifting,
high jumping and sprint performance.
Strength training results in an increase in size
(girth and therefore cross-sectional area) of type
II muscle fibres and the muscles themselves.
Capillarization can evidence either no change or
a ‘dilution effect’, where the hypertrophy of
muscle cells spreads out the existing capillaries,
with the result that an individual capillary serves
a larger cross-sectional area of muscle.Fig. 1.6Many team sports such as
international football (soccer)
require combinations of aerobic
power, anaerobic power and
strength, as well as a wide variety
of skills. Photo © Allsport / S.
Bruty.