protein · kg–1body mass · day–1(Lemon 1992). A
diet containing 12–15% of its energy from protein
should be adequate for strength athletes (includ-
ing sprinters), assuming that the total energy
intake is sufficient to cover their high daily
energy expenditure (Lemon & Proctor 1991).
Should sprinters consume a particular type of
diet? Total energy intake should be increased in
order to cover the demands of training and com-
petition. Most of the studies which have reported
the energy intakes of runners have focused on
endurance athletes. One study of trained univer-
sity track athletes (Short & Short 1983) reported
that the daily energy intake of these sprinters
was approximately 16.8 MJ (4000 kcal), similar to
the energy intake of university bodybuilders in
the same study. Unfortunately, no data on the
physical characteristics of these athletes were
documented. A well-balanced diet, containing a
wide variety of foods, is all that is recommended
to ensure that all needs for energy, vitamins and
minerals are met. At least 60–70% (7–8 g · kg–1) of
daily energy intake should come from carbohy-
drates, about 12% from protein (1.2–1.7 g · kg–1),
and the remaining energy provided by fat
(Devlin & Williams 1991; Lemon 1992). However,
only endurance athletes seem to comply with
these recommendations (C. Williams 1993). The
only nutrient supplementation which may
enhance sprinting is creatine (see Chapter 27)
and bicarbonate (see Chapter 29). Currently,
there is little evidence to suggest that sprinters
require any other supplements (including vita-
mins and minerals) in addition to a normal bal-
anced diet containing a wide range of foods
covering the individual’s energy requirements.
Further research is necessary to establish
whether some nutrients and combinations
of nutrients have an ergogenic effect during
sprinting.
Carbohydrate loading and sprinting
Muscle glycogen ‘supercompensation’ improves
performance during prolonged exercise (Costill
1988), and is a nutritional strategy used by
endurance athletes in preparation for competi-
tion. The importance of the initial glycogen
concentration on the performance of maximal
or high-intensity exercise remains an issue,
although it is clear that very low pre-exercise
glycogen concentrations are associated with
reductions in performance in high-intensity
exercise (Maughan & Poole 1981; Pizza et al.
1995). However, it is unlikely that increased
glycogen stores will affect sprinting perfor-
mance, as glycogen per seis not a limiting factor
during sprints over distances of 400 m or less
(Hirvonenet al. 1992). Laboratory studies on
brief, maximal exercise also support this conclu-
sion. The mean and peak power outputs of
athletes performing 30 s of maximal exercise
using the WAnT protocol on a cycle ergometer
were unchanged after carbohydrate loading
(Wootton & Williams 1984).
This lack of ergogenic effect is elucidated when
the metabolic responses to sprinting are exam-
ined in single fibres of human skeletal muscle
(Greenhaff et al. 1994). Biopsies were obtained
from six subjects before and after a 30-s sprint
on a non-motorized treadmill. Glycogen was
reduced by 20% and 27% in the type I and type II
fibres, respectively, in agreement with the signifi-
cant contribution from muscle glycogen during a
30-s sprint reported by Cheetham et al. (1986).
However, the 65% decline in power output
during the 30-s sprint was probably associated
with the large decline in PCr concentration in
both type I fibres (83% decrease), and particu-
larly the type II fibres (94% decline).
Varying the carbohydrate intake in the days
before exercise has been shown to influence per-
formance during high-intensity (not maximal)
exercise when undertaken either continuously
(Maughan & Poole 1981; Pizza et al. 1995), or
intermittently (Bangsbo et al. 1992; Nicholas et al.
1997). However, a relationship between carbohy-
drate status and exercise performance during
maximum exercise has not been consistently
reported (Symons & Jacobs 1989; Vandenberghe
et al. 1995). There may, however, be a critical
concentration of glycogen below which high-
intensity exercise is impaired. Indeed, it has been
shown that below a muscle glycogen concentra-