directed eating from the child’s parent or
guardian, inherent nutritional knowledge with
respect to carbohydrate was poor. In a survey of
97 competitive female gymnasts (11–17 years),
77% rated protein as their favourite energy
source; 53% were unaware of what a complex
carbohydrate was and 36% chose nutrient-poor
foods such as doughnuts and soft drinks as their
favourite energy food (Loosli & Benson 1990).
Whilst the lower levels of glycolytic and
higher levels of citrate-cycle enzyme activity of
the child would imply that increased dietary fat
would produce the best responses during pro-
longed exercise, it is clear that certain reserva-
tions apply to this procedure. Firstly, it would be
medically unsound, as the risk of developing
coronary heart disease, stroke and certain can-
cers has been associated with eating a chronic
high fat diet; and secondly, following the hypoth-
esis of central fatigue, increased FFA levels may
promote fatigue by enhancing free tryptophan
levels, leading to raised levels of serotonin in the
brain (Davis et al. 1992). However, it has also
been shown that increased FFA in the presence of
heprin increases endurance (see Chapter 13).
Serotonin (5-hydroxytrytamine or 5-HT) is
responsible for causing a state of tiredness in
both man and experimental animals (Young
1991). Hence, an elevation of serotonin may
exacerbate the sensation of fatigue.
Protein intake
There is no evidence that protein metabolism
differs between adults and children (Lemon
1992). Hence, the increased need for protein
intake by active adolescents is purely the product
of the extra demand imposed by exercise and
growth, and not the result of any inadequacies
of the child’s metabolism of protein. The RDA
values for the adult population vary widely
between countries (0.8–1.2 g · kg–1· day–1): where
separate values are established for adolescents,
they are generally in the region of 1 g · kg–1· day–1
(Lemon 1992). Bar-Or and Unnithan (1994)
suggest an increase, in non-athletic children,
from the adult value of 0.8 g · kg–1· day–1to 1.2 g ·
kg–1· day–1for boys and girls between 7 and 10
years, and a value of 1.0 g · kg–1· day–1for 11–14
years. These figures are based upon tables gen-
erated by the American Academy of Paediatrics
(1991): after this age, recommendations are in
line with adult figures.
O’Connor (1994) demonstrated that young
people (age range, 7–19 years) achieve a mean
dietary intake of 1.6 g · kg–1· day–1, even in those
sports where energy intake is restricted (e.g.
gymnastics). In contrast, Martinez et al. (1993),
assessing the diet of adolescent American foot-
ballers, via the use of dietary recall, found that in
87 subjects 95% consumed less than the RDA
(16.8 MJ · day–1or 4000 kcal · day–1) (Pipes 1989)
for the adolescent male athlete. These results par-
allel the findings for adolescents not engaged in
sports training and therefore it would appear
that those engaged in sports do not practice any
better nutritional habits than those who are not.
Concern was noted with regard to protein intake:
the mean protein intake was almost twice the
RDA and accounted for 16% of total energy con-
sumed (Martinez et al. 1993). Even taking into
account the validity of the RDAs, the resultant
excess protein in the blood could be harmful to
liver function. Although, the sports practitioner
(coach) and parent should be made aware of a
possible increased protein requirement during
periods of rapid growth and intensive train-
ing, protein supplementation, as seen in adults,
should also be discouraged. Finally, it still has to
be ascertained whether protein requirements
differ depending upon the sport selected and the
level of competition undertaken.Fluid intake and composition
In order to understand the significance of fluid
intake and drink composition for the child
athlete, it is necessary to review briefly the
underpinning thermoregulatory physiology of
the child compared to that of the adult.
Primarily as a result of their greater surface
area to body mass ratio, children and adolescents
absorb heat quicker at high ambient tempera-
tures and lose heat faster at low ambient tem-