NUTRITION IN SPORT

et al. 1989), suggesting that the short stature of
the elite gymnast is determined largely by
genetic rather than training and nutritional
factors. Although Theintz et al. (1989) found no
evidence that the predicted adult height for a
group of elite young female gymnasts, who had
already been training intensively for a period of 5
years, was less than the target height, their subse-
quent work suggested otherwise (Theintz et al.
1993). However, for this question to be resolved,
both groups of athletes (Theintz et al. 1993;
Baxter-Jones 1995) need to be reassessed to ascer-
tain their actual adult height.
The biological maturity status of athletes has
also been studied extensively, especially age at
menarche (Malina 1994; Beunen & Malina 1996).
When considering the influence of nutrition
on the biological development of the elite young
athlete, it is important to remember that this
analysis is beset with a number of difficulties.
Firstly, the definition of what constitutes an elite
young athlete is vague, and secondly, as already
discussed, it is likely that young athletes self-
selected themselves for their sport due to their
appropriate size and physique (Baxter-Jones &
Helms 1996). A girl’s menarcheal age is closely
related to her mother ’s menarcheal age and this
appears to be due mainly to a genetic influence
on hormonal changes (Tanner 1989). Potential
environmental influences include physical activ-
ity and nutrition (Malina 1983). In abnormal cir-
cumstances, nutrition may play an important
role in the attainment of menarche, although this
clearly relates to the malnourished child. It has
been hypothesized that young athletes undertak-
ing intensive training have delayed menarche
due to the effects of training at an early age. In the
British longitudinal study (Baxter-Jones & Helms
1996), all the sports (gymnastics, swimming and
tennis) had later mean ages of menarche (14.3,
13.3 and 13.2 years, respectively) than the previ-
ously reported UK reference value of 13.0 years
(Fig. 32.3). A positive correlation was found
between menarcheal age in mothers and daugh-
ters (n=201,r=0.27,P<0.01; Baxter-Jones et al.
1994). Analysis of covariance, using maternal
menarcheal age, socio-economic group, duration

of training and type of sport confirmed that

maternal menarcheal age and type of sport have

a significant influence on the subject’s age of

menarche. As maternal menarcheal age and

sport were the best predictors of menarcheal age

in the athletes studied, it would appear that

menarche was intrinsically late rather than

delayed (Baxter-Jones et al. 1994); this suggests

that some form of sport-specific selection had

occurred.

Nutrition and performance

The remainder of this review will be limited to

nutritional factors that could affect performance

in the young athlete. Performance will be delim-

ited to three major sporting areas: strength and

flexibility-based sports (gymnastics), endurance

sports (running/cycling) and high-intensity

intermittent sports (soccer, rugby, basketball).

Carbohydrate and fat

The major substrates used by the muscles during

the young athlete 433

15

12

14

13

Gymnastics

Age of menarche (years)

Swimming

UK

median

age

Tennis

Fig. 32.3Mean age of menarche and associated

standard errors for British mothers (
) and daughter

athletes ( ) in different sports, with reference to the

UK median age (Tanner 1989). Significant differences

were found between mothers’ and daughters’ age of

menarche in gymnastics and tennis (P<0.05). From

Baxter-Jones et al. (1994), with permission of Taylor &

Francis.