Apart from the implications for the develop-
ment of osteoporosis in later life, a low bone
density may be detrimental in athletes. Myburgh
et al. (1990) found that athletes with lower
extremity stress fractures had significantly lower
femoral and lumbar mineral densities than
matched athletic control subjects. Athletes with
stress fractures had significantly lower calcium
intakes and had lower intakes of dairy products.
Injured female athletes were more likely to have
irregular menstrual cycles and less likely to use
oral contraceptives. This was not confirmed
among female ballet dancers but a great number
of dancers with stress fractures avoided dairy
products (Frusztajer et al. 1990). A lifetime
history of calcium intakes exceeding 800 mg ·
day–1appears to reduce the risk for hip fractures
in older women compared with women with
lower calcium intake (<450 mg · day–1) and this
also seems to hold for men (Matkovic et al. 1979).
Milk consumption during childhood and adoles-
cence and as an adult was associated with a
greater bone mass in postmenopausal women,
but total calcium intake was not associated with
bone mass (Sandler et al. 1985; Bauer et al. 1993).
Exercise appears to be more important in pre-
venting trabecular bone loss while calcium
intake may be a more important influence on cor-
tical bone loss.
Conclusion
Intake of sufficient amounts of energy to balance
the expenditure, maintenance of circulating
hormone levels, and regular participation in
some form of weight-bearing exercise are of
greatest importance to achieve and preserve
skeletal health. This is important for the avoid-
ance of stress fractures in young athletes and for
the preservation of bone health in later life. An
adequate dietary intake of calcium is also essen-
tial, and this can be achieved by consumption of
dairy products (which may be reduced-fat vari-
eties) and other foods rich in calcium. Exercise
per sedoes not seem to lead to an increased
requirement for calcium by the body and there is
generally no need for calcium supplementation
for athletes provided that the amount of energy
consumed is sufficient. The RDA for calcium in
both men and women is different in different
countries, and is usually between 800 and 1200
mg · day–1. The recommended intake is the same
for males and females of all ages, except when
females are pregnant or lactating. In post-
menopausal women, adequate hormone supple-
mentation, physical exercise and dietary calcium
intake will prevent loss of bone tissue and delay
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