NUTRITION IN SPORT

(Martin Jones) #1

ing complex carbohydrates, are consumed. Since
most of the gymnastic surveys indicate an under-
consumption of energy, an appropriate strategy
for improving vitamin B 1 intake in gymnasts is
an improvement in total energy consumption.
(See Chapters 20 and 21 for information on
vitamins.)


Vitamin B 2 (riboflavin)


With the exception of a single survey (Benardot
et al.1989), all other nutrient intake studies indi-
cate that riboflavin intake is below the RDA of
1.5–1.8 mg · day–1. However, when evaluated as
0.6 mg per 4.2 MJ (1000 kcal) consumed (the basis
of the RDA, assuming normal energy consump-
tion), the vitamin B 2 intake of gymnasts meets or
exceeds the required level in all of the surveys.
There are some reports, however, that athletes
may have higher rates of vitamin B 2 utilization,
and may have a predisposition to mild symp-
toms of riboflavin deficiency (particularly cheilo-
sis), especially when involved in aerobic work
(Belkoet al. 1983). It is unclear whether gym-
nasts, who consume less energy than their pre-
dicted requirements and who have less total
vitamin B 2 intake than the RDA, would be at
similar risk, especially since the majority of their
training is anaerobic. (See Chapters 20 and 21 for
information on vitamins.)


Niacin


Using the niacin RDA for young and adolescent
females of 15 mgNE, three groups of surveyed
gymnasts had niacin intakes below the recom-
mended level (Moffatt 1984; Reggiani et al. 1989;
Ersoy 1991). These groups, including gymnasts
in high school, elite gymnasts and very young
competitive gymnasts, had intakes of niacin that
ranged between 89% and 57% of the recom-
mended levels. There is no discernible pattern in
the intake of niacin in the published surveys, so it
is not clear whether a recommendation should be
made for an additional intake on niacin in gym-
nasts. It is clear, however, that with a balanced
intake of food high in complex carbohydrates,


moderate in protein, and moderately low in fat,
gymnasts would have little difficulty in obtain-
ing the needed niacin from consumed foods. (See
Chapters 20 and 21 for information on vitamins.)

Calcium
The results of several surveys on gymnasts indi-
cate a level of calcium intake that is significantly
lower than the recommended level of intake (see
Table 45.4). With the exception of the survey con-
ducted by Lindholm et al. (1995) on elite adoles-
cent females, which found an average calcium
intake at the recommended level of 1200 mg, all
other surveys indicate a calcium intake ranging
between 397 mg (10–12-year-old females) and
1059 mg (college-age males). Given the fre-
quency with which gymnasts suffer from muscu-
loskeletal injury, and the degree to which calcium
intake is associated with a reduction of skeletal
injury risk, it is alarming that the calcium intake
of gymnasts appears to be so inadequate across
all groups evaluated (Dixon & Fricker 1993;
Nattiv & Mandelbaum 1993; Sands et al. 1993).
Even with inadequate calcium intakes, there
is evidence that gymnasts have higher bone
mineral densities than those of age-matched con-
trols (Nichols et al. 1994; Kirchner et al. 1995). It is
likely that the physical stresses placed on the
skeleton from gymnastics activity stimulates
calcium deposition in the bone (Slemenda et al.
1991; Carbon 1992; Fehily et al. 1992; Vanden-
Bergh et al. 1995). It is confounding, however,
that gymnasts have high bone densities despite
having multiple risk factors related to poor bone
development and bone loss, including primary
and secondary amenorrhoea (Sundgot-Borgen
1994), high cortisol levels (Licata 1992), low
calcium intake (VandenBergh et al. 1995), low
weights (Miller et al. 1991), and low heights
(Milleret al. 1991). Given the high level of lean
body (muscle) mass found in gymnasts (in the
75th percentile for their height and age (Benardot
& Czerwinski 1991), it may be that bone density,
while high, remains insufficient to support this
level of muscular force. This latter possibility is
supported by the disproportionately high level

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