an average of 0.15 MJ · kg–1(36 kcal · kg–1). Dis-
tribution of energy for these athletes was 49%
of energy from carbohydrate and 34% of energy
from fat for the men, while the women reported
53% of energy from carbohydrate and 30% of
energy from fat.
Berninget al. (1991) reported energy intakes
of adolescent developmental level swimmers
attending a training camp. Males consumed an
average of 21.9 MJ · day–1(5230 kcal · day–1) while
females reported 15.0 MJ · day–1 (3580 kcal ·
day–1). Distribution of energy among the energy
macronutrients was not different from the
general population, prompting the authors to
conclude that these swimmers consumed too
much fat and inadequate carbohydrate.
In an attempt to determine the influence of
training volume on the energy intake of competi-
tive swimmers, Barr and Costill (1992) examined
diet records of 24 males during a period of ‘low
volume’ training (22 km · week–1) and during
‘high volume’ training (44 km · week–1). Energy
intake averaged 15.3 MJ · day–1(3650 kcal · day–1)
during the lower volume training and increased
significantly to 17.7 MJ · day–1(4230 kcal · day–1)
during the 6 weeks of high-volume training. It
was noted that this increase in energy intake did
not fully compensate for the higher energy
demand of the longer training, since the swim-
mers maintained their body weight while they
lost subcutaneous fat.
Costillet al. (1988a) examined male collegiate
swimmers before, during and after 10 days of
increasing training. Their training distance was
increased from 4266 to 8970 m · day–1 while
average intensity was maintained at 94% of their
maximum oxygen uptake. This resulted in an
average energy cost during training of 9.6 MJ ·
day–1(2300 kcal · day–1). It was noted that four of
the 12 swimmers could not tolerate the higher
training volume and were forced to swim their
training bouts at slower speeds. In addition,
these swimmers had reduced muscle glycogen
concentration as a consequence of the combined
effect of the intensified training and their low
carbohydrate intakes. These findings led the
authors to conclude that some swimmers have
610 sport-specific nutrition
difficulty in meeting the energy demands of
high-volume training and experience chronic
muscle fatigue as a result of their failure to ingest
sufficient carbohydrate to match the energy
demands.
The studies reviewed above suggest that
male competitive swimmers in the age range of
16–23 years typically ingest approximately
18.0 MJ · day–1(4300 kcal · day–1), while females
consume only about 10.9 MJ · day–1(2600 kcal ·
day–1) despite the fact that female and male
swimmers perform similar training volume and
intensity. When these data are compared with the
estimated energy requirements of swimming
training proposed by Sherman and Maglischo
(1992), males tend to remain in energy balance
(18.0 MJ · day–1average intake vs. 16.8–22.6 MJ ·
day–1 (4300 vs. 5400 kcal · day–1) estimated
requirement) while female swimmers tend to
maintain a negative energy balance (10.9 MJ ·
day–1average intake vs. 14.2–16.8 MJ · day–1(2600
vs. 3400–4000 kcal · day–1) estimated require-
ment). These data illustrate the nutritional
dilemma facing competitive swimmers, espe-
cially females, and their coaches. The tremen-
dous training demands imposed on these
athletes require careful consideration of the
swimmer’s diet to make sure that adequate
amounts of food are eaten to provide the energy,
macronutrients and micronutrients necessary to
support the enormous training loads.Body composition
With such high energy demands of daily training
in competitive swimming, one might wonder
why body fat percentages of swimmers are not
lower than they are. Typically, male competitive
swimmers have body fat percentages in the
range of 8–15% and females at 15–22%. Indeed,
studies have confirmed that body composition of
competitive swimmers is usually about 4–6%
greater than age- and ability-matched endurance
runners (Novak et al. 1977; Thorland et al. 1983).
There are a number of possible explanations
for the tendency of swimmers to carry more fat
than runners despite similar training loads. One