given to athletes. It is also expected that most
female athletes will have a different weight/
height ratio as compared to the women in the UK
or US surveys. This difference is illustrated by
comparing estimates of body fat and weights for
national-level competitive female rhythmic gym-
nasts to controls of the same age and height.
Female gymnasts averaged 10% body fat (range,
6–17%) as compared to controls, whose mean
percentage body fat was 19% (range, 14–27%).
An average weight of the gymnasts was reported
to be 42 kg as opposed to 54 kg average weight
for the controls (Sundgot-Borgen 1996).
Depending upon desired level for accuracy of
energy estimates and in spite of the identified
limitations, TEE equations may still be useful to
calculate an estimate of energy expenditure for
the female athlete. Additional research is needed
to better predict TEE for athletic populations and
understand the influence of exercise on TEE, par-
ticularly in relation to the female athlete. Gender
differences in substrate metabolism as discussed
in the next section also support this need.
Substrate metabolism
Levels of triacylglycerol, total cholesterol (TC),
high-density lipoprotein cholesterol (HDL-C)
and low-density lipoprotein (LDL-C) can be
affected by the presence of oestrogen. Major
proteins for HDL and LDL are apo A-1and apo
B, respectively, and were investigated in 25
female runners and 36 age-matched non-
exercising women (controls) (Lamon-Fava et al.
1989). Lower concentrations of TC, apo B, triacyl-
glycerol and higher apo A-1to apo B ratios were
observed in the eumenorrhoeic female runners
(n=16) as compared with nonexercising controls.
All blood parameters in the amenorrhoeic
runners (n=9) were similar to levels in the con-
trols, except that apo B-values were 20% lower.
Except for the effect on apo B levels, the positive
effects of exercise on serum lipids were negated
in those females with decreased oestrogen, i.e.
amenorrhoeic runners.
In considering oestrogen’s effect on lipid
metabolism, one may ask whether there is a
difference between men and women in the
substrates used for energy during exercise.
Tarnopolsky et al.(1990) matched subjects for
maximal oxygen consumption, training status,
and competition histories; tested females during
the midfollicular phase of their menstrual cycles;
and controlled the macronutrient content of the
diet to prevent confounding effects of these
factors on results. Subjects ran 15.5 km on a tread-
mill at a velocity requiring oxygen consumption
of about 65% of maximal. Glycogen utilization
was estimated from muscle biopsies, with respi-
ratory exchange ratio (RER) used to determine
substrate utilization during the exercise. Females
demonstrated greater lipid utilization based on
RER values, less muscle glycogen use and less
urea nitrogen excretion than males during
moderate-intensity, long-duration exercise.
Given that a female athlete could oxidize greater
fat stores while preserving CHO and protein,
females would have an advantage in endurance
and ultra-endurance events in which fat oxida-
tion becomes metabolically more important.
However, one may also argue that controlling for
training level and substrate availability between
genders is unlikely. This presents researchers
with a challenging task in answering the ques-
tion of gender-related substrate use.
Hormonal status of the female may need con-
sideration by the researcher and sport nutrition-
ist when evaluating energy intake of the female
athlete. Barr et al.(1995) provide evidence that
energy intakes of normally ovulating women are
higher during the luteal phase of their menstrual
cycles. While it is possible to ignore differences
when conducting cross-sectional studies, it
would be necessary to consider these energy
intake differences in longitudinal studies.
Whether a dietary assessment is taken over time
or for 1 day, inquiry about the athlete’s menstrual
cycle may provide useful information related to
energy intake, as well as nutritional and health
status.Carbohydrate recommendations
Recommended percentages of energy from CHO