remarkably weight stable (Sariset al.1989; A.E.
Jeukendrup & G. Leinders, unpublished find-
ings). Anecdotal evidence suggests that racers
who lose weight may not be able to finish the
race.
Brouns and colleagues (Brounset al.1989b–d)
performed a simulation study in the laboratory
in which the effect of diet manipulation was
studied in athletes expending 26 MJ · day-^1
(6200 kcal · day-^1 ) by exercising for 5 h in a respi-
ration chamber. Subjects received ad libituma
conventional solid diet with a high carbohydrate
content (62.5% CHO diet) supplemented with
water or the same diet supplemented with a 20%
CHO solution (80% CHO diet). Although food
intake was allowed ad libitumin both trials, the
CHO supplement enabled the subjects to main-
tain their daily energy balance, which they could
not when supplemented with water. As a conse-
quence, exercise performance was improved.
These data show that during stage races or multi-
ple days of intensive training, energy expendi-
ture is very high and CHO-containing drinks
may be required to maintain energy balance in
cyclists involved in such rigorous programmes,
since digestion and absorption of solid meals
will be impaired and hunger feelings are sup-
pressed during intensive physical exercise
(Brouns 1986).
Other reports in the literature regarding
energy intake of cyclists include those of the Race
Across America, a race from the West coast to the
East coast of the United States (Lindeman 1991).
Energy intake in one individual taking part in
this race was 35.4 MJ (8429 kcal) daily of which
78% was derived from CHO. During the prepa-
ration, this individual rode a 24-h race where
his energy intake was as much as 43.4 MJ · day-^1
(10 343 kcal · day-^1 ) with 75% of the energy from
CHO.
Eating behaviour of cyclists
An important observation from several of the
investigations which have reported very high
energy intakes in athletes is that a significant
amount of the day’s nutrient intake may be con-
564 sport-specific nutrition
sumed while the individual is exercising. For
example, CHO-rich foods and drinks consumed
while riding provided nearly 50% of the total
energy, and 60% of the daily CHO intake of
cyclists competing in the Tour de France stages
(Sariset al.1989). Only by adopting such a nutri-
tional regimen do these cyclists maintain energy
balance over the 20 days of the Tour de France.
Suitable food choices to attain such goals include
concentrated sports drinks and portable CHO-
rich foods such as fruit, confectionery, bread,
cakes and sports bars. It has also been reported
that a large part of the carbohydrates is from
snacks. These snacks usually contain simple car-
bohydrates, a fair amount of fat and little or no
micronutrients, and therefore it has often been
recommended that riders should replace these
snacks by fruit and snacks that contain less fat
and more micronutrients (Brouns 1986).Preparing for a race
Athletes involved in prolonged moderate- to
high (>70% of maximal oxygen uptake) intensity
exercise not only have unusually high energy
requirements but they also have greatly
increased CHO needs. The extra CHO is neces-
sary to optimize fuel availability during training
sessions used, and to promote postexercise
muscle glycogen resynthesis. A well-known
method to restore glycogen levels to the pre-
exercise level or even above that is known as
glycogen loading or glycogen supercompensa-
tion.Glycogen loading
Muscle glycogen depletion and low blood
glucose levels have been shown to be major
factors in the development of fatigue during
endurance exercise. It is therefore important to
ensure optimal glycogen storage prior to exercise
and optimal delivery of CHO during exercise.
These aspects have been discussed in detail
in Chapter 7. Supercompensation protocols
as described by Bergström and Hultman
(Bergström et al. 1967) and later adapted by