taining ‘proper amounts of carbohydrates
and/or electrolytes’ is recommended. The evolu-
tion of this series of American College of Sports
Medicine Position Stands demonstrates the
progress made in our understanding of this
complex area.
Because of the difficulty in making specific
recommendations that will meet the needs of all
individuals in all situations, the only possible
way forward is to formulate some general guide-
lines, to suggest how these might be adapted to
suit the individual, and to indicate how these
should be modified in different circumstances.
Assuming that athletes are willing and able to
take fluids during training, the recommenda-
tions for fluid use in training will not be very
different from those for competition, except in
events of very short duration. The sprinter or
pursuit cyclist, whose event lasts a few seconds
or minutes, has no opportunity or need for fluid
intake during competition, but should drink
during training sessions which may stretch over
2 h or more. The body does not adapt to repeated
bouts of dehydration: training in the dehydrated
state will impair the quality of training, and
confers no advantage. Training is also the time to
experiment with different rehydration strategies
and to identify likes and dislikes among the
variety of drinks available. Drinking in training
will also allow the individual to become habitu-
ated to the sensation of exercising with fluid in
the stomach: most athletes cite abdominal dis-
comfort and a sensation of fullness as the reason
for not drinking more during exercise (Brouns et
al. 1987).
The choice of the fluid to be used is again a
decision for the individual. Water ingestion is
better than fluid restriction, but adding carbohy-
drate is also beneficial: Below et al. (1994) showed
that the effects of fluid and carbohydrate provi-
sion on exercise performance are independent
and additive (Fig. 17.7). Dilute carbohydrate–
electrolyte drinks will provide greater benefits
than water alone (Fig. 17.8) (Maughan et al. 1989,
1996; Maughan 1994). The optimum carbohy-
drate concentration in most situations will be in
the range of about 2–8%, and a variety of differ-
water and electrolyte loss and replacement 235
Exercise time (min)1012Placebo CHO Fluid Fluid +
CHOFig. 17.7Ingestion of water and carbohydrate (CHO)
have independent and additive effects in improving
exercise performance. A time trial was performed at
the end of a prolonged exercise test in which either a
small or large fluid volume with a small or large
amount of carbohydrate was given. A faster exercise
time indicates a better performance. Values are mean±
SEM. Data from Below et al.(1994).75
Exercise time (min)12515025200175100500
No drink Water Isotonic
drinkHypotonic
drink
Fig. 17.8Effects of ingestion of different drinks on
exercise capacity during a cycle ergometer test to
exhaustion at a power output requiring about 70% of
maximum oxygen uptake. Ingestion of water gave a
longer time to exhaustion than the no drink trial, but
the two dilute carbohydrate–electrolyte drinks gave
the longest exercise times. Values are mean±SEM.
Data from Maughan et al.(1996).