Page 97 - Athletic Health Handbook
P. 97
During Exercise

To calculate the percent carbohydrate in sports drinks,
multiply the # of grams of carbohydrate per 8 oz
serving by 0.42.

During exercise most people can tolerate 1/2–3/4
cup of beverage every 15 to 20 minutes. There is little
evidence to suggest that carbohydrate-containing
beverages will enhance performance during exercise
that lasts less than one hour. However, beverages such
as sports drinks may enhance performance in competi-
tive events lasting longer than 60 minutes. The optimal
beverage composition during exercise is probably one
that provides a small amount of sodium and sugar
(glucose, glucose polymers, or sucrose). Beverages
containing less than 6 percent carbohydrate are
unlikely to extend performance, while those which
contain more than 8 percent are associated with
abdominal upset, and may slow gastric emptying and
therefore absorption. Since sodium is lost in the sweat
and is required by the gut to transport glucose, bever-
ages containing carbohydrates should also contain
sodium chloride. Although low blood sodium is a rela-
tively rare occurrence in events lasting a few hours, it
occurs with surprising frequency in ultra-endurance
events. Ultraendurance athletes should not rely upon
plain water alone.

Rehydration
Determine body weight prior to and immediately after
exercise. For each kg lost, 1–1.5 liters of fluid should
be consumed over the next few hours.

Restoration of fluid balance after exercise is essential,
particularly if the athlete plans subsequent bouts
of exercise. Optimally, the beverage should contain
carbohydrate to replenish depleted glycogen stores
as well as sodium and potassium to restore the
extracellular and intracellular spaces. Alternately the
athlete may consider drinking plain water with solid
high-carbohydrate, salted foods such as pretzels.
Restoration of lost fluid will be more complete if salt
is consumed post exercise, since it maintains the
thirst mechanism.

© AMERICAN ORTHOPAEDIC SOCIETY FOR SPORTS MEDICINE, 2008,
ALL RIGHTS RESERVED

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