Development of Individual Hydration Strategies for Athletes

Ronald J. Maughan and Susan M. Shirreffs

Athletes are encouraged to begin exercise well hydrated and to consume sufficient
amounts of appropriate fluids during exercise to limit water and salt deficits. Available
evidence suggests that many athletes begin exercise already dehydrated to some
degree, and although most fail to drink enough to match sweat losses, some drink too
much and a few develop hyponatremia. Some simple advice can help athletes assess
their hydration status and develop a personalized hydration strategy that takes account
of exercise, environment, and individual needs.

Preexercise hydration status can be
assessed from urine frequency and volume, with additional information from urine
color, specific gravity, or osmolality. Change in hydration during exercise can be estimated
from the change in body mass that occurs during a bout of exercise. Sweat rate
can be estimated if fluid intake and urinary losses are also measured. Sweat salt losses
can be determined by collection and analysis of sweat samples, but athletes losing
large amounts of salt are likely to be aware of the taste of salt in sweat and the development
of salt crusts on skin and clothing where sweat has evaporated. An appropriate
drinking strategy will take account of preexercise hydration status and of fluid,
electrolyte, and substrate needs before, during, and after a period of exercise. Strategies
will vary greatly between individuals and will also be influenced by environmental
conditions, competition regulations, and other factors.