Fluids may be the most critical factor to ensure that the athlete can perform up to his/her trained or conditioned ability. Since heat production is increased with ALL forms of exercise, it is necessary for athletes to maintain fluid balance so this excess heat can be dissipated through the production of sweat. With the evaporation of sweat, heat is lost from the blood that circulates near the skin. The rate of sweat loss varies between people and with the ambient temperature and humidity, but it is common to see body fluid losses of up to 3 liters (over 6 quarts!) per hour in trained athletes exercising in hot and humid environments. Fluid losses that represent 6% of body weight may occur with 2 hours of training in high heat.

DEHYDRATION occurs when fluid losses are greater than 1% of body weight, and athletic ability is measurably impaired with a 2% loss of body weight. This means a 100 lb athlete who loses 2 pounds during exercise may no longer be performing up to his/her trained ability because of the excessive body fluid loss. Typical symptoms of inadequate fluid intake during exercise include: thirst, fatigue, loss of coordination, mental confusion, irritability, dry skin, elevated body temperature, and reduced urine output. Heat stroke, caused by severe heat injury and inadequate hydration, has a mortality rate of 80%. To assure that an athlete learns to drink sufficient amounts of fluid during exercise, weight should be taken before exercise and after exercise. The difference in weight in pounds is equal to the the amount of fluid, in pints (1 lb = 1 pint or 16 ounces), the athlete should have consumed during exercise. For instance, an athlete losing 4 pounds during exercise should learn to consume 4 additional pints of fluid during that activity.

GENERAL GUIDELINES: