Elizabeth S. Reames | 7/9/2009 8:29:47 PM
During preseason football practices with high heat and humidity, athletes should be well-hydrated, have access to fluids and be monitored for heat-related illness, says LSU AgCenter nutritionist Dr. Beth Reames.
The risks of dehydration and heat injury increase dramatically in hot, humid weather. Athletes need adequate fluids for optimal physical performance and should begin each practice well-hydrated, well-rested and well-nourished.
Evaporation of sweat during physical activity helps cool the body. If fluid losses from sweat aren't replaced, the body may become dehydrated and overheat. Dehydration can lead to higher body core temperature, which increases strain on the cardiovascular system and may lead to heat stroke, heat injury or even death. Dehydration also impairs performance by causing cramps, weakness and headache.
Adequate fluid replacement helps maintain hydration and, therefore, promotes the health and safety of athletes, according to the American College of Sports Medicine. Experts recommend athletes hydrate with fluids before, during and after activity or competition to help regulate body temperature and replace body fluids lost through sweat.
Dehydration of just 1 to 2 percent of body weight (only 1.5 to 3 pounds for a 150-pound athlete) can negatively influence performance. Dehydration of greater than 3 percent of body weight increases an athlete’s risk of heat illness such as heat cramps, heat exhaustion and heat stroke.
According to a report in the “Journal of the American College of Sports Medicine,” fluid replacement should be encouraged by providing chilled fluids, easy access and adequate time for ingestion. This combination expedites sufficient fluid intake and lessens progressive dehydration on the field.
Reames offers several tips to ensure proper hydration:
– Drink before, during and after practices and games.
– Drink early; by the time you’re thirsty, you’re already dehydrated.
– Include liquids with the pre-competition meal.
– Drink fluids based on the amount of sweat and urine loss during the activity.
– Drink cool fluids.
– Replace fluids lost in sweat and urine after the competition.
Reames recommends plain water for most types of exercise lasting an hour or less under moderate temperature conditions. For intense exercise lasting more than an hour, she recommends sports drinks or diluted juices containing carbohydrates in concentrations of 4 percent to 8 percent. Carbohydrates provide energy.
Sports drinks also replace electrolytes such as sodium, which is lost in sweat. Foods eaten after the event, however, are usually sufficient to replace sodium.
Athletes often prefer sports drinks over plain water because they are flavored. The drinks are also suitable for intense events lasting less than an hour.
Reames sets these guidelines for fluid replacement: about two hours before exercise or competition, athletes should drink about 2 cups of fluid; during exercise, athletes should start drinking early and regularly to replace water lost during sweating – one-half to 1 cup every 15 to 20 minutes; after exercise, drink at least 2 cups of fluid per pound of body weight lost during exercise.
Editor: Mark Claesgens