This is an excerpt from Fundamentals of Athletic Training-3rd Edition by Lorin Cartwright & William Pitney.
When preparing for athletic competition in hot weather, athletes must remember that the body needs time to get used to temperature extremes. In Steps to Prevent Heat-Related Illness, we present suggestions that will help athletes cope with heat. Rushing into athletic competition without proper conditioning and training can cause a heat-related injury.
Clothing affects heat dissipation in several ways. Dark colors absorb heat, so light-colored clothes should be selected to reflect the sun. A layer of air between the clothing and the skin helps the process of evaporation, which subsequently cools the body. Air flowing through the clothing can improve evaporation, so jersey material in a loose weave is often desirable.
Choosing athletic clothing with wicking properties can aid in evaporation. Wicking means the sweat is pulled away from the body and efficiently evaporated. Cotton material will absorb sweat and can create difficulty with evaporation. Athletes should avoid heavy clothing, long sleeves, long socks, and additional taping or wraps. Rubber suits, such as those sometimes worn by high school wrestlers, are dangerous because they prevent cooling through evaporation and lock the heat around the body.
Equipment such as helmets, padding, and uniforms reduces the amount of body surface exposure, limiting the body's ability to evaporate moisture. Moreover, the athlete must work harder with the added weight of the equipment, which causes an increased energy expenditure that generates more heat. Coaches should modify practices so that some equipment does not have to be worn when there is a high heat index. During extremely hot and humid days, for example, if football players avoid contact, they can practice without shoulder pads and wear shorts instead of pants.
Heat-related illnesses can be prevented if athletes gradually acclimatize to the heat and humidity for 10 to 14 days, drink plenty of water or sport drinks, and take rest breaks as needed to keep cool. Ideally, if an athlete is physically fit and not overweight, is well nourished, and drinks plenty of fluids before, during, and after activity, she will be better able to prevent heat-related illnesses. Almost no one drinks enough fluids during activity to replace the water lost during participation, and most athletes drink enough to replace only half of the fluids they lose, so the AT should encourage athletes to drink more fluids. The NATA fluid replacement guidelines suggest that athletes ingest 17 to 20 ounces (503-591 ml) of fluid two to three hours before an activity and 7 to 10 ounces (207-296 ml) about 15 minutes before exercise. Also, they should drink approximately 10 ounces (296 ml) of water every 10 to 20 minutes during activity until they feel full. They will be able to drink more if the water temperature is about 50° to 60° Fahrenheit (10-15 °C).
We do not recommend fluids containing high amounts of sugar because they are absorbed more slowly than those without sugar. Drinking fluids with high salt content is usually unnecessary because most people get enough salt with a well-balanced diet. Sport drinks with some sodium and low levels of sugar work well for most athletes. Athletes should weigh themselves before and after practice—at least 2 cups of water should be consumed for every pound (.5 kg) of weight lost. If possible, workouts and practices should be scheduled in the morning or evening to avoid the hottest times of the day.
Heat-related deaths that have occurred in sports such as football have prompted some companies to develop technology to detect when an athlete is overheating. Schutt Sports, for example, has created the HotHead heat observation system, which consists of a sensor placed inside an athlete's football helmet. The sensor monitors the athlete's temperature and transmits the data to a PDA that is monitored by the athletic training staff.