Football players are at much higher risk of heat-related illness than athletes in other sports, according to a report by the Center for Disease Control and Prevention.

The report published in the CDC's Morbidity and Mortality Weekly Report for Aug. 20, 2010, said thirty-one high school football players have died from heat stroke since 1995 according to data from the National Center for Catastrophic Sports Injury Research. More than 9,000 heat-related illnesses occur among high school athletes each year, nationwide.

For the study, the researchers analyzed data for the 2005-2009 seasons provided by the National High School Sports-Related Surveillance Survey Study. They estimated national numbers based on a sample of 100 high schools and examined nine sports including boys' football, wrestling, soccer, baseball, and basketball and girls' volleyball, soccer, basketball and softball. The survey looked at incidence of “time-loss heat illness” that resulted in more than one day of illness.

The study showed that football players suffer heat-related illnesses at 10 times the rate of athletes in eight other high school sports. Almost two-thirds of heat injuries occur in August and 70.7% during practice or while playing football.

Almost 65% of the football players who developed heat-related illnesses-- defined as dehydration or health exhaustion or heat stroke – had a body mass index indicating they were overweight (37.1%) or obese (27.6%).

"Heat-related illness is preventable. The more we know about how and when it happens, the better we can prepare people who may be most at risk," says Michael McGeehin, PhD, MSPH, and director of CDC's Division of Environmental Hazards and Health Effects.

Coaches and adults should implement a 14-day acclimitization period that gradually increase practice duration and intensity. Also, athletes need to drink 6.5 ounces to 10 ounces of fluid every 10 to 20 minutes during exercise to prevent losing more than 2% of their body weight per day, the CDC said.