Jan 29, 2015
High School Heat Tips

By Dawn Comstock

The Center for Injury Research and Policy at The Research Institute at Nationwide Children’s Hospital in Cincinnati examines simple tactics high schools can use to prevent dehydration and heat illness during the fall season’s very warm early-season practices.

— Recently, a well-written piece titled “Heat Illness Study Roundup” was featured on this Web site. This timely work gave some great insights into cutting edge research that may one day become standard for lowering body temperatures and preventing heat illness among all athletes.

However, in the here and now, very few high school teams have access to such advanced techniques, and consequently this previous feature may have left you wondering what an athletic director, coach, or athletic trainer at the typical high school can do today to prevent heat illness. The good news is that several basic steps can be taken by all coaches and athletic trainers to decrease the risk of heat-related illness during the strenuous preseason conditioning programs that your teams are likely embarking on already. First, let’s take a step back and examine just how common dehydration and heat illness is in high school athletes. The National High School Sports-Related Injury Surveillance Study is currently the only surveillance system in the U.S. collecting nationally representative data of such incidences among high school athletes. While only the most severe cases make the news, dehydration and heat illness are not uncommon events.

During the past three academic years, this surveillance study collected 97 cases of heat illness or dehydration. These 97 cases represent a nationally estimated incidence of almost 28,000 cases, suggesting that roughly 9,000 U.S. high school athletes sustain some type of heat illness or dehydration-related event every year. The majority of these events (70 percent) occur during practice, with just over half (60 percent) occurring during the preseason weeks.

Although most (80 percent) heat illness and dehydration events occurred amongst football players, it is important to note that athletes in other sports are not immune to these incidents. Almost nine in 10 athletes were able to return within a few days of the incident, likely due in part to timely on-the-field diagnosis and treatment. However, a small fraction missed almost 3 weeks of play or did not return to their sport. Most cases of dehydration and heat illness are preventable. Here are a few simple things you can do to prevent these conditions in your athletes: • Acclimate your athletes to hot weather by gradually increasing training intensity. • If multiple practices are held during the day, ensure that break periods in between are adequate. • Mandate water breaks at least every 10 to 15 minutes during activity. All athletes should drink during these times, regardless of whether or not they are thirsty. Previous studies have found increased body temperatures and decreased work capacities when dehydration levels exceeded three percent of one’s body weight. However, athletes often don’t become thirsty until dehydration levels exceed five percent body weight. Also do your best to encourage your athletes to drink fluids before and after activity. • Avoid sports drinks that contain caffeine or ephedrine. Also, avoid very cold drinks because they can cause stomach cramps. • Refer to a heat index chart to determine if practices should be modified. • Use weight charts to monitor all athletes before and after warm weather practices. Athletes with over three percent weight loss should not be allowed to return to practice until they have brought their weight back up. • Encourage athletes to wear lightweight, light-colored clothing. Do not permit any rubber clothing to be worn, as this prevents the skin from being able to properly regulate body temperature. • In sports with large amounts of protective equipment, such as football and boys’ lacrosse, gradually increase the amount of protective gear being worn over several days. This allows for an acclimatization period during which their bodies become used to the increase in temperature with the additional equipment. • Pay particular attention to athletes with higher body fat percentages, as they can become dehydrated faster than athletes with lower body fat percentages. • Be on the lookout for potential signs of heat illness–nausea, vomiting, incoherence, lightheadedness, excessive fatigue, visual disturbance, and chills. Any case of dehydration or heat illness should be treated seriously because they have the potential to become severe. Remove the athlete from activity immediately, give them fluids, and consult your healthcare personnel.

For additional information on keeping athletes safe during the hot fall days, visit the NFHS for its Recommendations for Hydration to Prevent Heat Illness.

Dawn Comstock, PhD, is a principle investigator at the Center for Injury Research and Policy at The Research Institute at Nationwide Children’s Hospital. She is also an assistant professor at The Ohio State University in the College of Medicine and the College of Public Health. Her research interests include the epidemiology of sports, recreation, and leisure activity-related injuries among children and adolescents as well as the life-long health benefits associated with an active childhood. She can be reached at: [email protected].


Barr, SI. “Effects of Dehydration on Exercise Performance.” Canadian Journal of Applied Physiology 24 no. 2 (1999): 164-172.

Murray, R. “Dehydration, Hyperthermia, and Athletes: Science and Practice.” Journal of Athletic Training 31 no. 3 (1996): 248-252.

Seto, CK, Way D, et al. “Environmental Illness in Athletes.” Clinical Sports Medicine 24 no. 3 (2005): 695-718.

Barrow, MW and Clark, KA. “Heat-Related Illnesses.” American Family Physician 58 no. 3 (1998): 749-756, 759.

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