Active Voice: ACSM’s Partner, USMST, Shares First-hand Insights on Heat Illness Issues During Competition at Recent World Cup Soccer – Part I

By Gautam S. Nayak, M.D., FACC, FACP and Felipe Lobelo, M.D., Ph.D., FAHA

Viewpoints presented in SMB commentaries reflect opinions of the authors and do not necessarily reflect positions or policies of ACSM.

Gautam Nayak, M.D., is a cardiologist at Confluence Health in the Department of Cardiology, Wenatchee, WA. He earned his M.D. degree from Tulane University in New Orleans, LA, and completed training in both internal medicine and cardiology at the National Naval Medical Center in Bethesda, MD. Dr. Nayak is a playing member of the United States Medical Soccer Team (USMST), a member of their board of directors and currently serves as president of USMST.

Felipe Lobelo, M.D., Ph.D., is a medical epidemiologist in the Division of Diabetes Translation, at the National Center for Chronic Disease Prevention and Health Promotion, Centers for Disease Control and Prevention, Atlanta, GA. He completed his medical training at the Rosario Medical School, Bogota, Columbia and his Ph.D. in epidemiology at the University of South Carolina in Columbia, SC. As a member of ACSM, he currently chairs the Exercise is Medicine® (EIM) Pediatrics Committee. Dr. Lobelo also is a member of the USMST.

The USMST is an organization of physicians representing the U.S. in the Annual World Medical Football Championship. In addition to a passion for soccer, the USMST is committed to continuing medical education and community outreach. USMST and ACSM launched a partnership in 2013 aimed at advancing EIM’s agenda to encourage health care providers to integrate exercise routinely in medical treatment plans for all patients (see USMST web pages for more on the partnership). Shortly before the FIFA World Cup, ACSM asked Drs. Nayak and Lobelo to share their expertise with our readers on the unique environmental challenges facing athletes at the Brazil venues. Remarkably, our co-authors were just about to fly to Brazil with their teammates to compete in their soccer championships at some of the same venues. This is the initial installment of their two-part commentary, which presents their perspectives on the heat stress issues – affecting both athletes at the FIFA and the World Medical Soccer Championships. Part 2 will follow in a future issue of SMB.


The recently completed 2014 Fédération Internationale de Football Association (FIFA) World Cup in Brazil captivated sports enthusiasts throughout the United States. We rooted for the U.S. Men’s National Team, marveling at some of the globe’s finest athletes. The competition on the pitch was intense, with national pride at stake, but a constant focus for many teams centered on the hot, humid environment in which a number of the matches were played. Sites such as Manaus in the Amazon Rainforest featured 80-90 degree weather with more than 80 percent humidity (see related news report). Much discussion occurred around the safety issues of playing in this climate, as well as the challenge facing many teams that sought to replicate these conditions in their training leading up to the World Cup. Given the baseline physical and physiologic demands already required for soccer at any level, watching this World Cup was fascinating from a medical perspective, as the athletes weathered both competitions and environmental elements.

The U.S. Medical Soccer Team (USMST) had a unique opportunity this summer to compete in the World Medical Football Championships in Natal, Brazil — the same site where the U.S. Men’s National Team had its dramatic 2-1 victory over Ghana in the group stage. Watching the effects of the heat play out on the televised FIFA World Cup games, prior to our arriving in Natal merely a couple weeks later, was intimidating. However, this gave our diverse group of soccer-playing physicians on the USMST an opportunity to examine the data and guidelines on preventing heat-related illness. Important resources in this area include one of the ACSM position stands, a section in a related Team Physician Consensus Statement and a section from the FIFA's Footbal l Medicine Manual.

Heat illness during exertion occurs in active individuals worldwide regardless of temperature, but most frequently in hot and humid conditions. There is a wide clinical spectrum, ranging from muscle cramps to exertional heatstroke (EHS). Prevention measures are simple and can mitigate problems and optimize performance. When heat illness does occur, early recognition and prompt treatment is paramount, often significantly reducing the risk of serious morbidity and mortality. Exertional hyperthermia is influenced by exercise intensity, environmental conditions, clothing, equipment and individual factors, such as physical conditioning and hydration. Higher ambient temperatures reduce convective heat loss from the skin and high humidity reduces evaporative sweat losses since the air is saturated with moisture. In addition, maximum performance of the athletes may be limited under these conditions with increasing heat production, since more and more cardiac output must be directed to the skin to ensure heat dissipation. Physiologically, hyperthermia is influenced by complex feedback mechanisms involving every organ system. This can lead to variable clinical manifestations, though prevention measures and treatment are similar regardless of the severity of presentation.

Our recent experiences in Brazil underscored and personalized these issues as we and our USMST teammates competed in the World Medical Football Championships. In the final installment of this commentary, we’ll dive into more of the clinical specifics related to heat illness in sports and exercise and how best to prevent and treat exertional hyperthermia.