Focus on Fitness: Exertional Heat Illness in Athletes

June/July 2025 Issue

Focus on Fitness: Exertional Heat Illness in Athletes
By Dana Angelo White, MS, RD, ATC
Today’s Dietitian
Vol. 27 No. 6 P. 16

Experts Weigh in on Prevention

We’re approaching months of preseason training for athletes throughout the country. In all sports, at all levels, preseason brings the intensity and the heat! High volume training combined with environmental exposures can quickly and dramatically impact athletic performance, while also posing serious health and safety risks.

According to data published by the National Collegiate Athletic Association (NCAA), most heat illness occurs during preseason practices. States with warmer climates tend to have higher rates of exertional heat illness (EHI), and football players experience the greatest number of EHI events. But athletes in any sport, in any location, can experience EHI.1 Heat injuries don’t occur only in competitive athletes; active military and other occupations are also susceptible.2 There are several steps health care providers can take to better recognize and help prevent EHI in active populations.

What Is EHI?
EHI can include a variety of conditions caused by dangerous increases in body core temperature during strenuous physical activity.2 EHI can present with a range of symptoms, including muscle cramps, heat exhaustion, and the most dangerous type of EHI, exertional heat stroke.3

Muscle Cramps
Exercise-associated muscle cramps are sudden or progressive muscle tightening and contractions during or after exercise. These cramps usually occur because of a combination of potential factors, including heavy sweat loss, dehydration, electrolyte imbalances, inadequate fueling, and fatigue.

Heat Exhaustion
Heat exhaustion is an extreme inability to exercise in the heat. This can occur as a result of cardiovascular strain and altered blood pressure that is triggered by heavy sweat losses and elevated body core temperature. While debilitating, this condition isn’t as severe as heat stroke.

Heat Stroke
The prevalence of heat stroke is lower than the other conditions, but it can be the most life-threatening,3 as body core temperature rises above 105˚ F. Initial signs and symptoms include confusion, irritability, and altered level of consciousness. Patients suffering from heat stroke often aren’t sweating due to failure of the body’s thermoregulatory mechanisms. This can lead to multisystem organ failure when not treated quickly and appropriately.

Many factors contribute to the increased risk of EHI in athletes, including poor hydration and fueling practices, extreme environmental conditions, poor acclimatization, wearing of equipment, and playing surface. Active illnesses, medication use, and other medical conditions may put athletes at additional risk.3

It’s important that athletes, coaches, caregivers, and medical professionals working with athletes at all levels understand the risks of EHI and use best practices in trying to prevent cases from occurring. Certified athletic trainers are often present at practices and competitions and can provide some of the best expertise when it comes to preventing heat-related illnesses.

Sports Medicine Expertise
Some of the best and most experienced athletic trainers in college sports can be found at Quinnipiac University. Today’s Dietitian asked a group of them to reflect on their decades of collective experience with all types of sports and share some of the most common causes and risks associated with EHI. They also shared some of the biggest mistakes they see athletes make.

“The National Athletic Trainers’ Association (NATA) and NCAA have worked together to put out best practices and mandates for fluid intake during a practice or competition,” says Sara MacDonough-Civitello, MS, LAT, ATC, senior associate athletic trainer. Both organizations dedicate extensive time and effort to help educate athletes and support staff on the dangers and ways to prevent EHI. The NCAA directive is clear: “The NCAA mandates that athletes should consume adequate fluids before, during, and after practices to maintain proper hydration and reduce the risk of heat illness.” Sports medicine organizations like the NATA work to establish these guidelines. “The NATA best practice suggests having a hydration protocol for an organized, consistent, daily approach, which is best overall for digestion and prevention of EHI,”3 MacDonough-Civitello adds.

What Sports Medicine Pros Wish Athletes Knew
In managing the risk of EHI, there are several key elements for athletes to keep in mind.

Consider Playing Surface
“Athletes often don’t take into consideration the surface they are playing on,” shares Michele Merwin, ATC, LAT, PT, DPT, physical therapist and associate athletic trainer. Synthetic turf fields and other nongrassy surfaces retain heat differently, leading to an increase in temperature as much as 70˚ higher than the air temperature if the conditions are appropriate.4 “Athletes that play on these surfaces need to take extra steps to keep their bodies cooler when those temps rise on the track, court, or field,” Merwin says.

What’s in Your Water?
Most sports medicine experts would agree that many athletes make the mistake of relying on water alone to help stay cool and hydrated. “We see athletes focus on volume of water without putting enough emphasis on what is in the water,” MacDonough-Civitello says. “We stress the need for sodium, potassium, and properly timed carbohydrates when hydrating.”

Time of Exposure
Baseball Athletic Trainer Brandon Austin, MS, ATC, LAT, EMT-B, highlights some of the unique issues he encounters with the sport. “There is a lot of time spent at the stadium, often five to six hours at a time, including long bouts of being stationary, and it’s easy to forget to drink enough to support all this time outdoors.” Like many spring sports, the timing of baseball season often encounters dramatic shifts in temperature throughout the season, which can make it difficult for athletes to determine best hydration practices for their changing needs.

All Sun Counts
Whether you live in a climate with changing seasons or spend most months of the year in warmer climates, athletes should also consider time spent outdoors when they are not training, according to Laura Kotsyubinskiy, MBA, LAT, ATC, an associate athletic trainer. “All sun exposure impacts heat status; those athletes who love to sunbathe need to be mindful of how this contributes to body temp.” On the same note, an athlete may underestimate the toll of exposure on a cloudy day, as pointed out by Merwin, “Just because it’s not sunny, doesn’t mean it’s not hot. Clouds don’t make athletes immune to heat exposure and sweat losses.” Much like sunscreen is still needed, so is proper hydration and other efforts to keep cool when the temperature and humidity are high, with or without overt sunshine.

Indoors vs Outdoors
Even though they compete indoors, basketball, hockey, and other indoor athletes are not immune to EHI. “The biggest misconceptions indoor athletes tend to make regarding EHI is that it only happens to outdoor athletes, equipment-laden athletes, or athletes in preseason in full sun,” MacDonough-Civitello shares.

Role of the RD in Sports Medicine
A collaborative approach is crucial to reducing cases of heat illness in an athletic population. Athletic trainers, sports dietitians, and strength and conditioning professionals all play a role, and when they work together, athlete safety is enhanced.5

In addition to helping athletes learn more about optimal hydration, fueling, and electrolyte replenishment, working with the entire sports medicine team and paying attention to training load and nutrient timing can go a long way in preventing EHI from occurring.

— Dana Angelo White, MS, RDN, ATC, is a dual registered dietitian nutritionist and certified athletic trainer with over 20 years of clinical experience. She is a media dietitian, cookbook author, and full-time professor and sports RDN at Quinnipiac University in Hamden, Connecticut.

References
1. Yeargin SW, Dompier TP, Casa DJ, Hirschhorn RM, Kerr ZY. Epidemiology of exertional heat illnesses in national collegiate athletic association athletes during the 2009-2010 through 2014-2015 academic years. J Athl Train. 2019;54(1):55-63.

2. Epstein Y, Charkoudian N, DeGroot DW, et al. Exertional heat illness: international military-oriented lessons learned and best practices for prevention and management. Front Physiol. 2025;16:1456984.

3. Casa DJ, DeMartini JK, Bergeron MF, et al. National athletic trainers’ association position statement: exertional heat illnesses. J Athl Train. 2015;50(9):986-1000.

4. Heat levels on artificial turf. Safe Healthy Playing Fields website. https://www.safehealthyplayingfields.org/heat-levels-synthetic-turf. Accessed May 1, 2025.

5. Lambert V, Carbuhn A, Culp A, Ketterly J, Twombley B, White D. Interassociation consensus statement on sports nutrition models for the provision of nutrition services from registered dietitian nutritionists in collegiate athletics. J Athl Train. 2022;57(8):717-732.