Exertional heat stroke is one of the most serious medical events in sports and exercise. Sadly it is often fatal. In fact, it is one of the most common causes of non-traumatic death among athletes. Serious cases of exertional heat stroke outnumber serious cardiac events at racesJoggers running on road 10-fold.

Rapid recognition and treatment of an athlete developing exertional heat stroke is crucial. Transporting a runner from the road to a nearby hospital can take valuable time that could delay treatment. Therefore sporting events with large numbers of participants, such as road races, should plan for on-site evaluation and treatment of these problems.

A recent study by Brian K. Sloan and others at the Indiana University School of Medicine studied the effectiveness of an on-site treatment protocol devised for runners at the Indianapolis Mini-Marathon. This race is the largest half marathon in the United States. During the study period from 2005 to 2012, over 235,000 runners participated in the 13.1-mile race.

Heat illness protocol

The physicians prepared a protocol to best identify and quickly treat any runner felt to have exertional heat stroke. In the medical triage tent, the medical staff quickly assessed each runner. Any runner who presented with altered mental status and a palpable pulse was taken to the cooling tent. In the cooling tent, a physician, nurse or paramedic would take the runner’s core body temperature, draw blood for glucose and sodium levels and place an IV. If the patient had a core body temperature at or above 104°F, he or she was placed in a cooling tub filled with ice and water. Rectal temperatures were obtained, and IV fluids were administered.

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When a runner’s core body temperature dropped to 102°F and they regained normal mental status, they were removed from the tub. If the tubs were full with runners, medical personnel placed ice packs around the groin, neck and axilla of the runners. Any patient who still had altered mental status or unstable vital signs was taken to the hospital. If the patient returned to lower, stable temperatures and normal vital signs and mental status, he was discharged home.


Over the eight years studied, 22 runners were treated at the medical tent for exertional heat stroke. Combined with 10 patients transported to local hospitals, 32 runners developed heat stroke, for an incidence rate of 1.3 per 10,000 participants. The highest number of heat stroke deaths occurred when the 10 AM temperature was 64.9°F.

Female marathon runner

69% of the runners who developed EHS were treated on site in the medical tent. These runners had core body temperatures between 102.4° and 108.5°F. Most underwent cold water immersion. 59% were discharged home from the tent after treatment, while six runners were seen inlocal emergency departments before being sent home. Two runners were admitted to local hospitals overnight, and one was admitted to an ICU.


Clearly a well-planned protocol for exertional heat stroke along with adequate medical professionals and equipment are critical to recognize athletes developing this serious problem and quickly treat them. Treatment on-site is often successful, at least based on the program used in Indianapolis.

Also athletes training for demanding physical competitions need to prepare for the weather conditions and not just the physical demands of the competition. Often people train in cooler climates than those where the race will be held. Runners and other athletes should think about taking several weeks to adjust to the warmer temperatures.

Runners or triathletes, have you ever competed in warm temperatures and feared developing heat illness? Healthcare providers, what do you do to prepare for exertional heatstroke when you cover sporting events? I’d love to hear your thoughts and experiences!

Sloan BK, Kraft EM, Clark D, Schmeissing SW, Byrne BC, Rusyniak DE. On-site treatment of exertional heat stroke. Am J Sports Med. 2015 Apr;43(4):823-9.

Yankelson L, Sadeh B, Gershovitz L, et al. Life-threatening events during endurance sports: is heat stroke more prevalent than arrhythmic death? J Am Coll Cardiol. 2014;64:463-469.