Heat-related illness in athletics is a common condition. The National Center for Catastrophic Sports Injury Research reports a total of 52 deaths in football players due to exertional heat stroke (EHS) from 1995 to 2012.1 Although heat injury can be fatal, the majority of cases are not and are preventable. Hot and humid conditions are the single most critical predisposing risk factor.2 As with many medical conditions, the best treatment is prevention, which can be accomplished by using a good preparticipation exam, evaluating for predisposing conditions or medications, ensuring proper hydration, and observing weather conditions. During sports events, monitoring exercising athletes for signs of disease and having a good emergency plan in place for possible EHS is critical for protecting athletes. Heat illness may present as mild heat edema or heat cramps to more severe heat syncope, heat exhaustion, or heat stroke. Early recognition based on signs and symptoms should prompt immediate action to limit progression of injury (Table 1).
Heat Illness Symptoms, Signs, and Treatment
Exertion-associated muscle cramps (EAMC) are defined as painful muscle spasms following prolonged strenuous exercise, often in the heat.3 Treatment is aimed at stopping the cramps and limiting progression. Immediate treatment of EAMC is with a prolonged stretch of the affected muscle at full length. Muscle cramps can be debilitating and extremely painful. Allow the athlete to rest out of play while you manage the cramps. If possible, cool the affected muscle with ice packs or a towel soaked in cold water. Gently stretch the muscle group past neutral as tolerated to try to “break” the spasm. Replace sweat-induced fluid and sodium loss. This is ideally accomplished by oral rehydration, such as with a commercial sports drink, or these can be made with 1/8 to 1/4 teaspoon of table salt added to 300 to 500 mL fluids.3 Replacement can also be in the form of salt tablets taken with 300 to 500 mL of fluid or salty snacks.3 With severe cramping, oral replacement is difficult and may require parenteral administration. Intravenous normal saline provides rapid relief, usually with 1 to 2 L; however, this requires establishing intravenous access and monitoring clinically, typically with a physician present. This may be too time consuming for immediate return to play, but possibly necessary if cramping is severe. Refractory cramping can be treated with benzodiazepines intravenously; however, these require monitoring for sedation and exclude return to play that day.3 Intravenous benzodiazepines would also require the presence of a physician to monitor the patient. Once cramping has resolved, the athlete can return to play as tolerated but is at risk for recurrent cramping. Muscle soreness may limit participation, and the athlete may need one or more days to recover. Severe cramping may be a warning sign of impending heat exhaustion4 and should be monitored closely.
Heat syncope is a transient loss of consciousness in an athlete, with abrupt cessation of exertion or sudden elevating postural changes in the heat.4 The syncope is due to orthostatic hypotension and inadequate blood flow to the brain.4,5 The diagnosis is clinical.
Treatment of heat syncope relies on recognizing athletes and areas (such as at the finish chute of an endurance event) most at risk. Try to keep the participants from standing still immediately after exertion. Continuing movement will help venous blood return to the heart by using the muscle pump of the contracting leg muscles. If the individual is near fainting or has fainted, lay him or her supine and elevate the legs above heart level to assist in venous return.4,5 Monitor vital signs, including rectal temperature, if EHS is considered. Replace fluids, ideally by mouth, if dehydration is a factor. This clinical scenario is usually short lived, and the goal is to avoid the dangers of falling. Ensure that the patient is safe when getting up to avoid the dangers of fainting/falling again. Prevent the athlete from rising too quickly from a supine or sitting position.
Exertional heat exhaustion is defined as the inability to continue exercise during heavy exertion in the heat and may include physical collapse.3,5 Treatment of exertional heat exhaustion involves cooling, rest, and fluid rehydration. The athlete should be moved to a cool or shaded place for closer evaluation and treatment. Cooling therapy improves medical status. Monitor vital signs. If the rectal temperature cannot be checked, empiric cooling therapy, as described in the next section, should be considered.3 Lay the athlete down, with legs elevated to aid blood flow return. Oral fluids are preferred, but for the athlete who cannot tolerate oral ingestion or has more severe dehydration, intravenous fluids with normal saline can lead to a rapid improvement from heat exhaustion.3 Monitor the patient until he or she is alert with clinically stable vital signs. The athlete can then be discharged from the event or sidelines with instructions for continued rest and rehydration. Return to play that day is not advised. If athletes do not improve despite these efforts, or exhibit a progressive clouding of consciousness, they should be transported to an emergency facility for further medical management.
EHS is defined as hyperthermia with a core temperature greater than 40°C and associated central nervous system disturbances and multiple organ failure.3 Any individual with possible EHS should have his or her rectal temperature measured.5
Treatment of suspected or confirmed EHS involves removal of any clothing or gear that limits heat dissipation and immediately cooling the whole body via cold-water immersion (Figure 1). EHS is a true medical emergency, as it can be fatal, and any delay in cooling can worsen the prognosis. Cold-water immersion provides the fastest cooling rate with lowest morbidity and mortality.3 Any event where EHS has a high likelihood of occurring should have cold-water tubs available. If there are no means of immersing the athlete in cold water, use ice packs and towels/sheets dipped in cold water and apply them to the neck, groin, axilla, and extremities. Constantly rotate the ice packs or towels every 2 minutes for more rapid cooling. Monitor the blood pressure, rectal temperature, and heart rate continuously. Intravenous normal saline will maintain intravascular volume and ensure good renal blood flow. If no intravenous fluids are available, oral rehydration should be used if the patient is coherent and able to swallow. Ensure that the individual is cooled until the rectal temperature is safely below 40°C,3 other vital signs are normal, and mental status is normal. If the patient continues to decline despite cooling efforts, immediately transfer him or her to an emergency facility for further management. Those whose conditions are recognized early and who are cooled instantly often show a complete return of vital signs to baseline. Emergency medical personnel should always be contacted in cases of suspected EHS.
An athlete immersed in a cold-water tub, attended by 2 athletic trainers.
Heat-related illnesses are very common. They range from heat cramps to potentially fatal EHS. There are several modifiable risks, such as length and intensity of heat exposure. These can be optimized by ensuring good hydration and, when possible, coordinating heat acclimatization. Although there are several signs and symptoms of exertional heat exhaustion and stroke, they are not specific and require early recognition, treatment, and monitoring. Outcomes are generally good with early and appropriate intervention.5 Most important is educating athletes, coaches, and athletic training staff about the dangers of exercise in the heat.5 When managing events, ensure that the appropriate medical staff and equipment5 is on hand to monitor patients, estimate core temperatures with a rectal thermometer, and rapidly cool and rehydrate athletes.
- Kucera KL, Klossner D, Colgate B, Cantu RC. Annual survey of football injury research, 1931–2013. National Center for Catastrophic Sports Injury Research, University of North Carolina at Chapel Hill, March2014.
- Marshall SW. Heat Injury in youth sport. Br J Sports Med. 2010;44:8–12. doi:10.1136/bjsm.2009.068171 [CrossRef]
- Armstrong LE, Casa DJ, American College of Sports Medicine et al. American College of Sports Medicine position stand. Exertional heat illness during training and competition. Med Sci Sports Exerc. 2007;39(3):556–572. doi:10.1249/MSS.0b013e31802fa199 [CrossRef]
- Coris EE, Ramirez AM, Van Durme DJ. Heat illness in athletes: the dangerous combination of heat, humidity, and exercise. Sports Med. 2004;34(1):9–16. doi:10.2165/00007256-200434010-00002 [CrossRef]
- Casa DJ, et al. National Athletic Trainers' Association position statement: exertional heat illnesses. J Athl Train. 2015;50.
Heat Illness Symptoms, Signs, and Treatment
|Exertional associated muscle cramps
||Painful muscle cramps
||Palpable muscular spasm
||Stretch, ice, massage, oral fluids
||Loss of consciousness
||Rest, supine with feet up, monitor vital signs
|Exertional heat exhaustion
||Fatigue, inability to continue exercise, mild confusion, nausea, vomiting, syncope, “chills” of head and neck
||Hypotension, orthostasis, elevated core temperature (up to 40.5°C), syncope
||ABCs, cool, rest, monitor temp/VS, oral fluids
|Exertional heat stroke
||Pronounced mental status changes, fatigue, nausea, vomiting, syncope
||Elevated core temp > 40.5°C, hypotension, tachycardia, tachypnea, syncope, possible cessation of sweating, coma, DIC, ARF
||ABCs, cool urgently, call emergency services, monitor VS, IVF if available.