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National Athletic Trainers’

Association Position

Statement: Exertional

Heat Illnesses

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Helen M. Binkley*; Joseph Beckett†; Douglas J.

Casa‡; Douglas M. Kleiner§; Paul E. PlummerⅡ

*Mesa State College, Grand Junction, CO;

†University of Charleston, Charleston, WV;

‡University of Connecticut, Storrs, CT; §University

of Florida, Jacksonville, FL; Indiana State Ⅱ

University, Terre Haute, IN

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Recommendations

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Prevention

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1. Ensure that appropriate medical care is available and that rescue personnel are familiar with exertional heat illness prevention, recognition, and treatment. Table 2 provides general guidelines that should be considered. Ensure…

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1. (continued) …that ATCs and other health care providers attending practices or events are allowed to evaluate and examine any athlete who displays signs or symptoms of heat illness and have the authority to restrict the athlete from participating if heat illness is present.

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2. Conduct a thorough, physician-supervised, preparticipation medical screening before the season starts to identify athletes predisposed to heat illness on the basis of risk factors and those who have a history of exertional heat illness.

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3. Adapt athletes to exercise in the heat (acclimatization) gradually over 10 to 14 days. Progressively increase the intensity and duration of work in the heat with a combination of strenuous interval training…

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3. (continued)…and continuous exercise. Well-acclimatized athletes should train for 1 to 2 hours under the same heat conditions that will be present for their event. In a cooler environment, an athlete can wear additional clothing during training to induce…

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3. (continued)…or maintain heat acclimatization. Athletes should maintain proper hydration during the heat-acclimatization process.

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4. Educate athletes and coaches regarding the prevention, recognition, and treatment of heat illnesses9and the risks associated with exercising in hot, humid environmental conditions.

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5. Educate athletes to match fluid intake with sweat and urine losses to maintain adequate hydration. (See the “National Athletic Trainers' Association Position Statement: Fluid Replacement in Athletes.”) Instruct athletes to drink…

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5. (continued)…sodium-containing fluids to keep their urine clear to light yellow to improve hydration and to replace fluids between practices on the same day and on successive days to maintain less than 2% body-weight change. These strategies will…

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5. (continued)…lessen the risk of acute and chronic dehydration and decrease the risk of heat-related events.

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6. Encourage athletes to sleep at least 6 to 8 hours at night in a cool environment, eat a well-balanced diet that follows the Food Guide Pyramid and United States Dietary Guidelines, and maintain proper hydration…

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6. (continued)… status. Athletes exercising in hot conditions (especially during twice-a-day practices) require extra sodium from the diet or rehydration beverages or both.

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7. Develop event and practice guidelines for hot, humid weather that anticipate potential problems encountered based on the wet-bulb globe temperature (WBGT) (Table 3) or heat and humidity as measured by a sling psychrometer (Figure 1), the number of participants,…

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7. (continued)…the nature of the activity, and other predisposing risk factors. If the WBGT is greater than 28°C (82°F, or “very high” as indicated in Table 3, Figure 1), an athletic event should be…

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7. (continued)…delayed, rescheduled, or moved into an air-conditioned space, if possible. It is important to note that these measures are based on the risk of environmental stress for athletes wearing shorts and…

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7. (continued)…a T-shirt; if an athlete is wearing additional clothing (ie, football uniform, wetsuit, helmet), a lower WBGT value could result in comparable risk of environmental heat stress (Figure 2). If the event…

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7. (continued)…or practice is conducted in hot, humid conditions, then use extreme caution in monitoring the athletes and be proactive in taking preventive steps. In addition, be sure that emergency supplies and equipment are easily accessible and…

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7. (continued)…in good working order. The most important factors are to limit intensity and duration of activity, limit the amount of clothing and equipment worn, increase the number and length of rest breaks, and encourage proper hydration.…

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7. (continued)…Modify activity under high-risk conditions to prevent exertional heat illnesses. Identify individuals who are susceptible to heat illnesses. In some athletes, the prodromal signs and symptoms of heat illnesses are not evident before collapse, but in…

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7. (continued)… many cases, adept medical supervision will allow early intervention.

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8. Check the environmental conditions before and during the activity, and adjust the practice schedule accordingly. Schedule training sessions to avoid the hottest part of the day (10 AM to 5 PM) and to avoid radiant heating from direct sunlight, especially in the…

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8. (continued)… acclimatization during the first few days of practice sessions.

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9. Plan rest breaks to match the environmental conditions and the intensity of the activity. Exercise intensity and environmental conditions should be the major determinants in deciding the length and frequency of rest breaks. If possible,…

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9. (continued)…cancel or postpone the activity or move it indoors (if air conditioned) if the conditions are “extreme or hazardous” (see Table 3) or “very high” (see Figure 1) or to the right of the circled line (see Figure 2). General guidelines during…

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9. (continued)…intense exercise would include a work:rest ratio of 1:1, 2:1, 3:1, and 4:1 for “extreme or hazardous” (see Table 3) or “very high” (see Figure 1), “high,” “moderate,” or “low” environmental risk, respectively. For activities…

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9. (continued)…such as football in which equipment must be considered, please refer to Figure 2 for equipment modifications and appropriate work:rest ratios for various environmental…

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9. (continued)…conditions. Rest breaks should occur in the shade if possible, and hydration during rest breaks should be encouraged.

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10. Implement rest periods at mealtime by allowing 2 to 3 hours for food, fluids, nutrients, and electrolytes (sodium and potassium) to move into the small intestine and bloodstream before the next practice.

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11. Provide an adequate supply of proper fluids (water or sports drinks) to maintain hydration and institute a hydration protocol that allows the maintenance of hydration status. Fluids should be readily available and…

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11. (continued)…served in containers that allow adequate volumes to be ingested with ease and with minimal interruption of exercise. The goal should be to lose no more than 2% to 3% of body weight…

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11. (continued)…during the practice session (due to sweat and urine losses). (See the “National Athletic Trainers' Association Position Statement: Fluid Replacement in Athletes.”)

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12. Weigh high-risk athletes (in high-risk conditions, weigh all athletes) before and after practice to estimate the amount of body water lost during practice and to ensure a return to prepractice weight…

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12. (continued)…before the next practice. Following exercise, athletes should consume approximately 1–1.25 L (34-50 oz) of fluid for each kilogram

of body water lost during exercise.

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13. Minimize the amount of equipment and clothing worn by the athlete in hot or humid (or both) conditions. For example, a full football uniform prevents sweat evaporation from more than 60% of the body. Consult Figure 2…

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13. (continued)…for possible equipment and clothing recommendations. When athletes exercise in the heat, they should wear loose-fitting, absorbent, and light-colored clothing; mesh clothing…

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13. (continued)…and new-generation cloth blends have been specially designed to allow more effective cooling.

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14. Minimize warm-up time when feasible, and conduct warm-up sessions in the shade when possible to minimize the radiant heat load in “high” or “very high” or “extreme or hazardous” (see Table 3, Figure 1) conditions.

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15. Allow athletes to practice in shaded areas and use electric or cooling fans to circulate air whenever feasible.

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16. Include the following supplies on the field, in the locker room, and at various other stations:

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• A supply of cool water or sports drinks or both to meet the participants' needs (see the “National Athletic Trainers' Association Position Statement: Fluid Replacement in Athletes” for recommendations regarding the appropriate composition…

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… of rehydration beverages based on the length and intensity of the activity)

• Ice for active cooling (icebags, tub cooling) and tokeep beverages cool duringexercise

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• Rectal thermometer to assess body-core temperature

• Telephone or 2-way radio to communicate with medical personnel and to summon emergency medical transportation

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• Tub, wading pool, kiddy pool, or whirlpool to cool the trunk and extremities for immersion cooling therapy

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17. Notify local hospital and emergency personnel before mass participation events to inform them of the event and the increased possibility of heat-related illnesses.

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18. Mandate a check of hydration status at weigh-in to ensure athletes in sports requiring weight classes (eg, wrestling, judo, rowing) are not dehydrated. Any procedures used to induce dramatic…

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18. (continued)…dehydration (eg, diuretics, rubber suits, exercising in a sauna) are strictly prohibited. Dehydrated athletes exercising at the same intensity as euhydrated athletes are at increased risk for…

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18. (continued) …thermoregulatory strain (see the “National Athletic Trainers' Association Position Statement: Fluid Replacement in Athletes”).

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Recognition and

Treatment

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19. Exercise-associated muscle (heat) cramps:

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• An athlete showing signs orsymptoms including dehydration,thirst, sweating, transient musclecramps, and fatigue is likelyexperiencing exercise-associated muscle (heat) cramps.

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• To relieve muscle spasms, theathlete should stop activity, replacelost fluids with sodium-containingfluids, and begin mild stretchingwith massage of the muscle spasm.

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• Fluid absorption is enhanced withsports drinks that contain sodium.A high-sodium sports product maybe added to the rehydrationbeverage to prevent or relieve cramping in athletes who lose largeamounts of sodium in their sweat.A simple salted fluid…

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…consists of two 10-grain salt tablets dissolved in 1 L (34 oz) of water. Intravenous fluids may be required if nausea or vomiting limits oral fluid intake; these must be ordered by a physician.

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• A recumbent position may allowmore rapid redistribution of bloodflow to cramping leg muscles.

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20. Heat syncope:

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• If an athlete experiences a brief episode of fainting associated with dizziness, tunnel vision, pale or sweaty skin, and a decreased pulse rate but has a normal rectal temperature (for exercise, 36°C to 40°C [97°F to 104°F]), then heat syncope is most likely the cause.

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• Move the athlete to a shadedarea, monitor vital signs, elevatethe legs above the level of thehead, and rehydrate.

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21. Exercise (heat) exhaustion:

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• Cognitive changes are usuallyminimal, but assess central nervoussystem function for bizarrebehavior, hallucinations, alteredmental status, confusion,disorientation, or coma (see Table1) to rule out more seriousconditions.

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• If feasible, measure body-coretemperature (rectal temperature)and assess cognitive function(see Table 1) and vital signs.Rectal temperature is the mostaccurate method possible in thefield to monitor body-coretemperature. The ATC should...

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not rely on the oral, tympanic, or axillary temperature for athletes because these are inaccurate and ineffective measures of body-core temperature during and after exercise.

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• If the athlete's temperature iselevated, remove his or her excessclothing to increase the evaporativesurface and to facilitate cooling.

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• Cool the athlete with fans, icetowels, or ice bags becausethese may help the athlete witha temperature of more than38.8°C (102°F) to feel betterfaster.

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• Remove the athlete to a cool orshaded environment if possible.

• Start fluid replacement.

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• Transfer care to a physician ifintravenous fluids are needed or if recovery is not rapid anduneventful.

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22. Exertional heat stroke:

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• Measure the rectal temperature iffeasible to differentiate betweenheat exhaustion and heat stroke.With heat stroke, rectal temperature is elevated (generally higher than 40°C [104°F]).

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• Assess cognitive function, which ismarkedly altered in exertional heatstroke (see Table 1).

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• Lower the body-core temperature as quickly as possible. The fastest way to decrease body temperature is to remove clothes and equipment and immerse the body (trunk andextremities) into a pool or tub…

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• …of cold water (approximately 1°C to 15°C [35°F to 59°F]). Aggressive cooling is the most critical factor in the treatment of exertional heat stroke. Circulation of the tub water may enhance cooling.

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• Monitor the temperature during thecooling therapy and recovery(every 5 to 10 minutes). Once theathlete's rectal temperature reachesapproximately 38.3°C to 38.9°C(101°F to 102°F), he or she shouldbe removed from the pool or tub toavoid overcooling.

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• If a physician is present to managethe athlete's medical care on site,then initial transportation to amedical facility may not benecessary so immersion cancontinue uninterrupted. If aphysician is not present,…

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• …aggressive first-aid cooling should be initiated on site and continued during emergency medical system transport and at the hospital until the athlete is normothermic.

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• Activate the emergency medicalsystem.

• Monitor the athlete's vital signs and other signs and symptoms of heat stroke

(see Table 1).

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• During transport and whenimmersion is not feasible, othermethods can be used to reducebody temperature: removing theclothing; sponging down the athlete with cool water and applying cold towels; applying ice…

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• …bags to as much of the body as possible, especially the major vessels in the armpit, groin, and neck; providing shade; and fanning the body with air.

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• In addition to cooling therapies,first-aid emergency procedures forheat stroke may include airwaymanagement. Also a physician maydecide to begin intravenous fluidreplacement.

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• Monitor for organ-systemcomplications for at least 24 hours.

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23. Exertional hyponatremia:

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• Attempt to differentiate betweenhyponatremia and heat exhaustion.Hyponatremia is characterized byincreasing headache, significantmental compromise, alteredconsciousness, seizures,…

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• …lethargy, and swelling in the extremities. The athlete may be dehydrated, normally hydrated, or overhydrated.

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• Attempt to differentiate between hyponatremia and heat stroke. In hyponatremia, hyperthermia is likely to be less (rectal temperature less than 40°C [104°F]. The plasma-sodium level is less than…

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…130 mEq/L and can be measured with a sodium analyzer on site if the device is available.

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• If hyponatremia is suspected,immediate transfer to an emergency medical center via the emergency medical system is indicated. An intravenous line should be placed to administer medication as needed to…

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…increase sodium levels, inducediuresis, and control seizures.

• An athlete with suspectedhyponatremia should not beadministered fluids until aphysician is consulted.

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24. Return to activity

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• In cases of exercise-associatedmuscle (heat) cramps or heatsyncope, the ATC should discussthe athlete's case with thesupervising physician. The cases of athletes with heat exhaustion who…

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…were not transferred to thephysician's care should also be discussed with the physician. Afterexertional heat stroke or exertional hyponatremia, …

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…the athlete must be cleared by a physician before returning to athletic participation. The return to full activity should be gradual and monitored.

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Table 1. Signs and Symptoms of Exertional Heat Illnesses

ConditionSign or Symptom*

Exercise-associated muscle (heat) cramps)DehydrationThirstSweatingTransient muscle crampsFatigue

*Not every patient will present with all the signs and symptoms for the suspected condition.

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Table 1. (continued)

Condition Sign or Symptom*

Exercise (heat) exhaustionNormal or body-core temperatureDehydrationDizzinessLightheadednessSyncopeHeadacheNausea

*Not every patient will present with all the signs and symptoms for the suspected condition.

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Table 1. (continued)

Condition Sign or Symptom*

Exercise (heat) exhaustion (continued)Anorexia ChillsDiarrhea Cool, clammy skin Urine output Intestinal cramps Persistent muscle Urge to defecate cramps WeaknessPallor HyperventilationProfuse sweating

*Not every patient will present with all the signs and symptoms for the suspected condition.

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Table 1. (continued)

Condition Sign or Symptom*

Exertional heat strokeHigh body-core temperature (>40C [104F])Central nervous system changes Dizziness Irritability Drowsiness Emotional instability Irrational behavior Hysteria Confusion Apathy

*Not every patient will present with all the signs and symptoms for the suspected condition.

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Table 1. (continued)

Condition Sign or Symptom*

Exertional heat stroke (continued)Central nervous system changes (continued) Aggressiveness Seizures Delirium Loss of consciousness Disorientation Coma Staggering

*Not every patient will present with all the signs and symptoms for the suspected condition.

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Table 1. (continued)

Condition Sign or Symptom*

Exertional heat stroke (continued)Dehydration HypotensionWeakness HyperventilationHot and wet or dry skin VomitingTachycardia (100-120 bpm) Diarrhea

*Not every patient will present with all the signs and symptoms for the suspected condition.

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Table 1. (continued)

Condition Sign or Symptom*

Exertional hyponatremiaBody-core temperature Low blood-sodium level < 40°C (104°F) Progressive headacheNausea ConfusionVomiting Significant mentalExtremity (hands and compromise feet) swelling Lethargy

*Not every patient will present with all the signs and symptoms for the suspected condition.

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Table 1. (continued)

Condition Sign or Symptom*

Exertional hyponatremia (continued)Altered consciousness SeizuresApathy ComaPulmonary edemaCerebral edema

*Not every patient will present with all the signs and symptoms for the suspected condition.

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Table 2. Prevention Checklist for the Certified Athletic Trainer

1. Pre-event preparation___Am I challenging unsafe rules (eg, ability to receive fluids, modify game and practice times)?___Am I encouraging athletes to drink before the onset of thirst and to be well hydrated at the start of activity?___Am I familiar with which athletes have a history of a heat illness?___Am I discouraging alcohol, caffeine, and drug use?___Am I encouraging proper conditioning and acclimatization procedures?

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Table 2. Prevention Checklist for the Certified Athletic Trainer

2. Checking hydration status___Do I know the preexercise weight of the athletes (especially those at high risk) with whom I work, particularly during hot and humid conditions?___Are the athletes familiar with how to assess urine color?___Do the athletes know their sweat rates and, therefore, how much to drink during exercise? ___Is a refractometer or urine color chart present to provide additional information regarding hydration status in high-risk athletes when baseline body weights are checked?

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Table 2. (continued)

3. Environmental assessment___Am I regularly checking the wet-bulb globe temperature or temperature and humidity during the day?___Am I knowledgeable about the risk categories of a heat illness based on the environmental conditions?___Are alternate plans made in case risky conditions force rescheduling of events or practices?

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Table 2. (continued)

4. Coaches’ and athletes’ responsibilities___Are coaches and athletes educated about the signs and symptoms of heat illness?___Am I double checking to make sure coaches are allowing ample rest and rehydration breaks?___Are modifications being made to reduce risk in the heat (eg, intensity, change practice times, allow more frequent breaks, eliminate double sessions, or change equipment or clothing requirements, etc?___Are rapid weight-loss practices in weight-class sports adamantly disallowed?

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Table 2. (continued)

5. Event management___Have I checked to make sure proper amounts of fluids will be available and accessible?___Are carbohydrate-electrolyte drinks available at events and practices (especially during twice-a-day practices and those that last longer than 50 to 60 minutes or are extremely intense in nature)?___Am I aware of the factors that may increase the likelihood of a heat illness?___Am I promptly rehydrating athletes to preexercise weight after an exercise session?___Are shaded or indoor areas used for practices or breaks when possible to minimize thermal strain?

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Table 2. (continued)

6. Treatment considerations___Am I familiar with the most common early signs and symptoms of heat illnesses?___Do I have the proper field equipment and skills to assess a heat illness?___Is an emergency plan in place in case an immediate evacuation is needed?___Is a kiddy pool available in situations of high risk to initiate immediate cold-water immersion of heat-stroke patients?

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Table 2. (continued)

6. Treatment considerations (continued)___Are ice bags available for immediate cooling when cold-water immersion is not possible?___Have shaded, air-conditioned, and cool areas been identified to use when athletes need to cool down, recover, or receive treatment?___Are fans available to assist evaporation when cooling?___Am I properly equipped to assess high core temperature (ie, rectal thermometer)?

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Table 2. (continued)

7. Other situation-specific considerations

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Table 3. Wet-Bulb Globe Temperature Risk Chart

WBGT Flag Color Level of Risk Comments

<18°C

(<65°F)

Green Low Risk low but still exists on the basis of risk factors

18-23°C

(65-73° F)

Yellow Moderate Risk level increases as event progresses through the day

23-28°C

(73-82°F)

Red High Everyone should be aware of injury potential; individuals at risk should not compete

>28°C (82°F) Black Extreme or hazardous

Consider rescheduling or delaying the event until safer conditions prevail; if the event must take place, be on high alert

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Table 4. Physiologic Responses After Heat Acclimatization Relative to

Nonacclimatized StatePhysiologic Variable After Acclimatization (10-

14 Days’ Exposure)

Heart rate Decreases

Stroke volume Increases

Body-core temperature Decreases

Skin temperature Decreases

Sweat output/rate Increases

Onset of sweat Earlier in training

Evaporation of sweat Increases

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Table 4. (continued)

Salt in sweat Decreases

Work output Increases

Subjective discomfort (rating of perceived

exertion [RPE])

Decreases

Fatigue Decreases

Capacity for work Increases

Mental disturbance Decreases

Syncopal response Decreases

Extracellular fluid volume Increases

Plasma volume Increases

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Figure 1. Risk of heat exhaustion or heat stroke while racing in hot

environments

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Figure 2. Heat stress risk temperature and humidity graph

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