Exertional Heat Illnesses in
Athletics
Did you know…
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From 2001-2009, the Centers for Disease Control and
Prevention (CDC) found that 75% of patients treated for heat
illnesses in emergency departments were males; 35% were
between the ages 15 and 19.1
On average, 6,000 people per year seek emergency medical care
for heat related illnesses suffered while participating in outdoor
recreational activities.2
In the athletic population, exertional heat stroke (EHS) is the
third leading cause of death among athletes3 and first during
the summer months.4
Heat illnesses are an inherent to physical activity and increase
with rising ambient temperature, relative humidity and poor
planning and preparation.
Without prompt and appropriate medical care; patients suffering
from EHS are at risk for organ failure, brain damage, or death.1
What is exertional heat illness?
Exertional heat illnesses (EHI) occur when the body’s temperature control system
becomes overwhelmed and body fluid is lost through dehydration or sweating.
This results in the inability to cope with excess heat produced during activity.3-6
The evaporation of sweat from the skin is the most efficient means of losing this
heat; however, during hot and humid weather sweating may not be enough to
dissipate the buildup of excess body heat.3-4 Failure to regulate an elevated body
temperature increases the risk of multi-system organ failure, brain damage, cardiac
arrhythmias, and death.3-4, 7-9
Are there different types of exertional heat illness?
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Exertional heat stroke is a medical emergency and
requires immediate rapid cooling and activation of
EMS!
There are 3 main types of EHI: (1) exercise-associated muscle (heat)
cramps, (2) exercise (heat) exhaustion, and (3) exertional heat stroke. Two
other heat related illnesses that should not be overlooked are heat syncope
and exertional hyponatremia.
How do I know if I am suffering from an exertional heat illness?
To properly manage EHI requires being able to define and identify each condition's characteristics:
• Exercise-associated muscle (heat) cramps: acute, painful, involuntary muscle contractions that present during or after
intense exercise.5,6 Possible causes include: (1) excessive sweating, (2) dehydration, (3) electrolyte imbalances, (4)
muscle fatigue, or (5) a combination of these factors.5 It does not have to be very hot for heat cramps to occur.8
•
Exercise (heat) exhaustion: occurs frequently during hot, humid weather and results in the inability to continue
exercising due to: (1) excessive sweating, (2) dehydration, (3) electrolyte imbalance, (4) fatigue, or (5) combination
of these factors. Other warning signs: cool, clammy, and pale skin, muscle cramps, dizziness, headache,
nausea/vomiting, decreased urine output, and increased body-core temperature. If untreated, heat exhaustion can
quickly progress to EHS.5
•
Exertional heat stroke: a life-threatening condition with an elevated core temperature > 104°F. Body-core
temperature can rise to 106°F or higher within 10-15 minutes resulting in complete thermoregulatory system
failure.3,5 Neurological changes to the central nervous system are often the first sign of EHS. Warning signs
include: (1) increased heart rate, (2) low blood pressure, (3) cessation of sweating (skin may be wet or dry at the
time of collapse), (4) increased breathing rate, (5) altered mental status, (6) vomiting, (7) diarrhea, (8) seizures, and
(9) other circumstances (i.e., hot and humid environment, intense exercise). The longer the body temperature
remains elevated, the greater the likelihood of permanent disability or death if NOT treated rapdily.3,5, 7-10
What should I do now?
Immediate and proper care is necessary to treat EHI.
• Exercise-associated muscle (heat) cramps: to relieve cramps you must stop
activity, stretch the tissue, and massage the muscle. Replace lost fluids with
sodium-containing fluids (sports drink). A recumbent position also allows
more rapid redistribution of blood flow to cramping leg muscles.5
• *Exercise (heat) exhaustion: body-core temperature measured with a rectal
thermometer is the most accurate way to distinguish between exercise
exhaustion and EHS. Because this is often not practical, assess cognitive
(memory, judgment, and reasoning) function and vital signs.
If core temperature is elevated or abnormal: (1) remove to a cool/shaded
area, (2) remove excess clothing, (3) start replacing lost fluid, and (4) cool
the individual using: fans, ice towels, or ice bags. Contact EMS if recovery
is not rapid, uneventful, the person begins vomiting, shows signs of EHS, or
loses consciousness.8
• *Exertional heat stroke: begin RAPID body cooling and summon
medical personnel.3,5,10 Aggressive cooling is the MOST critical factor in
treating EHS.3,5 The fastest way to decrease body-core temperature is to
immerse the body in a tub of cold water (≈35°F-59°F). Monitor core
temperature during the cooling therapy via a rectal thermometer and
remove when the body-core temperature reaches 102°F. When this is
not feasible, remove from the tub once cognitive function improves or
after 20 minutes to avoid overcooling.10 Monitor vital signs and other
signals of EHS.5,10 If immersion is not feasible, other methods can be
3
used to reduce body temperature: (1) remove clothing, (2) wet ice towels
rotated and placed over the entire body (3) cold water dousing with or
without fanning (4) ice bags to as much of the body as possible, especially the major vessels in the armpit, groin, and
neck, (5) provide shade and fan the body with air while waiting for EMS.3,5
How do I prevent exertional heat illnesses?
The best method to prevent EHI from occurring is to be PREPARED and know how to manage and reduce risk.
Simple strategies include:3,5
Ø Ensure appropriate medical care (eg., certified athletic trainer) is available and personnel are familiar with EHI
prevention, recognition, and treatment strategies.
Ø Establish policies and procedures for cooling athletes before transport to the
hospital with all personnel.
Ø Conduct a thorough, physician-supervised, medical screening before the season
starts to identify at-risk individuals. Factors include: (1) history of EHI, (2)
poorly acclimatized, (3) poor physical fitness, (4) recent illness, (5) obesity, and
(6) poor nutrition habits.
Ø Adapt activities in the heat gradually over 10-to-14 days and progressively
increase workload and duration of work in the heat. Also, incorporate a
combination of strenuous interval training and continuous exercise.
Ø Maintain proper hydration during the season before, during, and after activity.
NEVER withhold water as punishment.
Ø Match fluid intake with sweat and urine losses to maintain adequate hydration (see the chart above). Drink
sodium-containing fluids to keep urine clear to light yellow to improve hydration.
Ø Avoid exercising in hot, humid environmental conditions.
Ø Modify protective equipment during periods of high environmental stress.
Ø Avoid the ‘‘never give up’’ or ‘‘warrior’’ mentality.
Ø Sleep at least 6 to 8 hours each night in a cool environment.
Ø Eat a well-balanced diet.
*Note: Measuring rectal temperature with a flexible probe thermometer is the MOST accurate method possible in the field
to assess body-core temperature. You should NOT rely on the oral, tympanic, or axillary temperature for active individuals
because these are inaccurate and ineffective measures of body-core temperature during and after exercise.3,5
References
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Hendrick, B. Heat illness sends thousands to ER each year. Web site. http://www.webmd.com/fitness-exercise/news/20110728/heat-illness-sends-thousands-to-er-each-year. Accessed July 12, 2012.
Hazards - heat wave. Web site. http://www.disastersrus.org/emtools/heatwave/heatwave.htm. Accessed July 12, 2012.
Casa D., et al. National Athletic Trainers’ Association position statement: preventing sudden death in sports. J Athl Train. 2012:47(1):96-118.
Bergeron MF, McKeag DC, Casa DJ, et al. Youth football: heat stress and injury risk. Med Sci Sports Exerc. 2005;37(8):1421-1430.
Binkley H, et al. National Athletic Trainers’ Association position statement: exertional heat illnesses. J Athl Train. 2002; 37(3), 329-343.
MMWR. (2006, July 28). Heat-related deaths --- United States, 1999-2003. Web site. http://www.cdc.gov/mmwr/preview/mmwrhtml/mm5529a2.htm. Accessed July 12, 2012.
Rav-Acha M, et al. Fatal exertional heat stroke: a case series. Am J Med Sci. 2004;328(2):84-7.
Rav-Acha M, et al. Unique persistent neurological sequelae of heat stroke. Mil Med. 2007;172(6):603-6.
Dematte JE, et al. Near-fatal heat stroke during the 1995 heat wave in Chicago. Ann Intern Med. 1998;129(3):173-81.
American Red Cross. Emergency Medical Response. Yardley, PA: Staywell; 2012.
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Original works by the authors.
Developed and funded by the Athletic Training Education Program.