HEAT ILLNESS
During this time of year, athletes need to take precautions against heat illness. Even when the temperature isn’t as hot, humidity can cause problems. There are several different types of heat illnesses. This month, the AT Corner will teach you how to prevent them, recognize them when they do occur, and properly treat them.
Exercise-Associated Muscle (Heat) Cramps
• Presents during or after exercise
• Acute, painful, involuntary muscle contractions
• Caused by dehydration, electrolyte imbalances, neuromuscular fatigue or any combination of these factors
Heat Syncope
• Occurs when a person is exposed to high environmental temperatures
• Attributed to
o Peripheral vasodilation
o Postural pooling of blood
o Diminished venous return
o Dehydration
o Reduced cardiac output
o Cerebral ischemia
• Usually occurs during the first 5 days of acclimatization, before the blood volume expands, or in persons with heart disease or those taking diuretics
• Occurs after long periods of standing, immediately after cessation of activity, or after rapid assumption of upright posture after resting or being seated
Exercise (Heat) Exhaustion
• The inability to continue exercise associated with any combination of heavy sweating, dehydration, sodium loss and energy depletion
o Occurs in hot, humid conditions
o Difficult to distinguish from heat stroke without measuring rectal temperature Exertional Heat Stroke
• Occurs when temperature regulation system is overwhelmed due to excessive heat production or inhibited heat loss in challenging environmental conditions
o Neurologic changes are often the first marker
o Elevated core temperature (>104◦ F) associated with signs of organ system failure due to hyperthermia
o Can progress to complete thermoregulatory system failure
• Life threatening and can be fatal unless promptly recognized and treated
• Risk of morbidity and mortality is greater the longer an athlete’s body temperature remains above 106◦ F and is significantly reduced if body temperature is reduced rapidly
Exertional Hyponatremia• Rare condition defined as a serum-sodium level less than 130mmol/L
o Usually occurs when activity exceeds 4 hours
o Can result in death if not treated properly
• Can occur two different ways
o Athlete ingests water well beyond sweat losses (water intoxication)
• Low sodium levels are the result of excessive fluid intake and inappropriate body water retention
o Athlete’s sweat losses are not adequately replaced
• Insufficient fluid intake and inadequate sodium replacement
• Can be prevented by matching fluid intake with sweat and urine losses and by rehydrating with fluids that contain sufficient sodium
Heat Illness Signs and Symptoms
| Heat Cramps | Heat Syncope | Heat Exhaustion | Heat Stroke | Hyponatremia |
|---|
| Dehydration | Dehydration | Normal or elevated core body temperature | High core body temp(>104◦ F) | Body core temperature (104◦ F) |
| Thirst | Fatigue | Dehydration | CNS Changes | Nausea |
| Sweating | Tunnel vision | Dizziness | Dizziness | Vomiting |
| Muscle cramps | Pale or sweaty skin | Lightheaded | Drowsiness | Extremity swelling |
| Fatigue | Decrease pulse | Syncope | Irrational behavior | Low blood-sodium level |
| | Dizziness | Headache | Confusion | Progressive headache |
| | Lightheaded | Nausea | Irritability | Confusion |
| | Fainting | Anorexia | Emotional instability | Significant mental compromise |
| | | Diarrhea | Hysteria | Lethargy |
| | | Decrease urine output | Apathy | Altered consciousness |
| | | Muscle cramps | Aggressiveness | Apathy |
| | | Pallor | Delirium | Pulmonary edema |
| | | Profuse Sweating | Disorientation | Cerebral edema |
| | | Chills | Staggering | Seizures |
| | | Cool, Clammy skin | Seizures | Coma |
| | | Intestinal Cramps | Loss of consciousness | |
| | | Urge to defecate | Coma | |
| | | Weakness | Dehydration | |
| | | Hyperventilation | Weakness | |
| | | | Hot and wet or dry skin | |
| | | | Tachycardia | |
| | | | Hypotension | |
| | | | Hyperventilation | |
| | | | Vomiting | |
| | | | Diarrhea | |
Prevention
1. Ensure appropriate medical care is available and that rescue personnel are familiar with heat illness prevention, recognition, and treatment.
2. Encourage pre-participation medical screening to identify athletes predisposed to heat illness.
3. Adapt athletes to exercise in the heat (acclimatization) over 10 to 14 days.
4. Educate athletes and coaches regarding the prevention, recognition and treatment of heat illnesses and the risks associated with them.
5. Educate athletes on proper hydration and fluid replacement.
a. Instruct to drink sodium containing fluids to keep urine clear to light yellow.
b. Replace fluid between practices on the same day and on successive days to maintain a less than 2% body weight change.
6. Try to get 6 to 8 hours of sleep each night in a cool environment.
7. Eat a well-balanced diet that follows the Food Guide Pyramid and the United States Dietary Guidelines.
8. Develop event and practice guidelines for hot, humid weather that anticipate potential problems encountered based on wet-bulb globe temperature.
a. If the WBGT is >82◦ F, the event should be delayed, rescheduled, or moved into an air conditioned space. This should be monitored before and during practices / events.
9. Weigh high-risk athletes before and after practice. a. Athletes should consume 16oz of fluid for each kilogram of body water lost during exercise. If they have lost more than 2-3% of body weight, then don’t allow them to practice until they get it back.
10. Minimize amount of equipment and clothing worn during hot or humid conditions.
11. Minimize warm-up time and/or warm-up in the shade
Wet-Bulb Globe Temperature Risk Chart
Extreme / Hazardous
| WBGT | Level of Risk | Comments |
|---|
| >65◦ F | Low | Risk low but still exists on the basis of risk factors |
| 65◦ -73◦ | Moderate | Risk level increases as event progresses through the day |
| 73◦-82◦ | High | Everyone should be aware of injury potential; individuals at risk should not compete |
| >82◦ |
| Consider rescheduling or delaying event until safer conditions prevail |
Heat Stress risk temperature and humidity graph
• Regular practices with full gear can be conducted for conditions that plot to the left of the triangles
• Cancel all practices for conditions that plot to the right of the circles
• For conditions that plot between squares and circles, increase rest to work ration with 5-10 minute rest and fluid breaks every 15-20 minutes
o Practice should be in short only with all protective equipment removed
• For conditions that plot between the triangles and squares, increase rest to work ration with 5-10 minute rest and fluid breaks every 20-30 minutes
o Practice should be in shorts with helmets and shoulder pads only
Treatment
Muscle Cramps
o To relieve muscle spasms, an athlete should stop activity, replace lost fluids with sodium-containing fluids and begin mild stretching with massage of the spasm
o Fluid absorption is enhanced with sports drinks that contain sodium
o A recumbent position may allow more rapid redistribution of blood flow to cramping leg muscles
Heat Syncope
o Move the athlete to a shaded area, monitor vital signs, elevate legs above head and rehydrate
Heat Exhaustion
o Assess CNS function for bizarre behavior, hallucinations, altered mental status, confusion, disorientation, or coma to rule out more serious conditions
o If feasible, measure rectal temperature and assess cognitive function and vital signs. Rectal temperature is the most accurate.
o If temperature is elevated, remove excess clothing to increase the evaporative surface and facilitate cooling
o Cool with fans, ice towels or ice bags
o Remove to a cool, shaded environment
o Start fluid replacement
o Transfer care to a physician if IV fluids are needed
Heat Stroke
o Measure rectal temperature to differentiate between heat exhaustion and heat stroke. (Heat stroke is usually >104◦ F)
o Assess cognitive function
o Lower core body temperature as quickly as possible. (Quickest way is to remove clothes and equipment and immerse in cold water 35◦ - 59◦ F) This is the most critical factor in treatment.
o Monitor temperature during the cooling and recovery (every 5-10 minutes)
o If a physician is present to manage medical care on site, initial transportation to a medical facility may not be necessary so immersion can continue uninterrupted.
o If a physician is not present, aggressive cooling should be initiated
on site and continued during transport
o Activate EMS
o Monitor vitals and signs/symptoms
Exertional Hyponatremia
o Activate EMS
o Needs to be transferred immediately.
o An IV line should be placed to administer medication as needed to increase sodium levels, induce dieresis, and control seizures
o Don’t administer fluids until a physician is consulted
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