Heat Intolerance Problems

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Heat Intolerance Problems

• Kambiz Behzadi, M.D.
• Orthopaedic Surgeon
• Fremont/Pleasanton

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What Causes Heat Related Illness?

• Bodys failure to keep itself cool
• Sweat/Evaporation releases heat
• Humidity impairs release of heat
• Increased body temperature
• Heat Illness

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Heat Intolerance

• gt 300 people die of heat related illness in U.S.
• Heightened awareness in athletes
• Identify athletes at risk
• Not a disease
• Accident waiting to happen

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Heat Intolerance

• Heat Stroke can occur in best athletes
• Korey Stringer, Vikings, professional
• Estrate Autin, Florida, college

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Heat Intolerance

• Preseason Football, Marathon, Soccer
• Mild to Fatal
• High Temperature High Humidity
• Preventable awareness,
  recognition, treatment

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Hypothalamus

• Bodys Thermostat
• As temperature hypothalamus responds
• 1. Increase blood flow to skin
• 2. Increase sweating

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Temperature Regulation

• Conduction jumping into the pool
• Convection standing in front of fan
• Evaporation water from liquid to gas
• Radiation electromagnetic heat waves

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Temperature Regulation

• Conduction

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Temperature Regulation

• Convection

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Temperature Regulation

• Sweating Evaporation

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Temperature Regulation

• Radiation

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Sweating/Evaporation

• In hot a environment, Evaporation becomes the
  Primary source of Heat Dissipation
• Humidity decreases our ability to get rid of Heat

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Exercise Work Heat

• Heat increases core body temperature
• Warm blood bathes the hypothalamus
• Blood diverted from warm core to cool shell
  (conduction, convection, radiation)
• Sweat glands release hypotonic saline solution
  (sweat) evaporation

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Physiology

• Exercise work heat
• Hypothalamus
• Blood Flow Skin
• Sweat

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Hot Environment

• Sweat/Evaporation
• Conduction
• Convection
• Radiation

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Exercise in Heat Two Demands on Circulatory
System

• Blood (Nutrients and Oxygen) to Working Muscle
• Blood to Skin to Cool Body

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Heat and Exercise

• Muscle
• G.I. Tract Kidney
• Circulatory System
• Liver Brain
• Skin

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Early Heat Intolerance

• Shock Weak pulse, low blood pressure, dizziness,
  syncope, headache, nausea, vomiting, lack of
  appetite, weakness
• Temperature below 102 F or 39 C

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Stressed Out Circulatory System

• Dehydration Fluid Loss
• Worsening State of Shock

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Heat Stress Exercise

• Overwhelmed Cardiovascular System
• Heat Exhaustion

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Heat Stroke

• Break down cooling mechanism
  Increase core body temperature Shock Damage
  to cells in body Multi-system failure
  Death

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Heat Intolerance Problems

• Heat Syncope
• Heat Cramps
• Heat Exhaustion
• Heat Stroke

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Heat Syncope

• Athlete stands still after exercise
• Pooling of blood in extremities
• Light-headed, dizzy, faint
• Core body temperature is normal
• Lie on ground, shaded area, legs elevated
• Oral fluids usually not required
• Recovery rapid

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Heat Syncope Treatment
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Heat Cramps

• Painful contractions large muscle groups ( legs,
  abdomen)
• Dehydration Loss of balance between salt and
  water in muscle
• Treatment 1. Rest and Passive stretch2. Fluid
  replacement (water, sports drink)
• Prevention Adequate hydration before and
  throughout exercise

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Heat Cramps Treatment
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Heat Exhaustion

• Most common form of heat intolerance
• Fatigue, weakness, sweating, nausea, diarrhea,
  mental status normal to slightly impaired
• Symptoms of mild shock
• Temperature lt 102 F or 39 C

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Heat Exhaustion Treatment

• Lie in cool, shaded area
• Fluid replacement
• IV Fluids
• Do not allow return to vigorous activity until
  normal body weight is reached

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Heat Stroke

• True Medical Emergency
• Hyperthermia (Tempgt105F or gt40C)
• Failure of Thermoregulatory Mechanism
• Central Nervous System Dysfunction
• Second most common cause of death in U.S. athlete

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Animals Built-in Protective Mechanism
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Exercise Heat Mild Shock

• Fluid Loss
  and
• Shock Dehydration
• Overwhelming Temperature
• Heat regulatory
• Mechanism
• 
  Metabolism

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Diagnosis Heat Stroke Rectal Temp gt 105 F

• Aggressiveness
• Irritability
• Emotional Instability and hysteria
• Apathy
• Disorientation
• Unsteady gait
• Hot, dry skin
• Unconsciousness

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Treatment Heat Stroke

• Call Ambulance
• Remove clothing
• Immerse in cool/iced water bath
• Cover wet sheets and compressfan
• Airway, Oxygen, Rehydration
• Support Multi-organ failure

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Prevention

• Acclimatization bodys adaptation to heat
  stress, and increased capacity to work in high
  temperature and humidity
• 7 days to several weeks
• 30 minutes 2 hours
• Lower resting body temperature
• Increased plasma volume
• Lower threshold for sweating

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Prevention

• Practice in early morning or late afternoon
• Night games early in season
• Uniforms light weight, porous, light in color
• Sleeves short and socks low
• Much skin exposed to air

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Prevention

• Hydration is key
• Free intake of fluids during games
• Regular fluid breaks no less than every half hour
• 1 pint (2 cups) for each 1 pound sweat lost
• 10 oz. Every 30 minutes
• Only 50 fluid loss made up by thirst (encourage
  fluid intake between and during sessions)
• Events lt 90 min, electrolyte replacement usually
  unnecessary

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Prevention

• Glucose concentration lt 5 to 8
• Dilute twofold
• 10 glucose (soft drinks and juices) cause
  stomach cramps, nausea, diarrhea, slow gastric
  emptying
• Fructose (fruits) absorbed slowly and causes G.I.
  distress

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Prevention

• Sports drinks
• Replacement glycogen in (muscle and liver) in
  exercise lasting gt 90 minutes
• Dilute solution Sodium and Glucose increase
  absorption of water in small intestine

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Prevention

• Cumulative Hypohydration
• Weigh before and after each practice
• No player should be allowed to return to play
  until fluid loss is replaced and normal weight is
  achieved

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Electrolyte Make-up

• Goal to replace sweat that has evaporated
• Sweat water small concentration of salts and
  other electrolytes
• Concept Sport drink Sweat
• Evaporated sweat replaced before next exercise
• Normal diet replaces lost electrolytes
• Electrolytes in drinks increase absorption of
  water