Thermoregulation

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Thermoregulation

• Thermal Balance
• Hypothalamus
• Heat Stress
• Cold Stress

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Mechanism for Temperature Regulation -Cold

• Decreases heat loss-vasoconstriction
• Increases in heat production-Shivering and
  increased voluntary activity
• Increased thyroxin and epinephrine secretion

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Mechanism for Temperature Regulation-Heat

• Increased heat loss-Vasodilatation
• Decreases heat production-Decreased muscle tone
  and voluntary activity
• Decreased secretion of thyroxin and epinephrine

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Heat Loss

• Radiation
• Conduction
• Convection
• Evaporation

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Complications

• Heat Cramps-Spasms in exercising muscles
• Heat Exhaustion-weak and rapid pulse,low
  BP,HA,dizzy,weakness
• Heat Stroke-excessive core temp,no sweat,altered
  mental status,life threatening

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ACSM Recommendations

• Above 82 degrees-very high risk-postpone
• 73-82 degrees-high risk-Heat sensitive
  individuals should not compete
• 65-73 degrees-mod risk
• Below 65-low risk

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Exercising -Heat

• Vascular adjustments-Blood flow to skin
  increases,compromising blood to working muscles
  and other vital organs
• SV decreases,AC and CO also decrease because of
  fluid deficit
• Attempts to maintain BP
• Core Temp Increases

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Water

• Fluid loss .5-1.0 L for mod exercise in 1 hour
• 3 L loss for intense exercise
• Must constantly replenish fluids.Must exceed
  25-50 above sweat loss(urine loss)
• Water replacement is more important than mineral
  replacement
• Electrolyte replacement and water is optimal

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Clothing-Warm Weather

• Cotton or linen
• Light colors
• Changing into a dry shirt from a wet one while
  exercising will negatively affects the cooling
  process

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Exercising in the Cold

• Peripheral vasoconstriction can lead to tingling
  and numbness
• Burning sensation in nose and ears
• Tissue damage-Frostbite
• Surgical removal of damaged tissue

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Cold Weather-Clothing

• Numerous layers is better than a single bulky
  layer
• Moisture must be allowed to pass to outer layers
• Wools and synthetics insulate and dry fast
• Wear a hat(30-40 Heat loss by Head)
• Wet clothing loses 90 of its insulating
  properties