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Thermoregulation. Thermal Balance Hypothalamus Heat Stress Cold Stress. 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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Thermoregulation • Thermal Balance • Hypothalamus • Heat Stress • Cold Stress
Mechanism for Temperature Regulation -Cold • Decreases heat loss-vasoconstriction • Increases in heat production-Shivering and increased voluntary activity • Increased thyroxin and epinephrine secretion
Mechanism for Temperature Regulation-Heat • Increased heat loss-Vasodilatation • Decreases heat production-Decreased muscle tone and voluntary activity • Decreased secretion of thyroxin and epinephrine
Heat Loss • Radiation • Conduction • Convection • Evaporation
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
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
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
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
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
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
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 it’s insulating properties