Exercise in the heat (Bb)

Exercise in the - Environmental Physiology Exercise in the heat MOV 365 Clinical Exercise Physiology Heat Humidity Exercise Lecture Objectives

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Environmental Physiology: Exercise in the heat MOV 365 – Clinical Exercise Physiology
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2 Lecture Objectives Consider the physiological responses to exercise in a hot and humid environment (hot = greater than 30 degrees C) Both together and at high capacities is not a good thing Highlight strategies to cope with heat and humidity
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3 Exercise in the Heat Heat loss through radiation, conduction and convection is reduced (the gradient) then reversed in a hot environment (the gradient is) Evaporation becomes the only means Hydration will become a key trying to cope 2% decrease in body mass is negative and starts to affect physiological factors Thirst is our early indicating system Urine concentration (color) – specific gravity (solutes-osmolality – sodium) (change in ion concentration) Electrolytes (Sodium, Potassium , magnesium) Sodium and salted fluid will include your thirst. Drink more and longer) Water will switch off your thirst drive Caffeinated drinks switch off thirst and act as an anti diuretic Sweat evaporation determined by: Surface Area exposed Temperature and relative humidity of air Convective currents
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4 Relative Humidity and Heat Stress Water content of air, expressed as a percentage of maximal capacity Total saturation – the air is carrying as much water as possible High humidity reduces evaporation and heat loss. Risk of ‘heat illness’ increased Without heat loss body temp will increase quickly. ..then physical and mental impairment begins
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Atlanta Olympic Games, 1996 31 ºC, 69% RH (39 ºC , 100% RH) Kuala Lumpur Commonwealth Games, 1998 36 ºC, 60% RH Athens Olympic Games, 2004 25-30 ºC, 50-60% RH – 30 ºC, 39% RH for marathon pollution! Timing (earlier morning later in the evening) 5
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6 Combined Heat Stress Humidity can be accounted for by: heat stress index wet bulb-globe temperature index (WBGT) Lab tool used to measure all diff. Factors that contribute to heat stress Dry temp Radiant heat gain Driven by the wet bulb (70%)which is a humidity affect, 10 % from radient
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8 Effects of Heat on Exercise vasodilation (25% of Q distributed to skin) Purpose to get body heat down by pushing blood 2 peripheries Issue with pushing blood to the periphery
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This note was uploaded on 05/29/2011 for the course MOV 365 taught by Professor Rosssherman during the Spring '11 term at Grand Valley State University.

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Exercise in the - Environmental Physiology Exercise in the heat MOV 365 Clinical Exercise Physiology Heat Humidity Exercise Lecture Objectives

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