EDU2EXP Exercise & Performance Environment and Exercise

EDU2EXP Exercise & Performance Thermoregulation

EDU2EXP Exercise & Performance Body temperature Different temperatures: –Surface / Skin –Core body –Tympanic –Esophogeal –Rectal –oral

EDU2EXP Exercise & Performance

Regulation Regulated by hypothalamus to within 1 degree (37 + or – 1) Fig 11.5 a and b pg 258, 259 Negative feedback loop  Thermal receptors in the skin  Temperature changes in blood

EDU2EXP Exercise & Performance Mechanisms of Heat Loss/gain Radiation –The release of heat via electromagnetic heat waves Conduction –Direct transfer of heat through contact with a liquid, solid, or gas Convection –Carrying heat on air currents Evaporation –Provides the major physiologic defense against overheating

EDU2EXP Exercise & Performance

Primary mechanisms?? At rest? During exercise??

EDU2EXP Exercise & Performance Mechanisms of Heat Conservation Vascular adjustments –Vasoconstriction of peripheral blood vessels Muscular activity –Voluntary physical activity –Involuntary- Shivering Hormonal output –Increased secretion of E, NE, thyroxine

EDU2EXP Exercise & Performance Mechanisms Facilitating Heat Loss Circulatory adjustments Evaporation Hormonal adjustments

EDU2EXP Exercise & Performance Circulatory Adjustments Two competitive cardiovascular demands exist during exercise in the heat –Oxygen delivery to muscles must increase to sustain exercise energy metabolism –Peripheral blood flow to the skin must increase to transport metabolic heat from exercise for dissipation at the body’s surface

EDU2EXP Exercise & Performance Evaporation depends on Surface exposed to environment Temperature and humidity of air Convective air currents

EDU2EXP Exercise & Performance Clothing Cloth traps air next to skin and warms it to provide insulation However if sweat is not absorbed and drawn away from skin to be kept dry, clothing loses 90% insulating property

EDU2EXP Exercise & Performance Exercise in the Heat

EDU2EXP Exercise & Performance Heat Beijing Fig 11.6 shows that compared to thermoneutral environments, HR higher SV lower in hot conditions degrees- brain sends signals to stop exercise

EDU2EXP Exercise & Performance

Consequences of Dehydration Reduced plasma volume Increased submaximal heart rate Reduced rate of sweating Impaired ability to thermoregulate

EDU2EXP Exercise & Performance

hyperthermia Prevention –Avoid holding competition when temp >28 degrees –Drink fluids before and after and have breaks every mins –clothing Treatment –Immerse in ice bath/ cold water

EDU2EXP Exercise & Performance Clothing for the heat Cover as little SA as possible Loose fitting to allow convective air currents near skin Wet allows increased evaporation Colour –Dark = absorbs radiant heat –Light – reflects radiant heat

EDU2EXP Exercise & Performance Factors Affecting Heat Tolerance Acclimatisation Exercise training Age Gender Body composition Hydration

EDU2EXP Exercise & Performance Acclimatisation to heat Physiologic adaptive changes that improve heat tolerance Training increases heat tolerance As does 9-14 days of exercising in heat –Lower Heart rate –Lower skin temp –Lower core body temp –Increased plasma volume –Double sweating capacity (volume), Greater area of the body is used for sweating, More dilute –Sweat response earlier in exercise session during exercise

EDU2EXP Exercise & Performance Exercise in the Cold

EDU2EXP Exercise & Performance Cold Physiological –Peripheral Vasoconstriction –Non shivering thermogenesis –Shivering Behavioural adjustments –Huddle –Voluntary movement –Put more clothes on –Exercise indoors

EDU2EXP Exercise & Performance Exercise in water in the cold Body loses heat 4 x as fast in cool water as in air the same temperature  Shivering Swimming in 18degrees as opposed to 26 degrees = 500 ml/min more o2

EDU2EXP Exercise & Performance Exercise in the cold Increased consumption o2 to compensate for that used in shivering Increased mobilisation FFA’s for fuel –If low blood glucose  reduced shivering  reduced temperature Cold muscle = decreased contractile force –Particularly when fatigued –Large inner muscles insulated and protected –Peripheral muscles  decreased dexterity

EDU2EXP Exercise & Performance Dry Mouth Air is warmed and humidified by the bronchial tract  27/30 degrees When air is humidified it takes moisture from the respiratory tract Especially during exercise Therefore –Dry mouth –Burning throat –Irritation respiratory passages

EDU2EXP Exercise & Performance

Evaluating cold stress S/A node in heart  slow HR Frostbite warning signs Tingling & numbness fingers and toes Burning sensation – nose & ears

EDU2EXP Exercise & Performance Acclimatisation to cold Genetic- Eskimo Habituation- Repeated exposure of extremities to cold  increased peripheral blood flow to reduce possibility of frostbite

EDU2EXP Exercise & Performance Exercise in Pollution

EDU2EXP Exercise & Performance Pollution Carbon monoxide, sulfur oxides, nitrogen oxides, ozone, peroxyacetyl nitrate, aerosols, soot, dust and smoke Large particles and highly soluble gases are usually filtered out in nasal passages

EDU2EXP Exercise & Performance Effects Irritation of the upper respiratory tract 30 min submax exercise = smoking a pack of cigarettes Carbon monoxide - reduces the blood’s capacity to transport oxygen to the tissues. Asthma attacks

EDU2EXP Exercise & Performance Beijing 2008 Pollution levels 2-3 x higher than those deemed safe by WHO Trial to take 1 million cars off the road to see if pollution levels go down

EDU2EXP Exercise & Performance Exercise and Altitude

EDU2EXP Exercise & Performance Exercise at Altitude –Reduced barometric pressure –Reduced partial pressure of oxygen (Po 2 ) –Reduced relative humidity –Reduced ambient temperature

EDU2EXP Exercise & Performance Immediate adjustments to altitude above 2300 m Hyperventilation –Chemoreceptors detect that not getting enough oxygen –Increase ventilation to compensate –  evaporation fluids respiratory tract Cardiovascular –Increased HR and cardiac output –At rest and during submaximal exercise

EDU2EXP Exercise & Performance

Exercise Capacity at Altitude Aerobic capacity –Progressively decreases as altitude increases –1-3.5% reduction Vo2 max every 300m increase from 1500 m –Greater rate decline for trained athletes Circulatory factors –Decreased MHR and SV

EDU2EXP Exercise & Performance Acclimatisation Adaptive responses to improve one’s tolerance to altitude 2 weeks to adapt to 2300 m Additional 610 m = 1 week

EDU2EXP Exercise & Performance Cellular adaptations –Increased capillary density –Increased mitochondrial densities Blood volume- –Plasma volume decreases –Erythropoietin released  increase RBC Acid-base adjustment -Ambient air at altitude contains very little Co2 -Affects gradient of o2/Co2 volumes -Combined with hyperventilation causes low Co2  increased pH Longer-Term Adjustments

EDU2EXP Exercise & Performance Altitude Training Acclimation to altitude improves one’s capacity to exercise at altitude However inability to train at equivalent intensity  no improvement Vo2 max on return to sea level  Live High, Train Low

EDU2EXP Exercise & Performance

Summary Environment critical to optimal performance Be aware of environment in case of negative effects Use to your advantage –Heat Humidity –Cool –Pollution –Altitude