Exercise in the Heat

• Thermoregulation: a process that allows the body to maintain its internal core temperature and is vital to health.
• Thermoreceptors: deep in the body core sense a change in temperature and help to regulate temperature.
• Humidity: the amount of water in atmospheric air. Humidity effects the rate of heat loss through sweating.

  Low humidity increases sweating and the cooling process

  High humidity decreases sweating and the cooling process.
• Dehydration is a loss of water in the body tissues, largely caused by sweating.
• Hyperthermia is elevated body temperature due to poor thermoregulation that occurs when a body produces/abosrbs more heat than it gets rid of.
• Cardiovascular drift: a raise id heart rate during sustained steady state activity associated with an increase in body temperature.
• Thermoregulation is the process that allows the body to maintain its internal core temperature
• When body temperature rises, thermoreceptors sense an increase in core body temperature. Blood vessels vasodilate and metabolic heat is transported by circulating blood to body surface. This heat is released by evaporation (sweat) and convection. This can lead to fluid loss and cools the body, but if fluids aren't replaces it can lead to dehydration, this increases the loss of electrolytes.
• Dehydration impairs the body's ability to thermoregulate and core body temperature rises. This can affect performance significantly and the body can eneter hyperthermia
• Hyperthermia is elevated body temperature where body produces/absorbs more heat than it can get ride of
• A cause of hyperthermia is poor thermoregulation
• A cause of hyperthermia is high and prolonged exercise intensity
• A cause of hyperthermia is high air temperature
• A cause of hyperthermia is high relative humidity
• An immediate effect of heat, humidity and the body's thermoregulatory response on the cardiovascular system is blood flow is redirected to skin for cooling purposes
• An immediate effect of heat, humidity and the body's thermoregulatory response on the cardiovascular system is it limits blood flow to muscles and lowers venous return
• An immediate effect of heat, humidity and the body's thermoregulatory response on the cardiovascular system is cardiovascular drift can occur.
• Cardiovascular drift is a raise in HR during sustaines steady state activity associated with an increase in body temperature caused by prolonged exercise in heat. Blood plasma volume reduces due to water loss which causes an increase in blood viscosity. Stroke volume decreases. O2 transport to working muscles is reduced. HR increases to compensate for decreased SV to maintain cardiac output. This causes an increased strain to the cardiovascular system.
• An immediate effect of heat, humidity and the body's thermoregulatory response on the respiratory system is dehydration causes dry airways, makes breathing difficult which results in: increased mucus production; constriction of airways; and a decreased volume of air for gas exchange.
• An immediate effect of heat, humidity and the body's thermoregulatory response on the respiratory system is breathing frequency increases to maintain O2 consumption
• An immediate effect of heat, humidity and the body's thermoregulatory response on the respiratory system is high levels of sunlight increase poulltants in air cause increased irritation of airways, wheezing and coughing
• An immediate effect of heat, humidity and the body's thermoregulatory response on the respiratory system is asthma is worsened in sufferers.
• An overall immediate physiological effect of heat is increased O2 cost of activity.
• An overall immediate physiological effect of heat is decreased aerobic energy production
• An overall immediate physiological effect of heat is carbohydrate stores are used quicker
• An overall immediate physiological effect of heat is the body tries to produce energy anaerobically
• An overall immediate physiological effect of heat is a build up of lactic acid means fatigue occurs earlier
• An overall immediate physiological effect of heat is an increase in core body temperature affects rate of chemical reactions
• An effect of heat on performance without acclimatisation is perceived exhaustion will feel worse
• An effect of heat on performance without acclimatisation is performance times hindered in endurance events
• An effect of heat on performance without acclimatisation is strength endurance and aerobic capacity is reduced
• An effect of heat on performance without acclimatisation is exercise duration and intensity is reduced
• An effect of heat on performance without acclimatisation is maximal based activities are not hindered
• 7-14 days in the same conditions as competition is ideal for heat aclimatisation . This could be done through a thermal chamber.
• Heat acclimatisation increases the body's tolerance to heat by: increasing plasma volume; increasing onset and rate of sweating; increasing efficiency of cardiac output distribution; decreases the loss of electrolytes within sweat limiting faitgue and cramp; and lowers HR at a particular pace and temp.
• Cooling aids e.g. ice vests can be used to lower core body temperature and delay effects of increased temp and dehydration.
• During competitions in heat athletes should wear suitable clothing that maximises heat loss, removing sweat away from the skin.
• During competitions in heat athletes should rehydrate often with hypotonic or isotonic solution to replace fluid, glucose and electrolytes lost through sweat.
• During competitions in heat athletes should pace themselves
• After competitions in heat, athletes should use cooling aids e.g. towels and fans to aid the return to core body temperature