Heat Flashcards
(17 cards)
1
Q
what is humidity
A
the amount of water in the atmospheric air
2
Q
how does humidity affect sweating
A
- the rate of heat loss through sweating is affected by humidity
- low humidity = increases sweating
- high humidity = decreases sweating + cooling process
3
Q
what is hyperthermia
A
significantly raised core body temperature
4
Q
what are the 3 main causes of hyperthermia
A
- high + prolonged exercise intensities
- high air temperatures
- high relative humidity
5
Q
what is thermoregulation
A
the process that allows the body to maintain its internal core temperature, which is essential for an individuals health
6
Q
what are thermoreceptors
A
sensory receptors, deep in the core of the body, which sense a change in temperature and relay information to the brain
7
Q
what happens in thermoregulation
A
- thermoreceptors in the core detect changes in temperature
- if core temperature rises, metabolic heat is transported by the circulating blood to the surface of the body + released by convection + evaporation (sweat)
- sweating has a cooling effect on the body, it removes excess heat quickly
8
Q
what is dehydration
A
loss of water in body tissues, largely caused by sweating
9
Q
how does heat affect thermoregulation
A
- sweating has a cooling effect on the body, it removes excess heat quickly
- athletes exercising in the heat can lose approximately 2-3 litres of sweat per hour
- if fluid lost isn’t replaced, blood volume decreases + causes dehydration
- dehydration impairs the ability of the body to thermoregulate + core temperature will rise
10
Q
what is cardiovascular drift + what impact does it have on the athlete
A
- an upwards drift in heart rate during sustained steady-state activity associated with a rise in body temperature
- the redirection of blood flow to the skin for cooling limits blood flow to the muscles + venous return
- 1 degree C increases heart rate by 10bpm
- rise in core temperature alters the function of proteins such as enzymes and receptors
11
Q
what is the effect of heat + humidity on the cardiovascular system
A
- dilation of arterioles + capillaries to the skin –> leading to increased blood flow + blood pooling in the limbs
- decreased blood volume, venous return, stroke volume, cardiac output + blood pressure –> leading to increased HR to compensate, increased strain on the CV system, reduced oxygen transport to the working muscles
12
Q
what is the effect of heat + humidity on the respiratory system
A
- dehydration + drying of the airways in temperatures above 32 degrees C makes breathing difficult –> leading to increased mucus production, constriction of the airways, decreased volume for gaseous exchange
- increased breathing frequency to maintain oxygen consumption –> leading to increased oxygen ‘cost’ of exercise, high levels of sunlight increase the effects of pollutants in the air, causing increased irritation of the airways leading to coughing, wheezing or asthma symptoms
13
Q
what are the overall effects of thermal strain on the CV system and respiratory systems
A
- increased oxygen ‘cost’ of activity + decreased aerobic energy production
- there is more emphasis on anaerobic energy production using carbohydrate (glycogen + glucose) stores more quickly
- exercise duration decreases due to lactic acid accumulating more readily, leading to early fatigue
- strength endurance + aerobic capacity reduced, declining performance in mid to long distance events e.g. cycling, athletics, football
- athletes with EIA (exercise induced asthma) must take precautions e.g. bronchodilators prior to dry heat exposure + staying hydrated
14
Q
what is the overall impact on performance
A
- at higher temperatures, perceived exertion will feel higher for the performer
- strength and endurance based activities are affected differently due to the different intensity, duration + opportunity for fluid intake
- hyperthermia doesn’t affect maximal strength production - explosive and maximal events are unaffected e.g. sprinting, shot put, long jump
- the longer the event, the greater the effect on performance (due to rise in heart + metabolic rate associated with an increase in core temperature)
- the more elite the endurance athlete, the lower the impact of heat due to physiological adaptations, precautions taken + acclimatisation
- if the coach + performer fails to understand the impact of heat + humidity on the body + performance, they may severely underestimate the effects + fatigue in the race if the athletes ‘pace per mile’ isn’t adapted
15
Q
what are the precaution procedures pre competition
A
- acclimatise to increased temperature
- 7-14 days of acclimatisation in the same conditions increases the body’s tolerance to heat by:
- increasing plasma volume, the onset and rate of sweating, and the efficiency of cardiac output distribution
- decreasing the loss of electrolytes within the sweat, which limits fatigue and cramping
- decreasing heart rate at a given pace and temperature
- use cooling aids, such as ice vests to reduce core temperature and delay the effects of high temperature and dehydration
16
Q
what are the precaution procedures during competition
A
- use pacing strategies to alter goals and reduce feelings of exertion at low exercise intensities
- wear suitable clothing that maximises heat loss, removing sweat from skin rapidly, such as lightweight compression wear
- rehydrate as often and as much as possible with a hypotonic or isotonic solution that replaces primarily lost fluids but also glucose and the electrolytes lost through sweat
17
Q
what are the precaution procedures post competition
A
- cooling aids, such as cold towels and cold fans, aid the return of core body temperature gradually
- rehydrate using isotonic solutions that replace lost fluids, glucose and electrolytes
