exercising in the heat - lesson 2 Flashcards
1
Q
what do heat loss mechanisms depend on?
A
ENVIROMENT
- Ambient (room) temperature = if above the body’s core temperature, then evaporation is the only method of heat loss.
- Forced convection = heat loss via convection will occur if it is windy or water is flowing or you are moving in water.
- Barriers to convection = clothing will minimise the effect of convection as it will insulate the boundary layer of air.
- Temperature radiating surfaces – light clothing will not absorb as much heat as dark clothing
- Relative humidity = if 100%, no heat loss via evaporation.
- Body will continue to sweat but no heat loss occurs and core temperature will rise.
PHYSIOLOGICAL STATE
- Rate of heat production
- Hydration state = determine rate of evaporation as a reduction in plasma volume leads to a decrease in sweat rate
2
Q
what is the double heat load
A
- the 2 forms of heat
1. Metabolic heat is created by working muscles
2. Environmental heat in hot conditions - creates competition for blood flow = muscles + skin
3
Q
what is cardiac drift?
A
- occurs when in hot conditions with limited fluid intake
- The decrease in blood plasma volume = a decrease in stroke volume
- The body will increase heart rate in an attempt to maintain cardiac output
- competition for blood flow (skin + working muscles)
4
Q
what is dehydration?
A
occurs when the amount of water leaving the body is greater than the amount being taken in.
5
Q
how do we lose water?
A
- Breathing, as humidified air leaves the body
- Sweating, which is used as a cooling mechanism
- Urination or bowel movements in the removal of waste products.
6
Q
what is the order of heat-related injuries?
A
- dehydration = when fluid replacement does not match fluid loss
- heat exhaustion = when the dehydrated athlete continues to exercise and sweat = lose more fluid
- heatstroke = body stops sweating = the core temperature rising to dangerous, life-threatening levels, caused by a lack of evaporative cooling.
