Exercise In The Heat Flashcards
(12 cards)
How can exercising in the heat affect performance?
An athlete can lose around 2-3 litres per hour, which if not replaced decreases blood volume and causes dehydration, impair body’s ability to thermoregulate.
What is thermoregulation?
The process of maintaining internal core temperature.
What are the thermoreceptors and how does the body respond?
Thermoreceptors are sensory receptors which sense a change in temperature and relay information to the brain.
If core temp rises, metabolic heat is transported by circulating blood to the the surface of the body and released mostly by convection and evaporation(sweat)
What is dehydration?
Loss of water in body tissues, largely caused by sweating.
What is humidity and how does it affect heat loss?
Humidity is the amount of water vapour in the atmospheric air.
Low humidity increases sweating, High humidity decreases sweating and the cooling process.
What is hyperthermia and how is it caused?
HyPERthermia is significantly raised core body temperature.
It’s 3 main causes are:
1. High and prolonged exercise intensities
2. High air temperatures
3. High relative humidity.
With high humidity, warm moisture stays on skin longer,making it feel hotter, increasing core body temp.
What can hyperthermia cause?
- Dehydration
- Fatigue/muscle cramping
- Heat exhaustion/Heat stroke
- Fainting
What is cardiovascular drift?
Cardiovascular drift is an upward drift in heart rate during sustained steady-state activity associated with an increase in body temp.
1 degree Celsius increases heart rate by 10bpm
How is cardiovascular drift caused?
During prolonged exercise in heat, the increased rate of muscular contraction and chemical reactions produce metabolic heat. This may not be removed quickly enough to maintain core body temp resulting in CV drift.
What are the effects of heat/humidity and the body’s thermoregulatory response on the CV system?
- Dilation of arterioles/capillaries to the skin- increased blood flow and blood pooling
- Decreased blood volume,venous return, SV, CO and Blood pressure- increased heart rate, increased strain on CV system, reduced o2 transport to the working muscles
What are the effects of heat/humidity and the body’s thermoregulatory response on the respiratory system?
- Dehydration/drying of all airways in high temperatures make breathing difficult.- increased mucus, constriction of airways,decreased volume of air for gaseous exchange
- Increased breathing frequency- increased oxygen ‘cost’ of exercise.
What are the main overall effects of the thermal strain placed upon the CV and respiratory system?
- Increased oxygen ‘cost’ of activity
- Decreased aerobic energy production
This shifts more emphasis to an aerobic energy production, using glycogen and glucose stores more quickly.
