Lecture 10 Flashcards
Exercising in the heat and cold (25 cards)
What is homeothermic regulation in humans?
Having a stable internal body temperature regardless of the environment — known as being warm-blooded (e.g., humans).
What is Thermoregulation:
The process by which the body maintains its internal temperature.
Explain what core and shell temperature are?
Core temperature refers to the temperature of the internal organs, brain, and blood — it is tightly regulated and vital for survival.
Shell temperature refers to the temperature of the skin and outer tissues, which can vary depending on the environment.
How is metabolic heat produced during exercise?
When you exercise, your body uses energy. Only about 25% of this energy does work, and the other 75% turns into heat. Body will store heat and core temp will rise.
This heat is called metabolic heat.
How does the body dissipate heat?
Body heat must move from the CORE to the SHELL (skin).
What are the four primary methods of heat transfer for the body?
Conduction: direct contact (e.g., sitting on hot surface. pan handle)
Convection: air/water movement (wind, fan)
Radiation: heat from infrared rays (sun, body)
Evaporation: sweat → gas (main method during exercise)
What is the primary avenue for heat loss during exercise?
Evaporation is the primary avenue for heat loss during exercise
Sweat turns into vapor to cool body
What is heat acclimation?
Short-term adaptations (9-14 days) that occur after repeated exercise in hot conditions, leading to improved heat tolerance and performance.
Difference between acclimation and acclimatisation?
Acclimation: short term (9–14 days) - Pre season camp
Acclimatisation: long term (months/years) - Lives and trains year round at high altitude
What are the 3 heat illnesses
Heat Cramps
Heat Exhaustion
Heat Stroke
What are Heat Cramps and their treatment?
Heat cramps
- Least serious heat illness; causes painful muscle cramps from sodium loss and dehydration.
Prevention
- Drink water and consume salt.
Treatment
- Cool environment, oral or IV saline.
What is Heat Exhaustion and its treatment?
Heat exhaustion
- Caused by severe dehydration; symptoms include fatigue, dizziness, nausea, and fainting.
- Blood flow can’t meet demands of muscles and skin.
Treatment
- Cool environment, elevate feet, oral or IV fluids.
What is Heatstroke and its treatment?
Heat stroke
- Most dangerous heat illness; thermoregulation fails.
Signs
>40°C, confusion, NO sweating = emergency
Wet-Bulb Globe Temperature (WBGT)
Measure of exercise in heat
How does the body defend against cold?
Vasoconstriction: conserve core heat
Shivering: involuntary heat generation
Non-shivering thermogenesis: ↑ metabolism
Behavioural changes: clothing, shelter
What’s the body’s thermostat?
POAH (Preoptic Anterior Hypothalamus)
What limits heat loss during exercise?
Humidity → ↓ evaporation
Clothing → resistance
Dripping sweat ≠ cooling; evaporation is key
What is the limitation of exercising in heat?
Cardiovascular overload (can’t supply muscle + skin + brain)
Critical temperature theory: brain halts exercise at ~40–41°C
What are the key adaptations to heat?
↑ Plasma volume
↑ Sweat rate, earlier onset
↓ Sweat NaCl concentration
Better temp regulation, lasts weeks
How is heatstroke treated?
Cool whole body ASAP (ice bath best)
Fanning + wet sheets if needed
Can occur in mild temps if thermoregulation fails
Why is cold water especially dangerous?
Conducts heat 4× faster than air
Hypothermia risk ↑ in moving water
What is hypothermia?
core <34.5°C → loss of regulation
What is Frostbite?
skin freezes from ↓ circulation
