(4A, Ch25) Thermal Stress Flashcards
Rise in core temperature during exercise is dependent on…
A. whether or not a person is wearing heavy uniform, pads, and helmet
B. whether or not it’s sunny
C. work intensity
D. whether or not it’s humid
E. all of the above
E. all of the above
What is the main cause of heat production?
Through muscle contraction
(NOTE: this is directly related to workout)
what are the 4 ways body heat can be lost?
- radiation
- conduction
- convection
- evaporation
During aerobic exercise under hot conditions, blood flow to the skin is ________ than under temperate conditions, so blood flow to skeletal muscle is _________ than under temperate conditions.
higher; lower
_____ is how a person perceives heat, taking into account humidity
heat sensation
On a day with low humidity, 85 degree Fahrenheit temperature, and bright sun, what is the primary means of heat exchange from the body to the environment during aerobic exercise (e.g. an hour run)?
A. heat lost in the breath
B. muscle contractions
C. evaporation of sweat
D. radiation
E. convection
C. evaporation of sweat
Main contributors to body heat (4)
- solar radiation (AKA sunlight)
- metabolic rate
- physical activity
- thermic effect of food
aerobic training _____ sweat NaCl concentration
decreases
Compared to exercise under temperate conditions, during exercise in hot conditions, blood flow to the skin is:
A. lower
B. higher
C. about the same
B. higher
What is a limiting factor in rehydration?
gastric emptying rate
Sodium in drink when rehydrating after exercise decreases urinary output. Why?
retains fluid AKA improving hydration
If core temp is constant, total heat loss is _____
the same
If core temps increases, ______ increases
sweating rate
Evaporative heat loss is more efficient in ____ temps
high temps
(increases w increasing temps)
Core temp and swimming
decreases, especially in winter when water temps are lower
Sodium in drink when rehydrating after exercise _____ urinary output
decreases
heat acclimation increases ____
performance
Dehydration impairs _____
aerobic performance
What is the effect of the following heat acclimatization response:
Inreased sweat output
Maximizes evaporative cooling
What does fluid replacement do in aerobic events under hot conditions?
improves performance
What happens to the core temperature at rest? At maximal exercise?
Rest: remains the same
Maximal exercise: increases
At low air temperatures (e.g. 40 degrees Fahrenheit), which is most important to body heat loss?
A. convection
B. evaporation
C. radiation
A. convection
(NOTE: not much sun–not much radiation; not hot out so not much evaporation)
Which is greater?
A. maximal rate of sweating
B. maximal rate of rehydration
C. they’re always the same
A. maximal rate of sweating
(NOTE: up to 2L can be lost)
Who has a higher heart rate during low workload conditions?
Elderly
What is the effect of the following heat acclimatization response:
Lower threshold to begin sweating
evaporative cooling begins earlier