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Flashcards in Lecture 14 Deck (22)
1

Why is heat dissipation necessary?

Heat dissipation is to avoid critical hyperthermia

2

What are the 4 mechanisms of heat loss during exercise?

conduction

Convection

radiation

evaporation

3

What is the problem with humid conditions?

High humidity conditions prevent evaporation due to water vapour pressure gradient.

4

What happens to core temperature during exercise?

Core temperature increases during exercise and levels off eventually. Heat loss mechanisms take time to kick in

5

What 3 mechanisms correlate with exercise intensity?

Sweating

Heat production

VO2 max

6

Is sweat hypo or hyper tonic to plasma?

Sweat is hypotonic to blood plasma

7

Can sweat glands reabsorb sodium?

Yes

8

Why do trained individuals have less sodium in their sweat?

Trained individuals have less sodium in sweat due to increased sodium reabsorption as a response to aldosterone,

9

What happens to cardiac output during exercise and why does this happen?

Cardiac output increases at rest in hot weather with a big percentage caused by increased skin circulation.

High core temperature increases directing of blood flow to the skin which directs blood flow away from muscles.

10

What happens to glycogen utilization during exercise in hot weather?

In hot environment more glycogen is utilized due to higher amounts of plasma adrenaline and higher muscle temperatures

11

What happens to lactate production when exercising in warmer temperatures?

Lactate production is higher in hot temperatures

12

Why does the body work exert less during times of hot temperatures?

Higher body temperature decreases performance to keep temperature stable.

13

What is the result of lower core temperature?

Longer exercise time

14

What happens to exercise time in preheated athletes?

preheating athletes before exercise decreases exercise time and vice versa.

15

What are the central fatigue mechanisms that are affected by exercise-heat stress?

increase in rated percieved exertion

Reduced voluntary activation of muscle

Reduced cerebral blood flow but increased VO2.

Hyperprolactinaemia (increase in prolactin associated with fatigue)

16

What is the central mechanism to avoid too much heat production?

reduced neuromuscular performance with hyperthermia. The brain increases inhibitory signals to muscles to avoid too much heat productio from muscles

17

What are the physiological and metabolic adaptations to heat acclimatisation?

Increase in blood volume

Reduced heart rate

Lower skin and core temperature

Increased sweat rate and earlier onset of sweat

more diute sweat

Reduced muscle glycogen use

18

What happens to hyperthermia if fluids are replaced during exercise?

hyperthermia's effect is attenuated by fluid replacement.

19

What is the effect of dehydration on exercise performance?

Prior dehydration impairs exercise performance. This is due to decreased central cardiovascular function.

20

What are the benefits of fluid ingestion during exercise?

Increased blood volume

lower heart rate

increased stroke volume and cardiac output

lower core temperature

lower plasma sodium and osmolality

reduced muscle glycogen use

enhanced exercise performance

21

What is the function of renin and aldosterone?

fluid and salt retention

22

Is decrease in exercise time due to excess glycogen utilization that occurs in warmer temperatures?

No