Week 09

Question 1

Skeletal muscle “motor” of children and adults works at about 20% efficiency, this means that during exercise ____ times as much energy generates heat as produces locomotion

Answer 1

four

Question 2

Radiation:

Answer 2

heat loss through rays or waves of energy

Question 3

Conduction:

Answer 3

losing heat through physical contact

Question 4

Convection:

Answer 4

losing heat through air or water molecules (fan)

Question 5

Evaporation:

Answer 5

losing heat through conversion of water to gas

Question 6

Dehydration can cause a rise in ?????

Answer 6

Core body temperature

Question 7

Sweating rate in boys is _____ than in men

Answer 7

Much lower

Question 8

Due to lower sweating rate in boys, they rely more on increased ??????? for convective skin heat loss than men

Answer 8

cutaneous blood flow

Question 9

Men sweat ____ more than women

Answer 9

3x

Question 10

Is there a difference in girls vs women’s sweat rate?

Answer 10

Some studies show no differences, however, conflicting evidence

Question 11

The number of sweat glands increase or is fixed at infancy?

Answer 11

Fixed at infancy, doesn’t increase

Question 12

Children have _____ surface area relative to their body mass

Answer 12

greater

Question 13

Because of their relatively greater body surface area, children have more effective heat loss via _____ than adults

Answer 13

convection

Question 14

Responses to Exercise in the Heat: cardiovascular drift

Answer 14

• increase body temp
• increase BF to skin
• Shift of fluid from vascular space
• less ventricular filling
• stroke volume smaller
• smaller CO
• compensate with increase in HR
• called cardiovascular drift

Question 15

In the heat, children sweat less than adults and must rely upon diminishingly effective _____ loss to prevent a rise in core temp

Answer 15

convective

Question 16

Children’s greater body surface area relative to body mass also becomes a liability when the…

Answer 16

skin-to-air temperature gradient is reversed

Question 17

Concentration of sodium in sweat tends to be _____ in children

Answer 17

lower

Question 18

Given the lower sweating rates in young subjects (at least among males), total sodium losses through sweating can be expected to be ____ in children

Answer 18

less

Question 19

Children generate ____ heat relative to body mass than adults when performing the same task

Answer 19

more

Question 20

The number of sweat glands ______ during puberty

Answer 20

stays the same

Question 21

• We would expect children to demonstrate an exaggerated rise in core temp at high ambient temp
• However, experimental data suggests ____ changes in core temp between children and adults under hot conditions

Answer 21

similar

Question 22

It is more common for ____ to experience symptoms of fatigue when air temperature is greater than skin temperature by over 10 degrees C (47C)

Answer 22

children

Question 23

Drinkwater et al performed walking tests in hot temperatures among women and girls and found….

Answer 23

Women performed these walks for longer and could deal with temperatures better–> heat tolerance is better in adults.

Question 24

What are the potential factors responsible for exercise fatigue in the heat in adults?

Answer 24

• Cardiovascular insufficiency from the shunting of blood volume to cutaneous circulation for convective cooling
• Dehydration and depressed blood circulation from fluid losses as sweat
• Metabolic or substrate alterations
• Impairment of myocardial contractility

Question 25

Traditional explanation for exercise intolerance in heat is shunting of blood to cutaneous circulation and away from working muscles. However, evidence suggests ....?

Answer 25

muscle blood flow is not limited in the heat.

Question 26

Is blood flow to muscle responsible for lack of exercise performance in the heat?

Answer 26

No

Question 27

Dehydration caused by significant sweating may diminish left ventricular filling and thereby decrease SV, however, studies indicate only small reductions in ____

Answer 27

CO

Question 28

Was there a reduction in CO observed in dehydration or hyperthermia?

Answer 28

No, only reduction in CO when they had BOTH

Question 29

Optimal muscle temperature range for force production: _______degrees C

Answer 29

30-37C

Question 30

Febbraio found that metabolic consequences (Ca+ uptake, reduced integrity of membranes) only occurred when muscle temp reached ....?

Answer 30

40 degrees C

Question 31

Nielsen et al reported no effects of exercise in the heat on ????????? of elbow flexors and knee extensors

Answer 31

muscular strength

Question 32

Once core temperatures exceed 40 degrees C, evidence suggests deterioration of ___ _____ capacity

Answer 32

heart pumping

Question 33

Data in adults fail to identify a single factor that clearly explains limitations of exercise performance in the heat.----> as...

Answer 33

- CO has fallen little - Muscle blood flow has not decreased - Muscle glycogen stores are adequate - Muscle contractile force is not affected - Myocardial contractility is preserved

Question 34

Nielsen et al suggested that "the high core temp per se, and not _____ _____, is the critical factor for exhaustion during exercise in heat stress"

Answer 34

circulatory failure

Question 35

Core temp of >__C may reduce the function of motor centres and the ability to recruit motor units. However, evidence is limited

Answer 35

39C

Question 36

Jokinen et al. studied cardiovascular adjustments to 10 min of sauna heat, symptoms only evident in ____ age group:

Answer 36

young, 25% complained of "dizziness and feeling too hot"

Question 37

Jokinen et al. found that there was a greater fall in ___ in the youngest children and greater rise in ____

Answer 37

SV, core body temp

Question 38

Rowland et al found no difference in SV, however, in girls vs women in heat exercise, this may be due to...?

Answer 38

They had fluids to replenish fluid loss, and temperature was not as hot as Jokinen et al study.

Question 39

Lower tolerance of heat in ____ than in ____, primarily due to...?

Answer 39

girls, women.... due to cardiovascular problem

Question 40

These limited data suggest that children tolerate exercise in the heat as well as adults except in....?

Answer 40

Very high ambient temperatures

Question 41

Is there compelling evidence that cardiovascular insufficiency is responsible for possible differences in performance in the heat between children and adults ??

Answer 41

No

Question 42

Drinking ad libitum (desired amount) generally only replaces up to ____% of the fluid lost

Answer 42

70%

Question 43

- Limited evidence suggests that the magnitude of involuntary dehydration in children is ____ to that of adults.

Answer 43

Similar

Question 44

___% of adult weight gained during growth spurt

Answer 44

50%

Question 45

Physically active boys did/did not differ in stature or age of peak height velocity compared to sedentary boys

Answer 45

did not

Question 46

Male testosterone levels are x___ after puberty

Answer 46

20