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Exercise Physiology Across the Lifespan > Week 09 > Flashcards

Week 09 Flashcards

1
Q

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

A

four

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2
Q

Radiation:

A

heat loss through rays or waves of energy

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3
Q

Conduction:

A

losing heat through physical contact

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4
Q

Convection:

A

losing heat through air or water molecules (fan)

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5
Q

Evaporation:

A

losing heat through conversion of water to gas

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6
Q

Dehydration can cause a rise in ?????

A

Core body temperature

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7
Q

Sweating rate in boys is _____ than in men

A

Much lower

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8
Q

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

A

cutaneous blood flow

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9
Q

Men sweat ____ more than women

A

3x

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10
Q

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

A

Some studies show no differences, however, conflicting evidence

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11
Q

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

A

Fixed at infancy, doesn’t increase

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12
Q

Children have _____ surface area relative to their body mass

A

greater

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13
Q

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

A

convection

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14
Q

Responses to Exercise in the Heat: cardiovascular drift

A
  • 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
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15
Q

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

A

convective

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16
Q

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

A

skin-to-air temperature gradient is reversed

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17
Q

Concentration of sodium in sweat tends to be _____ in children

A

lower

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18
Q

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

A

less

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19
Q

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

A

more

20
Q

The number of sweat glands ______ during puberty

A

stays the same

21
Q
  • 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
A

similar

22
Q

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

A

children

23
Q

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

A

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

24
Q

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

A
  • 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
25
Q

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

A

muscle blood flow is not limited in the heat.

26
Q

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

A

No

27
Q

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

A

CO

28
Q

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

A

No, only reduction in CO when they had BOTH

29
Q

Optimal muscle temperature range for force production: _______degrees C

A

30-37C

30
Q

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

A

40 degrees C

31
Q

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

A

muscular strength

32
Q

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

A

heart pumping

33
Q

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

A
  • 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
34
Q

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

A

circulatory failure

35
Q

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

A

39C

36
Q

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

A

young, 25% complained of “dizziness and feeling too hot”

37
Q

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

A

SV, core body temp

38
Q

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

A

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

39
Q

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

A

girls, women…. due to cardiovascular problem

40
Q

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

A

Very high ambient temperatures

41
Q

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

A

No

42
Q

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

A

70%

43
Q
  • Limited evidence suggests that the magnitude of involuntary dehydration in children is ____ to that of adults.
A

Similar

44
Q

___% of adult weight gained during growth spurt

A

50%

45
Q

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

A

did not

46
Q

Male testosterone levels are x___ after puberty

A

20

Exercise Physiology Across the Lifespan (13 decks)

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