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SPEX203 > Lecture 19 > Flashcards

Lecture 19 Flashcards

Cold Stress

1
Q

three factors that lead to cold stress

A

cold, wet, wind

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2
Q

4 problems that can arise from cold stress for exercise

A
  • impaired performance
  • discomfort
  • glycogen depletion
  • injury / illness
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3
Q

how can exercise performance be impaired by cold stress

A
  • power
  • strength
  • dexterity
  • aerobic capacity
  • early fatigue
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4
Q

what injury / illnesses can arise from exercise in cold stress

A
  • hypothermia
  • non freezing tissue
  • frostbite
  • soft tissue strains
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5
Q

what determines the net level of cold stress

A

the balance between heat gain and heat loss

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6
Q

4 ways heat is lost from the body

A

evaporation

radiation

convection

conduction

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7
Q

heat will be lost if air temperature is less than skin temperature, in which ways

A
  • radiation
  • convection
  • conduction
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8
Q

what is the optimal environment for exercise (compared to rest) and why

A

optimal environment for exercise is cooler than at rest, more so as intensity increases

because heat itself is a stressful

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9
Q

what is the biggest method heat loss from the body when exercising in the cold and how does this happen

A

convection

  • heat lost to the environment, when the environment is cooler than the body temperatire
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10
Q

example of behavioural response to cold

A

clothing

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11
Q

when is behavioural responses not the most effective to combating the cold

A
  • cognitively impaired by hypothermia (and alcohol)
  • cold-impaired strength, dexterity or coordination
  • injured
  • competitive exercise and behaviour choices
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12
Q

when is exercise not effective response to cold

A
  • cool / cold water (but can still be best option)
  • fatigued (decreased production, increased loss of heat)
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13
Q

what are the 2 major physiological responses to cold

A
  1. vasoconstriction of skin and muscle
    - allows both of them to be insulators
  2. shivering
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14
Q

what other processes are affected by shivering

A

movement increases heat loss if in water - boundary layer

dilates blood vessels muscle (decreases its insulation)

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15
Q

what are the two minor physiological responses to cold

A

counter-current heat exchange in limbs

non shivering thermogenesis

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16
Q

what is the boundary layer that occurs when we are in water and what can disturb this

A

thin layer of water that is in direct contact with the skin,

this layer can be warmer than the surrounding water as it is in contact with the body

shivering can disturb it

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17
Q

what is the resting comfort skin temperature

A

33 degrees

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18
Q

what type of drive occurs in the cooling defence zone and what is it driving

A

provides feedforward drive for vasoconstriction, also contributes to drive for shivering

19
Q

what occurs at a core temperature of 36

A

moderate shivering, reduced strength, power and dexterity

20
Q

what occurs at a core temperature of 35

A

hypothermia

  • maximal shivering and decreased performance
21
Q

how quickly will you develop hypothermia

A

depends on many factors, especially temperature but it still takes a reasonably long time to develop

22
Q

what occurs at a core temperature of 33

A

cardiac arrhythmias; highly variable inter individual responses

23
Q

what happens at a core temperature of 29

A

severe cardiac arrhythmias and unconsciousness common

24
Q

what happens to sensory and motor functions due to decreased peripheral temperature (skin, muscle and nerves) due to cold

A

decreased sensory and motor functions

25
Q

what are hand and foot temperatures governed by (3)

A
  • if body is in +ve heat balance overall
  • clothing coverage
  • local muscle activity
26
Q

what does not help prevent hypothermia

A
  • ectomorphy
27
Q

what is ectomorphy

A

this is having a thin body build

28
Q

who is most at risk during exercise in cold conditions

A
  • small, ectomorphic body shape
  • young
  • elderly
29
Q

who can be at risk during exercise in cold conditions but it depends

A

sedentary people

males + females

30
Q

why does it depend is sedentary people are at risk during exercise in the cold

A

typically they have a higher body mass, but aerobic fitness plays against them

so depends on balance between these if they are at risk or not

31
Q

will a fit or unfit person maintain their core body temperature better in the cold

A

fit person

32
Q

humans do not adapt cold defence with repeated cold stress, instead what happens ? and what is this called

A

we cool faster while feeling more comfortable

  • habituation
33
Q

how much faster does water conduct heat than air

A

25x faster

34
Q

is convection increased or decreased in water compared to air

A

convection is increased in water

35
Q

how long does the cold shock response typically last

A

1.5 - 3 minutes

36
Q

if the initial gasp response that occurs in cold shock was to occur under water what could happen

A

drowning as it is a large breath

37
Q

how rapidly can we adapt to the cold shock response

A

rapidly = only takes a few immersions

38
Q

what is incapacitation (over the first few minutes) of immersion into cold water

A
  • difficulty breathing and muscle contraction
  • strain on the heart
39
Q

why is there strain on the heart in incapacitation

A

severe sympathetic drive on the heart but also parasympathetic drive = dual activation on SA node

40
Q

what temperature is beneficial to exercise in water in terms of maintaining heat balance

A

28 degrees

41
Q

what temperature is detrimental to exercise in water

A

10 degrees

42
Q

implications that can occur exercising in the cold if you have had prior exercise or heat stress and why

A
  1. cool faster during cold stress
    - cause skin vasodilated so as soon as we enter cold heat will be removed
  2. can decrease energy capacity
    - due to decreased insulative capacity
43
Q

symptoms of hypothermia

A
  • cold and shivering
  • disorientation
  • obvious alteration in mood, lethargy
  • muscle weakness
  • symptoms variable
44
Q

what should you attempt to warm first when treating someone with hypothermia

A

warm their torso and core

SPEX203 (33 decks)

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