Cold acclimation Flashcards
define adaptation
- changes that reduce the physiological strain produced by stressful components
- changes can be phenotypical or genotypical
- Does not require specification of the climatic component of the total environment
- no distinct terms relating to genotypic adaptations
Define habituation
- desensitization or dampening of the normal response to a stressor
What metabolic, peripheral blood flow and insulator changes are associated with cold acclimation
- decrease in metabolic rate (by ~20%)
- reduced peripheral blood flow
- little effect on insulation; maybe an increase in the gradient between core and skin temp
What are the 3 categories of adaptations we can see in the cold
- metabolic adaptations
- hypothermic adaptations
- insulative adaptations
In chronic cold stress when there is no body heat loss what is the body’s response
- Cold habituation: Blunted shivering/cutaneous vasoconstriction
In chronic cold stress when there is body heat loss and metabolic heat is sufficient to defend body temp what is the body’s response
Metabolic acclimation: Enhanced shivering thermogenesis/NST
In chronic cold stress when there is body heat loss and metabolic heat is not sufficient to defend body temp what is the body’s response
- insulative acclimation: Enhanced vasoconstriction, improved muscle blood flow
What metabolic adaptions can be seen in humans
- Results are varied: but
- increased BMR
- more intense shivering/elevated NST
What metabolic adaptations have been shown in mice and rats
- mice: increased energy expenditure in mice; varied by strain
- Rats: increased sensitivity to NE/greater production of NE
Describe the BAT/NST experiment in the knock-out mice, what were the results
- UCP-1 KO mice shown a decrease in NST and no response to NE when cold adapted
- Mice with UCP-1 showed an increase in NST
How does the amount of BAT change based on the climate someone lives in
- Increase BAT in cold climate
- ex. homeless alcoholic vs average person
- possible confounding factors??
What adaptations do the Ainu people have
- increased metabolic response in the cold
- more FFA oxidation
Looking at BAT around the body, what type of adaptations?
- post-acclimation there is a large difference in BAT NST when exposed to cold
How does exercise affect these metabolic adaptations?
- low impact on shivering and metabolism during exercise
- meaning training in the cold has minimal-no effect
What types of hypothermic adaptations do we see in cold acclimated individuals
- greater fall in core temperature
- skin temperature is maintained or decreased
- redistribution of circulation to periphery to give warmer skin ie maintain a colder core
- reduced NE response (habituation, not acclimation)
- maintained or decreased metabolic rates
When looking at the Ama divers vs control divers, what can be concluded about their shivering
- start shivering at a lower core temperature
- Therefore cold acclimated
what insulative changes can be expected in response to cold acclimation
- more vasoconstriction or an improved countercurrent heat exchange
- therefore lower skin temperature
How does the maximal tissue insulation/subcutaneous body fat of the ama divers compare to the regular population
- greater max tissue insulation/unit of subcutaneous body fat
- cold adapted
How does maximal insulation change with exercise
- maximal insulation decreases due to perfusion of muscle
Does cold acclimation improve exercise performance in the cold
- no; after insulative acclimation cycling performance was equally impaired during cold exposure as it was prior to acclimation
Does acclimation to extreme cold have an effect on exercise performance
- in dynamic exercise neuromuscular functions may adapt to repeated whole body cryotherapy (ex. drop test)
