wk2 personal factors governing heat tolerance Flashcards
how does body type make a difference in heat
larger body surface area provides more area for sweat production
dry heat loss is also enhanced with a larger body surface
influences heat production and thermoregulatory responses
how does body surface area-to-mass ratio affect heat storage
higher ratio means less heat storage, due to larger area for dry and evaporative heat loss
what is the similarity between total body water and blood volume
both experience expansion with endurance exercise - independent of body size or sex
what are heat shock proteins induced by
heat + exercise
hypoxia
infections and inflammation
how do HSP play a sig. role in heat adaption
proposed mechanism via maintenance of gut tight
epithelial junctions
reducing risk of endotoxemia (gut leakage)
how does aerobic fitness improve heat tolerance
total body weight and blood volume, helps offset quicker dehydration
Increased sweat and skin blood flow
Small benefit from increased work rate
Lower core temp at rest and submax
Higher absolute core temp tolerated
More HSP production
Glycogen sparing
what are the two predictors of exercise tolerance
maximal aerobic power
training status
how can sex differences affect heat stress
women had lower vo2 max, body surface area and body mass index
however women had a higher body surface area-to-mass ratio and body fat% so more likely to be heat tolerant
sex differences in exertional heat stroke
females had lower risk of EHS but may be modifiable by age
similarity in both sex’s dealing with heat stress
sweat production
increase in skin blood flow
onset thresholds
thermosensitivity
sweat gland activation
sweat gland output
how do men cope better with heat stress
ONLY IN VERY HIGH AMBIENT TEMPS
sweat production
sudomotor thermosensitivty
sweat gland output
what is the process of dealing with heat production and high temps
higher temp -> thermoreceptors -> CNS -> sudomotor activity + vasomotor activity
what are the differences between sex’s in temporal adaption heat acclimation
females require longer to achieve thermoregulatory and cardiovascular heat adaptions
what affect does ageing have on heat stress
reduced sweat gland output
reduced skin blood flow
smaller increase in cardiac output
less redistribution of blood flow from renal and splanchnic circulations
how does spinal cord injury affect heat stress
causes a loss or reduction in sweating capacity impaired vasomotor control
results in an imbalance between heat gain and heat loss occuring more readily with exercise in the heat
what factors affect exercise in hot conditions
body size
aerobic fitness
sex
age
spinal cord injury
relative vs absolute vo2 max
relative - relative to individual body mass
why do smaller athletes have a worse time dealing with heat
less capacity means they got hotter faster
what is sweat production linear to
the body surface area
link between fitness and tolerance
fitter = better tolerance
how does fitness affect thermoeffector response
causes ‘shift to left’ means start sweating sooner and causes steeper rate of increase and higher maximal value
link between HSP and tolerance
linear relationship, more = higher tolerance
what happens in the gut within high heat
cell walls become further apart and proteins slip through the gut causing stomach aches
how can training status change tolerance
acute effects on - kindeys Na retention and albumin production alongside HSP production
what can drive sex differences in heat tolerance
anthropometrics and cardiovascular fitness impacts the most
different characteristics that can affect sex differences
men have higher:
vo2 max
bm
men have lower:
BSA : MASS
hormone fluctuation
what happens to women during the menstrual cycle
causes a higher core body temperature, may allow them to reach higher temps and increase heat tolerance (only a maybe,, start higher end higher)
differences between sex’s in acclimation
females may take longer to see thermoregulatory and cardiovascular heat adaptions, takes around 9days rather than 4/5
over a longer period (3wks) changes adapt similarly
sex differences in thermoeffector adaptions
males increased forearm blood flow
females increased forearm sweat gland activation
how does hormonal contraception
dims variation that can occur during the menstrual cycle
how does spinal cord affect thermoregulation
damage central drive affects/impairs:
sweating
skin blood flow
muscular heat production
other factors affecting performance in heat
medication
illness
fatigue and sleep deprivation
initial thermal stress
