extreme environments Flashcards
what does acute heat exposure lead to
impaired exercise capacity
what’s different heat acclimation and acclimatisation
acclimation chamber
acclimatisation is natural environment
what’s role of heat acclimation/acclimaatisation
plays a large role in the body’s physical responses and overall ability to cope with heat exposure
define heat acclimation
complex series of changes or adaptions that occur in response to heat stress in a controlled environment
adaptations of heat acclimation
heart rate
internal body temp responses
skin temp responses
sweat electrolyte concentration
rpe
sweat rate
sweat onset
blood flow
exercise performance in heat and cooler conditions
sweat rate with heat acclimation
improved sweat response = hallmark indication of heat acclimation
adaptations mostly occur in 3-4 days
sweat begins at lower body temp
sweat production increases for given body temp
sweat sodium conc decreases linearly for 7 days
blood volume with heat acclimation
expansion occurs rapidly after 3-4 days
expansion variable 3-27% (patterson or perriard)
improves vascular refilling to support cardiovascular stability (increase sv and bp)
increase heat of blood to aid transfer to skin
increased plasma volume to aid heat dissipation
cv adaptations with heat acclimation
improved sweat rate and blood volume facilitate heat flow to the surface
spares blood flow for rest of circulation, relives circulatory strain
BP stabilises
adjustment in sympathetic and parasympathetic activity
what % of adaptations occur over first 4/7 days of heat acclimation
75/80%
what are kinetics of adaptation based on
daily exposure - 10 days
intermittent - 3 days for 30 days
similar response but 3x as long
fein, gill and sievert
what does intermittent exposure with a week in between elicit
no adaptations (barnett and maughan)
how long do elite athletes need for near complete cv and sudomotor adaptations
2 or more weeks to optimise aerobic performance
perceptual and cognitive adaptations to heat acclimation
improves rating of thermal/sensation comfort during training/competition
unclear how much this extends to physical performance in heat
improves various cognitive tasks such as psychomotor performance, attention tasks, planning tasks from deleterious effect of hyperthermia
rule to induce heat acclimation
increases whole body temperature
induce profuse sweating
elevate skin blood flow
achieve heat acclimation
passive heat exposure
self paced exercise
constant work rate exercise
isothermal controlled hyperthermia
controlled heart rate response
short medium and long term heat acclimation
short 7 days (incomplete 75%)
medium 8-14 days
long term 15 days+
heat shock protein response
major pathway for adaptation
associated with resistance to stress and may be central to the understanding at a cellular level of thermotolerance after acclimation
thermo tolerance depends on HSP72 response
thermo tolerance is a cellular level adaptation allowing cells and organism to survive higher heat strain
HSP72 prevents thermal injury, enhances signalling pathways of cytoprotective mechanism and immune system
decay in adaptations occurs in
7 days to 4 weeks
2.5% per day (daanen)
reaccliamtion occurs
faster 4-5 days (ashley 2015)
symptoms of heat stress
confusion
dark urine (dehydration)
dizziness
fainting
fatigue
headache
muscle or abdominal cramps
nausea, vomiting, diarrhoea
pale skin
rapid heart beat
profuse sweating
