Lecture 18 Flashcards
Heat Stress
most important defence against heat injury
behavioural thermoregulation
also sweating is physiological mechanism
4 things that limit performance under heat stress
- critical body core temperature
- cardiovascular strain
- psychophysical strain
- metabolic strain
2 things affecting cardiovascular strain when exercising during the heat
different to normal temperature
- decreased blood pressure
- decreased blood flow to several tissues and organs
- decreased blood flow to skin, muscle and brain
what is the psychophysical strain of exercising in the heat
- increased perceived exertion
what is the metabolic strain of exercising in the heat
muscle glycogen depletion
what are the 5 major personal factors governing performance in the heat
- aerobic fitness
- heat acclimatisation
- initial physiological status
- recent illness
- hydration
what is the difference between heat acclimation and heat acclimatisation
acclimation = artificial, periodic exposure
acclimatisation = go to a warm place and naturally adapt to it
what processes does hypohydration (low body water) impair
- cardiovascular function
- sweat production
- cognition
how long should you allow for optimal acclimatisation
around 2 weeks
what is meant by hypo-hydration can wipe out the benefits of short term increase in fitness or acclimation
if you are dehydrated you are less able to tolerate the heat
5 other personal factors affecting performance in the heat
- medications
- body size
- age
- sex
- fatigue and sleep deprivation
how can age affect performance in the heat
mainly due to impaired cardiovascular response
- less behavioural capacity for young and older are less fit
is there such thing as sun stroke
no
how does sunburn effect the bodies ability to perform
- impairs sweat and skin blood flow responses
- tattoos do the same
what is heat syncope
fainting
what is the main feature and cause of heat syncope
main feature : especially if 1st day of exercise in the heat
cause : inadequate vasoconstriction and HR response to maintain blood pressure
why is heat exhaustion considered to be “less bad”
because it tends to prevent you from being active enough to get heat stroke
what is the main feature and cause of heat exhaustion
main feature : exhaustion, hot, flushed, sweaty, rapid HR
cause : homeostatic capacity exceeded, especially the cardiovascular system
what is the main feature and cause of exertional heat stroke
mai feature : complete exhaustion with central nervous system disturbance
cause : major cellular disturbances, mainly due to increased body temperature
what is the fastest way to cool someone down
immersion in cool or cold water
what can be dangerous with highly motivated, recreationally fit athletes exercising in the heat
they are competitive but dont have the high levels of fitness to deal with it
why can intense practice sessions have high heat strains for individuals
- early in summer
- unseasonally warm
- least fit people in team training drills
- protective clothing
5 strategies to decrease heat strain and increase heat performance
- increase aerobic fitness and heat acclimatisation
- decrease clothing and carried weight
- decrease exercise volume
- optimise plasma volume and osmolality
- artificial cooling
how could you decrease the exercise volume to decrease heat strain and increase heat performance
- shorten warm up
- decrease intensity
- decrease work to rest cycle
