Exercise environmental stress Flashcards
result in heat transfer from the body to the environment.
,it is a vital route for heat loss during exercise and in hot climatic conditions.
Evaporation
Loss of 1 liter of water?
leads to transfer of 2500KJ of heat to the environment
Factors that affect evaporative heat loss
individual’s level of fitness and/or acclimatization
Who sweats more ?
Fitter and acclimatized people sweat more and sweat earlier, the individual’s hydration level (de- or hypo-hydrated people sweat less)
Humidity and water vapour on air and skin
as well as the wind speed (windier conditions promote evaporation) and the humidity of the environment.
A humid environment already contains significant amounts of water vapor and thus is less able to accept water vapor from the surface of the skin.
adjustments to the body’s physiological responses to heat and humidity is called :
Acclimatization
acclimitzation helps perserve or lose sweat?
This makes the body more efficient at losing heat and more tolerant of heat stress.
Basic changes with acclimatization is affecting blood flow and sweating.
Humans are ……………… and are constantly exchanging (normally losing) heat to the environment.
homeothermic
humans have to be ………….. (i.e. they have to generate heat) normally via metabolism.
thermogenic
Is exercise thermogenic or homeothermic
thermogenic as large muscles causes metabolism which exerts heat
Whats more hard on the body , losing or gaining heat
It is also important to note that unlike heat generation (an active process) the body finds it more difficult to lose heat (in essence a passive process).
Summary of exercising in hot and humid environment
-Higher the exercise intensity the greater the sweat rate
-Maximal sweat rates is 2–3 L per hour
-Decrease in plasma volume - decreasing central blood volume and stroke volume.
-Increase in heart rate and thus more cardiac work.
-Aldosterone and Antidiuretic hormone, which will result in less urine production.
If heat stroke not treated, temperature will continue to rise and tissues such as muscles will begin to break down releasing proteins into the bloodstream (……………………) which can cause damage and failure in organs such as the heart and kidney
rhabdomyolysis
After acclimatization
Sweating starts earlier / Higher
Sweat is more dilute, preserving electrolyte balance
Reducing heart rate and cardiac output
The risk of heat illness is reduced.
Full acclimatization seems possible in 2–3 weeks.
Negative consequence
Increased chance of dehydration and thus hypovolemia.
Care - monitor fluid intake and recognize the increased fluid requirements after acclimatization.
After acclimatization
Sweating starts earlier / Higher
Sweat is more dilute, preserving electrolyte balance
Reducing heart rate and cardiac output
The risk of heat illness is reduced.
Full acclimatization seems possible in 2–3 weeks.
Negative consequence
Increased chance of dehydration and thus hypovolemia.
Care - monitor fluid intake and recognize the increased fluid requirements after acclimatization.
