Editing Hyperthermia (section)

===Exertional===
Significant physical exertion in hot conditions can generate heat beyond the ability to cool, because, in addition to the heat, humidity of the environment may reduce the efficiency of the body's normal cooling mechanisms.<ref name=Harrisons>{{cite book|author-link=Anthony Fauci |last=Fauci |first=Anthony |title= Harrison's Principles of Internal Medicine |edition=17th |publisher=McGraw-Hill Professional |year=2008 |isbn=978-0-07-146633-2 |pages=[https://archive.org/details/harrisonsprincip00asfa/page/n155 117]–121 |display-authors=etal |title-link=Harrison's Principles of Internal Medicine}}</ref> Human heat-loss mechanisms are limited primarily to sweating (which dissipates heat by [[evaporation]], assuming sufficiently low [[humidity]]) and [[vasodilation]] of skin vessels (which dissipates heat by [[convection]] proportional to the [[temperature]] difference between the body and its surroundings, according to [[Newton's law of cooling]]). Other factors, such as insufficient water intake, consuming alcohol, or lack of [[air conditioning]], can worsen the problem.

The increase in body temperature that results from a breakdown in thermoregulation affects the body biochemically. [[Enzyme]]s involved in metabolic pathways within the body such as cellular respiration fail to work effectively at higher temperatures, and further increases can lead them to [[Denaturation (biochemistry)|denature]], reducing their ability to catalyse essential chemical reactions. This loss of enzymatic control affects the functioning of major organs with high energy demands such as the heart and brain.<ref>{{Cite web|date=2020-09-22|title=Medically Sound: Crossing Thermometric Barriers (Searing Heat and Freezing Cold)|url=https://urmedlife.blogspot.com/2020/09/crossing-thermometric-borders-searing.html|access-date=2020-11-07|website=Medically Sound}}</ref> Loss of fluid and electrolytes cause [[heat cramps]] – slow muscular contraction and severe muscular spasm lasting between one and three minutes. Almost all cases of heat cramps involve vigorous physical exertion. Body temperature may remain normal or a little higher than normal and cramps are concentrated in heavily used muscles.