It is a question of a serious picture that develops after a person produces a heat quantity that is not eliminable for the system of refrigeration of the organism (dilation of the superficial blood glasses and sudoración), well because the production of corporal heat is excessive, well because the temperature ambience is very high or because the heat elimination mechanisms do not work perfectly, although the most common thing a combination of the three is. There are in special risk the elders, the small children, the disabled persons and those who realize physical works or sport exposed to high temperatures. There is no sure temperature limit: it depends on the realized exercise and on the mechanisms of adaptation.

In general it is recommended not to realize sport if the temperature ambience overcomes them 27,8th C, or, in any case, to be becoming accustomed progressively in the successive days, to drink abundant liquids and to suspend the exercise as soon as there appear muscular cramps, discomfort, weakness or morning sickness; if the environmental temperature overcomes them 34th C (more if the relative moisture is major than 60 %, because it makes the transpiration difficult) the heatstroke risk is high and it is necessary to avoid all kinds of exercise, to dress light clothes and to drink abundant liquids, although one does not feel thirst; cold baths are recommended, also. If in spite of everything fever appears and adormilamiento, one must come without delay to a hospitable center.