Physical exercise in hot environment therefore poses additional problem. In spite of all the thetmoragulatory mechanisms, the temperalurense

redistribution to some extent and increases the load on the circulatory system. Anyway, keeping the body cod is more important than the redistribution d the blood. Physical exercise in hot environment therefore poses additional problem. In spite of all the thetmoragulatory mechanisms, the temperalurense d the body after a hard exercise may be considerable ithe body temp, becomes, say. about 39 C from a noirmal value of Second Wind' : Little after the onset d a long drawn physical exercise (e,g. long distance running) the breathing is often labored, and marked dyspnea left. But inspite d this, if the participant continues to do the exercise, sometmies after, the breathing eases up and the discomfort re-maikabry lessens {although the exercise is being continued; This phenomenon 10! easing up d the breathing and lessening up of the discomfort) is known as the second wind. Second wind can develop in the worki class athlete, as well as in untrained person. The explanation d the second wind is not satisfactonty known During the phase d discomfort, the PC02 c4 the lung alvedi becomes higher Than normal, with the development d second wind it becomes normal again. Thks suggests, that the removal of C02 from the lung alvedi. to the exterior, is at first, little unsatisfactory but Liter on becomes satisfactory. The higher C02 cone enttation of The lungat^eoli. therefore, may be one of the reasons ot the inrtial discomfort Water and electrolyte changes Sweating during exercise causes bss d bcdy water and sodium In prolonged exercise, particularly when the environment is both hot and humid Ihe loss may be considerable. Endccrinal changes Secretions d adrenalin and growth hoimone of anterior pituitary inclease. These explain the