When heavy work has to be carried out in ambient temperatures of 25 C ,the elimination of excess heat throws an additional load upon the heart. An example of such a double loading is drop forging. . Hunting and his colleagues [1974] were able to show that holding the forging tongs during the operation caused considerable loads on the back and and arms,both static and dynamic. Working conditions were certainly strenuous and deliberate pauses of up to 60 per cent of the working time were noted.