The physique of the recruit is systematically developed 



by setting-up exercises, marching, rifle and . . , M 



\ & . . ' ?.' Avoidance of 



sabre exercises, applied gymnastics, swim- _ . 



ming and athletic games. It is overstrain 



which the soldier must avoid, and " soldier's heart" has been 



a common complaint in Europe during the present war. 



Exercises should be varied so as not to overtax any one 



group of muscles and they should never be carried to the 



point of exhaustion. Breathlessness is a valuable danger 



signal of overload of the heart. 



It is not hard work that kills. It is prolonged strain at 

 dull tasks without variety, on the one hand, p , 



worry and excitement on the other. With __ . 



a proper variety of work it is marvellous 

 what the human mind and hand can accomplish, but they 

 cannot endure too long a pull without interruption. The 

 operatives in the Zeiss Optical Works at Jena actually did 

 more work in an eight-hour day than in one of nine hours. 

 They could keep fresh and vigorous for the shorter period, 

 while they began the nine-hour day in poor condition be- 

 cause imperfectly rested from the day before. 



The studies made in the English munition factories dur- 

 ing the present war have shown clearly that a limitation of 

 hours of labor may often lead to such an increase in pro- 

 duction; and this is a lesson we must bear in mind in this 

 country in the present crisis. 



The first rule of the hygiene of rest, then, is to avoid so 

 far as possible overstrain due to prolonged w - 



work of a similar kind. People vary a p ti 



good deal in their rest needs. Some men 

 are rested by a change of work, some by active play and 

 some by complete rest. Nothing, however, can take the 

 place of necessary sleep, and the average individual needs 

 about eight hours of sleep out of the twenty-four. No one 

 can work hard all day and play half the night. Nervous- 

 ness and irritability are danger signals. They mean that 



15 



