64 MUSCULAR WORK 



are in excessive amounts, they weaken and fatigue the 

 whole body, including even those portions which have not 

 shared in the activity. From this more general form of 

 fatigue, prolonged rest in the form of sleep is necessary. 

 Recuperation. During rest, especially during sleep, 

 the waste products are removed from the body, and the 

 food supplies of the tissues are renewed and built up 

 into the special forms required for quick combustion, so 

 that .the body as a whole is ready to enter upon a new 

 period of activity. If the rest and sleep periods are too 

 short, recovery from fatigue is not complete and growth 

 in the young or full development of strength and effi- 

 ciency in the adult is impeded. 



