CHAPTER VI 

 MUSCULAR WORK 



Influence of muscular activity upon development. 

 The muscular system determines very largely the ac- 

 tivity of the other organs by its demands for food, oxy- 

 gen and the removal of its waste products. During the 

 years of growth from early infancy to the age of about 

 twenty, the various organs and tissues of the body are 

 being developed and perfected by these demands. If the- 

 muscular activity is slight, not only the muscular sys- 

 tem, but the heart, lungs, nervous system and every 

 other part of the body remain weak and poorly- 

 developed. If, on the contrary, the muscles are given 

 work in proportion to their strength and endurance, 

 every tissue of the body gets a generous and healthy 

 development. 



Play. All young animals possess an instinct for that 

 muscular development which is essential for their proper 

 growth. The joyous rolling and tumbling of kittens 

 and babies, the apparently aimless racing about and 

 frolicking of puppies and children, the happy play of 

 all growing animals, is nature's provision to insure ac- 

 tivity for the muscles, in order that their bodies may 

 attain full strength and complete development in every 

 part. The most valuable forms of play are active games, 

 which develop the strength and endurance demanded for 

 their success. They differ from both exercise and work 

 in that they are full of joyous excitement. During child- 



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