258 MOTION AND COORDINATION 



causes changes to take place more rapidly in the liquids 

 around the cells, thereby increasing the supply of food 

 and oxygen, and hastening the removal of waste. 



One should plan for Exercise. Since exercise is de- 

 manded by the nature and plan of the body, to neglect it 

 is a serious matter. People do not purposely omit exer- 

 cise, but from lack of time or from its interference with the 

 daily routine of duties, the needed amount is frequently 

 not taken. Especially is this true of students and others 

 who follow sedentary occupations. People of this class 

 should plan for exercise as they plan for the other great 

 needs of the body food, sleep, clothing, etc. It is only 

 by making a sufficient amount of muscular work or play a 

 regular part of the daily program that the needs of the 

 body for exercise are adequately supplied. 



Amount and Kind of Exercise. The amount of exer- 

 cise required varies greatly with different individuals, and 

 definite recommendations cannot be made. For each indi- 

 vidual also the amount should vary with the physical con- 

 dition and the other demands made upon the energy. 

 One in health should exercise sufficiently to keep the mus- 

 cles firm to the touch and the body in a vigorous condition. 



Of the many forms of exercise from which one may 

 choose, the question is again one of individual adaptability 

 and convenience. While the different forms of exercise 

 vary in their effects and may be made to serve different 

 purposes, the consideration of these is beyond the scope of 

 an elementary text. As a rule one will not go far wrong 

 by following his inclinations, observing of course the con- 

 ditions under which exercise is taken to the best advantage. 



General Rules for Healthful Exercise. That exercise 

 may secure the best results from the standpoint of health, 

 a number of conditions should be observed: i. It should 



