3/8 APPLIED PHYSIOLOGY 



to carry on the actions of the internal organs. Then 

 there will be less food prepared for the repair of the cells, 

 and to replenish the fuel for oxidation. So the whole 

 body, including the brain, will remain fatigued. Besides 

 the energy expended by the muscles, the brain also does a 

 large amount of work in sending orders for their work. 

 Probably the nervous system always becomes fatigued 

 before the muscles. 



679. Kinds of exercise. It is a problem for students 

 and clerks to determine how much exercise will rest and 

 stimulate the brain to the greatest degree, and yet take 

 no energy from it. The kind which a person enjoys best 

 is the best exercise for that person. If possible, the exer- 

 cise should be of a form which will turn one's thoughts 

 completely from the day's work and from the exercise 

 itself. So a useful occupation or some absorbing game is 

 especially valuable as exercise. Dumb bells, chest weights, 

 and all kinds of gymnastic exercises are excellent for 

 developing the muscles. Their only disadvantage is that 

 their use becomes monotonous, and a person must force 

 himself to use them. They have the advantage that they 

 can be exactly regulated to develop any defective part of 

 the body. When done in classes and under an instructor 

 they are especially valuable. 



680. Amount of exercise. A few moments of brisk 

 running or romping will set the blood flowing faster and 

 produce a clearer brain than an hour of slow walking. A 

 person's own feelings should warn him when to stop, 

 Boys and girls need plenty of exercise toward the. end of 

 their time of growth. A body well developed by exercise 

 carries its strength through life. 



In a school, a position upon either the baseball or football or athletic 

 team often uses the surplus energy which in former years was expended 



