Physical Exercise 73 



frequent but short rests. The trained runner, rinding his 

 respiration embarrassed, stops a moment to regain his 

 breath. Exercises of endurance cause fatigue less quickly 

 than those of speed, but require longer rest. 



105. Amount of Physical Exercise required. The amount 

 of physical exercise that can be safely performed by each 

 person is a most important and practical question. No 

 rule can be laid down, for what one person bears well may 

 prove very injurious to another. To a certain extent, each 

 must be guided by his own judgment. If, after taking 

 exercise, we feel fatigued and irritable, are subject to head- 

 ache and sleeplessness, or find it difficult to apply the mind 

 to our work, it is plain that we have been taxing our 

 strength unduly, and the warning should be heeded. 



It may be laid down as a fairly safe rule that an adult 

 of average height and weight, engaged in study or in any 

 indoor or sedentary occupation, should take an amount 

 of exercise equivalent to walking five or six miles a day. 

 Growing children, as a rule, take more exercise than this, 

 while most men working indoors take far less, and many 

 women take less exercise than men. Exercise may be 

 varied in many ways, the more the better ; but as far as 

 possible it should be taken in the open air. 



106. Amount of Exercise modified by Circumstances. 

 The proper amount of exercise must vary greatly with 

 circumstances. Thus, age is an important factor in the 

 problem. A young man may do with ease and safety 

 what might be injurious to an older person. In youth, 

 when the body is developing most rapidly, the judicious 

 use of games, sports, and gymnastics is most beneficial. 



Abundant evidence shows that physical development is 

 most active from the thirteenth to the seventeenth year; 

 this manifests itself clearly by increase in weight. Hence, 



