MOTION AND LOCOMOTION. 157 



should be avoided. A lad of twenty-one or so may, if trained, 

 safely run a quarter-mile race, but to a man of forty-five it 

 would be dangerous, for with the rigidity of the cartilages 

 and blood-vessels which begins to show itself about that time 

 comes a diminished power of meeting a sudden violent de- 

 mand. On the other hand, the man of thirty would more 

 safely than the lad of nineteen or twenty undertake one of 

 the long-distance walking matches which have lately been in 

 vogue; the prolonged effort would be less dangerous to him, 

 though a six-days' match, with its attendant loss of sleep, 

 cannot fail to be more or less dangerous to any one. Prob- 

 ably for one engaged in active business a walk of two or 

 three miles to it in the morning and back again in the after- 

 noon is the best and most available exercise. The habit 

 which Americans have everywhere acquired, of never walking 

 when they can take a street car, is certainly detrimental to 

 the general health; though the extremes of heat and cold to 

 which we are subject often render it unavoidable. 



For women during middle life the same rules apply: there 

 should be some regular but not violent daily exercise. 



In Old Age the needful amount of exercise is less, and it 

 is still more important to avoid sudden or violent effort. 



Exercise for Invalids. This should be regulated under 

 medical advice. For feeble persons gymnastic exercises are 

 especially valuable, since from their variety they permit of 

 selection according to the condition of the individual; and 

 their amount can be conveniently controlled. 



Training. If any person attempt some unusual exercise 

 he soon finds that he loses breath, gets perhaps a " stitch 

 in the side," and feels his heart beating with unwonted 

 violence. If he persevere he will probably faint or vomit, 

 as is frequently seen in the case of imperfectly trained men at 

 the end of a hard boat-race. These phenomena are avoided 

 by careful gradual preparation known as " training." The 

 immediate cause of them lies in disturbances of the circula- 

 tory and respiratory organs, on which excessive work is 

 thrown. 



