142 THE HUMAN BODY. 



sudden violent demand. 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 heen 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 dan- 

 gerous to any one. Probably for one engaged in active 

 business a walk of a couple of miles to it in the morning 

 and back again in the afternoon is the best and most avail- 

 able exercise. The habit which Americans have everywhere 

 acquired, of never walking when they can take a horse-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 ex- 

 ercise. 



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 attempts some unusual exer- 

 cise he soon finds that he loses breath, gets perhaps a 

 " stitch in the side," and feels his heart beating with un- 

 wonted violence. If he perseveres he will probably faint 

 or vomit,as is frequently seen in imperfectly trained men 

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

 avoided by careful gradual preparation known as "train- 

 ing." The immediate cause of them lies in disturbances 

 of the circulatory and respiratory organs, on which excessive 

 work is thrown. 



