THE PHYSIOLOGY OF MUSCULAR WORK 1 



subject further, but it may not be amiss to point out how efficiently 

 movements are carried out ; the means are adapted to the end in 

 view, and by practice the man or animal unconsciously learns to 

 perform the movement in the most economical manner. " Practice 

 makes perfect " ; natural movements cause less fatigue than con- 

 ventional ones, and herein lies the explanation of the fact that 

 the pace and style of one man may be quite unsuited for another. 

 An adult experiences more fatigue when he adjusts his pace to 

 that of a child than when he walks the same distance at his usual 

 speed. A child learns to crawl, walk and run, even if it receives 

 no assistance from its mother ; healthy exercise is all that is needed, 

 and the experience thus obtained is a far better guide than any 

 system of teaching or drill. A movement which is suitable for one 

 individual is unsuitable for another ; some men have long legs, 

 some short legs, and each walks most efficiently at his own pace. 

 This is not sufficiently recognised by many trainers, but the re- 

 cords of many a contest on land and water show that style 'is a 

 personal factor which can never be rigidly fixed. 



Muscular work is not a localised expenditure of energy ; all 

 parts of the body are involved in a greater or smaller degree ; it is 

 useless to attempt to simplify the analysis of the process by experi- 

 ments upon the isolated muscle. Such a preparation is artificial, 

 and the issue is confounded. A recognition of the complexity 

 of the changes involved in muscular work enables us to under- 

 stand how far reaching are the effects which can be produced by 

 exercise. Anatomical changes are produced in the body ; not 

 only do the muscles become larger, but the pull exerted by them 

 causes changes in the size and shape of the bones. In certain 

 cases such great changes are produced by the repeated contrac- 

 tions of certain groups of muscles that the occupation of a man 

 may be determined by an examination of his skeleton ( 17 ). 



The law of the conservation of energy shows that without an 

 adequate supply of energy in the form of food there can be no 

 transformation into the energy of muscular work. The food must 

 be adjusted to the work obtained from a man or beast, a truth 

 which is constantly neglected with disastrous results. A man or 

 horse works best when he is well fed, and feeds best when he is 

 well worked. This is recognised by those who have extracted the 

 greatest and most prolonged efforts from each. Napoleon is 

 credited with the saying that " a soldier fights on his belly." A. 



