60 THE LAW OF BIRTHS AND DEATHS 



of the nervous discharge. Therefore, to obtain more 

 rapid contraction it is necessary to expend energy on a 

 larger scale, and the swift sprint-runner expends a much 

 larger amount of nervous energy in a given time than the 

 long-distance runner. 1 



It would never do to train a man who is to run in 

 sprint races on the same system as the man who is to 

 run in long-distance races. Long-distance runners some- 

 times run in short-distance races with the object of im- 

 proving their speed. They are usually given a long 

 start, but are invariably hopelessly beaten. The sprint- 

 runner is generally of a more highly strung type than 

 the long-distance runner. The difference in the con- 

 stitutional organisation required for exercises of speed 

 and exercises of strength can be seen in the difference 

 between a race-horse and a cart-horse. The muscles of 

 the former cannot compare in bulk with those of the 

 latter, but the race-horse is the very embodiment of 

 nervous energy. The cart-horse, though possessing enor- 

 mous muscular strength, is of a placid disposition and 

 relatively deficient in nervous energy. If, then, speed 

 depends rather on nervous energy than muscular strength, 

 we can understand why a method of training suitable 

 for long-distance running is not suitable for sprint-running. 

 The exercises in the first case will be adapted to increase 

 muscular endurance ; in the second case mainly to increase 

 nervous energy. But if exercise does not increase the 

 amount of energy available, a special form of training 

 would practically be useless. 



A prize-fight demands an enormous expenditure both 

 of nervous energy and muscular strength. Throughout 

 the whole fight the contestant must keep his muscles 

 in a state which is known as " latent stimulation." The 



1 Physiology of Bodily Exercise, Fernand Lagrange, part i, chap. i. 



