158 THE ACTION OF THE LIVING CELL 



Nowadays it is universally recognized that regular 

 exercise is necessary to insure a normal functioning 

 of an animal's organs and their efficient coordination 

 in bodily activities. Further, college and professional 

 athletes after proper training engage almost daily in 

 the most violent forms of exercise, and not only do not 

 suffer any serious consequences, but seem to be actu- 

 ally benefited by their exhausting performances. 

 Indeed, there is a prevalent impression that the 

 mortality rate among athletes is lower than among 

 non-athletic individuals. While a few statistical 

 studies of college men have appeared to indicate the 

 correctness of this opinion, we cannot seriously con- 

 sider such data, because as a rule the college athlete 

 is at the outset a selected individual — selected for his 

 healthy and vigorous constitution. Admitting this 

 source of error in such studies does not in any way 

 invalidate the common knowledge that properly regu- 

 lated exercise is distinctly beneficial to any animal. 



At first glance this appears to be paradoxical in 

 view of what has already been said concerning cytost 

 and its possible relation to muscular fatigue. In the 

 past much mystery has surrounded the mechanism by 

 which exercise results in beneficial effects to the organ- 

 ism. While the increased blood flow through the vari- 

 ous organs results in a more rapid removal of metab- 

 olites and a better nutritive supply, this cannot be 

 the sole beneficial factor; otherwise violent anger 

 with its concomitant increase in circulation should be 

 as stimulating to the organism as is exercise. 



During exercise an increased metabolism takes 

 place, the energy liberated in excess of the body re- 

 quirements being utilized to do the external work 



