All travelers speak of the physical deterioration of American men and women from the average old world standard. All agree that the want of muscular exercise, or the prevalence of particular obnoxious kinds are the predisposing causes of this deterioration...-Missouri Republican, August 30, 1863
Within a decade - partly owing to the example set by the general introduction of the Turner's societies and an appreciation of our national defect by teachers and writers for youth - a reform has set in, in the shape of gymnastic clubs, base ball clubs, and other organizations devoted to the cultivation of the physical man. These associations are highly praiseworthy, and are generally conducted with decorum. Few, except the best of our citizens, whether minors or adults, would seek satisfaction in innocent and beneficial recreation. Hence we find the much more numerous class of both who might lower the respectability of such diversions...and turn to the race-course, the gambling house, the grog-shop or the brothel.
I don't know if I've ever heard of the possibility that baseball spread and grew in popularity because of some kind of progressive reform pushing physical exercise. There was a reform movement in the 1870s, supporting shorter work weeks, that played a role in the growth of the number of amateur baseball clubs but I'm talking more about the origins of the game and how it spread in the 1850s and 1860s. With the growth of the urban population and the physically negative effects of an urban life, it seems possible that there could have been some kind of movement encouraging physical exercise during this period and baseball was in a position to take advantage of that. I don't really know if that's true but it's an interesting thought.