STRENGTH OF MUSCLES.
A well-developed man can drag a little less than his own weight over a level surface, while a draught-horse can draw only two-thirds. The horse, therefore, is relatively weaker than man. There are some insects, however, which are able to move nearly fifty times their own weight.
From what you have learned about the importance of exercise, you will understand how necessary it is that every muscle should be trained. In no other way can you preserve sound, rugged health.