them. So, too, in walking, how few use the muscles of the calf of the leg? Most people merely stamp along the path or road. They do not use the foot from heel to toe. They fail to rise on the toes at the end of the step, and do not push themselves along with those important members of the foot. Thus they lose the best part of the leverage of that important muscle or set of muscles of the lower leg. The fault is frequently in the shoe of the walker. That has too high a heel, and pinches the toes, making any movement of them painful, even if it does not prevent them from moving at all.
By making regular daily use of the muscles—of all the muscles, if that were possible—we should do one thing toward establishing perfect health of body by allowing to one very large part of it a fair chance to appropriate its proper elements from the blood, and opportunity to give back its used-up tissue to be eliminated from the system in natural and healthy ways. We should be doing more than simply repairing the muscles. We should be also evolving heat—a very important factor of life. We should be assisting all the other parts of our organization to do their work.
Take the heart—itself a very bundle of muscular fibers. We know that as long as we live, whether sleeping or waking, that wonderful organ keeps up its regular contractions and expansions. But, when we use our muscles, their contractile force upon the blood-vessels helps the blood along its channels, and thus takes a little labor from the propelling heart. It beats faster but with less effort.
While helping the heart, muscular exercise helps the lungs also. More exercise means for the lungs more breath; that is, more air inspired, and more carbonic-acid gas expired. By deeper breathings the involuntary muscles are strengthened. Moreover, we are made to feel the need of greater lung-room. Even after the age when full stature is supposed to be attained, that lung-room often comes, Nature furnishing the supply according to the demand. McLaren notes the case of one man, in his thirty-sixth year, whose chest, under systematic exercise, increased in girth from thirty-two to thirty-six and a half inches in two months. There was an addition of four and a half inches to the circumference of the chest. "An addition of—inches to circumference of chest implies that the lungs, instead of containing 250 cubic inches of air before their functional activity was exalted, are now capable of receiving 300 cubic inches into their cells."[1] This great increase, of four and a half inches, meant not only increase of lung room, but increase of lung-power.
| Taking the quantity of air inspired in the reclining position in a given time as the unit | 1 | |
| In the same period of time the quantity of air inspired when standing is | 1 | ·33 |
| When walking one mile per hour, is | 1 | ·9 |
| When walking four miles per hour, is | 5 | |
| When riding and trotting, is | 4 | ·05 |
| When swimming, is | 4 | ·33[2] |
