When the circumference of the chest bears a due proportion to the size of the body generally; when its walls and the lungs possess a suitable degree of elasticity; when the strength of the respiratory muscles is adequate to their work, and no undue opposition is offered to the breathing motions by the clothing - then the vital volume is always up to the full requirements of the system. But when one or all of these are lacking in any important degree, the breathing capacity is proportionately diminished. If the testimony of the spirometer be corroborated by the impaired physical condition of the individual, its correction should be sought in part at least by enlarging the chest, increasing the elasticity of its walls and of the lungs, and by augmenting the strength of the respiratory muscles. These results may commonly be secured by diligent and persevering use of the following exercises:
A trapeze, Fig. 2, should be suspended from the ceiling, so that the bar shall be six inches above the head of the person who is to use it; the toes should be placed under straps nailed to the floor to keep them in position. Then if the bar be grasped and the body thrown forward, the trapeze, the arms, and the body will form the segment of a circle.
The exercise is taken by causing the body to describe a complete circle in the manner indicated in the cut. Little muscular effort is required if the motion be rapid, because the momentum is sufficient to carry the body around; but if the rotation be slow, more exertion is required. This movement is specially adapted to the breathing powers of weak persons, yet the most vigorous can readily get from it all the exercise their chest and lungs require.
By means of these exercises the chest is gently but effectively expanded in every direction and the elasticity of its walls promoted, the air cells are expanded, and the lungs are rendered more permeable to the respired air, and the strength of the respiratory muscles is developed.
Fig. 3 illustrates an exercise for the chest that is taken without any apparatus other than an ordinary doorway. The exerciser should stand in the position indicated in the engraving, and then step forward with each foot alternately as far as possible without stretching the chest too severely. The longer the step the more vigorous the exercise will be.
Fig. 4 shows an exercise taken between two chairs; the position indicated in the cut having been assumed, the chest is then slowly lowered and raised three to six times. This exercise is adapted to strong persons only.