Lung capacity is maintained by free movement and diminished by stooping postures and tight lacing.

Original passage

The lungs should be allowed the greatest freedom possible. Their capacity is developed by free action; it diminishes if they are cramped and compressed. Hence the ill effects of the practice so common, especially in sedentary pursuits, of stooping at one's work. In this position it is impossible to breathe deeply. Superficial breathing soon becomes a habit, and the lungs lose their power to expand. A similar effect is produced by tight lacing. Sufficient room is not given to the lower part of the chest; the abdominal muscles, which were designed to aid in breathing, do not have full play, and the lungs are restricted in their action.