A Misconception About the Diaphragm
Dennis Lewis

Over time, this diminished movement of the diaphragm becomes the norm for many people and the diaphragm in fact weakens and loses its ability to move through its entire potential range of motion (some five to six inches in the vertical direction), which means it often becomes incapable of moving fully downward or fully upward during the in-breath and the out-breath. When the diaphragm is unable to move freely and easily through its entire potential range of vertical motion, both our inhalation and our exhalation suffer and so does our voice, and eventually our health and well-being suffer as well. (Of course, it is not just the movements up and down that become restricted, it is also the horizontal and other movements and the shape and size of the diaphragm that is adversely affected.)