Originally Posted by
taai gihk yahn
that is so completely wrong, in so many ways, I almost can't even begin to tell you how much;
start with the fact that nothing "pulls down" on the diaphragm - it's a muscle, it contracts in two phases: centrally, and as such it descends, as a result of the contraction; the anterior abdominal wall expands because the diaphragm presses the abdominal viscera down and forward - and if you strongly contract your abdominals, it will counter this (ever heard of "reverse breathing", Mr. Qi?); the chest DOES expand to pull in air, because when the thoracic cavity expands, due to the secondary activity of the peripheral diaphragmatic fibers, (which can now contract because the central tendon is stabilized on top of the abdominal visceral mass), it create a negative pressure in the lungs when it does so; and if you do reverse breathing, you actually increase thoracic expansion, because the central tendon stabilizes sooner and more firmly, allowing a stronger and greater excursion of the peripheral fibers;
you know absolutely nothing about respiratory biomechanics / neuromuscular physiology, and I would suggest you at least go read a book on the topic before acting like an authority about something that you have no clue at all about in the slightest;