After a few long, slow, deep exhalations
there is an automatic tendency to breathe in more deeply from the
We are going to try to accentuate this
tendency as far as possible. It is important to empty the lungs
thoroughly, thereby getting rid of the greatest amount of air.
This piston-like structure is however not
rigid, and unlike that of a motorcar is not flat, but convex rather
like the lip of a casserole dish. The diaphragm has a rather rigid,
flat central section - the aponeurotic - and is surrounded by a girdle
of peripheral muscles whose contraction determines its downward
movements: the diaphragm muscles are among the strongest in the human
body, or perhaps we should say, they are designed to be the strongest,
because their owner alas, may allow them to atrophy.
We can also understand why complete
relaxation is only possible once the lungs are emptied without forcible
exhalation - because at that moment the diaphragm muscles are at rest.