The Duration of the Breath
It is clear that as modern people, we breath too rapidly. Rapid breathing is associated with sympathetic shift, and shallow breathing is associated with dorsal shift. Many people have breathing that is both rapid and shallow.
It is common for modern people to take 14-18 breaths per minute. An optimal breath rate for vegetative balance is 6 breaths per minute or less. An important point to make, is that 'holding' the breath is never advantageous. Instead each breath should be longer, hence the concept of slowing breathing can be referred to as lengthening the duration of the breath. This provides for the best oxygenation and the most ventral shift.