If your car runs out of gas in an intersection, and you have to push it out of the way or get
killed, you will open your car door, put your shoulder on the doorframe, take a great big breath,
and push the car. You will probably not exhale except to take another quick breath until the car
and you are out of the way.
Furthermore, you will not even think about this, since the many millions of years your ancestors have spent pushing on heavy things has taught your central nervous system the correct way to push. Or you might find yourself grunting aloud during the
effort, a vocalization produced by a marked restriction in the airway at the glottis which produces
an increase in pressure during the partial exhalation.
This is perhaps the origin of the "kiyah" in martial arts, the vocalization that allows for an increased focus of power at the striking of a blow.