This article is from the Stretching FAQ, by Brad Appleton Brad_Appleton@ivhs.mot.com with numerous contributions by others.
Proper breathing control is important for a successful stretch. Proper
breathing helps to relax the body, increases blood flow throughout the
body, and helps to mechanically remove lactic acid and other by-products of
You should be taking slow, relaxed breaths when you stretch, trying to
exhale as the muscle is stretching. Some even recommend increasing the
intensity of the stretch only while exhaling, holding the stretch in its
current position at all other times (this doesn't apply to isometric
The proper way to breathe is to inhale slowly through the nose, expanding
the abdomen (not the chest); hold the breath a moment; then exhale slowly
through the nose or mouth. Inhaling through the nose has several purposes
including cleaning the air and insuring proper temperature and humidity for
oxygen transfer into the lungs. The breath should be natural and the
diaphragm and abdomen should remain soft. There should be no force of the
breath. Some experts seem to prefer exhaling through the nose (as opposed
to through the mouth) saying that exhaling through the mouth causes
depression on the heart and that problems will ensue over the long term.
The rate of breathing should be controlled through the use of the glottis
in the back of the throat. This produces a very soft "hm-m-m-mn" sound
inside the throat as opposed to a sniffing sound in the nasal sinuses. The
exhalation should be controlled in a similar manner, but if you are
exhaling through the mouth, it should be with more of an "ah-h-h-h-h"
sound, like a sigh of relief.
As you breathe in, the diaphragm presses downward on the internal organs
and their associated blood vessels, squeezing the blood out of them. As
you exhale, the abdomen, its organs and muscles, and their blood vessels
flood with new blood. This rhythmic contraction and expansion of the
abdominal blood vessels is partially responsible for the circulation of
blood in the body. Also, the rhythmic pumping action helps to remove waste
products from the muscles in the torso. This pumping action is referred to
as the "respiratory pump". The respiratory pump is important during
stretching because increased blood flow to the stretched muscles improves
their elasticity, and increases the rate at which lactic acid is purged