Tentitive agreement exists on at least five mechanisms
for accomplishing the propulsion of the lymph that are
stimulated by Qigong and Yoga practices. These include:
- aerobic production
- intrinsic smooth muscle contraction
- movement of striated skeletal muscles
- gravity
- mechanical shifting of pressure gradients in the
body cavities.
a. Aerobic Propulsion-
The aerobic production of lymph contributes to lymph
propulsion by the cellular production of water as a
by-product of oxygen metabolism. The liquid holding capacity
of the tissue spaces is naturally limited. As the limit is
reached, the presence of additional lymph drives the excess
into the smooth muscle vessels of the lymphatic
system.(39,40,43,47)
In Qi Gong this mechanism is triggered by the
coordination of the breath with gentle movement which
increases oxygen demand in the cells. In response there is
an increased availability of oxygen which fuels chemical
energy productivity and consumption. The resultant
contribution of water as a by product increases tissue fluid
volume and drives the overflow into the vessels to become
lymph.(42)
It is noteworthy here that in Traditional Chinese
Medical theory it is taught that the "lungs regulate the
water passages"(48). To students from the west this seems
quite unusual and unfounded. However, we here can see that
the lungs and the breath both produce and circulate the
water in the body.
b. Intrinsic smooth muscle
contraction: autonomic propulsion-
The automatic response of the smooth muscle tissue of the
peripheral lymphatic vessels is to contract when filled and
stretched to a certain tolerance.(46) This moves the lymph
along in the vessel with the assistance of the one way
valves in much the same way as the heart moves the
blood.(42)
In Qi Gong and Yoga this mechanism is triggered by the
breath's contribution to lymph volume, as well as the
elevation of interstitial pressure caused by the postures
and the movement of the extremities. In addition, this
mechanism may be accelerated or enhanced by the shift of
autonomic function in the relaxation state that is a feature
of Qigong and Yoga.
c. Striated Skeletal Muscle: voluntary
propulsion-
Even the slight movement of skeletal muscle in a
sedentary individual propels the lymph in the one way
vessels. In an active person the lymphatic pumping of the
striated skeletal muscles is greatly multiplied. The effect
of muscle contraction on lymph is one of the classic
explanations for lymph motion.(40,42) In Qi Gong and Yoga
this mechanism is triggered by both the mechanical action of
the musculature of the breath apparatus and the action of
the skeleton through the relaxation and contraction of the
striated muscles in the moving forms of the practice.