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:

1. aerobic production
2. intrinsic smooth muscle contraction
3. movement of striated skeletal muscles
4. gravity
5. 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.