Some Questions on Qi Gong: On warming down after practicing Qi Gong, and on Qi Gong and the Chakras.

1) Why is it recommended not to expose your body to cold water after a Qi gong work out?

Essentially the reason is that, after a Qi Gong workout all the cells of your body, and the pores of the skin are energetically open. So, any cold energy that the body is exposed to, such as having a cold shower or jumping into a cold swimming pool will immediately penetrate the body which can result in a chill. So this is the same reason that when people are living in the tropics they should be careful of exposing their bodies to cool breezes (eg by going into an air conditioned environment after having been outside for a while). The ''cold'' energy will penetrate deeply into the body because the body's energy gateways are open. If you imagine a house with all its doors and windows open, any breeze will immediately penetrate into the heart of the house from outside. It is the same with our bodies in hot temperatures or when we have been doing an activity such as Qi Gong.

2) What is the relationship between the ''three dan tiens'' of Qi Gong philosophy and practice and the seven chakras taught in yoga and other spiritual traditions?

Quite a lot could be written on this one, but essentially Qi Gong identifies three main energy centers within the body; the lower dan tien which is in the sacral area, and houses the vital energy (jing) that overlights our physical body. The middle dan tien which resides in the center of our torso around the heart level, which is the center of our mental and emotional energy (qi) as well as our ''soul body''. Finally the upper dan tien which resides in the center of the head and houses our spiritual energy (shen) and is the center of our ''spiritual body''.
So, I would quite simply say that these three dan tiens are a three fold way of dividing energy up (energy, mind, spirit), whereas the chakras are a sevenfold, or slightly more complex way of dividing up the same energy (physical, energetic/sexual, emotional/mental, soul, atmic, causal and spiritual).
Another central facet of Qi Gong practice is the ''microcosmic orbit'', which essentially consists of a yang channel or meridian rising from the perineum up the spine, back of neck and head to the crown, and then a yin channel or meridian that travels from the crown down the front of the face (through the tongue, which is why we keep it placed on the roof of the mouth in Qi Gong workouts), neck and torso, all the way back down to the perineum.
These two channels have 14 points, 7 in each channel, spaced along them.
These 14 points form 7 pairs, each facing each other at various points along the torso, head and neck. These opposing yang/yin energy points then create 7 energy vortexes in the center of the body in roughly the places where we are taught the seven chakras are.
So, from a Qi Gong point of view the seven chakras are essentially energy vortexes created by the opposing yin/yang polarities of the microcosmic orbit.