For most qigong exercises, there are a number of details that make the practice more effective. The tongue position in the mouth is one of these details. The microcosmic orbit is an energy circuit that encircles the torso from front to back. This circuit consists of the Du Meridian, which starts at the perineum, goes up the back, over the head and to the upper palate of the mouth. The Ren Meridian goes from the tongue, down the throat, chest and abdomen to the perineum. Thus, placement of the tongue on the upper palate in the position indicated connects these two important extraordinary vessels when one is doing qigong exercises or meditation practices.
So, if you want to get the most out of your exercise as regards optimal energy flow, which is what qigong is all about, pay heed to this important detail.