Upside-down singing for Musical Theater

This is an old concept, really, put forth in the early 80's in a book called "Soprano on her Head," by Eloise Ristad.  Eloise very eloquently addressed some of  the mental processes that get in the way of free singing in her book and gave ideas for overcoming them.   I came back around to it this week, for two of my musical theater students.
When a singer is oriented to her low voice (chest register), both in speech and singing, then the head voice seems perceptually "high".  This perception alone give rise to certain types of tension in the back of the tongue and throat, as the singer then tries to  "reach" or "push up" the voice to the higher range.  So what if up became down?  Having a singer lean over at the hip joints until her head is even with her hips, face towards the floor, and sing, accomplishes several things at once.  It relaxes tongue and jaw, changes the head/spine relationship, activates the core stabilizer muscles of the cervical (neck) spine, opens the naso-pharynx (passage between throat and sinuses), encourages vibration in the facial bones (mask) and muddles the up/down perception.
Both singers who tried this idea in their lessons this week immediately had access to a clear, strong head voice with no "work" in their throats at all.  They did already have their breathing established and functioning well, which I think is a necessary precursor to this "trick".  And singers are marvelous creatures, really, because once they know what they are going for in terms of a sound or a coordination, they can head right back to it.  All you need to do sometimes is give them the experience.  Both singers then experimented with singing a high phrase both head over and then standing up, until the coordination was clear to them.  They also experimented with starting a phrase head over and then standing up while continuing to sing.  All the components, balanced head, deepened breath, loose jaw & tongue, loss of perception of "high" came together.
This trick certainly doesn't work for all students so immediately and easily, but at the appropriate time, can be a helpful tool in giving the singer an experience of what she is aiming for, when she is close to the goal already. The current musical theater sound in the upper middle register of the voice is very bright, clear and strong and requires the singer to find all the facial bone (mask) resonance available to her.  Both these singers already had access to their head voice, but not all the resonant power they needed and not all the freedom they needed.