Q. What do you think about the machines that hang you upside down? They seem like they would feel good on my aching bones and probably help circulation but I think they would make me dizzy. I think they are called gravity machines or you wear gravity boots and hang like a bat.

A. Sorry that it took me some time to answer your question, but I admit that I have never used a gravity machine, studied them or known anyone who has. This is what I have discovered through research.

These devices are called inversion tables, gravity arcs and, yes, gravity boots. They are designed to "stretch, strengthen, and decompress your spine, neck and back; increase flexibility; and reduce stress." They are also supposed to "help strengthen your arms and legs, take the strain off the back and to strengthen the stabilizing muscles that hold the spine in its correct position."

I say "supposed" to because they sound too good to be true, just like so many of the other exercise machine claims.

Besides costing a large amount of money, these devices should be used with a great deal of care, and, I also feel, with the blessings of your physician. Even though the most sensible source of information I found agreed that using the inversion gravity boots can relieve back pain, decompress your spine, stretch your back and muscles, relieve stress, increase circulation, and help you maintain overall good health, they cautioned that inversion is not for everyone.

Do not use inversion products without your medical advisor's approval or if you have any of the following:

• Hiatal Hernia, Ventral Hernia
• Glaucoma, retinal detachment, or conjunctivitis.
• High blood pressure, hypertension, recent stroke or transient ischemic attack.
• Heart or circulatory disorders for which you are being treated.
• Spinal injury, Cerebral Sclerosis, and acutely swollen joints.
• Bone weakness (osteoporosis), recent unhealed fractures, meduallary pins, and surgically implanted orthopedic supports.
• The use of anti-coagulants, including high doses of aspirin.
• Middle ear infection.
• Extreme obesity
.

Personally, I don't think that we were made to hang upside down, but if inversion appeals to you, check out some of the more advanced Yoga positions with the legs up over the head or resting on the wall or on the exercise ball (which by the way costs less than $30 and will strengthen your back, help with flexibility, reduce stress, establish stability, and is a whole lot of fun!).