Thanks to my handy Google Alert I found the About.com CFS/Fibromyalgia page which has little blurb on Pilates...
"The Pilates method is not just a set of exercises but a complete approach to developing body awareness. It is a conditioning program that focuses on subtle movements to improve muscle control, flexibility, coordination, balance, strength and tone. Its application will strengthen and stretch the body’s core muscles. By taking weak abdominal muscles and strengthening them, the body becomes aligned. Since these core muscles support the spine and protect the body’s organs, as they become stronger the body as a whole becomes stronger. This result is reached over time as part of a natural evolution rather than other exercise programs that force the results.
[OK, the body does not simply become aligned simply by taking weak abdominal muscles and strengthening them! It becomes aligned through balanced strength and tone in all muscles around all joints. And the core muscles are not just abs, but include the diaphragm, pelvic floor, glutes, inner thighs, and back muscles. Realistically, other exercise programs do not have to force the results either.]
By practicing Pilates a person becomes more aware of their body as an integrated unit. By also practicing proper breathing techniques, as the body becomes more aligned you develop an increased efficiency of movement. The final result is a heightened sense of awareness.
[Proper breathing helps strengthen the abdominal muscles, unload the spine from the forces of gravity, and strengthen the diaphragm & pelvic floor. It's not just about awareness.]
Unlike weight bearing exercises, Pilates is designed to stretch and strengthen the muscles, open joints and release tension. Thus, the muscles grow longer and leaner. Blood flow is increased and energy begins to stream into specific areas of the body. Those who practice Pilates feel more energized and find their movements less restricted."
[Yes, yes, yes to what Pilates is designed to do. But that doesn't magically lengthen the muscles. It is the actual stretching in the closed kinetic chain environment of the equipment that allows for length & space. And Pilates when standing or working against the spring resistance is in fact weight bearing and can be properly modified for osteoporosis.]
I have done a lot of Pilates for CFS, Chronic Pain, Fibromyalgia. Equipment is better than mat; breathing and efficient movement are key; extension helps more than flexion; stretching between sessions is crucial! Pilates mat is NOT the best venue for people in chronic pain. Go slow, work with a good teacher, and you will feel better in about 6-8 weeks of 2-3 times per week sessions.