The brain's wiring of our organs enabled participants who just imagined exercising a limb to become significantly stronger (by 22 percent). Of course the group that actually performed the exercise had muscle strength increases of 30 percent. But, wow! Who would have thought? The details on the study can be found here: http://jn.physiology.org/content/67/5/1114.short but the explanation lies in " the motor neurons of the brain that program movements. During these imaginary contractions, the neurons responsible for string together sequences of insturctions for movements are activated and strengthened, resulting in increased strength when the muscles are contracted." (Doidge, p. 204)
Norman Doidge, MD wrote "The Brain that Changes Itself". There are many audiences for this book: health care professionals, educators, significant others of persons afflicted with stroke, OCD, amputation...or those interested in maintaining their optimal brain function. Written in an easy to read format he brings new light to the adage "use it or lose it." The studies on amputation were fascinating. He of course cited the mirror box experiment that has helped so many amputees with phantom pain. He explains why some amputees have increased sensation to other body areas because of the way the brain is wired. (Some male leg amputees, not complaining of suffering from leg pain as they now feel the orgasm not just in the area wired by male genitalia, but throughout the whole section of the brain that the leg once wired. These men are not complaining, one commented it was as if his genitalia was the size his leg had been!
Tantalizing as these tidbits are, the book is a fascinating read regarding stroke and OCD rehabilitation among other topics. These are the more sensationalized findings in a book with much to offer, to those who have "normal brains" as well as those with variations in pathology of the brain.