From San Diego, at the Society for Neuroscience meeting
Brainpower can equal muscle power. So conclude Guang H. Yue of the Cleveland Clinic Foundation and his colleagues, who asked volunteers to think about contracting a finger or bending an elbow but not to perform the task. Over a 12-week regimen, in which volunteers did 50 mental contractions 5 days per week, the muscles powering the finger and elbow strengthened by 35 and 13.5 percent, respectively.
The muscles didn't actually grow in size, so Yue proposes that the mental practice strengthened the brain's signals to the muscles. He plans to test such mental flexing on people otherwise unlikely to exercise, such as stroke patients or the elderly.