Have you ever broken a bone and had to immobilize a limb in a cast? Do you remember how weak your muscles were once the cast was cut off? A new study indicates that imagination can be a useful tool in retaining muscle strength despite immobilization.
Brian C. Clark and colleagues from Ohio University called their study “The power of the mind: the cortex as a critical determinant of muscle strength/weakness.” Because mental imagery is known to activate the brain’s cortex, the research team put 29 adults in rigid casts that immobilized their left hand and wrist. Fourteen were told to perform this mental exercise: “Begin imagining that you are pushing in as hard as you can with your left wrist, push, push, push . . . and stop. [Five-second pause.] Start imagining that you are pushing in again as hard as you can, keep pushing, keep pushing . . . and stop.” This group did four blocks of 13 imagined contractions per session, for five sessions a week. The others performed no such exercises.
After four weeks, tests showed that the exercise group lost 50 percent less strength than the others. (Both groups were measured against a control group that was not immobilized at all.)
The study was published in December in the Journal of Neurophysiology.