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 mental 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 the Journal of Neurophysiology.