Study looks at pitting mind over muscle loss

When broken bones have to be immobilized in a cast, muscles grow weaker through disuse -- a necessary evil. A new study suggests that imagining the muscle activity involved in using the broken limb could be a useful tool in retaining muscle strength despite immobilization.

To test their hypothesis that the nervous system, especially the cortex of the brain, plays a crucial role in the maintenance or loss of muscle strength, Brian C. Clark and colleagues at Ohio University put 29 adults in rigid casts to immobilize the nondominant hand and wrist for four weeks. A control group of 15 people were not made to wear casts. All were in their late teens or early 20s.

Fourteen of the immobilized people were told to do regular 2-minute bouts of a mental exercise, imagining they were pressing against a handgrip off and on for five seconds at a time. For instance, they were told, "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 2-minute session, for five sessions a week. The other people in the study did no such exercises.

After four weeks, tests showed that the mental-exercise group had lost half as much strength as the group that did no mental exercise.

Among limitations of the study the authors acknowledge is the fact that they did not take muscle biopsies of test subjects, did not record the actual amount of muscle activity during the mental imaging exercises and were not able to quantify how well participants performed the mental exercise. Nevertheless they observed a significant result.

The study, "The Power of the Mind: The Cortex as a Critical Determinant of Muscle Strength/Weakness," was published in October in the Journal of Neurophysiology.

Nancy Szokan of The Washington Post contributed information to this report.

ActiveStyle on 01/19/2015

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