The Effects of Aging Upon Nerve and Muscle Function and Their Importance for Neurorehabilitation

Abstract

Muscle strength and muscle mass are reduced with advancing age. There is now sub stantial evidence that these changes are due, at least in part, to a loss of motor units, but the selective atrophy of Type II fibers in some muscles suggests that inactivity or reduced motor unit recruitment may also play a role. With the steady expansion of the elderly population, clinicians involved in neurologic rehabilitation must be aware of the phys iologic changes that occur with advancing age as a result of a reduced number of nerve fibers, changes in the nerve fiber membrane, reduction in nerve fiber size, and decreased number of muscle fibers. There is also a remodeling and enlargement of the motor unit with increasing age. The practical implications of age-related changes for neurologic rehabilitation will be reviewed.