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.
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