The candidate is a Junior investigator and physical therapist presently conducting quantitative studies of balance and movement control as they pertain to the evaluation and restoration of functional movement in adults. His immediate long-term objectives are: to establish an independent research line dedicated to the study of movement dysfunction which impairs upright mobility in older adults; to identify age-related changes in functional movement control processes which lead to impaired upright mobility; to develop, implement, and test a comprehensive interactive systems model for the quantitative assessment of upright mobility in the aged; to identify patient specific and process specific interventions for the rehabilitation training of upright mobility in the elderly; and to test the efficacy of these rehabilitation approaches. The general hypotheses of this research are that protective stepping responses represent an important strategy for the preservation of balance in human bipeds, and that such responses deteriorate due to age-related changes in one or more neuromusculoskeletal mechanisms. Stepping response function among young adults and older individuals without and with a history of falls will be evaluated by examining muscle activation patterns, kinetic responses (ground reaction forces and resultant joint torques), and total body motion during intentional and induced stepping. The senior advisor and his research group are at the leading edge of Investigating fundamental interactive neural and musculoskeletal movement control processes and their applications to rehabilitation medicine. This approach has not previously been specifically applied to the multifactorial movement control problems which confront aging human beings. Close collaborations with the Sensory Motor Performance Program of the Rehabilitation Institute of Chicago, the Buehler Center on Aging of Northwestern University Medical School (NUMS), and the Division of Geriatric Medicine, (NUMS) will boost dramatically the applicant's research training efforts to advance physical therapy applications to problems of upright mobility in the aged. Additional training in operant conditioning based approaches to balance rehabilitation in the elderly will be acquired at the Rehabilitation and Training Center of Emory University which is a leading facility in the use of biofeedback rehabilitation.