BACKGROUND AND AIMS: Aging is frequently accompanied by a deterioration in postural control, but it is not clear whether the primary contributor is increasing age or a progressive loss of functional balance capacity. The purpose of this study was to test the hypothesis that functional balance capacity contributes more than age to changes in postural response in the elderly. METHODS: The study considered 3 groups of healthy young, and functionally-stable and functionally-unstable older adults (N = 16 each group). Postural responses, including behavioral response patterns, joint angular displacement, displacement of the center of mass and center of pressure, and ground reaction forces, were induced and examined by submitting standing subjects to unexpected backward displacements in the surface supporting them. RESULTS: Functionally-stable older adults showed similar postural response patterns to those of young adults, whereas functionally-unstable older adults differed from young adults in the control of hip, trunk, shear force, and center of pressure trajectory during balance recovery. CONCLUSIONS: These findings support the hypothesis that changes in postural control in the elderly correlate with their functional balance capacity and are not just a matter of age.
BACKGROUND AND AIMS: Aging is frequently accompanied by a deterioration in postural control, but it is not clear whether the primary contributor is increasing age or a progressive loss of functional balance capacity. The purpose of this study was to test the hypothesis that functional balance capacity contributes more than age to changes in postural response in the elderly. METHODS: The study considered 3 groups of healthy young, and functionally-stable and functionally-unstable older adults (N = 16 each group). Postural responses, including behavioral response patterns, joint angular displacement, displacement of the center of mass and center of pressure, and ground reaction forces, were induced and examined by submitting standing subjects to unexpected backward displacements in the surface supporting them. RESULTS: Functionally-stable older adults showed similar postural response patterns to those of young adults, whereas functionally-unstable older adults differed from young adults in the control of hip, trunk, shear force, and center of pressure trajectory during balance recovery. CONCLUSIONS: These findings support the hypothesis that changes in postural control in the elderly correlate with their functional balance capacity and are not just a matter of age.