POSTURAL CONTROL IN YOUNG AND ELDERLY ADULTS WHEN STANCE IS CHALLENGED - CLINICAL VERSUS LABORATORY MEASUREMENTS

The use of dynamic posturography (EquiTest) for the characterization o f postural control biomechanics would be aided by specific knowledge o f what the measured data imply about body segment movements. To invest igate this issue, the biomechanics of a group of 15 healthy elderly su bjects were compared to those of healthy young subjects by using both dynamic posturography and a laboratory movement and force measuring sy stem. The results from EquiTest were analyzed by 1) routine clinical i nterpretation of data and 2) a clinical research interpretation by sub jecting the EquiTest parameters to additional statistical comparison o f mean performance of the young and elderly groups. The young-elderly differences from the 2 EquiTest analyses were then compared to the you ng-elderly differences derived from the laboratory protocol. The routi ne clinical interpretation of EquiTest data identified the same increa ses in sway shown by the laboratory study, but did not reveal the more subtle differences indicated by the laboratory study. When the EquiTe st data were subjected to additional statistical analysis, the charact erization of difference between young and elderly subjects was the sam e as that of the laboratory study, with the exception of issues of hea d versus trunk movement, a measure not made by EquiTest. This essentia l similarity in the characterization of elderly compared to young subj ects by both systems suggests 1) that EquiTest is able to detect subtl e differences in biomechanics of postural control between young and el derly healthy adult groups and 2) that implied movements of center of gravity, trunk versus lower limbs, and strength of reaction measures a re consistently detected by both EquiTest and the laboratory kinematic s and dynamics measurement systems.