The multicomponent nature of equilibrium in persons with parkinsonism: a regression approach.

Lower extremity strength and joint range of motion, body sway, and electromyography responses have all been determined to be factors in balance control of healthy older individuals. The purpose of this study was to identify variables which effect balance control (equilibrium scores) of persons with Parkinsonism, and examine their relationships and predictive abilities. The composite equilibrium score from the sensory organization protocol of the Equitest was used as the dependent variable for the regression analysis. The independent variables included: 1) strategy score; 2) path sway during voluntary body displacement; 3) percent peak torque of knee flexion relative to that of knee extension (%PTKFKE); 4) peak torque of inversion of the ankle at (PTINV); 5) dorsiflexion ROM; and 6) medium loop latency (EMG). The model produced a significant overall relationship accounting for 88% of the variability in equilibrium scores. Positive and significant coefficients indicated a predicted increase in the equilibrium composite score with increases in the strategy score, PTINV and %PTKFKE. These results suggest that postural control of persons with Parkinsonism can be strongly predicted by these three variables.