Figure 4.

The relationship among the center of mass (COM) anteroposterior (AP) velocity relative the base of support (BOS) (Velocity_COM,AP) at seat-off, the hip height (Height_hip) at the instant of the peak COM vertical velocity, and the outcome (success vs failure) during the sit-to-stand (STS) task for patients with Parkinson disease, including 18 successful trials and 14 failed trials. Individuals within the shaded area would be classified as likely to fall by the derived logistic regression model: p(fall) = [1 + exp(61.91Velocity_COM/BOS,AP + 76.02Height_hip − 35.17)]⁻¹ (P<.05 for all model coefficients). The limits of recovery differentiating successful and failed trials (the thick solid line) was derived based on the logistic regression equation. It is Height_hip=−0.814 Velocity_COM/BOS,AP + 0.463. This limits of recovery correctly classified 87.5% of the STS task outcome. Also shown is the mean and standard deviation of the 2 predictive variables for both groups. *P<.001.