Trunk Control in Unstable Sitting Posture during Functional Activities in Healthy Subjects and Patients with Multiple Sclerosis

Objective: To examine trunk stability in unstable sitting posture in 2 different functional activities. Design: A randomized crossover design. Setting: Rehabilitation center in Italy. Participants: Ten healthy subjects and 10 patients with multiple sclerosis. Interventions: Subjects were seated on an unstable support surface. A task in which the subjects had to keep their trunk as stable as possible was compared with tasks in which they had to track an object with the head or grasp an object. Main Outcome Measures: Angular displacement and mean absolute angular velocity in the anteroposterior and mediolateral planes of the support surface. Results: Angular displacement showed differences between patients and healthy subjects both in the sagittal plane (P