Quantitative analysis of rising from a chair in healthy and hemiparetic subjects.

In 15 healthy and 20 hemiparetic persons we studied standing-up by two force-plates. Phases before and after the seat-off, force distribution and centre of gravity displacement were assessed. The patients rose significantly slower. The force ratios after seat-off differed significantly between the groups (0.88 vs 0.68). Left/right hemiparetic patients put more weight on the affected limb in 18%/11% of the trials before seat-off, with its insufficient use after it mainly in the left patients. At seat-off, projection of the centre of gravity fell within the support area in hemiparetic patients, and 3 cm behind it in healthy subjects. With larger lateral displacement of the centre of gravity in the hemiparetic group, left hemiparetic patients mostly shifted their weight to the non-affected side and right hemiparetic patients to both sides. Weight distribution and mediolateral displacement of the centre of gravity in the left and right hemiparetic patients were considered.