Interlimb coordination deficits in patients with Parkinson's disease during the production of two-joint oscillations in the sagittal plane.

Two-limb coordination patterns involving cyclical flexion-extension movements, performed in the same or in different directions, were studied in patients with Parkinson's disease and a group of elderly subjects. The three patterns referred to the homologous (both arms or legs), homolateral (right or left arm and leg), and heterolateral (right arm and left leg or vice versa) limb segment combinations that were performed in the sagittal plane from a seated position. Findings revealed that interlimb coordination deficits were evident in patients with Parkinson's disease. Moreover, mean cycle duration and its variability were increased, particularly during the production of nonhomologous limb movements in different directions. These temporal findings suggest that movement slowness was not a primary consequence of an intrinsic inability to move the limb segments at the required speed but rather reflected an intentional strategy to cope with the complexity of the coordination pattern. Finally, movement amplitude was substantially smaller and more variable in patients with Parkinson's disease, suggestive of hypometria during the production of these cyclical tasks.