Dynamic joint analysis as a method to document coordination disabilities associated with Parkinsonʹs disease

Objective. The purpose of the present study was to introduce dynamic joint analysis and subsequent phase partitioning of the movement pattern as a method for investigating the force control deficits associated with Parkinsonʹs disease. Design. Pilot data were collected from four non-impaired individuals and four patients afflicted with Parkinsonʹs disease while performing arm movements of different spatiotemporal features. Background. Investigation of motor performance in Parkinsonʹs patients has related the clinically observed symptoms to the ability to control muscular force. Methods. Experimental movements were filmed using a high speed camera operating at 200 Hz. The mechanical power characteristics of the elbow and shoulder were determined by applying inverse dynamic solutions to the kinematic data. Movement was reflected in a series of goal-directed phases describing the functional role of muscle activity across the joint. Results. The analysis revealed that Parkinsonʹs disease impairs the ability of the muscles to produce the energy required for performing ballistic, segmental movements. Moreover, patients demonstrated greater difficulty in controlling a two-joint task as opposed to a single-joint one; this was reflected by additional phases of activity at the elbow. Conclusions. Slowness of movement is associated with the inappropriate scaling of the muscle force, as well as with the limited use of motion-dependent forces in accelerating distal segment movement.