In this study, phase plane analysis was used to describe the mechanisms involved in human intralimb dynamics during a multijoint coordinated task. Nonhandicapped, spastic, and athetoid cerebral palsied individuals were videotaped as they performed a stepping task. Kinematic data for the hip and knee joint angles were digitized, smoothed, differentiated, and plotted. Phase plane analysis of movement data reveals striking differences between nonhandicapped and cerebral palsied individuals. Whereas nonhandicapped individuals have trajectories in the phase plane that suggest a self-contained second-order dynamical system, cerebral palsied individuals have self-interesting loops in their phase planes. Based upon these patterns some dynamical distinctions are offered, and suggestions are made toward a possible model.
Request reprints from Dr. Anne Beuter, PED 107 Motor Behavior Laboratory, University of Southern California, Los Angeles, CA 90089-0652.
The authors wish to thank Professor Ralph Abraham (UC Santa Cruz) for his valuable ideas and comments. Partial funding for this study was provided by the USC Biomedical Research Fund.