Comparison of Motor Control Deficits During Treadmill and Overground Walking Poststroke

Background. Force-sensing split-belt treadmills (TMs) provide an alternative to the conventional overground (OG) setting and allow new avenues for analyzing the biomechanics and motor control of walking. However, walking control may differ on a TM compared with walking OG. Objective. To compare spatiotemporal, kinematic, and EMG-based measures of motor control between TM and OG walking at self-selected and fastest comfortable speeds in persons with poststroke hemiparesis. Methods. Individuals with chronic hemiparesis (56) and similarly aged healthy individuals (17) walked over an instrumented walkway and on an instrumented split-belt TM; 16 channels of EMG recorded bilateral muscle activity, and a 12-camera motion capture system collected bilateral 3D kinematics. The authors applied a nonnegative matrix factorization (NNMF) algorithm to examine the underlying patterns of motor control. Results. Self-selected walking patterns differed on the TM versus OG in controls: speed decreased, stride length decreased, stance percentage increased, and double-support percentage increased. Poststroke, responses were similar, but cadence also decreased, and step length asymmetry increased. Kinematic patterns were similar except those associated with slower walking speeds. NNMF demonstrated similar EMG variance in the 2 environments. Conclusion. Persons, both healthy and poststroke, walk with different gait parameters on the TM. Although measures of motor control were mostly similar between the 2 environments, the TM induced step length asymmetry in 30% of participants (60% of whom took longer paretic steps). TM walking, therefore, is a valid method for detecting motor control deficits.