Constraining movement reveals motor capability in chronic stroke: an initial study

Objective: To determine if persons with chronic stroke and decreased hip and knee flexion during swing can walk with improved swing-phase kinematics when the task demands constrained gait to the sagittal plane. Design: A one-day, within-subject design comparing gait kinematics under two conditions: Unconstrained treadmill walking and a constrained condition in which the treadmill walking space is reduced to limit limb advancement to occur in the sagittal plane. Setting: Outpatient physical therapy clinic. Subjects: Eight individuals (mean age, 64.1 +/- 9.3, 2 F) with mild-moderate paresis were enrolled. Main measures: Spatiotemporal gait characteristics and swing-phase hip and knee range of motion during unconstrained and constrained treadmill walking were compared using paired t-test and Cohen's d (d) to determine effect size. Results: There was a significant, moderate-to-large effect of the constraint on hip flexion (p < 0.001, d = -1.1) during initial swing, and hip (p < 0.05, d = -0.8) and knee (p < 0.001, d = -1.1) flexion during midswing. There was a moderate effect of constraint on terminal swing knee flexion (p = 0.238, d = -0.6). Immediate and significant changes in step width (p < 0.05, d = 0.9) and paretic step length (p < 0.05, d = -0.5) were noted in the constrained condition compared with unconstrained. Conclusion: Constraining the treadmill walking path altered the gait patterns among the study's participants. The immediate change during constrained walking suggests that patients with chronic stroke may have underlying movement capability that they do not preferentially utilize.