The relation between limb loading and control parameters of gait initiation in persons with stroke

Objective: This study investigated the relation between limb loading and selected characteristics of gait initiation in patients after stroke. Subjects and Setting: Thirteen patients attending a rehabilitation clinic volunteered for the study. Design: For the description of clinical features, patients were divided into two groups dependent on the amount of body weight shared by the involved limb during stance before gait initiation. Main Outcome Measures: Patients performed six trials of gait initiation with either their involved or noninvolved limb on a force platform. Peak ground reaction forces and bilateral tibialis anterior and gastrocnemius electromyographic (EMG) activity were used for group comparison. Results: All patients showed the correct loading and unloading characteristics in the vertical and medial-lateral direction during gait initiation. Strong correlations were noted between initial limb loading and ground reaction forces during gait initiation ( r = .79 to .95). Changes in ground reaction forces were significantly less ( p < .001) for those patients who demonstrated decreased weight bearing on their involved limb before gait initiation. These patients were also unable to generate forward momentum, as evidenced by the fore-aft ground reaction force, with the involved limb. For all patients, increased gastrocnemius activity was noted in the stance (noninvolved) limb. The data are further discussed in regard to the relationship of the interaction of bilateral EMG activity and ground reaction forces. Conclusion: This study suggests that there is a correlation between symmetrical weight bearing and the ability to provide those forces than generate forward momentum in the initiation of gait.