These legs were made for propulsion: advancing the diagnosis and treatment of post-stroke propulsion deficits

摘要

THE fast, economical, and stable gait that is characteristic of healthy bipedal locomotion [1–6] requires the coordination of three locomotor subtasks—propulsion, limb advancement, and bodyweight support. During the propulsion locomotor subtask, positive work by the trailing limb accelerates the body into the next gait cycle [7]. To walk faster, people with intact neural control symmetrically increase the positive work performed by each limb [8–10]. The coordinated modulation of the work performed by each limb leverages the natural oscillatory dynamics that arise from repeating foot-ground interactions to optimize stability and economy of effort while regulating walking speed [6, 10]. In contrast, the hemiparetic gait observed after stroke [11–13] is slow [14–17], metabolically expensive [10, 15, 18–20], and unstable [21–24]. In neurologically unimpaired individuals, the plantarflexor muscles are the primary generators of positive work [9]; however, post-stroke neuromotor deficits result in a distal-to-proximal redistribution of the positive work generated by the muscles of the paretic limb [10, 25, 26], and, ultimately, a markedly altered profile for the anterior ground reaction force (i.e., the propulsion force) [27].