“Task-Oriented” Exercise Improves Hamstring Strength and Spastic Reflexes in Chronic Stroke Patients

Abstract

Background and Purpose —Despite the belief that after cerebral infarction only limited functional gains are possible beyond the subacute period, we tested the hypothesis that a 12-week program of “task-oriented” treadmill exercise would increase muscle strength and decrease spastic reflexes in chronic hemiparetic patients. Methods —Fourteen subjects, aged 66±3 (mean±SEM) years, with residual gait deviations due to remote stroke (>6 months), underwent repeated measures of reflexive and volitional (concentric and eccentric) torque with use of isokinetic dynamometry on the hamstring musculature bilaterally. Torque output was measured at 4 angular velocities (30 o , 60 o , 90 o , and 120 o /s). Results —After 3 months of 3 times/wk low-intensity aerobic exercise, there were significant main effects (2 legs [ P <0.01]×2 times [ P <0.01]×4 angular velocities [ P <0.05]) for concentric torque production. Torque/time production in the concentric mode also improved significantly in the paretic (50%, P <0.01) and nonparetic hamstrings (31%, P <0.01). Eccentric torque/time production increased by 21% ( P <0.01) and 22% ( P <0.01) in the paretic and nonparetic hamstrings, respectively. Passive (reflexive) torque/time generation in the paretic hamstrings decreased by 11% ( P <0.027). Reflexive torque/time was unchanged in the nonparetic hamstrings ( P =0.45). Conclusions —These findings provide evidence that progressive treadmill aerobic exercise training improves volitional torque and torque/time generation and reduces reflexive torque/time production in the hemiparetic limb. Strength changes associated with improved functional mobility in chronic hemiparetic stroke survivors after treadmill training will be reported in future articles.