Treadmill Aerobic Exercise Improves Quadriceps Strength in Patients with Chronic Hemiparesis Following Stroke: A Preliminary Report

Chronic neuromuscular impairments contribute to functional disability following stroke. Despite the widely held notion that only limited gains in motor performance are possible beyond the initial subacute stroke recovery period, we tested the hy pothesis that a “task-oriented” aerobic treadmill training program would improve lower extremity muscle strength and alter spastic reflexes in chronic hemiparetic patients. Fourteen subjects, aged 66 ± 3 (mean ± SEM) years, with mild to moderate hemi paresis and gait deviations due to remote stroke (>6 months) were entered in a pro gram of low intensity aerobic exercise (AEX) three times a week. Repeated measures of volitional (eccentric and concentric) and reflexive (spastic) torque generated by the quadriceps muscles were performed bilaterally using isokinetic dynamometry at four angular velocities (30°, 60°, 90°, and 120°/sec) before and after 3 months of AEX. Regular exercise training increased mean eccentric torque production significantly across all angular velocities in the more affected (51 percent) and less affected (25 percent) limbs. Similarly, concentric torque output increased in the more paretic and less paretic quadriceps by 38 percent and 17 percent, respectively. Reflexive torque gen eration was unchanged statistically. The greatest relative strength gains were seen in the more affected limb at higher eccentric angular velocities and at lower concentric velocities. These findings demonstrate that treadmill AEX training improves leg strength, which may in turn improve functional mobility in subjects with chronic hemi paresis.