Effects of treadmill exercise on transcranial magnetic stimulation-induced excitability to quadriceps after stroke

Objective: To determine characteristics of transcranial magnetic stimulation (TMS)-induced measures of central motor excitability to the paretic and nonparetic quadriceps muscles of chronic hemiparetic stroke patients in the context of a short-term, submaximal bout treadmill exercise. Design: Cross-sectional. Setting: Motor control and gait biomechanics laboratory. Participants: Convenience sample of 11 patients including cohorts of treadmill untrained (n=8) and trained (n=3) stroke patients with chronic hemiparetic gait. Intervention: Short-term submaximal treadmill exercise. Main Outcome Measures: Thresholds, amplitudes and latencies of TMS-induced motor evoked potentials at vastus medialis in paretic and nonparetic lower extremities. Results: Baseline characteristics of the motor evoked potentials (MEPs) show significantly higher motor thresholds, longer latencies, and reduced amplitudes on the paretic side. In cross-sectional comparisons a group of treadmill-trained patients had greater paretic MEP amplitude changes after treadmill exercise versus paretic MEP responses from a group of untrained patients. Conclusions: These results indicate that treadmill training for 3 months or more may alter responsiveness of the lower-extremity central motor pathways to a short-term treadmill stimulus.