Electrical muscle stimulation is widely used during rehabilitation to promote muscle function recovery. Transcutaneous electrical nerve stimulation was recently used to relief dyspnea and improve pulmonary function in patients with chronic respiratory disease. Moreover, spinal anesthesia with fentanyl has been shown to be effective in improving exercise tolerance in patients with chronic obstructive pulmonary disease (inhibiting group III and IV muscle afferents). As transcutaneous electrical muscle stimulation stimulates the same receptors in the spinal cord dorsal horn as fentanyl, it is hypothesized that it could also improve exercise capacity.