Functional magnetic stimulation for conditioning of expiratory muscles in patients with spinal cord injury

Objective: To evaluate the effectiveness of functional magnetic stimulation (FMS) in conditioning expiratory muscles patients with spinal cord injury (SCI). Design: A prospective before-after trial. Setting: The Functional Magnetic Stimulation Laboratory of the SCI Health C are Group, VA Long Beach Health Care System, and the Spinal Cord Injury Ser vices, Department of Veterans Affairs, Pale Alto Health Care System. Participants: Eight men with tetraplegia. Intervention: Expiratory muscle training was achieved by placing a magnetic stimulator with a round magnetic coil along subjects' lower thoracic spine . Main Outcome Measures: Measures taken were the maximal expired pressure at total lung capacity (MEP-TLC) and at functional residual capacity (MEP-FRC) , expiratory reserve volume (ERV), and the forced expiratory flow rate at T LC (FEF-TLC) and at FRC (FEF-FRC) by subjects' voluntary maximal efforts. Results: After 4 weeks of conditioning, the mean +/- standard error of the mean values were. MEP-TLC, 55.3 +/- 8.6cmH(2)O; MEP-FRC, 29.6 +/- 5.6cmH(2) O; ERV, .57 +/-.08L; FEF-TLC, 4.3 +/- 0.5L/s; and FEF-FRC, 1.9 +/- 0.2L/s. These values correspond to, respectively, 129%, 137%, 162%, 109%, and 127% of pre-EMS conditioning values. When FMS was discontinued for 2 weeks, the MEP-TLC returned to its pre-FMS training value. Conclusion: A 4-week protocol of FMS of the expiratory muscles improves vol untary expiratory muscle strength significantly, indicating that FMS can be a noninvasive therapeutic technology in respiratory muscle training for pe rsons with tetraplegia.