OBJECTIVE: To determine the efficacy of using modulated middle frequency alternating current (MFAC) muscle stimulation for functional electric stimulation-propelled cycling by people with spinal cord injury (SCI) compared with the conventional method of using standard low-frequency rectangular pulses (LFRP). DESIGN: Repeated-measures. SETTING: Laboratory setting. PARTICIPANTS: Eleven otherwise healthy volunteer subjects with SCI (8 with American Spinal Injury Association [ASIA] grade A, 3 with ASIA grade B). INTERVENTIONS: To evaluate cycling-relevant differences between LFRP and modulated MFAC stimulation, we exposed participants to isometric measurements and cycling experiments performed during both 20 Hz LFRP and 4 KHz modulated with 50 Hz MFAC. MAIN OUTCOME MEASURES: We recorded maximal isometric torque, maximal dynamic work during 20 minutes of ergometer cycling, and perceived discomfort for each of the 2 stimulation patterns. RESULTS: Both the isometric torque (P<.02) and work generated (P<.001) during MFAC stimulation were significantly lower than during standard LFRP stimulation. Four participants reported discomfort and 1 of them also developed skin burns during MFAC stimulation. CONCLUSIONS: Our findings suggest that in SCI subjects, stimulated cycling with low frequency is generally more effective than cycling with modulated MFAC in terms of torque, work, and pain sensation.
OBJECTIVE: To determine the efficacy of using modulated middle frequency alternating current (MFAC) muscle stimulation for functional electric stimulation-propelled cycling by people with spinal cord injury (SCI) compared with the conventional method of using standard low-frequency rectangular pulses (LFRP). DESIGN: Repeated-measures. SETTING: Laboratory setting. PARTICIPANTS: Eleven otherwise healthy volunteer subjects with SCI (8 with American Spinal Injury Association [ASIA] grade A, 3 with ASIA grade B). INTERVENTIONS: To evaluate cycling-relevant differences between LFRP and modulated MFAC stimulation, we exposed participants to isometric measurements and cycling experiments performed during both 20 Hz LFRP and 4 KHz modulated with 50 Hz MFAC. MAIN OUTCOME MEASURES: We recorded maximal isometric torque, maximal dynamic work during 20 minutes of ergometer cycling, and perceived discomfort for each of the 2 stimulation patterns. RESULTS: Both the isometric torque (P<.02) and work generated (P<.001) during MFAC stimulation were significantly lower than during standard LFRP stimulation. Four participants reported discomfort and 1 of them also developed skin burns during MFAC stimulation. CONCLUSIONS: Our findings suggest that in SCI subjects, stimulated cycling with low frequency is generally more effective than cycling with modulated MFAC in terms of torque, work, and pain sensation.
Authors: Brian A Karamian; Nicholas Siegel; Blake Nourie; Mijail D Serruya; Robert F Heary; James S Harrop; Alexander R Vaccaro Journal: J Orthop Traumatol Date: 2022-01-06