['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).', 'Repeated-measures.', 'Laboratory setting.', 'Eleven otherwise healthy volunteer subjects with SCI (8 with American Spinal Injury Association [ASIA] grade A, 3 with ASIA grade B).', '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.', 'We recorded maximal isometric torque, maximal dynamic work during 20 minutes of ergometer cycling, and perceived discomfort for each of the 2 stimulation patterns.', '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.'] Is low-frequency rectangular pulse superior to middle frequency alternating current stimulation in cycling of people with spinal cord injury?