Physical therapy
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Randomized Controlled Trial Clinical Trial
Quadriceps femoris muscle torques and fatigue generated by neuromuscular electrical stimulation with three different waveforms.
Neuromuscular electrical stimulation is used by physical therapists to improve muscle performance. Optimal forms of stimulation settings are yet to be determined, as are possible sex-related differences in responsiveness to electrical stimulation. The objectives of the study were: (1) to compare the ability of 3 different waveforms to generate isometric contractions of the quadriceps femoris muscles of individuals without known impairments, (2) to compare muscle fatigue caused by repeated contractions induced by these same waveforms, and (3) to examine the effect of sex on muscle force production and fatigue induced by electrical stimulation. ⋯ Muscle torque and fatigue of electrically induced contractions depend on the waveform used to stimulate the contraction, with monophasic and biphasic waveforms having an advantage over the polyphasic waveform. All tested waveforms elicited, on average, stronger contractions in male subjects than in female subjects when measured as a percentage of MVIC.