[Interference versus low frequency. A comparison of 2 methods of electric muscle stimulation]

The purpose of this study was to determine whether inferential or low-frequency stimulation can produce a stronger and less painful contraction of the quadriceps femoris muscle in 20 healthy subjects. Both currents used a pulse rate of 50 Hz. The perceived discomfort experienced with each type of electrical stimulation was quantified by the use of a visual analogue scale. An isokinetic dynamometer (Cybex) was used to assess peak torque. Paired t-test demonstrated that inferential stimulation was perceived to be significantly less uncomfortable than low-frequency stimulation and that inferential stimulation produced a significantly greater peak torque of muscle contraction than low-frequency stimulation. This study indicates that inferential stimulation can produce an electrically induced muscle contraction which is stronger and less unpleasant than low-frequency stimulation.