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Optimal frequencies for electric stimulation using medium-frequency alternating current.

Alex R Ward·Valma J Robertson·Raphael J Makowski
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Abstract

OBJECTIVE: To determine the effect of single cycles of alternating current of various frequencies on sensory and motor thresholds and on relative thresholds (motor threshold/sensory threshold). DESIGN: Repeated-measures design. SETTING: Laboratory setting. PARTICIPANTS: University student and staff volunteers (N=16; mean age, 34y). INTERVENTIONS: Single cycles of sinewave frequencies between 1 and 35kHz were delivered at 50Hz. The frequencies were applied in a random order. MAIN OUTCOME MEASURES: The motor and sensory thresholds were recorded at each applied frequency. RESULTS: Both sensory and motor thresholds showed a smooth decrease to a minimum at approximately 3kHz. The relative threshold reached a minimum close to 9kHz. Comparison with previous studies showed that although absolute thresholds reach a minimum at a frequency that depends on electrode size, the frequency at which the relative threshold is a minimum was independent of electrode size and independent of whether the stimulus was applied as single pulses or in burst mode. CONCLUSIONS: The optimal frequency for transcutaneous stimulation using medium-frequency alternating current depends on the outcome measure used. It would therefore be desirable for clinical stimulators to provide a selection of carrier frequencies.

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AdultElectric StimulationElectrodesFemaleHumansMaleMiddle AgedMuscle, SkeletalPain ThresholdReference ValuesRegression AnalysisSensory ThresholdsClinical TrialJournal ArticleRandomized Controlled TrialResearch Support, Non-U.S. Gov't

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Alex R Ward, Valma J Robertson, Raphael J Makowski. 2002. Optimal frequencies for electric stimulation using medium-frequency alternating current.. https://doi.org/10.1053/apmr.2002.33116

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