Wrist extensor torque production and discomfort associated with low frequency and burst-modulated kilohertz-frequency currents

Background and Purpose. A randomized controlled trial to compare 2 forms of monophasic pulsed currents with 2 forms of burst-modulated, kilohertz-frequency alternating current ("Russian current" and "Aussie current") was conducted to establish whether different amounts of wrist extensor torque were produced and whether discomfort varied with stimulus type. Subjects. The 32 subjects were adults who were healthy and were drawn from a population of staff and students at La Trobe University. Methods. Each subject received all 4 currents. Maximal electrically induced torque (MEIT) of the wrist extensors was measured for each stimulus type. Relative discomfort of stimulation also was assessed. Results. Russian current elicited lower mean torque than those elicited by Aussie current and monophasic pulsed currents. The Russian and Aussie currents elicited significantly less discomfort than the 2 monophasic pulsed currents. Discussion and Conclusion. When force production and relative discomfort were jointly used as the criteria, Aussie current was found to be more effective than either of the monophasic pulsed currents or Russian current stimulation.