Comparison of Voluntary and Electrical Stimulation Contraction Torques

Abstract

Informed male volunteers completed maximal isometric knee extension efforts under each of three contraction conditions: 1) voluntary, 2) electrical stimulation (ES) only, and 3) superimposed (ES superimposed onto voluntary). Ten subjects completed the three contraction conditions using each of the following current formats: 1) asymmetrical biphasic rectangular wave, 2) asymmetrical biphasic spike wave, and 3) symmetrical monophasic square wave. Under the voluntary and the superimposed contraction conditions no significant differences in mean torque were observed between the three current formats. However, under the ES contraction condition, the torque associated with the symmetrical monophasic square wave was significantly less than that associated with the other two current formats. As well, the torque associated with the asymmetrical biphasic spike wave was significantly less than that associated with the asymmetrical biphasic rectangular wave format. No significant difference was observed between the maximum voluntary contraction (MVC) and the superimposed contraction conditions for the groups receiving the asymmetrical biphasic spike and the symmetrical monophasic square wave current formats, or between all three contraction conditions for the group receiving the asymmetrical biphasic rectangular wave format. However, the ES condition was associated with significantly less torque than were the MVC and the superimposed conditions for the asymmetrical biphasic spike and the symmetrical monophasic square wave formats. In response to a posttest questionnaire, 18 of 30 subjects felt that the ES contraction produced greater torque than did MVC, and 26 subjects selected the superimposed condition as having produced greater torque than the ES condition. The different current formats, resulting in different levels of sensation and preception, and the different output capabilities of each electrical stimulator are considered to have been jointly responsible for the ES only torque discrepancies. It is suggested that ES does not recruit more motor units, resulting in a greater force of contraction, than are recruited under MVC.J Orthop Sports Phys Ther 1984;5(6):324-331.

Effects of unilateral electromyostimulation superimposed on voluntary training on strength and cross‐sectional area

“…It is proposed that subjects might perceive less discomfort, and therefore higher stimulation and training intensities could be achieved. 19,31,35 Previous studies have attempted to compare the effects of EV, EMS, and voluntary training and to examine the relationship between strength gains and EV training intensities. 31,35 However, these studies had some limitations.…”

“…16,45 In one study, the intensity of EMS was defined as 65% of MVC, 45 whereas the outcomes of the training were similar to the VC group, which trained at the same intensity. In another study, the EMS intensity was adjusted to each subject's level of tolerance, 16 even if it was not high enough to reach the torque levels shown in MVC 19 ; however, the strength gain was greater than that of the voluntary training group.…”

“…19 In our study, the EMS was superimposed on MVCs. It was hypothesized that EV training would cause additional training effects and greater cross-education compared with VC training, because it should activate the same neural pathways that are used normally in voluntary exercise, with an addition of the afferent inputs caused by the stimulation.…”

Effect of transcutaneous electromyostimulation on pressure pain threshold and tolerance in athletes under eccentric exercise

“…However, there are different opinions about the level of stimulation frequency in the current state of research. Although Kramer (1984) achieved the highest Mmax with 20 Hz, Cometti (1998) recommends impulse frequencies from 50 to 100 Hz. Binder-Macleod and Guerin (1990) came to a similar result.…”

Efecto del entrenamiento combinado de pliometría y electroestimulación en salto vertical. (Effect of combined plyometric and electrostimulation training on vertical jump).

“…Así por ejemplo, respecto al tipo de corriente empleada, ya Kramer, Lindsay, y Magee (1984) compararon la eficacia de diferentes tipos de corriente, donde la corriente bifásica asimétrica rectangular fue percibida como más confortable. Desde la década de los 90, en que Lake (1992) concluyó que la corriente bifásica era la más efectiva para provocar el mayor porcentaje de fuerza isométrica, y que la bifásica simétrica conseguía mejores resultados que la asimétrica, se comenzaron a establecer las bases para protocolos de entrenamiento, sirviendo de referente a estudios posteriores (Duchateau y Hainaut, 2003;Brocherie, Babault, Cometti, Maffiuletti, y Chatard, 2005;Babault, Cometti, Bernardm, Pousson, y Chatard, 2007).…”