Effect of rectangular and exponentially climbing waveforms on knee extension torque during neuromuscular electrical stimulation

Article type: Research Article

Authors: Tanino, Genichi^{a; b; *} | Tomita, Yutaka^a | Orand, Abbas^a | Takeda, Kotaro^a | Tomida, Ken^b | Miyasaka, Hiroyuki^{a; b} | Ohno, Kensuke^a | Okamoto, Sayaka^b | Sonoda, Shigeru^{a; b}

Affiliations: [a] Fujita Memorial Nanakuri Institute, Fujita Health University, Aichi, Japan | [b] Fujita Health University, Nanakuri Memorial Hospital, Mie, Japan

Correspondence: [*] Corresponding author: Genichi Tanino, Fujita Memorial Nanakuri Institute, Fujita Health University, 423 Oodori, Tsu, Mie 514-1296, Japan. Tel.: +81 59 252 2741; Fax: +81 59 252 0710; E-mail:[email protected]

Abstract: BACKGROUND: Electrical stimulation is shown to be effective for the amelioration of paralysis. The stimulation pattern can have a direct relation to injected charge in the stimulated area resulting in a wider area stimulation and consequently better recovery. OBJECTIVE: In this study, we investigated the effect of two electrical stimulation waveforms, rectangular and exponentially climbing. Three parameters of current, voltage, and knee extension torque of the 2 waveforms were recorded and used for the comparison of the two waveforms. METHODS: Fifteen male and 15 female able-bodied subjects (age: 25.0 ± 3.2) were recruited. Electrical stimulation was applied to right quadriceps muscles. At the maximum tolerable intensity, the 3 parameters were recorded for each of the 2 waveforms. Using the recorded knee extension torques, the adjusted maximum electrically induced contraction to voluntary torques in percent (%MEIC) of the two waveforms were calculated. Together with the other two parameters, current and voltage, the 2 waveforms were compared. RESULTS: The %MEIC and maximum voltage were significantly higher with the exponentially climbing waveform than with the rectangular waveform (%MEIC: p < 0.05, max voltage: p < 0.01). The maximum current did not differ significantly between conditions. CONCLUSION: These results indicate that an exponentially climbing waveform may induce stronger torque than a rectangular waveform and might thus be useful when applying NMES in clinical situations.

Keywords: Neuromuscular electrical stimulation, electrical stimulation waveform, knee extension torque

DOI: 10.3233/TAD-160450

Journal: Technology and Disability, vol. 28, no. 4, pp. 139-144, 2016