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. 2025 Apr 1;38(2):187-197.
doi: 10.3344/kjp.24332. Epub 2025 Mar 20.

Effectiveness of intramuscular electrical stimulation using conventional and inverse electrode placement methods on pressure pain threshold and electromyographic activity of the upper trapezius muscle with myofascial trigger points: a randomized clinical trial

Sukumar Shanmugam  1   2 , Fabio Vieira Dos Anjos  2   3 , Arthur de Sá Ferreira  2   3 , Ramprasad Muthukrishnan  1 , Praveen Kumar Kandakurti  1 , Satheeskumar Durairaj  1
Affiliations

Effectiveness of intramuscular electrical stimulation using conventional and inverse electrode placement methods on pressure pain threshold and electromyographic activity of the upper trapezius muscle with myofascial trigger points: a randomized clinical trial

Sukumar Shanmugam et al. Korean J Pain. .

Abstract

Background: This study investigates whether intramuscular electrical stimulation (IMES) with inverse electrode placement (IEP) or conventional electrode placement (CEP) more effectively modulates pain. The current study's aim was to compare the effects of IMES using IEP and CEP, and sham-IMES on the pressure pain threshold (PPT), EMG activity, upper trapezius (UT) muscle length and pain severity among adults with UT myofascial trigger points (MTrPs).

Methods: Thirty-six male adults with UT-MTrPs were allocated into three groups. IEP, CEP and sham groups were respectively treated with a single IMES session using IEP, CEP, and sham-IMES. Pain intensity, PPT, EMG activity (root mean square, RMS) and UT muscle length were measured on day one before the treatment, day one post treatment and at a day three follow-up to determine the immediate and short-term effectiveness of IMES.

Results: IMES using both IEP and CEP methods produced significant higher changes in UT-PPT (median, interquartile-interval, IEP group: 3.25, 2.56-3.50 and CEP group: 2.75, 1.75-3.00, vs. sham group: 1.07, 0.89-1.71 kg/cm2), RMS (IEP: 0.31, 0.26-0.35 and CEP: 0.36, 0.23-0.38, vs. sham: 0.21, 0.16-0.25 mV), and UT muscle length (IEP: 9.50, 8-12.75 and CEP: 8, 7-10, vs. 1.5. 1-2.75 degrees) and UT-pain severity (IEP: 3.00, 2.25-4 and CEP: 3, 3-3, vs. sham: 2, 2-2.75 points on VAS) compared to the score change in sham-IMES at day three follow up.

Conclusions: Pain modulation can be effectively achieved using IMES regardless of electrode placement method, with different electrode configurations.

Keywords: Electric Stimulation; Electromyography; Muscles; Neck Pain; Pain Measurement; Pain Threshold; Shoulder Pain; Skeletal; Trigger Points.

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Conflict of interest statement

CONFLICT OF INTEREST

No potential conflict of interest relevant to this article was reported.

Figures

Fig. 1
Fig. 1
Electrode placement method for delivering intramuscular electrical stimulation.
Fig. 2
Fig. 2
CONSORT (Consolidated Standards of Reporting Trials) flow chart presenting the study procedure. IMES: intramuscular electrical stimulation, IEP: inverse electrode placement, CEP: conventional electrode placement.
See this image and copyright information in PMC

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