Changes in electromyographic activity of latent trigger points after a dry needling intervention: a randomised controlled trial

Objective To analyse the effects of dry needling (DN) in upper trapezius latent trigger points (LTrPs) on pressure pain threshold (PPT) and surface electromyography (sEMG). Design Randomized, double-blind, placebo controlled clinical trial. Settings Sports Rehabilitation Laboratory, University of Castilla-La Mancha. Participants Forty-six participants (18-35 years old) with LTrP in the upper trapezius were divided into two groups: DN-group and Sham-DN-group. Interventions In the DN-group, the needle was inserted 10-times through the skin, and it was manipulated up and down using a "fast in and out " technique. In the Sham-DN-group, non-penetrating needles were used. Main outcome measures PPT, sEMG at rest, and sEMG in isometric contraction of the LTrP of the upper trapezius muscle were evaluated at baseline, 30 min after treatment, and after 24 h, and 72 h of follow-up. Results The mean change in sEMG at rest between baseline and 30 min was - 0.38 (0.38) %refRMS for the DN group and - 0.05 (0.31) % refRMS for the Sham-DN group (mean difference -0.34, 95% confidence interval (CI) of the difference: - 0.54 to - 0.13), and between baseline and 24 h was - 0.35 (0.35) %refRMS for the DN group and - 0.06 (0.58) %refRMS for the Sham-DN group (mean difference -0.29, 95% CI: -0.57 to -0.01). In addition, the DN-group showed higher values of PPT than the Sham-DN group at 72 h (5.22 (1.23) to 4.65 (1.03) kg/cm(2); p < 0.05). Conclusions A single session of DN intervention was effective in reducing the electromyographic activity, muscle fatigue and pain of the upper trapezius muscle in LTrP.