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/cm2; 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. CONTRIBUTION OF PAPER:In healthy volunteers dry needling is effective.