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.

Effects of dry needling on mechanical and contractile properties of the upper trapezius with latent myofascial trigger points: A randomized controlled trial.

BACKGROUND: Latent trigger point (LTrP) can cause motor dysfunction and disturb normal patterns of motor recruitment. OBJECTIVE: To analyze the effects of DN in the upper trapezius (UT) LTrP on pain and the mechanical and contractile properties of the muscle. DESIGN: A randomized, double-blinded, parallel-group-trial. METHODS: Fifty healthy volunteers with LTrPs in the UT were randomly divided into a DN-group (n = 26) and a Sham-DN-group (n = 24) and received one session of DN or placebo treatment. Mechanical and contractile properties of the muscle and pressure pain perception (PPP) were evaluated before treatment and in a 30min, 24 h and 72 h follow-up after treatment. RESULTS: In the mechanical properties, the DN-group showed lower values than the Sham-DN-group for dynamic stiffness at 72 h (p = 0.04). The DN-group showed lower values for dynamic stiffness at 72 h from baseline (278.74 ± 38.40 to 261.54 ± 33.64 N/m; p = 0.01) and for tone at 72 h from 30min (16.62 ± 1.27 to 15.88 ± 1.31 Hz; p = 0.01). In the contractile properties, the DN-group showed higher values for maximal radial displacement (Dm) of the muscle belly at 72 h from baseline (5.38 ± 1.67 to 6.13 ± 1.70 mm; p = 0.04), higher values for contraction time at 30min (28.53 ± 8.80 s; p = 0.03) and lower ones at 72 h (24.74 ± 4.36 s; p = 0.04) from baseline (26.97 ± 6.63 s). The DN-group showed a decrease of PPP from baseline to 72 h after treatment (5.16 ± 1.33 to 4.02 ± 0.97 mm; p < 0.01). CONCLUSION: The application of DN in healthy volunteers over LTrPs in the UT decreased dynamic stiffness, tone and contraction time and increased Dm at 72 h after treatment. Additionally, the PPP showed a decrease at 72 h after needling. CLINICALTRIALS.GOV: NCT04466813.