Effects of Dry Needling on Muscle Stiffness in Latent Myofascial Trigger Points: A Randomized Controlled Trial

The aim of this study was to analyze the effects of dry needling (DN) in upper trapezius latent trigger points (LTrPs) on muscle stiffness. A total of 51 recreational physically active subjects with LTrPs in the upper trapezius volunteered to participate and were randomly divided into a DN-group (n = 27) and a sham-DN group (n = 24). Volunteers received 1-session of DN or placebo treatment. Muscle stiffness, measured with strain and shear-wave elastography, pressure pain threshold (PPT), post-needling soreness, and muscle thickness were evaluated before treatment, and at 30-min, 24-hours, and 72-hours follow-up after treatment. The DN-group showed lower values from baseline for muscle stiffness measured with shear-wave elastrography at 24-hours (from 44.44 +/- 15.97 to 35.78 +/- 11.65 kpa; P < .01) and at 72-hours (35.04 +/- 12.61 kpa; P < .01) and with strain elastography at 72-hours (from 1.75 +/- 0.50 to 1.36 +/- 0.40 AU; P < .01). The DN-group showed higher values of PPT than the sham-DN group at 72-hours (4.23 +/- 0.75 vs. 5.19 +/- 1.16 kg/cm(2); P < .05). There was a progressive decrease in post-needling soreness compared to pain during needling of 33.13 +/- 21.31% at 30-min, 80.92 +/- 10.06% at 24-hours, and a total decrease in post-needling soreness in all participants at 72-hours. DN therapy is effective in reducing short-term muscle stiffness and increasing the PPT in volunteers with LTrPs in the upper trapezius after a treatment session. Perspective: This study found that one session of DN intervention in latent trigger points of the upper trapezius muscle reduced muscle stiffness and the pressure pain threshold for the dry needling group compared to the sham dry needling group. (C) 2021 by United States Association for the Study of Pain, Inc.