The effect of dry needling on trapezius muscle activity and post needling soreness in participants with latent trapezius myofascial trigger points
Authors:   , Peter Steven J. 
Published: February 2022

Dry needling (DN) is an established and effective modality which is used globally for the treatment of myofascial trigger points (MFTPs). Post-needling soreness (PNS) is a common side effect which is felt shortly after DN at the site of needle insertion and peaks at 24 hours post-treatment. Research of its effects on muscle activity, range of motion, numerical pain rating scale and pain pressure threshold exist but focuses on pre- and post-needling measurements and a follow up measurement at 24 hours. This study objectively tried to investigate the effects of DN in the first few hours after treatment, in terms of pain pressure threshold (PPT), range of motion (ROM), surface electromyography (sEMG), and post needling soreness. Objectives To determine the effect of dry needling latent myofascial trigger points (LMFTPs) in the upper trapezius muscle with respect to: numerical pain rating scale (NRS), PPT, ROM and sEMG in the first four hours after treatment. Methodology This was a quantitative pre-test post-test design study with repeated follow up measurements. Through a purposive convenient sampling strategy, 15 asymptomatic volunteers were recruited into the study. Baseline readings were taken for the NRS, sEMG, PPT and ROM readings were then taken. After baseline readings were taken, the LMFTP was dry needled, and the measurements were taken again in the same order. The measurements were taken every hour for four hours post needling. IBM SPSS version 25 was used to analyse the data. A p value <0.05 was considered as statistically significant. Comparison of measurements over time were achieved using non-parametric Friedman tests for paired data. Post hoc tests were done in the case of a significant Friedman’s test in order to determine which pairs of measurements differed. Correlations between the changes over time of each measurement were done using non-parametric Spearman’s correlation. Results For the NRS there was a statistically significant increase in perceived pain at the first measurement post treatment (p < 0.001). While there was no significant difference in algometer measurements over time (p = 0.321). CROM showed an improvement in all tested movements: ipsilateral PA rotation (p < 0.001), contralateral PA rotation (p < 0.001), ipsilateral lateral flexion (p = 0.001) and contralateral lateral flexion (p < 0.001). With regards to sEMG root mean square (RMS) There was no difference between the time points (p = 0. 534). The following correlations were noted: Changes in contralateral and ipsilateral PA rotation were strongly positively correlated together (rho = 0.711). Changes in ipsilateral PA rotation was negatively correlated with change in 1- minute rest (rho = -0.569). Changes in contralateral PA rotation was positively correlated with change in mean contraction (rho = 0.527). Conclusions In conclusion, the results of this study show that DN of LMFTPs in the upper trapezius muscle may be effective at improving CROM without eliciting a strong PNS effect or a significant drop in PPT. As this is one of the few studies that exist to test objective and subjective results in the first four hours after needling, it is difficult to draw strong conclusions.