An investigation into the effectiveness of latent myofascial trigger point dry needling on muscle activation patterns.

Abstract

Background: Recent research on latent trigger points (LTrP) provides an opportunity to investigate the efficacy of trigger point (TrP) treatments without pain influencing results. One proposed negative outcome of LTrPs is an alteration in muscle activation patterns (MAPs), which is also associated with scapular dyskinesis and shoulder pathology. Using subjective (scapular dyskinesis tests) and objective (surface electromyography (sEMG) data) outcome measures to assess the efficacy of TrP treatment would be of benefit to both clinicians and researchers. Aim: To investigate the effectiveness of dry needling versus manual release and placebo dry needling on LTrPs in periscapular muscles. Methods: Inter- and intra-tester reliability and validity of the scapular dyskinesis test (SDT) and the scapular control test (SCT) were examined on 30 participants, prior to the inclusion of one in the main study. ICC analysis was used to assess reliability and t-tests were performed on sEMG data to assess validity. The effectiveness of LTrP dry needling, manual release, and placebo dry needling was then assessed on 60 participants to determine their effects on MAPs. Both subjective (SCT) and objective (sEMG data) outcome measures were utilised to assess the efficacy of the individual treatments. Wilcoxon signed rank and Kruskal-Wallis tests were carried out on the SCT data and a mixed between-within ANOVA was used for the sEMG data. Results: The SDT and SCT demonstrated good to excellent inter- and intra-tester reliability, however they were not valid at determining the presence of altered MAPs. There were no statistically significant differences in MAPs after any of the interventions, as assessed using both the SCT and sEMG data. Conclusion: The use of the SDT and the SCT to determine abnormalities in MAPs may be unjustified. LTrP dry needling and manual release treatments were ineffective at altering MAPs and further research is needed to assess their efficacy.