Immediate Changes in Resting and Contracted Thickness of Transversus Abdominis After Dry Needling of Lumbar Multifidus in Healthy Participants: A Randomized Controlled Crossover Trial

Abstract

ObjectiveThe purpose of this study was to investigate changes in resting and/or contraction thickness of the transversus abdominis (TrA) muscle after dry needling (DN) of the lumbar multifidus (LM) in asymptomatic participants. MethodsA randomized controlled laboratory trial with crossover design was performed. Forty-seven healthy individuals who had not experienced low back pain in the previous 6 months were randomly assigned to receive DN to the LM or a sham-DN intervention. Participants received both interventions separated at least 7 days apart. They were instructed on how to perform a concentric contraction of TrA. Resting and contraction thicknesses of the TrA were obtained through real-time ultrasound measurements before and immediately after each intervention by an assessor blinded to the intervention received. Data from 4 individuals had to be excluded because of poor image quality. ResultsTwo-way analysis of variance revealed a significant contraction with treatment interaction (F[1,42] = 11.489; P = .002). Simple main effects using paired-samples t tests and a Bonferroni post hoc analysis revealed differences in contracted states of the TrA for DN vs sham-DN (P = .009) and between contracted and resting states for the DN group (P = .001): after DN, TrA thickness at rest exhibited a mean decrease of 0.03 cm and a mean increase of 0.05 cm during contraction. ConclusionThis study suggests that application of DN to LM was accompanied by a decreased resting thickness and an increased contraction thickness of the TrA in asymptomatic participants.