Influence of pain, sequential movement or short-term rest performance on the evaluation results of neck muscle mechanical properties: a case-control study

Introduction: Individuals with neck pain (NP) often experience altered muscle mechanical properties (MMPs), such as increased tone and stiffness. Myotonometry has become a reliable, noninvasive tool for measuring MMPs. However, the effect of movement and rest on MMPs in acute neck pain (ANP) individuals remains insufficiently explored. Objective: This study aimed to evaluate how sequential movement and short-term rest influence the MMPs of neck muscles in subjects with ANP. Methods: A case-control study was conducted with 37 subjects with APN and 37 matched healthy controls. Muscle mechanical properties were assessed by myotonometry at baseline, post-movement (after a motion assessment sequence), and post-rest. The outcome measures of MMPs were frequency or tone, stiffness, decrement, which is the inverse of elasticity, relaxation, and creep. Results: Subjects with ANP showed higher muscle tone, stiffness and decrement, and lower relaxation than controls, all with p < .05. In the ANP group, decrement was the only property that showed a significant change after movement and rest, both with p < .05. Reduced means values (m) with its standard deviation (SD) were observed post-movement (m = 1.35 & Oslash;, SD = 0.03) and post-rest (m = 1.33 & Oslash;, SD = 0.03) compared to baseline values (m = 1.43 & Oslash;, SD = 0.04). The other MMPs remained stable across evaluation times (p > .05). Conclusion: The evaluation of MMPs should be conducted prior to any mobility protocol to ensure that the results reflect the basal tissue characteristics in individuals with ANP, highlighting decrement as a sensitive marker of these changes.