Contextual and placebo effects of suboccipital myofascial release: evaluating its influence on pain threshold, cervical range of motion, and proprioception

Abstract

Background: Suboccipital myofascial release (MR) is widely used in manual therapy for addressing cervical dysfunction. However, its specific therapeutic effects remain unclear, especially when compared to sham interventions, raising questions about the roles of contextual and placebo influences. Objective: This study aimed to evaluate the immediate effects of suboccipital MR on pain pressure threshold(PPT), cervical range of motion (ROM), and proprioception, while considering the influence of non-specific effects such as placebo and contextual factors. Methods: A single-blind, sham-controlled randomized study was conducted with 30 asymptomatic participants (15 per group). The MR group received five minutes of suboccipital myofascial release, while the sham group received light touch without therapeutic pressure.Outcomes included PPT, cervical ROM (flexion, extension, and rotation), and proprioception, measured before and immediately after the intervention. A 2 × 2 mixed ANOVA was used to analyze group × time interaction and main effects. Paired t-tests were used as supportive within-group analyses. Results: The MR group showed within-group improvements in PPT (e.g., left-side PPT increased from 7.31 ± 2.58 to 8.67 ± 1.98 kg/cm², p = 0.028), cervical ROM (e.g., flexion improved from 57.00 ± 9.05° to 64.00 ± 9.60°, p = 0.0004), and proprioception (e.g., flexion reposition error decreased from 5.77 ± 2.24° to 3.70 ± 2.40°, p = 0.006). However, no significant group × time interactions were observed for any outcome, suggesting similar changes in both MR and sham groups. Conclusions: Suboccipital MR produced significant within-group improvements in PPT, cervical ROM, and proprioception. However, the absence of significant differences between the MR and sham interventions suggests that non-specific or contextual factors may account for the observed effects. Further studies are needed in symptomatic populations with longer follow-up and objective outcome measures to determine the specific efficacy of MR. Trial registration: This study was retrospectively registered with ClinicalTrials.gov under the identifier NCT06761391 on January 5, 2025.