Short-term effects of diaphragmatic myofascial release on pain, mobility, and disability in chronic nonspecific low back pain: a randomized sham-controlled trial.

Chronic nonspecific low back pain (CNSLBP) is a common condition often associated with impaired diaphragmatic and trunk function. The therapeutic effect of diaphragmatic myofascial release (DMR) in this population requires clarification. The aim of this study was to investigate the short-term effects of DMR on pain, mobility, balance, and disability in CNSLBP. In a randomized sham-controlled trial, twenty-four adults with CNSLBP were randomly assigned to receive three sessions of either DMR or a sham intervention. Both groups also received standardized transcutaneous electrical nerve stimulation (TENS). The primary outcome was pain intensity measured on a Visual Analog Scale (VAS). Secondary outcomes included lumbopelvic mobility (fingertip-to-floor test), static and dynamic balance (single-leg stance and functional reach tests), disability (Roland-Morris Disability Questionnaire, RMDQ), and chest expansion, were measured at baseline, after the third intervention session, and at one-week follow-up. A significant group × time interaction was detected for VAS (p < 0.001, η²ₚ = 0.33); the intervention group showed a significantly larger pain reduction than the sham group. Fingertip-to-floor also showed a significant group × time interaction (p = 0.04, η²ₚ = 0.13). Post-hoc tests showed a non-significant trend towards improvement in the intervention group from baseline to post-intervention (MD = 2.54 cm, p = 0.07) and from baseline to follow-up (MD = 1.93 cm, p = 0.08), whereas no such trend was observed in the control group (p > 0.05). Single-leg stance tests improved over time in both groups (p < 0.01) but there was no significant group × time interaction. No significant group or interaction effects were observed for functional reach or chest expansion. The RMDQ score decreased significantly in both groups, and the between-group comparison for disability change scores was statistically significant (p = 0.036), favoring the intervention group. DMR combined with TENS resulted in greater short‑term pain reduction and disability improvement, both exceeding minimal clinically important differences, compared with sham, and a non‑significant trend toward improved lumbar mobility. Static balance improved over time in both groups, with no between‑group differences. These results support DMR as a promising adjunct for managing pain, disability, and potentially balance in CNSLBP, but larger trials are needed to confirm its specific effects.Trial registration: IRCT20221216056836N1 (IRCT), registered on 28 February 2023.