Diaphragmatic dysfunction and activation interventions for chronic nonspecific low back pain: A systematic review and meta-analysis

Background Chronic nonspecific low back pain (CNLBP) is a leading cause of disability, with diaphragm dysfunction implicated in impaired spinal stability. However, systematic evidence on targeted interventions remains limited. Objective To quantify the efficacy of diaphragm-focused interventions on pain and function in CNLBP. Methods The systematic review/meta-analysis followed PRISMA-Cochrane guidelines. Analyzed randomized controlled trials (RCTs) assessing diaphragmatic interventions (manual therapy, respiratory training, neuromuscular re-education). Databases were searched until February 2025. Random-effects models and subgroup analyses were applied. Results Meta-analysis of 7 RCTs (n = 283) showed diaphragmatic interventions significantly reduced pain (overall SMD = −1.11, 95%CI: −1.52–−0.71, p < 0.01). Diaphragmatic training (SMD = −1.37) and manual therapy (SMD = −1.25) were most effective, while neuromuscular re-education was not significant (SMD = −0.62). For disability, overall SMD was −0.83（95%CI: −1.14–−0.52, p < 0.01, with manual therapy showing the largest effect size (SMD = −1.30), followed by diaphragmatic training (SMD = −0.69) and neuromuscular re-education (SMD = −0.47). Excluding one 4-week DNS study eliminated heterogeneity and increased pain effect to SMD = −1.24. Evidence certainty was low (GRADE). Conclusion Diaphragm-targeted interventions improve short-to-midterm pain and function. Future high-quality RCTs are needed to confirm long-term efficacy and standardize protocols.