The effectiveness of neuromuscular spinal manipulation- an updated systematic review and meta-analysis

Background: Spinal manipulation has been increasingly researched over the past two decades for its potential to enhance motor function. In our review, we use the term Neuromuscular Spinal Manipulation (NSM) to specifically identify studies focused on the motor facilitation effects of spinal manipulation. Objective: To evaluate the efficacy of NSM in increasing muscle strength among healthy individuals through a systematic review and meta-analysis. Design: Systematic Review and Meta-Analysis. Methods: Databases including PubMed Central, Virtual Health Library, Cochrane Library, OSTMED.DR, and Google Scholar were searched up to September 2023. Eligible studies were randomized controlled trials and crossover studies on adults aged 18–65, assessing high-velocity, low-amplitude thrusts and Maitland grade III or IV mobilizations. Exclusions were studies on patients with pain/pathology, peripheral joint interventions, instrumental mobilizations, or co-interventions. Quality was appraised using the PEDro scale, and evidence graded with the Grading of Recommendations, Assessment, Development, and Evaluations (GRADE) approach. This review was registered with PROSPERO (CRD42022351923). Results: Of 7308 records, 10 articles met inclusion criteria, with 8 undergoing meta-analysis. A significant pooled effect on isometric muscle strength was observed (standardized mean difference +0.95, 95 % CI + 0.62 to +1.29) between NSM and controls, with heterogeneity I2 = 38 %. A high level of GRADE recommendation was; proposed according to the quality of evidence. Conclusion: NSM significantly enhances short-term isometric muscle strength in asymptomatic individuals, underscoring its potential clinical utility. Future research should aim to address the limitations noted, particularly regarding the long-term effects and underlying mechanisms of NSM.