Low-Frequency Whole-Body Electromyostimulation (WB-EMS) for Nonspecific Chronic Back Pain: A Systematic Review and Meta-Analysis.

This systematic review aims to evaluate the effectiveness of low-frequency (LF) whole-body electromyostimulation (WB-EMS) in reducing pain and improving function in patients with nonspecific chronic back pain (NSCBP). Given the global prevalence of NSCBP and the limitations of conventional exercise due to time constraints and comorbidities, LF WB-EMS, a time-efficient and joint-friendly intervention, has emerged as a potential alternative. All prior PubMed studies on WB-EMS and back pain have exclusively investigated LF-EMS (0-999 Hz), and this review assesses its efficacy compared to a passive control group (PCG) or active control group (ACG), addressing a gap in understanding its clinical utility for NSCBP management. Following Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, PubMed and Physiotherapy Evidence Database (PEDro) were systematically searched for clinical trials from database inception to the present using inclusion criteria encompassing adults with NSCBP (pain >12 weeks, no specific cause), WB-EMS interventions, and randomized controlled trials (RCTs) or controlled clinical trials (CCTs) reporting pain and function outcomes. Data were extracted by two independent reviewers using a standardized form, and quality was assessed with the PEDro Scale. A narrative synthesis described study characteristics, while a meta-analysis using IBM SPSS Statistics software, version 22 (IBM Corp., Armonk, NY), employed an inverse variance-weighted method to pool standardized mean differences (SMD) with 95% confidence intervals, assessing heterogeneity with I². Studies lacking a distinct non-WB-EMS control group or with mixed control groups not clearly assignable to passive or active controls were excluded from comparative analysis but included in within-group analysis where appropriate. Six studies (n = 677, WB-EMS: 278, controls: 329) were included, comprising four RCTs, one CCT, and one meta-analysis (2017-2023). LF WB-EMS (20-minute sessions, once a week, eight to 16 weeks, 50-85 Hz) significantly reduced pain (-0.60 to -1.58 Numeric Rating Scale (NRS)/Visual Analog Scale (VAS)) and improved function (+7.19 kg to -15.8 Oswestry Disability Index (ODI)) within groups. Meta-analysis of five studies showed a pooled pain reduction of -0.87 (95% CI (-1.02, -0.72), I² = 70%) and functional SMD of 0.84 (95% CI (0.68, 0.99), I² = 76%). Against passive controls (n = 15/group), effect sizes were 0.75 (pain) and 0.85 (function), while versus active controls, pooled effects were 0.33 (pain, I² = 96%) and 0.28 (function, I² = 92%), with high heterogeneity. The results indicate that LF WB-EMS can reduce pain and improve function in NSCBP, with within-group effects of -0.87 NRS and 0.84 SMD and comparative effects of 0.75/0.85 vs. PCG and 0.33/0.28 vs. ACG, indicating potential benefits despite high heterogeneity and modest effect sizes. WB-EMS shows comparable efficacy to established methods, offering a promising option for patients with time or mobility constraints, supported by its safety and joint-friendly nature. However, limitations, including a small PCG sample (n=15) and limited research on medium-frequency WB-EMS, necessitate larger trials and further studies to optimize protocols and confirm long-term efficacy.