Efficacy of Neuromuscular Electrical Stimulation in Mitigating Muscle Mass Loss: A Systematic Review and Meta-Analysis of Randomized Controlled Trials.

Abstract

Introduction/aims: Evidence for the stand-alone effect of neuromuscular electrical stimulation (NMES) on muscle mass in adults with sarcopenia or secondary muscle loss remains fragmented. This systematic review and meta-analysis aimed to quantify this effect and explore whether population, stimulation parameters, and assessment methods modified treatment effects.

Methods: Six electronic databases, including PubMed, Embase, and the Cochrane Library, were systematically searched for randomized controlled trials (RCTs) published between January 2000 and June 2025. Pooled effect sizes (standardized mean difference, SMD) were calculated using random-effects models (PROSPERO: CRD420251114043).

Results: Eighteen RCTs involving 676 participants yielded 19 independent effect estimates. NMES improved muscle mass compared with control conditions (SMD = 0.66, 95% CI = 0.30-1.02), with substantial heterogeneity. Leave-one-out sensitivity analyses did not alter the direction of effect. Subgroup analyses suggested differences by population and assessment method: community-dwelling older adults showed the most consistent benefit, whereas hemodialysis patients showed no clear improvement. CT/DXA-based measures yielded larger estimates than ultrasound-based regional measures or indirect methods. Meta-regression suggested a potential positive association between pulse width and effect size, whereas stimulation site and intervention duration were not clearly associated with treatment effects.

Discussion: Low-certainty evidence suggests that NMES may improve muscle mass in selected adults with sarcopenia or secondary muscle loss. Future trials should use standardized NMES protocols, reliable muscle-mass assessments, and clinically meaningful outcomes.