Effectiveness of Different Exercise-Based Interventions Combined or Not with Electrotherapy Versus McKenzie Method Alone for Nonspecific Chronic Neck Pain: A Systematic Review and Meta-Analysis

<b>Background/Objectives:</b> Chronic nonspecific neck pain is a common global health problem that diminishes people's quality of life and functionality. Strengthening and mobility exercises are a fundamental tool in managing this condition. Combined treatment with electrotherapy appears to have promising results; however, the evidence is limited. The aim of this review was to compare the effectiveness of therapeutic exercise combined with electrotherapy versus the McKenzie method alone in improving pain and disability in adults. <b>Methods:</b> A systematic review and meta-analysis of randomized clinical trials was conducted following the PRISMA guidelines. Studies published up to June 2025 were extracted from major scientific databases. High-quality studies evaluating therapeutic exercise with or without electrostimulation and studies evaluating the McKenzie method alone were analyzed, measuring short-term pain and disability through meta-analysis using random-effects models. The risk of bias of the included studies was assessed using the Cochrane Collaboration tool. <b>Results:</b> Seven studies were included (<i>N</i> = 441). The combination of therapeutic exercise with electrotherapy showed a significant reduction in pain (SMD -0.76 [-1.36, -0.16] (<i>p</i> = 0.01; 95% CI)), without additional benefits for disability (SMD -0.94 [-2.08, 0.20] (<i>p</i> = 0.1; 95% CI)) compared to exercise alone. Similarly, the McKenzie method presented statistically significant differences compared to other active interventions in reducing pain (SMD -0.61 [-1.01, -0.21] (<i>p</i> = 0.003; 95% CI)), while no significant differences were found for disability (SMD -0.31 [-1.78, 1.15] (<i>p</i> = 0.67; 95% CI)). Heterogeneity among studies was generally high. The results show short-term effects measured after completion of the intervention. <b>Conclusions:</b> Electrotherapy combined with exercise may provide short-term relief of nonspecific chronic neck pain, although the certainty of evidence is very low. Interferential current plus exercise and isolated McKenzie exercises showed short-term pain improvements, with no consistent benefits for disability. The methodological limitations, heterogeneity, small samples, and short follow-up warrant cautious interpretation. High-quality trials with standardized protocols and longer follow-up are needed.