ABSTRACT Context Stable resistance training (SRT) effectively enhances trunk strength and endurance but may insufficiently develop muscular coordination. Unstable resistance training (URT) potentially offers superior benefits for trunk function development. Although research has explored the benefits of SRT and URT, a direct comparison of their effects on trunk strength and endurance is lacking. Objective The aims of this study were to evaluate the effects of URT versus SRT on trunk strength and endurance in healthy individuals. Design A comprehensive search of SPORTDiscus, Web of Science, Scopus, and Ovid (all resources) and a partial search of Google Scholar were conducted up to December 2024. Study quality was assessed using the Tool for the Assessment of Study Quality and Reporting in Exercise (TESTEX). Eligibility Criteria Eligible studies included healthy individuals, compared resistance training with and without additional unstable surfaces or equipment, and assessed trunk strength and/or endurance. Study Selection Data extraction was independently conducted by two reviewers. Main Outcome Measures Means and standard deviations for trunk strength and endurance were extracted to calculate mean differences. Random-effects meta-analyses calculated Hedges’ g with 95% confidence intervals (CI). Results Seventeen studies with 836 participants were included. URT produced a statistically significant improvement in trunk endurance versus SRT ( g = 0.34; 95% CI, 0.12–0.56; P < 0.01). Subanalysis showed that URT enhanced dynamic trunk endurance ( g = 0.45; 95% CI, 0.19–0.71; P < 0.01) but not isometric trunk endurance. No statistically significant differences between groups were found in trunk flexion and extension strength. The included studies had satisfactory quality (mean TESTEX score: 9.1/15). Conclusion URT is more effective than SRT for enhancing trunk endurance, particularly dynamic trunk endurance, in healthy individuals. However, URT does not provide additional benefits for trunk strength. Practitioners aiming to improve trunk endurance for injury prevention and athletic performance should consider incorporating URT into training programs.
Xu et al. (Thu,) studied this question.