Comment on: Effects of Sling Exercise Training on Walking Ability and Balance Function in Patients With Stroke: A Systematic Review and Meta‐Analysis

I read with great interest the systematic review and meta-analysis by Zhang et al. investigating the effects of sling exercise training (SET) on walking ability, balance function, and activities of daily living (ADL) in patients with stroke (Zhang et al. 2025). This comprehensive analysis of 23 studies involving 922 participants provides valuable evidence for the application of SET in stroke rehabilitation, particularly highlighting its beneficial effects on balance function, lower limb motor function, and walking ability. The study's rigorous search strategy across multiple databases and adherence to PRISMA guidelines enhance the credibility of its findings, filling an important gap in the evidence base for non-pharmacological stroke rehabilitation interventions. However, several critical considerations merit discussion to further contextualize the study's conclusions and guide future research. First, the substantial heterogeneity observed in key outcomes raises concerns about the generalizability of the results. For instance, the meta-analysis of balance function measured by the Berg Balance Scale (BBS) revealed a high level of heterogeneity (I2 = 89.4%), despite the use of a random-effects model. While the authors acknowledged this heterogeneity, they did not fully explore its potential sources—such as variations in SET intervention protocols (e.g., training frequency, duration, intensity, and suspension parameters) or patient characteristics (e.g., stroke subtype, severity, and rehabilitation stage). This lack of granularity makes it difficult to determine which specific subgroups of patients are most likely to benefit from SET and hinders the development of standardized clinical protocols. Notably, similar heterogeneity has been reported in previous meta-analyses of SET for stroke rehabilitation, emphasizing the need for more consistent study designs (Chen et al. 2016; Long et al. 2022). Second, the inconsistency in SET intervention standardization across included studies limits the translatability of the findings to clinical practice. The authors noted that SET implementation varied considerably among studies, with no uniform approach to training parameters (e.g., suspension height, resistance, and exercise content). This variability not only contributes to heterogeneity but also makes it challenging for clinicians to replicate the intervention and achieve consistent outcomes. For example, some studies may have focused on core stability training, while others emphasized gait simulation, leading to differential effects on the measured outcomes. The absence of a standardized SET protocol represents a critical barrier to the widespread adoption of this intervention in stroke rehabilitation, as highlighted in prior research (Long et al. 2022). Finally, the evidence for the effects of SET on ADL and walking endurance (assessed by the 6-min walk test, 6MWT) remains inconclusive and underdeveloped. The meta-analysis showed no statistically significant improvements in ADL (SMD = 0.73, 95% CI: −0.05 to 1.50) or 6MWT performance (SMD = 0.15, 95% CI: −0.22 to 0.53), yet the authors provided limited insight into the underlying reasons. Potential factors—such as insufficient intervention duration, suboptimal training intensity, or the multidimensional nature of ADL assessments—were not thoroughly explored. Additionally, the small number of studies included in these analyses (5 studies for ADL and 3 for 6MWT) raises concerns about statistical power and the potential for type II error, further weakening the reliability of these negative findings. Previous meta-analyses have also reported inconsistent effects of SET on ADL, suggesting that additional high-quality studies are needed to clarify this relationship (Chen et al. 2016). Despite these limitations, Zhang et al.'s study makes a valuable contribution to the field of stroke rehabilitation by confirming the potential of SET as an effective intervention for balance and motor function recovery. Future research should address these gaps by developing and validating standardized SET intervention protocols with clear parameters (e.g., training frequency, duration, and progression criteria) to reduce heterogeneity. Additionally, large-scale randomized controlled trials (RCTs) focusing on ADL and walking endurance outcomes are needed to clarify the long-term effects of SET, with subgroup analyses to identify optimal candidates for this intervention. Furthermore, exploring the combined application of SET with other rehabilitation strategies (e.g., robot-assisted gait training or virtual reality) may enhance its overall effectiveness, providing a more comprehensive approach to stroke rehabilitation (Akıncı et al. 2023). The authors are commended for their rigorous synthesis of existing evidence, and their work lays a solid foundation for advancing the clinical application of SET in stroke rehabilitation. Yi Wang: methodology, writing – original draft. Yang Duan: conceptualization, writing – review and editing. The authors have nothing to report. The authors declare no conflicts of interest.