Inter-rater reliability of the instrumented lean-and-release (iLEAN) test for manual assessment of reactive balance: a pilot study in simulated older adults.

[Purpose] Quantitative assessment of reactive balance often requires large, costly equipment, limiting its use in clinical practice. This study investigated the inter-rater reliability of the instrumented lean-and-release (iLEAN) test, a manual reactive balance assessment designed to provide a practical alternative for physiotherapists. [Participants and Methods] Sixteen healthy young women completed the iLEAN test in standing, where reactive balance control was assessed in forward, left, right, and backward directions. During tests, an assessor applied the iLEAN device against the shoulder and released support once the participant reached a target lean load, which was progressively increased until balance could not be regained with a single step. Inter-rater reliability was analyzed using intraclass correlation coefficients (ICC, model 2,1) and Bland-Altman plots. [Results] The ICCs (95% confidence intervals) for the iLEAN scores were 0.60 (0.17-0.84) for forward, 0.75 (0.34-0.92) for left, 0.80 (0.45-0.94) for right, and 0.83 (0.58-0.94) for backward. Bland-Altman analysis revealed no systematic bias between raters across all directions. [Conclusion] This study provides preliminary evidence that the iLEAN test has acceptable inter-rater reliability for assessing reactive balance, with the backward condition demonstrating the highest reliability and sensitivity to change.