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

Background and PurposeQuantitative 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. MethodsSixteen healthy young women wore knee braces, weighted vests, and ankle weights to simulate reduced physical function typical of older adults. Participants 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. ResultsThe 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. DiscussionThe iLEAN demonstrated acceptable inter-rater reliability in all directions, with the backward test showing the highest consistency. These findings suggest the iLEAN, particularly in the backward direction, may provide physiotherapists with a reliable and practical method to monitor changes in reactive balance control during exercise or rehabilitation, without reliance on specialized laboratory equipment.