Falls can be prevented by compensating postural reactions to maintain balance. Reactive postural control maintains the centre of mass within the base of support during destabilizing perturbations (Sibley et al., 2013). Ageing affects balance control during walking, but research has focused on the sagittal plane, with limited examination of frontal plane disturbances in older adults (Afschrift et al., 2019). In postural control assessment, people may use a stepping strategy to maintain balance. It involves taking steps when balance is lost or perturbations occur, serving as a compensatory mechanism. Lateral disturbances impose unique demands on mediolateral protective stepping compared to anteroposterior (A-P) stepping. (Maki et al., 1996). A lateral disturbance while standing still causes the Center of Mass (COM) to shift, leading to a redistribution of weight under each leg. The leg on the opposite side of the fall becomes passively unloaded, allowing for a quicker foot lift-off and reducing the need for weight redistribution when stepping (Mille et al., 2005). Compensatory lateral stepping correction is a key element of the reactive postural response assessed in the Balance Evaluation Systems Test (BESTest). This test measures an individual’s ability to recover balance by taking a lateral step when suddenly released from a lateral lean position. The extent of lean angle and its impact on lateral-stepping characteristics were not measured in any of the studies.

Research has shown that the leaning angle influences the stepping pattern, and more research is required to understand the spatiotemporal parameters and inter & intra-rater variability of stepping reactions in young adults.

The purpose of this study is to measure the spatiotemporal parameters and the inter- /intra-rater variability of lateral stepping, which is initiated by a release from lean in healthy young adults. The findings of this study will be beneficial for the clinical assessment and training of reactive postural control for lateral stepping.