Older adults prioritize postural stability in the anterior–posterior direction to regain balance following volitional lateral step

• We compared postural strategies following lateral step between young and older adults.
• Older adults prioritize control of postural stability in the AP direction after completing a lateral step.
• Older adults use a strategy similar to young adults in the AP direction, but delayed in time.
• Older adults display large ML CoP velocity up to thirty seconds after taking a lateral step.
• A perturbation within 30 s would increase risk of falling.

BackgroundPostural control in the medial–lateral (ML) direction is of particular interest regarding the assessment of changes in postural control, as it is highly related to the risk of falling.ObjectiveTo determine the postural strategies used to regain balance following a voluntary lateral step and compare these strategies between young and older adults.MethodsSixteen older adults (60–90 years) and 14 young adults (20–40 years) were asked to stand quietly for 30 s, walk in place and then take a lateral step and stand quietly (30 s). Balance Post was divided into 10 s intervals. Center of pressure displacement (CoP) and velocity (VCoP) in the anterio-posterior (AP) and ML directions were analyzed.ResultsIn both groups, CoP and VCoP in AP and ML increased in Post1 compared to Pre (P < 0.001). Dissimilar to young adults, VCoP-Post2, Post3 ML were larger than Pre (P = 0.01) in older adults. Age correlated with all VCoP (Pre and Post) in both ML (P < 0.05) and AP directions (P < 0.01).ConclusionsDissimilar to young adults, older adults use different postural strategies in ML and AP directions and prioritized postural stability in the AP direction to recover balance after completing a lateral step. In the ML direction, older adults took up to 30 s to regain balance. Considering that age was related to larger CoP displacement and velocity, the AP strategy to recover postural balance following a lateral step could become less efficient as older adults age and therefore increasing the risk of falls.