Effect of Increasing Obstacle Distances Task on Postural Stability Variables During Gait Initiation in Older Nonfallers and Fallers

•Older fallers conservatively vary anterior-posterior (AP) center of mass (CoM)-center of pressure (CoP) separation before toe-off of the gait initiation (GI).•Older fallers lean trunk more forward than nonfallers during swing phase of the GI.•AP CoM-CoP separation before toe-off of the GI distinguishes fallers vs non-fallers•GI during scaled obstacle distances can assess postural stability in older adults.•If task success affects AP CoM-CoP separation during the swing phase is unknown. To compare the scaling of the postural stability variables between older nonfallers and fallers during gait initiation (GI) while stepping over increasing obstacle distances. Cross-sectional study. University research laboratory. A sample of participants (N=24) divided into 2 groups: older nonfallers (n=12) and older fallers (n=12). Participants had no known neurologic, musculoskeletal, or cardiovascular conditions that could have affected their walking, and all were independent walkers. All the participants had an adequate cognitive function to participate as indicated by a score of more than 24 on the Mini-Mental State Examination. Not applicable. The primary dependent variables were peak anterior-posterior (AP) center of mass (CoM)-center of pressure (CoP) separation during anticipatory postural adjustments (APAs), AP CoM-CoP separation at the toe-off, and peak AP CoM-CoP separation during the swing. Secondary dependent variables were AP trunk angle during GI. Within- and between-repeated measures analysis of variance was used to compare means between groups across different task conditions for all the dependent variables. There was a main effect of group for peak AP CoM-CoP separation during APA (P=.018), an interaction effect between group and condition for AP CoM-CoP separation at toe-off (P=.009), and a main effect of condition for peak AP CoM-CoP separation during the swing (P