Aging Effects on Limb Trajectory Control and Dynamic Balance During Obstacle Negotiation.

Tripping over obstacles or an uneven walking surface is the most common cause of falls. This research investigated aging effects on swing foot clearance and dynamic balance during obstacle negotiation. Thirty-Four participants (15 young and 19 older adults) stepped over obstacles of 4 cm, 8 cm, and 16 cm with foot-obstacle clearance, toe-obstacle distance, Margin of Stability (MOS), and Available Response Time (ART) measured for the dominant and non-dominant lead and trail foot. Older adults exhibited higher toe clearance, particularly in the non-dominant limb, as a cautious adaptation to reduce tripping risk. Aging was, however, also associated with lower MOS and ART during trail limb clearance, decreasing the capacity for balance recovery. While the increased vertical margin between the foot and obstacle suggests a protective strategy, the concurrent decrease in MOS and ART indicates potential stability compromises. The finding of a cautious strategy to reduce tripping risk, countered by impaired balance recovery mechanics suggests the need for two targeted interventions - one to increase swing foot clearance and another to assist balance recovery in the event of tripping-related stability loss.