Age-Related differences in arm acceleration and center of mass control during a slip incident

Arm abduction motion can help reduce lateral center of mass (CoM) excursion and restore balance within the frontal plane during slip perturbations. This study aimed to quantify and compare frontal plane arm kinematics and their relationship with CoM control between older and younger adults experiencing a slip. Eleven older adults (age: 72.0 ± 5.0 years) and eleven younger adults (age: 25.5 ± 6.1 years) underwent an induced slip perturbation while walking. Although peak arm abduction angles were similar between groups, younger adults achieved peak arm abduction significantly earlier (542 ± 67 ms) compared to older adults (853 ± 509 ms; p = 0.03). Additionally, younger adults exhibited significantly higher peak arm abduction acceleration compared to older adults (3593.21 ± 1144.80 vs. 2309.83 ± 1428.48 degrees/s²; p = 0.03). Younger adults also demonstrated significantly reduced lateral CoM excursion relative to older adults (4.6 ± 3.5 cm vs. 10.47 ± 6.6 cm; p < 0.01). Peak arm abduction acceleration negatively correlated with lateral CoM excursion (r = -0.52, p < 0.02), indicating that rapid arm movements are associated with improved balance control. A regression analysis confirmed arm abduction acceleration as a significant predictor of lateral CoM displacement (p = 0.005) meaning every 1000 degrees/s² increase in arm acceleration results in an approximate 2 cm decrease in lateral CoM displacement during a slip. These findings suggest older adults' diminished arm acceleration in response to slips potentially compromises their ability to stabilize their CoM effectively, highlighting a possible target for fall-prevention interventions.