Young adults accelerate their arms significantly faster and earlier than old adults resulting in improved center of mass dynamics during an overground slip perturbation

Arm motions reduce the likelihood of falling from a slip in young adults, and injuries to older adults from falls are known to occur from a frontal plane fall. Therefore, the purpose of this study was to quantify the frontal plane trunk and arm motion in older and younger adults during a slip. Eleven older adults (age: 72.0 ± 5.0) and 11 younger adults (age: 25.17 ± 5.94) were subjected to a slip during walking. 27% of the older adults and 11% of the younger adults experienced a fall from the slip incident. The arm excursion did not significantly differ between groups, however younger adults’ average peak arm abduction occurred 310 ms prior to older adults (p = 0.03). There were no significant differences in peak trunk between groups. The arm abduction acceleration was significantly higher in younger adults compared to older adults (3593.2 ± 1144.8 vs. 2309.8 ± 1428.5 degrees/s 2 , p = 0.03). Furthermore, young adults exhibited a significantly reduced CoM excursion compared to old adults (4.55 ± 3.45 vs. 10.27 ± 6.62 cm, p < 0.01). Young adults may have exhibited lower fall rates due to the significantly higher acceleration of their arms compared to old adults.