Effects of obesity on slip-related falls among young adults during gait

Falls present serious medical, health, and societal challenges to not only the frail elderly or individuals with mobility disorders; but also the active and vigorous older adults. Slip-related falls account for about 40% of all falls among older adults. Individuals with obesity are subject to an elevated risk of falls associated with muscle weakness, abnormal body mass distribution, and postural instability. Dynamic gait stability has been identified as a key factor leading to falls after a slip during gait. Despite individuals with obesity suffer higher risk of falls compared to their lean counterparts, no study has investigated how the dynamic stability differs between obese and lean individuals during unperturbed (normal walking) or perturbed (gait slip) walking, and how obesity affects slip-related falls. The overall purpose of this study was to examine whether and to what extent the dynamic gait stability during unperturbed and perturbed gait, as well as the risk of falls in responding to an unexpected slip induced during walking differ between young lean and obese individuals. Forty-six young adults including 23 lean and 23 obese participated in the study. Participants were informed that they would be performing normal walking initially and would experience a simulated slip later without knowing when and how that would happen while walking on the treadmill. After approximately five normal walking trials, all subjects were exposed to the identical and unexpected slip with the perturbation level of 12 m/s2. Compared with the lean group, individuals with obesity exhibited comparable dynamic stability during normal walking possibly due to their cautious gait pattern. In response to the novel slip, individuals with obesity were less stable at the recovery foot touchdown in comparison with lean individuals. As a result, more people with obesity fell compared to their lean counterparts (p < 0.01, 78.3% vs. 40%, odds ratios = 18.9). The findings from this study could provide evidences that individuals with obesity have high risk of falls due to the less effective control of dynamic stability upon a slip induced in gait, and could be applicable to train older adults with obesity to reduce their risk of falls.