Multisystem predictors of dynamic gait stability across fall risk in older adults

Gait stability arises from interactions between physiological, cognitive, and psychological systems, yet these domains are often assessed in isolation. This study examined multisystem predictors of anteroposterior margin of stability during walking (MoS_AP) in community-dwelling older adults. Of 340 participants, 143 were retained after data quality screening (105 females; age: 70.8 ± 7.8 years). Participants completed the Physiological Profile Assessment (PPA), cognitive testing using Montreal Cognitive Assessment (MoCA), fear-of-falling evaluations using Modified Falls Efficacy Scale (MFES) and a biomechanical gait assessment during preferred and fast speeds. Participants were stratified into four PPA-based fall-risk groups: low, mild, moderate, and high risk. MoS_AP differed significantly across fall-risk groups at both preferred and fast walking speeds, indicating that dynamic stability varied by fall-risk severity and task demand. Principal component analysis reduced physiological, gait and cognitive variables, and PCA-based elastic-net models identified global and fall-risk-stratified predictors of MoS_AP. In global models, physiological, gait components and MFES were retained at preferred speed, whereas physiological, gait, MFES, and cognitive components were retained at fast speed. Stratified models showed risk- and speed-specific patterns. At preferred speed, physiological, gait, and MFES were most consistently retained, suggesting that habitual walking stability was associated primarily with sensorimotor, gait, and psychological factors. At fast speed, cognitive and psychological predictors were retained in mild- and moderate-risk groups, suggesting that increased walking demand may reveal additional cognitive and confidence-related associations. These findings suggest that MoS_AP reflects task- and risk-dependent multisystem associations in aging and may provide a clinically relevant biomechanical marker for fall-risk stratification.