Gait initiation (GI) is an important locomotor transition task that includes anticipatory postural adjustments and the joint propulsion necessary for the first step of walking. Discrete variable analysis between GI of fallers and non-fallers has shown important between-group differences. More complex time series analysis, such as functional principal component analysis (FPCA) may highlight group differences not detectable using discrete comparisons alone. This study aims to characterize the differences between fallers and non-fallers by examining the kinematics and kinetics of gait initiation using multivariate FPCA (mFPCA). A sample of 56 community-dwelling older adults completed five walking trials where GI was measured by force platforms. mFPCA of center of pressure kinematics and kinetics was conducted and functional principal component scores were compared between groups. Overall mFPCA provided a comprehensive assessment of GI that supports and enhances previous findings with respect to differences between faller and non-faller cohorts. During weight transfer and forward progress, fallers demonstrate a greater range of mediolateral movement and lower lateral force than non-fallers. During the first step, fallers have a more gradual rise in vertical force, as well as a greater lateral movement toward the edge of their base of support. Fallers also demonstrate a shorter step length, indicating an altered approach to GI, where mediolateral and anteroposterior stability may be prioritized over forward advancement.
Keywords: Biomechanics; Fall risk; Gait initiation; Kinematics; Kinetics; Older adults.
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