Abstract
BACKGROUND: Impairments to body systems contribute to mobility limitations. The objective of this study was to determine whether impaired gait coordination, as measured by the Phase Coordination Index (PCI), is significantly associated with mobility limitations in older adults, even after adjusting for other gait features. METHODS: We conducted a cross-sectional analysis of performance-based measures of mobility in older adults (N=164) 77-101years of age, participants in the population-based MOBILIZE Boston Study. Mobility outcomes included the Short Physical Performance Battery (SPPB) and each of its three components. Multivariable linear regression models, adjusting for age and gender, were used to examine the associations of PCI and the coefficients of variation of stride length, width and time, stance time, and step width with each outcome. RESULTS: PCI accounted for more variance in SPPB score (R(2)=0.21), gait speed (R(2)=0.17), chair rise score (R(2)=0.10), and balance score (R(2)=0.09) than any of the other gait measures. Impaired gait coordination was significantly associated with performance on the SPPB and each of its component tasks, even after accounting for gait measures previously linked to mobility tasks (all P<0.05). In multivariable linear regression modeling PCI accounted for an additional 9% of the variance in SPPB score (P<0.001), after accounting for the other gait variables, age, and gender. CONCLUSIONS: This study shows that impaired gait coordination is associated with poorer mobility performance in older adults, independent of other gait variables previously linked to mobility tasks.