Role of muscle power output as a mediator between gait variability and gait velocity in hospitalized older adults

Acute illness requiring hospitalization is a sentinel event leading to functional decline and frequently, long-term disability in older adults. Although functional decline has become a key outcome during and after hospitalization, there is currently no gold standard for measuring functional impairment. The purpose of this study was to compare gait characteristics and muscle performance endpoints of hospitalized older adults based on the Short Physical Performance Battery (SPPB) score (0-12 points) obtained at admission, and to determine the association underlying the gait impairment. A total of 130 hospitalized older adults (aged >= 75) were included. The primary endpoints were differences in functional capacity between groups, assessed with the 6-m Gait Velocity Test (GVT), verbal and arithmetic GVT, followed by gait pattern data recorded using an inertial sensor unit. Maximal muscle strength (MS) and muscle power (MP) were also measured as muscle performance endpoints. A mediation analysis was performed to understand gait disorders. The walking parameters measured at admission were related to functional status and showed significant differences among phenotype groups (disabled, frail, and prefrail groups), as well as muscle performance endpoints (p < 0.05). Finally, the indirect effect was significant (-0.27; 95%CI, -0.59 to - 0.05), confirming the mediation role of MP between gait variability and gait velocity in this model. MP slightly weakens the relationship between gait variability and gait velocity. In addition to MS and MP, gait velocity and gait pattern parameters are distinguishing factors among acutely hospitalized older adults.