What Physical Attributes Underlie Self-Reported vs. Observed Ability to Walk 400 m in Later Life?

OBJECTIVE: The aims of this study were to evaluate and contrast the physical attributes that are associated with self-reported vs. observed ability to walk 400 m among older adults. DESIGN: Analysis of baseline and 3-yr data from 1026 participants 65 yrs or older in the InCHIANTI (Invecchiare in Chianti) study was conducted. Observed and self-reported ability to walk 400 m at baseline and at 3 yrs were primary outcomes. Predictors included leg speed, leg strength, leg strength symmetry, range of motion, balance, and kyphosis. RESULTS: Balance, leg speed, leg strength, kyphosis, leg strength symmetry, and knee range of motion were associated with self-reported ability to walk 400 m at baseline (P < 0.001, c = 0.85). Balance, leg speed, and knee range of motion were associated with observed 400-m walk (P < 0.001, c = 0.85) at baseline. Prospectively, baseline leg speed and leg strength were predictive of both self-reported (P < 0.001, c = 0.79) and observed (P < 0.001, c = 0.72) ability to walk 400 m at 3 yrs. CONCLUSIONS: The profiles of attributes that are associated with self-reported vs. observed walking ability differ. The factor most consistently associated with current and future walking ability is leg speed. These results draw attention to important foci for rehabilitation.