Gait Speed and Dynamic Stability Decline Accelerates Only in Late Life: A Cross-sectional Study in Community-Dwelling Older Adults.

Background And Purpose: Incidence of falls increases with age whereas gait speed declines. The purposes of this study were to examine (1) whether gait speed and center-of-mass (COM) velocity declined steadily across ages in a linear fashion among community-dwelling older adults, and (2) whether such decline corresponded to the similar decline in dynamic stability, which is governed by the control of their COM position and COM velocity relative to base of support (BOS).

Methods: A total of 184 community-dwelling older adults (≥65 years) participated in the cross-sectional study. The participants were categorized into 5 age groups (65-69, 70-74, 75-79, 80-84, and 85+ years) and were asked to walk on the 7-m walkway at their preferred walking speed. Their speed, gait pattern, relative COM position, and relative COM velocity were measured.

Results: Very close relationship was confirmed between a clinical gait speed measurement and the COM velocity (R = 0.875, P < .05), which enabled us to use the 2 terms interchangeably. Gait speed decline was not noticeable from 65 to 84 years of age (P > .05), but it accelerated after 85 years of age. This decline was most likely influenced by a reduction in both step length (P < .05) and cadence (P < .05). Similarly, dynamic stability against backward loss of balance changed little between 65 and 84 years of age (P > .05). Yet, it declined significantly after 85 years of age (P < .05), primarily affected by the reduction in the COM velocity relative to the BOS, whereby the COM position relative to the BOS remained constant during their walking.

Conclusion: Expected steady decline in gait speed and in the control of gait stability cannot be confirmed. Rather, we found that both declined precipitously only after 85 years of age, when the risk of falls is likely to increase correspondingly.