INTRODUCTION:
Gait initiation (GI) is a transitional motor task that requires precise anticipatory postural adjustments (APA) and dynamic stability control. Mild cognitive impairment (MCI) has been associated with altered motor organization and reduced postural adaptability; however, the influence of task speed on biomechanical regulation during GI remains insufficiently understood. This study investigated whether older adults with MCI demonstrate altered speed-dependent modulation of postural control and dynamic stability during GI compared with cognitively healthy peers.
METHODS:
Thirty community-dwelling older adults (11 with MCI, 19 cognitively healthy controls) performed GI under two conditions: self-selected and fast speeds. Whole-body kinematics and ground reaction forces were recorded using a three-dimensional motion capture system and force plates. Spatiotemporal variables and postural control parameters were analyzed, including center of pressure (CoP) movement time, displacement, velocity during the APA phase, step length, step width, landing angle, and mediolateral dynamic stability. A mixed-design ANOVA was conducted to examine the main effects of group and speed, as well as their interaction.
RESULTS:
A significant group-by-speed interaction was observed for mediolateral dynamic stability. The control group improved mediolateral stability at the fast condition compared with self-selected speed, whereas the MCI group failed to demonstrate speed-dependent modulation. Across conditions, the MCI group exhibited faster posterior CoP velocity during the APA phase. At the self-selected speed, they also showed shorter weight-transfer duration and greater posterior CoP displacement relative to controls. These findings indicate altered temporal and spatial characteristics of APA in individuals with MCI.
CONCLUSION:
Older adults with MCI appear to adopt compensatory strategies characterized by faster and larger posterior CoP shifts to initiate gait. However, their inability to enhance mediolateral stability as task demands increase suggests impaired adaptability of dynamic balance control. These results highlight altered biomechanical regulation of GI associated with cognitive impairment and underscore the importance of incorporating speed-dependent assessments in early detection and intervention strategies targeting mobility decline in this population.