The influence of Tai Chi training on the center of pressure trajectory during gait initiation in older adults

Objective: To determine if a program of intense Tai Chi exercise that has been shown to reduce the risk of falling in older adults improves postural control by altering the center of pressure (COP) trajectory during gait initiation. Design: Before-after trial. Setting: Biomechanics research laboratory. Participants: Twenty-eight older adults transitioning to frailty who participated in either a 48-week intervention of intense Tai Chi training or a wellness education (WE) program. Interventions: Eight Tai Chi forms emphasizing trunk rotation, weight shifting, coordination, and narrowing of lowerextremity stance were taught twice weekly. WE program participants met once a week and received lectures focused on health. Main Outcome Measures: The COP was recorded during gait initiation both before and after the 48-week intervention by using a forceplate sampling at 300 Hz. The COP trajectory was divided into 3 periods (S1, S2, S3) by identifying 2 landmark events. Displacement and average velocity of the COP trace in the anteroposterior (x) and mediolateral (y) directions, as well as smoothness, were calculated. Results: Tai Chi training increased the posterior displacement of the COP during S1 and improved the smoothness of the COP during S2. Conclusions: Tai Chi improved the mechanism by which forward momentum is generated and improved coordination during gait initiation, suggesting improvements in postural control. (C) 2004 by the American Congress of Rehabilitation Medicine and the American Academy of Physical Medicine and Rehabilitation.