Online control ability affects precision fitting performances of long-term Tai Chi practitioners in older adults.

Background: Age-related decline in goal-directed behavior could be risky for older adults to maintain daily activities. Our previous studies have shown that long-term Tai Chi (TC) practice could improve motor performance and postural control during goal-directed tasks. However, there was a paucity of studies examining TC's effects on online control of goal-directed action.

Research Question: Do long-term TC practitioners have different kinematic characteristics in online control of goal-directed behavior compared to our control groups during precision fitting tasks?

Methods: 36 older adults were recruited for sedentary (SE), brisk walking (BW), and TC groups based on their exercise habits. Participants were required to fit a block (90 × 90 mm) through two different openings (130 × 130 mm and 100 × 100 mm) at two different distances (arm's length or 130 % of arm's length). Hand, trunk, and center of pressure (CoP) data were collected and analyzed, where velocities and timing variables were used to evaluate the manual motor control.

Results: We observed that: (1) TC group used significantly less time of completion in all three phases than SE and BW groups, especially in the ADJ phase when condition with more task constraints; (2) TC group demonstrated faster average hand velocity in all three phases than SE and BW groups; (3) TC group had a faster average trunk velocity than SE and BW groups and faster average CoP velocity than the BW group in the ADJ phase.

Significance: The long-term TC practitioners might exhibit better online control ability in the precision fitting task than the SE and BW groups, leading to more smooth and effortless goal-directed movement executions. Therefore, the long-term TC practice could be an effective intervention for maintaining precision manual motor control among older adults.