Purpose: Emerging evidence indicates exercise training improves mobility and cognition and reduces falls in older adults, but underlying mechanisms are not well understood. This study tested the hypothesis that change in dual-task walking capacity mediates the positive effect of Tai Ji Quan and multimodal exercise on physical performance, activity confidence, global cognition, and falls among community-dwelling older adults at high risk of falling.
Methods: We conducted a secondary analysis of a 6-month randomized clinical trial comparing Tai Ji Quan: Moving for Better Balance (TJQMBB) and multimodal exercise to stretching exercise in a sample of 670 adults older than 70 yr who had a history of falls or impaired mobility. Distal outcome measures, ascertained at a 12-month follow-up, were the Short Physical Performance Battery, Activities-Specific Balance Confidence, Montreal Cognitive Assessment, and falls. The mediator hypothesized to account for the intervention effects was dual-task cost estimated by calculating changes in gait speed from single-task to dual-task walking from baseline to the end of intervention.
Results: At 12 months, compared with stretching exercise, multimodal exercise significantly improved Short Physical Performance Battery and Activities-Specific Balance Confidence outcomes and reduced the number of falls (P < 0.05). However, it did not lower dual-task cost or mediate the intervention effects on distal outcomes. In contrast, TJQMBB significantly reduced dual-task cost relative to multimodal and stretching exercises (P < 0.05) which in turn resulted in improvements in lower-extremity physical performance, activity confidence, global cognitive function, and reductions in falls (P < 0.05) during follow-up.
Conclusions: Enhanced dual-task walking capacity as a result of Tai Ji Quan training mediated improvements in physical and cognitive outcomes in older adults at high risk of falling.