Effects of Tai Chi on pre-landing muscle response latency during stepping down while performing a concurrent mental task in older adults

William W. N. Tsang, Christina W. Y. Hui-Chan, Siu N. Fu

To investigate whether elderly Tai Chi practitioners are better able to descend a step while performing a concurrent mental task than non-practitioners. The design includes cross-sectional study. The setting includes university-based rehabilitation center. The subjects were 16 young women, 29 elderly women, and 31 elderly women who had been practicing Tai Chi regularly for at least half a year. Pre-landing muscle response latencies in their tibialis anterior (TA) and medial gastrocnemius (MG) muscles were measured during stepping down (single task) and stepping down while performing a concurrent mental activity (dual tasking). The non-practitioners had earlier onset of muscle activity in the TA in preparation for landing than the other subjects. The response latency of the Tai Chi practitioners was not significantly different from that of the young controls. When the cognitive task was added, the pre-landing response in the TA was significantly altered in both elderly groups. Response was significantly delayed among the non-practitioners, but significantly earlier among the Tai Chi subjects. The average change in response latency was significantly greater in the non-Tai Chi group compared with the young subjects and the Tai Chi practitioners (p = 0.006). Such findings suggest that practicing Tai Chi helps the elderly maintain the same strategy as much as younger subjects during stepping down. Tai Chi practitioners seem to have a greater capacity to shift attention between mental and physical tasks than other elderly women.