UVM Theses and Dissertations
Methods -- This study employed a longitudinal, experimental design. Forty three fall-risk elders aged 65 years and above were provided with a three-times-per-week, 15 week Tai Chi practice. Seven participants who practiced Tai Chi at or above 95% of all sessions, and seven participants who practiced at or below 55% of all sessions were selected and identified as the frequent Tai Chi group and the non-frequent Tai Chi group, respectively. Body sway of all subjects was evaluated under four postural conditions (i.e., eyes open, eyes closed, natural base of support and narrow base of support) before, and immediately after the intervention. The foot center of pressure (COP) during 60-second's quiet stance was measured by a biomechanical force platform, and was normalized by the foot dimension for each individual. The difference in COP displacement range and COP mean velocity between two visual conditions were computed and analyzed for each stance condition. Independent t tests were used for between-groups comparison; and paired t tests for within-group comparison.
Results -- (1) With natural stance, the frequent Tai Chi group showed smaller body sway increase after the vision was removed than the non-frequent Tai Chi group did, as well as than they did at pre-intervention test. (2) With narrow stance, both frequent and non-frequent Tai Chi groups showed a larger body sway increase after visual cues were eliminated at post test as compared to pre-test; and frequent Tai Chi group showed a larger body sway increase than the non-frequent Tai Chi group did.
Conclusions -- Frequent Tai Chi practice over a 15 week period does have an effect on the role of the somatosensory system in standing balance control among those elders who are at risk for falls. This effect, however, seems to be dependent on the size ofthe standing base of support. When standing with two feet naturally separated (normal size of base of support), people after frequent Tai Chi practice are able to achieve a steadier standing balance when relying mainly on the somatosensory system. In contrast, when standing with two feet touching (narrow size of base of support), people are less stable when relying mainly on the somatosensory system after frequent Tai Chi practice.