Full metadata record
|dc.contributor||Department of Rehabilitation Sciences||en_US|
|dc.publisher||Hong Kong Polytechnic University||-|
|dc.rights||All rights reserved||en_US|
|dc.title||Efficacy of tai chi in improving sensori-motor and postural control in the well elderly||en_US|
|dcterms.abstract||With aging, deficits of the multiple sensori-motor systems and neural mechanisms, as well as deterioration in postural control have been shown to contribute to an increased likelihood of falls in the elderly. Increasing evidence demonstrates that behavioral and neural plasticity occurs in response to enriched environment, multi-sensory, and complex motor skill training. Tai Chi, a Chinese mind-body exercise, is now practiced by millions of elderly and believed to be beneficial to their health. Investigation of the effects of Tai Chi practice on postural control has been conducted over the last two decades. However, a comprehensive study into the effects of Tai Chi on the sensory, motor and integrative components of postural control is lacking or inconclusive. Thus, proper studies were needed before broad recommendations on the use of Tai Chi in falls prevention in the elderly could be formulated. This project consisted of a cross-sectional as well as a prospective study. The hypotheses were that repeated practice of Tai Chi could improve the sensori-motor and postural control of elderly subjects when compared with age-, gender-, and physical activity level matched control subjects. The improved performances of these elderly practitioners could be comparable to those of the young, healthy subjects. Also, short term (8 weeks) intensive Tai Chi training could improve the balance control of healthy elderly when compared to an educational control group. Finally, we hypothesized that golf, like Tai Chi, could improve the joint proprioception and stability limits, as both exercises demands accurate knee joint positioning and weight shifting during practice. Four groups of subjects participated in the cross-sectional study. The elderly Tai Chi practitioners were recruited from local Tai Chi clubs. All had practiced Tai Chi for a minimum of 1.5 hour week-1 for at least 1 year. The elderly golfers were recruited from local golf clubs. Elderly control subjects were recruited from several community elderly centers. They had no previous experience in either Tai Chi or golf. Young healthy subjects were university students who exercised regularly for at least 2 hours week-1. Elderly participants in the prospective study responded to advertisements via pamphlets through several community elderly centers and voluntarily joined either a Tai Chi intervention program or a general education group. All the sensori-motor and postural control assessments were conducted at the Hong Kong Polytechnic University. Experiment 1: Passive knee joint repositioning was used to test joint proprioceptive acuity. Experiment 2: Body sway was measured during static standing. Experiment 3: Subjects' intentional weight shifting to eight different spatial limits of stability within their base of support was conducted using force platforms. Experiment 4: Body sway under different somatosensory, visual and vestibular conditions was measured using computerized dynamic posturography, whereby subjects underwent six combinations of visual and support surface conditions, the so-called sensory organization test. Experiment 5: Concentric and eccentric isokinetic tests of the subjects' dominant knee extensors and flexors were conducted at angular velocity of 30o.s-1. Experiment 6: Control of body sway was tested in single-leg stance perturbed by forward or backward platform perturbations. Experiment 7: The elderly subjects' perception of their balance confidence in daily activities was assessed. Subjects in the cross-sectional study participated in all 7 experiments, whereas subjects joining the intervention program participated in only experiments 3 and 4 only at four time intervals: before, at 4-week intervals during the 8 week of training, and at 4 weeks after the training ended. Outcome measurements included: 1) Absolute angle error in passive repositioning of the knee joint at 3o of knee extension, 2) Body sway in the anteroposterior and mediolateral directions during static standing, 3) Reaction time, maximum of leaning trajectory, and control of the leaning trajectory in the limits of stability test, 4) The amplitude of anteroposterior body sway under the 6 sensory conditions in the sensory organization test, 5) Peak torque-to-body weight ratios in the concentric and eccentric isokinetic muscle strength measurements of their knee extensors and flexors, 6) Maximum anteroposterior body sway of subjects undergoing perturbation during single-leg stance, and 7) The Activities-specific Balance Confidence score ratios were used to assess the elderly subjective report of their balance confidence. Results from our study demonstrated that long-term elderly Tai Chi practitioners achieved significantly better acuity in knee proprioception sense, in that they showed smaller knee angle errors in the passive knee repositioning test when compared with those of control subjects similar in age, gender, and physical activity level. No significant difference was found in the anteroposterior and mediolateral body sway during static standing. However, Tai Chi practitioners initiated voluntary weight shifting in the limits of stability test more quickly than elderly control subjects. They could lean further without losing stability, and showed better control of their leaning trajectory. In the sensory organization test, the Tai Chi practitioners had improved their balance control when there was an increased reliance on the visual and vestibular systems during stance. Of particular interest is that these practitioners attained the same level of balance control performance as did young, healthy subjects when standing under reduced or conflicting somatosensory, visual and vestibular conditions. Our results further showed that experienced Tai Chi practitioners had developed higher peak torque-to-body weight ratios in concentric and eccentric isokinetic muscle strength measurements of their knee extensors and flexors than those of the elderly control subjects. Their strength increase in the agonist and antagonist muscles was to a similar extent. In the perturbed single-leg stance test, Tai Chi practitioners achieved less body sway during both forward and backward platform perturbations than did the elderly control subjects. Also, they had greater balance confidence in performing their daily tasks when compared with that of the control elderly subjects. After 4 and 8 weeks of intensive Tai Chi training, the elderly subjects achieved significantly better: 1) vestibular ratio in the sensory organization test and 2) directional control of their leaning trajectory in the limits of stability, when compared with those of the control group. These improvements were maintained at 4 weeks follow-up afterwards. Furthermore, the improved balance performance from week 4 on was comparable to that of experienced Tai Chi practitioners. Our last study showed that, like elderly Tai Chi practitioners, elderly golfers also had better knee joint proprioceptive acuity than did the elderly control subjects. Their performance was even similar to that of the young subjects. Like Tai Chi practitioners in the limits of stability test, the golfers had faster reaction time, leaned further without losing stability, and showed better control of leaning trajectory than did elderly control subjects. The latter 2 outcome measures were also comparable to those of the young subjects. The above findings lead to 5 main conclusions: 1) Long-term Tai Chi practitioners had improved knee joint proprioception and expanded their limits of stability during weight shifting in stance. 2) Furthermore, long-term Tai Chi practitioners had improved balance control when there was an increased reliance on the visual and vestibular systems in the sensory organization test. They even attained the same level of balance control performance as did young, healthy subjects despite multi-systems degeneration with aging. 3) In addition, long-term Tai Chi practitioners had better knee muscle strength and less body sway in perturbed single-leg stance. 4) Four weeks of intensive Tai Chi training are sufficient to improve balance control in the elderly subjects. 5) Like experienced Tai Chi practitioners, experienced golfers had improved knee joint proprioception and limits of stability, when compared with those of elderly control subjects similar in age, gender (male) and physical activity level. Such improved outcome measures were also comparable to those of young male subjects. Taken together with the previous findings by other investigators that Tai Chi practitioners have decreased the probability of their falling, our present findings indicated that Tai Chi has the potential of being a cost-effective falls prevention program that could be implemented community wide.||en_US|
|dcterms.extent||xxiv, 231 leaves : ill. ; 30 cm||en_US|
|dcterms.isPartOf||PolyU Electronic Theses||en_US|
|dcterms.LCSH||Hong Kong Polytechnic University -- Dissertations||en_US|
|dcterms.LCSH||Older people -- Orientation and mobility||en_US|
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