Hadronic jet production at the CERN UA2 detector An experimental test of QCD

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Effects of Tai Chi on joint proprioception and stability limits in elderly subjects

Purpose: The objectives of this study were to examine whether elderly Tai Chi practitioners have developed better knee joint proprioception and standing balance control than control subjects. Methods: Tai Chi and control subjects (N = 21 each, aged 69.4 ± SD 5.5 and 72.3 ± 6.1 yr, respectively) were matched with respect to age, sex, and physical activity level. Passive knee joint repositioning was used to test joint proprioceptive acuity. Control of body sway during static standing and subjects' intentional weight shifting to eight different spatial limits of stability within their base of support were conducted using force platform measurements. Result: Tai Chi practitioners were found to have better knee joint proprioceptive acuity, in that they made less absolute angle error (2.1 ± 1.2°) than control subjects (4.0 + 3.4°, with P = 0.023) in passive knee joint repositioning. No significant difference was found in the anteroposterior and mediolateral body sway during static standing (P > 0.05). However, Tai Chi practitioners initiated voluntary weight shifting in the limits of stability test more quickly (reaction time: 0.8 ± 0.2 s for Tai Chi practitioners) than control subjects (1.1 ± 0.3 s; P = 0.008). Moreover, they could lean further without losing stability (maximum excursion: 5.2 ± 0.6% for Tai Chi practitioners and 4.6 ± 0.5% for control subjects; P = 0.001) and showed better control of their leaning trajectory (directional control: 75.9 ± 10.0% for Tai Chi practitioners and 68.5 ± 6.9% for control subjects; P = 0.008). Conclusions: These results demonstrate that long-term Tai Chi practitioners had improved kneejoint proprioception and expanded their limits of stability during weight shifting in stance.Department of Rehabilitation Science

Effects of exercise on joint sense and balance in elderly men: tai chi versus golf

Purpose: Our previous studies showed that experienced Tai Chi practitioners had better joint proprioception and balance control during weight shifting. The objective of the present study was to examine whether experienced golfers had attained similar improvement when compared with the Tai Chi practitioners, as well as healthy elderly subjects and young university students. Methods: We compared 12 experienced elderly Tai Chi practitioners, with 11 experienced elderly golfers, 12 healthy elderly subjects, and 12 young university students, who were all males, using: 1) passive knee joint repositioning test to assess their joint proprioceptive acuity and 2) limits of stability test to assess their ability to voluntarily weight shift within their base of support. Results: Both Tai Chi practitioners and golfers had better knee joint proprioceptive acuity than did the elderly control subjects (P Academic research: refereed > Publication in refereed journa

Comparison of muscle torque, balance, and confidence in older tai chi and healthy adults

Part of the study was presented at the Third Pan-Pacific Conference on Rehabilitation, Hong Kong (SAR), China, August 23–25, 2002.TSANG, W. W. N., and C. W. Y. HUI-CHAN. Comparison of Muscle Torque, Balance, and Confidence in Older Tai Chi and Healthy Adults. Med. Sci. Sports Exerc., Vol. 37, No. 2, pp. 280-289, 2005. Purpose: The objectives of this cross-sectional study were to examine whether older Tai Chi practitioners had better knee muscle strength, less body sway in perturbed single-leg stance, and greater balance confidence than healthy older adults. Methods: Tai Chi and control subjects (N = 24 each, aged 69.3 +/- 5.0 and 71.6 +/- 6.1 yr, respectively) were matched with respect to age, gender, height, weight, and physical activity level. Concentric and eccentric isokinetic tests of the subjects' dominant knee extensors and flexors were conducted at an angular velocity of 30degrees(.)s(-1). Control of body sway was assessed in static double-leg stance and in single-leg stance perturbed by forward or backward platform perturbations. The Activities-specific Balance Confidence (ABC) scale was used to investigate subjects' balance confidence in daily activities. Results: Tai Chi practitioners had higher peak torque-to-body weight ratios in concentric and eccentric isokinetic contractions of their knee extensors and flexors (P = 0.044). They manifested less anteroposterior body sway angles in perturbed single-leg but not static double-leg stance than did control subjects (P < 0.001). Tai Chi practitioners also reported significantly higher balance confidence score ratios (P = 0.001). Older adults' knee muscle strengths showed negative correlations with body sway angles in perturbed single-leg stance and positive correlations with ABC score ratios. Moreover, their body sway angles in perturbed single-leg stance were negatively correlated with their ABC score ratios (all P < 0.05). Conclusion: Our results demonstrate that long-term Tai Chi practitioners had better knee muscle strength, less body sway in perturbed single-leg stance, and greater balance confidence. Significant correlations among these three measures uncover the importance of knee muscle strength and balance control during perturbed single-leg stance in older adults' balance confidence in their daily activities.Department of Rehabilitation Science