Two studies evaluated the effects of Tai Chi practice on the endocrine or immune systems. A cross-sectional Chinese study of 98 elderly men reported that 10 years of Tai Chi practice might widely affect endocrine function, including the pituitary-thyroid system and the pituitary-gonad system, and may strengthen pituitary metabolic reaction among elderly men. The conclusion of this study is questionable because cross-sectional studies are not designed to evaluate causality.
An NRS of 60 elderly subjects found that the total number of circulating T cells, including active T lymphocytes, were significantly higher in the Tai Chi group (30 healthy subjects, aged =” type=”#_x0000_t75″>60 years, who regularly practiced Tai Chi for 4 or more years) than in the untrained group (30 age-matched subjects).
Both studies lacked explicit and appropriate eligibility criteria. In both studies, the Tai Chi intervention was not well described, and the follow-up rate and statistical analysis were not adequately reported.
Other Conditions
Several studies evaluated the beneficial effects of Tai Chi in other areas (Table 8). A recent RCT found that a 60-minute Tai Chi practice session twice a week for 6 months using a classical Yang style could significantly enhance self-efficacy in older adults. Two aspects of self-efficacy were measured: barriers and performance. The study also suggested that changes in self-efficacy cognitions were significantly related to class attendance.
A recent case-control study of 20 elderly men revealed that 10 elderly men who practiced Tai Chi for 11.2 years had a 34% higher O2 peak and higher skin blood flow, cutaneous vascular conductance, and skin temperature than the 10 sedentary men at rest and during exercise. Another NRS of 22 young people (mean age, 21 years) found that 20 days of Tai Chi practice significantly decreased nightmares.
Conslusions
Most of the studies evaluated in this systematic review have been performed in China and the United States to examine the physiological and psychosocial benefits of Tai Chi for all age groups.
Benefits were reported by the authors of these studies in cardiovascular and respiratory function in healthy subjects and in patients who had undergone coronary artery bypass surgery as well as in patients with heart failure, hypertension, acute myocardial infarction, arthritis, and multiple sclerosis.
Benefit was also found for balance, strength, and flexibility in older subjects; falls in frail elderly subjects; and pain, stress, and anxiety in healthy subjects. Overall, Tai Chi appears to have physiologic and psychosocial benefits and appears to be safe and effective in promoting balance control, flexibility, and cardiovascular fitness for older adults with chronic conditions.
Unfortunately, many studies of Tai Chi lack rigorous scientific methods, and most investigations have been retrospective and have not used randomized control groups. It is also difficult to obtain overall quantitative estimates of treatment effects owing to the heterogeneity of inclusion criteria, patients, and outcome definitions and inadequate information on design, details of the intervention, and outcomes. It should also be noted that none of the studies from Asia were RCTs. In contrast to those published in the United States and other Western countries, almost all the studies published in mainland China, Hong Kong, and Taiwan reported positive results. Studies may have been conducted with different levels of methodologic rigor, and publication bias may be greater in some countries than in others.
In addition, the mechanisms of the benefits from practicing Tai Chi for any of the conditions studied are not well understood. There are only 9 RCTs in this review, and they examined only short-duration practice of Tai Chi (8-16 weeks). Therefore, long-term effects of Tai Chi practice are still unknown, and there is insufficient information to recommend Tai Chi to patients with chronic conditions. Well-defined study questions, adequate selection criteria, groups similar at baseline, valid statistical methods, accounted-for confounders, appropriate outcome, and adequate follow-up are needed for proper evaluation of the effects of Tai Chi. Patients and physicians who use Tai Chi intervention will be better informed by high-quality RCTs that report short- and long-term risks and benefits.
