Forty-seven studies (n=2,762) were included: 9 RCTs (n=912), 23 non-RCTs (n=967) and 15 observational studies (n=883).
Methodological problems with the studies included: lack of a control group; small sample size; unclear study design; inadequate description of the study population and type of t'ai chi; lack of a blinded outcome assessment; lack of randomisation; potential selection bias; lack of control for confounding factors; lack of standardised outcome measures, lack of accounting for losses to follow-up; and unclear statistical analysis.
Balance and falls: 2 RCTs, 5 non-RCTs and 4 observational studies were identified (n=563). All 7 clinical trials (2 RCTs and 5 non-RCTs) found that 8 to 16 weeks of t'ai chi significantly improved balance, flexibility and strength, and reduced falls in older community dwellers. These results were supported by the results of the observational studies.
Musculoskeletal: 1 RCT and 3 non-RCTs were identified (n=168). The RCT (people with osteoarthritis) reported a statistically significant improvement in symptoms, self-efficacy, tension and satisfaction with health status after 12 weeks of t'ai chi. One non-RCT (people with rheumatoid arthritis) found no significant difference in disease activity between 10 weeks of t'ai chi and control, another (older community dwellers) found that t'ai chi increased muscle strength and endurance of knee extensors, while the third (people with multiple sclerosis) reported increases in some measures of function and flexibility, vitality, social functioning and mental health.
Hypertension: 2 RCTs and 2 non-RCTs were identified (n=401). All studies found that regular t'ai chi reduced the mean blood-pressure.
Cardiovascular and respiratory systems: 8 non-RCTs and 9 observational studies were identified (n=768). Seven of the non-RCTs reported an improvement in cardiorespiratory function, clinical symptoms or health fitness with t'ai chi; the remaining non-RCTs reported no difference in comparison with Wing Chun. The positive effects reported in the non-RCTs were generally supported by the results from the observational studies.
Psychological response: 3 RCTs and 3 non-RCTs were identified (n=568). Two RCTs (low activity older adults) found that t'ai chi for 16 weeks or 6 months improved measures of depression, psychological distress, well-being, life satisfaction and perceptions of health compared with control. One RCT (schoolchildren) reported a statistically significant improvement in perceived self-competence, visual-motor integration and anxiety with t'ai chi. Two non-RCTs found that t'ai chi improved mood and reduced stress and anxiety, and another (patients with dementia) found that reminiscence plus t'ai chi improved insight.
Endocrine and immune system: 1 non-RCT and 1 observational study were identified (n=158). Both studies reported a higher number of circulating T-cells in elderly people practicing t'ai chi compared with controls.
Other: 1 RCT, 1 non-RCT and 1 observational study were identified (n=163). The RCT (older adults) reported a statistically significant increase in self-efficacy with 6 months of t'ai chi. The non-RCT (young people) reported a statistically significant decrease in nightmares with 20 days of t'ai chi. The observational study reported an increased cutaneous microcircularity function during t'ai chi exercise.