PubMED: The effect of tai chi exercise on blood pressure: a systematic review.
Yeh GY, Wang C, Wayne PM, Phillips RS. Source Division of General Medicine and Primary Care, Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School Osher Institute, Boston, MA 02215, USA. email@example.com
"A systematic review of the
literature on the effect of tai chi exercise on blood pressure (BP) was
performed. The authors searched Medline, CAB, Alt HealthWatch, BIOSIS
previews, Science Citation Index, and EMBASE systems (inception through
January 2007); researched Chinese Medical, China Hospital Knowledge,
China National Knowledge Infrastructure, and China Traditional Chinese
Medicine databases (inception to June 2005); and performed hand searches
at the medical libraries of Beijing and Nanjing Universities. Clinical
studies of tai chi examining BP as an outcome published in English or
Chinese were included.
Studies reporting only acute exercise effects
were excluded. Data were extracted in a standardized manner and 2
independent investigators assessed methodologic quality. Twenty-six
studies examining patients with and without cardiovascular conditions
met inclusion criteria: 9 randomized controlled trials, 13 nonrandomized
studies, and 4 observational studies. Study heterogeneity precluded
Twenty-two studies (85%) reported reductions in BP with tai chi (3-32 mm Hg systolic and 2-18 mm Hg diastolic BP reductions). Five randomized controlled trials were of adequate quality (Jadad score > or = 3). No adverse effects were reported. Tai chi exercise may reduce BP and serve as a practical, nonpharmacologic adjunct to conventional hypertension management".
"T'ai chi, which has been studied by other scientists as a balance and flexibility exercise, consists of a series of 13 movements, each of which has 10 to 15 additional moves. After 12 weeks, systolic blood pressure had fallen significantly, an average of 8.4 millimeters of mercury (mm Hg), in the aerobic exercise group. However, it also fell significantly, 7 mm Hg, in the t'ai chi group. The beneficial effects were seen in both groups after only six weeks of exercise, Young adds. "It could be that in elderly, sedentary people, just getting up and doing some slow movement could be associated with beneficial reductions in high blood pressure," she says.T'ai chi and similar light-intensity activities are within the capabilities of most older people"
Her research is a pilot study
"The study was carried out by researchers from The Hong Kong Polytechnic University and the University of Illinois, USA, which funded the study. It was published in the peer-reviewed European Journal of Preventive Cardiology. Its findings were exaggerated in The Daily Telegraph and the Daily Mail, both of which incorrectly reported that tai chi practitioners were less likely to suffer high blood pressure. Although the study did measure people’s blood pressure it looked primarily at muscle strength and arterial compliance, which is a measure of the elasticity of the arteries. This was a cross-sectional study that investigated whether tai chi practitioners have better arterial compliance and muscle strength than non-practitioner.
The researchers say that the tai chi practitioners showed “better artery compliance” than the control group. The tai chi group also had statistically greater eccentric muscle strength (but not concentric muscle strength) in the muscles around the knee. That means they had greater strength when extending their legs but not when bending their knee. They also say there was no difference in physical activity levels between the two groups. A higher proportion of subjects in the control group had high blood pressure than in the tai chi group (61% versus 38%). On average, people in the control group also had significantly higher BMIs than the tai chi practitioners
Apart from the limitations caused by its small size, as a cross-sectional study it did not follow people up over time and, therefore, cannot show that lifestyle factors, such as type of exercise lead to particular health outcomes. The researchers mention some limitations, for example:
"Health benefits of Tai Chi exercise: improved balance and blood pressure in middle-aged women Everard W. Thornton1, Kevin S. Sykes2 and Wai K. Tang2 Abstract Tai Chi has been widely practiced as a Chinese martial art that focuses on slow sequential movements, providing a smooth, continuous and low intensity activity. It has been promoted to improve balance and strength and to reduce falls in the elderly, especially those ‘at risk’. The potential benefits in healthy younger age cohorts and for wider aspects of health have received less attention. The present study documented prospective changes in balance and vascular responses for a community sample of middle-aged women. Seventeen relatively sedentary but healthy normotensive women aged 33–55 years were recruited into a three times per week, 12-week Tai Chi exercise programme. A further 17 sedentary subjects matched for age and body size were recruited as a control group. Dynamic balance measured by the Functional Reach Test was significantly improved following Tai Chi, with significant decreases in both mean systolic (9.71 mmHg) and diastolic (7.53 mmHg) blood pressure. The data confirm that Tai Chi exercise can be a good choice of exercise for middle-aged adults, with potential benefits for ageing as well as the aged."
"In a 2006 study published in Alternative Therapies in Health and Medicine, Stanford University researchers reported benefits of tai chi in 39 women and men, average age 66, with below-average fitness and at least one cardiovascular risk factor. After taking 36 tai chi classes in 12 weeks, they showed improvement in both lower-body strength and upper-body strength.
In a Japanese study using the same strength measures, 113 older adults were assigned to different 12-week exercise programs, including tai chi, brisk walking, and resistance training. People who did tai chi improved more than 30% in lower-body strength and 25% in arm strength — almost as much as those who participated in resistance training, and more than those assigned to brisk walking"
"An article from Archives of Internal Medicine, as reported on NBC’s local WCAU Health explained a Tai Chi research program at Tufts-New England Medical Center in Boston revealed a great deal. The article authors wrote, "Overall, these studies reported that long-term Tai Chi practice had favorable effects on the promotion of balance control, flexibility and cardiovascular fitness and reduced the risk of falls in elders . . . Cardiovascular and respiratory function improvements were noted in healthy people and those who had undergone coronary artery bypass surgery as well as people 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.”