This paper is a review of empirical studies, systematic reviews and meta-analyses on tai chi that have been published over the past few years (since our last review in 2012) . The term tai chi was entered into PubMed and the selection criteria were empirical studies (single arm or randomized controlled studies) in which standard treatment, waitlist and treatment comparison groups were used as controls for the different style tai chi groups. Systematic reviews, bibliometric analyses and meta-analyses are also included. Exclusion criteria were case studies, qualitative studies, small sample pilot studies and research in which the assessors were not blind.
Brief summaries of papers are given on the demographics/ prevalence of tai chi as a practice as well as bibliometric analyses of tai chi. Most of the studies reviewed here involve tai chi effects on psychiatric and medical conditions. These include student stress, cognitive and physical function; psychological conditions including insomnia, anxiety, depression, obesity- related depression and schizophrenia; cardiovascular and cardio respiratory conditions including hypertension and stroke; pain syndromes including low back pain, arthritis, fibromyalgia and spinal cord injuries; autoimmune conditions including type II diabetes and multiple sclerosis; immune conditions including breast cancer and lung cancer; and aging problems including anxiety disorder, fear of falling and balance, osteoporosis, knee osteoarthritis and Parkinson’s. Most of the recent tai chi research has focused on balance problems in the elderly. The methods and results of those studies are briefly summarized along with their limitations, potential underlying mechanisms and suggestions for future research.
.Tai chi is a martial art that is basically a slowed down version of karate movements and they are typically performed alone rather than in contact with a partner. Tai chi is practiced as 5 different styles with the Yang and Sun forms being the most popular in the U.S. and those that have been practiced in the studies summarized here [1,2]. The Yang style was created by Yang Luchan in the early 1800s in China and is the most widely practiced and easiest to learn, although there are 20 variations of this style with varying numbers of movements. The Sun style was created by Sun Lutang as a combination of Yang and other styles in about 1900 in China and is well-known for its smooth, flowing movements, although it is a more upright, less flowing style than the Yang style and lacks the more physically vigorous leaping and crouching movements of the other more difficult styles.
Tai chi movements typically lead to large vertical and mediolateral displacements of the body compared to walking.
. During movements called, for example, repulse monkey” and “wave hand in cloud”, the knees remain flexed while range of motion involves larger abduction and adduction of the knees than for walking. When tai chi practitioners and non- practitioners have viewed videotapes of tai chi sequences, the practitioners were able to discriminate the technical from the aesthetic components of the actions .
The exercise intensity of tai chi has been evaluated by oxygen consumption and heart rate . These cardio respiratory and energy expenditure measures suggest that tai chi is a low intensity exercise. When the safety of tai chi was evaluated in a systematic review, only 33% of 153 eligible randomized controlled trials (RCTs) included the reporting of adverse events and of those, only 12% overall noted a monitoring protocol for adverse events . The adverse events reported were typically minor and basically musculoskeletal aches and pains typically in the knees and back. These results are tentative and much of the reporting of adverse events has been limited and inconsistent.
Barriers as well as promoters for participation in tai chi have included physical and mental health, time of day, socialization, accessibility and availability of teachers . These data came from a study in which 87 lower socioeconomic older adults from multiple ethnic backgrounds were interviewed before starting a 16-week tai chi program. Another study measured adherence to a 16-week tai chi program for multi-ethnic middle-aged and older adults living in a low socioeconomic environment . In this sample of 210 participants (mean age=68) greater adherence was associated with older age, greater perceived stress, higher education and higher scores on mental and physical scales. In contrast, lower adherence was associated with higher baseline weekly physical activity. A bibliometric analysis on 507 tai chi studies included8% systematic reviews, 50% randomized clinical trials, 18% randomized current controlled clinical studies and 23% single-arm (pre-post) studies . The most frequent diseases/ conditions studied were hypertension, diabetes, osteoarthritis, osteoporosis, breast cancer, heart failure, chronic obstructive pulmonary disease, coronary heart disease, schizophrenia and depression . The primary reason given for practicing tai chi was for health promotion. The most common tai chi style was the Yang style, and typically tai chi was practiced 2 to 3 one- hour sessions per week for 12 weeks. Tai chi was combined with other therapies including medications, physical therapies and health education in 41 %of the studies and was practiced alone in 59% of them. At least 95% of the studies reported positive effects while 5% of the studies noted uncertain effects, and no serious adverse events were mentioned. These data are highly suggestive, although only half the studies reviewed were randomized clinical trials. This breakdown is consistent with that of the current review.