The Chinese Art of Tai Chi Chuan And Its Effects on Health: a literature review
By Sifu Donald Kerr
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This literature review critically evaluates and discusses a number of research papers which investigate the potential benefits of Tai Chi Chuan and its regular practice. It tries to identify the main aspects of the intervention and some of the component parts of each piece of research to discover if the research has any validity. All of the research available aims to discover truths about the benefits of practicing Tai Chi Chuan. Where as it is much more common to find many studies based on using Tai Chi Chuan much like a low grade aerobics exercise.
Of the seven research papers identified only three of them used people in their study who had been practising Tai Chi for any length of time. However in the study by Xu et al (2004) Tai Chi Chuan is assessed next to the sports of running /swimming, both common in older peoples, and set against a sedentary control group. Despite all of the papers reporting positive outcomes for the use of Tai Chi Chuan there are a number of questions discussed that arise out of the methodology of the research.
Conclusions; Tai Chi Chuan has shown itself to be of practical use in maintaining well being, improving health and recovery from heart surgery. Yet there are questions that remain unanswered concerning how we should go about examining such types of intervention and the whole complementary field due the lack of an appropriate research model in this area.
Keywords: Tai Chi Chuan, Elderly, Health, medical research,
Online search engines: Google Scholar, Google
Online databases: Athens (1995 – 2006), Ovid (1995 – 2006)
British Heart Foundation
British Broadcasting Corporation
World Health Organisation
Electronic and Text Journals:
British Medical Journal
Journal of Chinese Medicine
Medicine & Science in Sports & Exercise
British Journal of Community Nursing
It is widely understood the Chinese practise Tai Chi Chuan, commonly abbreviated to Tai Chi, for the benefits of good health and a long life. Stories pervade both Chinese folklore and Tai Chi Chuan’s own history of practitioners living to very old age happily and healthily as well as displaying great abilities and near super human strength. Whether via the media, e.g. television, magazines, or through personal experience, we have an image of Chinese people, mostly the elderly, practising in parks in large groups. Indeed, watch any documentary or holiday programme on China and you will see many such images portraying local life and colour. In effect Tai Chi Chuan and its reputed benefits have become a part of folklore, not only in China but now throughout the west.
Tai Chi Chuan has its roots in the ancient Chinese philosophy of Taoism. The movements comply with principals that follow the laws of nature as defined within Taoist traditions. By applying these principals to the body and the nature of its movement it enables the body to remain, not only strong, but flexible and with a reduced risk of injury. Its characteristic slow practice helps strengthen muscles and improve balance yet still manages to increase heart rate enough to strengthen the heart, despite this slowness.
The guiding principles laid down centuries ago, teach the practitioner how
to move and maintain posture, whilst co-ordinating both sides of the body together. The
book “Tai Chi Chuan a comprehensive training manual” by R Rand
(2004, p49) sets out these principals and explains a method for how students
can be trained in them.
All the different types of Tai Chi Chuan have the same root and therefore should also follow the same principals regardless of what order these principals are taught in. In the authors opinion one aspect of Tai Chi Chuan could be seen in western terms as a system of “Bio – mechanics” (my own term, not used by the author); a method of the body maintaining posture and positions that make it naturally strong.
Furthermore the wide use of Tai Chi Chuan in Chinese institutions such as hospitals and universities has lead to many claims of benefits to health. These claims have been viewed in the west with some scepticism, though it has lead to serious studies being undertaken by researchers and institutions that have greater credibility. The kind of research that has already been done have examined a wide range of conditions such as;
- Balance and co-ordination in the elderly
- Various types of cancer
- Traumatic brain injury
- Cardio-respiratory fitness
to name but a few, and any keyword search via the internet will display many such reports.
One example of this research, closer to home, is the British Heart Foundation (BHF) funding research into the effects of Tai Chi Chuan on sufferers of heart failure http://www.bhf.org.uk/ (2001). Conducted at the Royal Hallamshire hospital in Sheffield under Dr Channer who was quoted on the BHF website as saying “Tai Chi has been shown to be effective in reducing heart rate and blood pressure after a heart attack”. The research and its findings were reported widely in the British press at the time and the information is still available on both the BHF and British Broadcasting Corporation news websites http://www.bbc.co.uk/1/hi/health/3728174.stm/ (2006).
We are living in an era with an increasingly aging population, which gives rise to ever increasing health costs. In 2003 the British Government announced a fifty million pound campaign to increase the number of hip operations and clear the huge waiting list http://www.dh.gov.uk/ (2006). Putting aside the human factor, health costs alone are a strong argument for focused research into any intervention, whether that intervention be medical or physical, that can improve the health of this sector of people and society as a whole. So the purpose of this review is to evaluate the research available to assess if there is any evidence to support such claims.
The criteria for this review began by first asking the question; what research has been done in the area of health and Tai Chi Chuan exercise? Using the keywords listed a search was begun via the “Athens” and “Ovid” databases for journal articles. Through a slow process of search, re-search and refinement of criteria, a large number of research articles were discovered, date restriction 1995-2006. Unfortunately a good percentage of these articles were not available, either in full text or at all. Furthermore even a ‘home-grown’ research quoted on British websites and in the British press and funded by a British organisation was printed in an American journal but unavailable in any format whatsoever.
Unfortunately only a limited number of full text articles were available. Of these only seven had their focus on Tai Chi Chuan as opposed to just being part of a wider piece of research. Some of the rejected articles merely mentioned Tai Chi Chuan once or simply had a reference to Tai Chi Chuan in the references section.
Research articles accepted in brief are as follows;
“Two Year Trends in Cardiorespiratory Function Among Older Tai Chi Chuan Practitioners and Sedentary Subjects” by Lai, J. S. Lan, C. Wong, M. K. and Teng, S. H. Published in The Journal of American Geriatrics Society (1995, p1222-1227).
Research based in a hospital with 84 of participants from a Tai Chi club measured against a sedentary control group, these were match paired groups with no major height, weight, age, sex differences. None of the participants had any significant cardiorespiratory, pulmonary or musculoskeletal disease. This study measured two year development of cardiorespiratory function in both groups. Conclusions favour the regular practice of Tai Chi Chuan.
“Reducing Frailty and Falls in Older Persons: An Investigation of Tai Chi and Computerised Balance Training” by Wolf, S. L. Barnhart, H. X. Kutner, N. G. McNeely, E. Coolger, C. Xu, T. and the Frailty and Injuries Cooperative Studies of Intervention Techniques Group. Published in The Journal of American Geriatrics Society (1996, p489-497).
A ground breaking study from 1995, quoted in nearly every article that can be located, compares Tai Chi Chuan against computerised balance training. Using a large subject group of 200 aged 70 years and older, the average age being 76.2 years. The study identifies that balance and frailty have a psychological and biological basis, in both Tai Chi Chuan proved to be of a benefit.
“Balance and Strength Training in Older Adults: Intervention Gains and Tai Chi Maintenance” by Wolfson, L. Whipple, R. Derby, C. Judge, J. King, M. Amerman, P. Schmidt, J. and Smyers, D. Published in The Journal of American Geriatrics Society (1996, p498-506).
This investigation measures three months of intensive balance and /or weight training and 6 months of low intensity Tai Chi training, the latter being used to maintain the gains achieved with the first three month blast. A group of 110 people with an average age of 80 years free of any serious health condition. The results show that Tai Chi Chuan helped maintain the gains but that there was some decrement.
“The effect of Tai Chi on cardiorespiratory function in patients with coronary artery bypass surgery” by Lan, C. Chen, S. Y. Lai, J. S. and Wong, M. K. Published in Medicine & Science In Sports & Exercise (1998, p634-638).
This study looked into cardiac rehabilitation and the potential benefits of Tai Chi Chuan for Coronary Artery Bypass Surgery (CABS). Using a subject group of 27 non-randomly assigned to either a non-supervised control group or a Tai Chi Chuan group which took place over a year. The Tai Chi Chuan group used it as a maintenance practice all were complete novices. The outcomes were positive in favour of Tai Chi Chuan as a suitable exercise for those recovering from heart surgery. One of the effects they point to is stress reduction.
“Balance control, flexibility and cardiorespiratory fitness among older Tai Chi practitioners” by Hong, Y. L. and Robinson, P. D. Published in the British Journal of Sports Medicine (2000, p29-34).
This investigation takes a deeper look into the effects of Tai Chi Chuan on the health of people who have practiced for longer than 10 years. It also aspires to look into “total body rotation flexibility and heart rate responses.” This was a cross sectional study using 28 elderly male practitioners of Tai Chi Chuan measured against 30 sedentary elderly males in the control group, with a comparable average age of each group. The conclusions weigh in favour of Tai Chi Chuan practice with regards to cardiovascular fitness, balance control and flexibility. Though the researchers do make the point that exercise is necessary in old age to maintain a level of physical well-being.
“Effects of Tai Chi exercise on proprioception of ankle and knee joints in old people” by Xu, D. Hong, Y. Li, J. and Chan, K. Published in British Journal of Sports Medicine (2004, p50-54).
This study chose a total of 68 people divided up into; 21 elderly long term Tai Chi Chuan practitioners that had practiced for four years or more for one and a half hours per day, compared to a group of 20 elderly long term swimmers / runners who also had practiced for four years and swum or ran for at least one hour a day and 27 elderly sedentary controls who had practiced being sedentary for most of their life. There was no apparent significant difference in age, sex, weight and height of all three groups. Tai Chi Chuan had a noticeably better effect on the practitioner’s health than either swimming or running. The benefits were even more noticeable when compared to the sedentary group.
“Effects of Sun-style Tai Chi exercise on physical fitness and fall prevention in fall-prone older adults” by Jung, H. C. Jung, S. M. and Rhayun, S. Published in the Journal of Advanced Nursing (2005, p150-157).
A “quasi-experimental” study was set up which measured a group
of 68 fall prone older adults of which there were 29 in the Tai Chi Chuan group
(who filled in the required information forms) against a non-equivalent control
group of 30 individuals.
The research focuses on “Sun style” Tai Chi Chuan for the participation group. The course was a 10 minute period of warm ups followed by 20 minutes of Tai Chi Chuan and then five minutes of cooling down, three times a week for 12 weeks. Trained research assistants measured various things e.g. muscle strength in the knee and ankle as well as balance with eyes open and closed. The results are presented in a reasonable fashion and the conclusion appears positive for Tai Chi Chuan.
All of the research available aims to discover truths about the benefits of practicing Tai Chi. Of the seven research papers only three of them used people in their study who had been practising Tai Chi Chuan for any length of time. This begs the first question “why, if it is widely accepted that the effects of exercise are accumulative, were so many studies based on using Tai Chi Chuan much like a low grade aerobics exercise?” A classic example of this is by Lan et al (1998), in their research into Tai Chi Chuan’s effects on cardiorespiratory function on heart patients, where they have CABS patients undergo a year of Tai Chi Chuan having never done Tai Chi Chuan before.
Notwithstanding the positive results found within this and other similar studies it seems that a proper explanation of the term “practicing” Tai Chi Chuan should be defined. For the reason that, as many of the studies point out, the participants merely imitated the movements of the instructor at the same speed and were not actually learning the art itself; so can they be said to be truly “practising” Tai Chi Chuan? It is likely that such short durations of practice cannot show the extent of the benefits to the body and mind that may be possible with an extended period of practice, which is surely the real purpose of such research.
Moreover if it could be shown, as the research seems to suggest, that the practice of Tai Chi Chuan has long term benefits for both body and mind of the individual; then it seems apparent that efforts should be made to develop the opportunities and encourage people in society to take up such practice for their own well being. This not only benefits the individual but also society as a whole, due to the costs of maintaining the health of an aging population by conventional means.
Another much quoted and used piece of research on the subject by Wolf et al (1996) who set about to reduce frailty and fear of falling. This time only 15 weeks of Tai Chi Chuan was implemented to test the improvements against 15 weeks of either education or computerised balance training. Again Tai Chi Chuan fairs well in this report, it shows itself to be effective and a cheaper alternative to the other two methods.
Balance is again the aim of another piece of research by Wolfson et al (1996). This time Tai Chi Chuan, practiced over 6 months, is measured against three months of intensive balance and strength training. Once again none of the participants have practiced Tai Chi Chuan before and on this occasion their Tai Chi Chuan training is limited to one hour once a week. Here Tai Chi Chuan was used as a method of maintaining the quick blast of initial training received by the subject group. Notwithstanding the positive results in Tai Chi Chuan’s favour this study seems not to have taken onboard the already accepted benefits of Tai Chi Chuan and there were no studies on Tai Chi Chuan shown in their literature research prior to the study.
The three studies that used subjects with both knowledge and many years of practice of Tai Chi Chuan have a greater potential for presenting more credible results. For the simple reason that, if we accept that the effects of exercise are accumulative, then studying those who have practised over many years enables us to quantify those benefits more acurately. In the study by Lai et al (1995) they measure a group of older Tai Chi Chuan practitioners against a sedentary group matched with age and body size. A baseline measurement of cardiorespiratory function was taken at the beginning of the study and repeated two years later to calculate the decline in cardio-respiratory function. Regular daily practice was monitored by the authors and the heart rates of some of the Tai Chi Chuan group were also monitored throughout the Tai Chi Chuan session.
The results showed less of a decline in cardio-respiratory function than in the sedentary group. They conclude that the decline in cardio-respiratory function was a natural occurrence with age but that regular practice of Tai Chi Chuan can decrease the rate of decline and, due to the low-intensity of Tai Chi Chuan as an exercise, it is suitable for older people who may benefit from such exercise. This is an example of good research in that the aim was clear and measurable with a subject group that was well practiced in the art of Tai Chi Chuan, which enabled the study to see far more into the benefits of regular practice.
In the study by Xu et al (2004) Tai Chi Chuan is assessed next to the sports of running and swimming, both common in older peoples, and set against a sedentary control group. Here the study group focuses on proprioception in the ankle and knees of old people to establish whether Tai Chi Chuan is better for this than the other forms of exercise considered in the study. The authors note that the constant repetitions in the practice of Tai Chi Chuan are a proprioceptive exercise. This can have a maintaining influence or even a delaying effect on the decline of proprioception. Their results showed that Tai Chi Chuan managed this better than both the sedentary control and the swimmers or runners. Bearing in mind that each of the exercise groups were regular devotees to their form of exercise shows a very positive outcome for Tai Chi Chuan and potential for preventative measures in the treatment of the elderly.
In Hong et al (1999) the study attempts to measure not only balance but also flexibility and cardio-respiratory fitness in a study group of elderly Tai Chi Chuan practitioners. The study group had at least 10 (an average of 13.2) years experience versus a control sedentary group. They note in their background studies that short term practice of Tai Chi Chuan yielded little in the way of improvement for a “single leg stance test with eyes closed” and in a “sit and reach test”. Their results are very positive in support of Tai Chi Chuan as a beneficial exercise.
The study suggests that for flexibility the old need to take longer and require
more regular practice which they get from Tai Chi Chuan. With cardio-respiration
they point out that other research has yielded good results from short term
training but that through long term training the full benefits could be gained
and ascertained, allowing for hereditary illness, e.g. heart conditions, to
Looking at the results given in these pieces of research, the first conclusion that can be drawn is that the practice of Tai Chi Chuan for even a short period of time is beneficial. And that longer practice over many years is far more beneficial. But is that enough?
It is already known and generally understood that exercise is good for you and is better still if it is regular exercise, so why Tai Chi Chuan when any form of regular exercise should yield good results? This is certainly true to some extent as Tai Chi Chuan will not suit everybody, but, as Xu et al (2004), point out in their study; Tai Chi Chuan appears to be more beneficial than swimming or running. They suggest that this could be due to the requirements of the exercise; i.e. that in Tai Chi Chuan it is necessary to be precise about your body positioning whereas in swimming and running it is less important.
Yet there is another aspect of these studies with the main focus on the elderly; which is the natural decline of the body in the aging process. A fact of nature that cannot be avoided, yet perhaps it is something that does not have to be as decrepit as would seem to be apparent. As a form of exercise Tai Chi Chuan is not as taxing or exhausting as other forms of exercise regularly practiced by the elderly. Therefore there is less chance of increased wear and tear on the joints and muscles not forgetting other improvements such as the strengthening of the heart, improvement of balance and flexibility mentioned in the above studies.
What's more, in the appraisal “The Effect of Tai Chi on Health Outcomes in Patients With Chronic Conditions A Systematic Review” (Wang, Collet and Lau 2004). The authors note that from four studies on the musculoskeletal conditions one reports that “Tai Chi significantly improved arthritic symptoms” another suggests that Tai Chi Chuan is suitable for patients with osteoarthritis with potential for bone and connective tissue growth. Though these studies used a small sample size it suggests further research could be constructive.
Three of the studies used sedentary groups as controls; matched in size, weight, age and numbers, one by Lan et al (1998) used an unsupervised home based exercise group; this study also fails to mention the gender of their groups. One of the most quoted pieces of research by Wolf et al (1996) use an education control though the control group also participated in six months of Tai Chi Chuan. Wolfson et al (1996) make no mention of their control except to say that the control group are made up of “those relegated to the control group” who also partake in the Tai Chi Chuan for incentive to participate in the study. They also make no mention whatsoever of gender. This is an area where this paper falls down; it is complicated and indistinct to read something which should be avoided in reports on research.
Whereas Choi, Moon and Sung (2005) use a control group that continue their “regular activities” but fail to state what these activities may be and point out that they were unsupervised although were not allowed to partake in any regular classes. Here again no mention of gender is made which detracts from the piece of work. However Lai et al (1995), Hong et al (1999), Hong et al (2000) and Xu et al (2003) all cite the gender of their control groups and made an effort to reduce the variants of these two groups.
The lack of an adequate control in four out of seven studies is bound to affect the credibility of these research papers. Controls are also known as comparison groups which give a clue to their purpose, they are the measure by which the intervention group can be evaluated against. This comparison group must be of a similar sex, age, weight and state of health to the intervention group so that the differences observed can be attributed to the intervention being tested (Crombie and Davies 1996, p127).
Randomised Control Trials
Random controlled trials (RCT), are a method of research that holds great credibility, here only four of these papers use any form of randomisation. Choi, Moon and Sung (2005) use the somewhat unexpected method of “tossing a coin” to allocate the subject groupings, this method is not often used these days but was popular in the early 20th Century (Crombie and Davies 1996, p130, Drummond 1998, p74). Wolf et al (1996) use a recognisable method of randomisation presented in the methods section as does Wolfson et al (1996).
Once again for research to be considered to be of top quality it has to be within a certain framework and that framework for clinical trials in health is that of the RCT. The use of RCTs helps prevent selection bias, among other things, which can affect the outcome of the research. Then again perhaps this method is not suitable when measuring an intervention like Tai Chi Chuan against either a control group or an alternative intervention group such as in Xu et al (2003). Also, when researching a subject group made up of experts in one field along side experts from another field with a sedentary group as a control, and they could arguably be described as experts in their field, then randomisation is not possible or useful. In short, randomisation may be a useful and rigorous method of clinical trial but may not suit all clinical trials though it is without doubt that RCTs carry much favour in the research community.
Blinding is not mentioned in any of the studies though potentially the assessors were blinded and if not then they could easily have been. This would make the results less open to human error, i.e. the assessor’s mental state / attitude affecting the results. However, it is common practice nowadays for assessor’s to be blinded and this may be the reason as to why it is not mentioned (Drummond 1998, p44).
The sample size in the above research papers ranges from as many as 200 in Wolf et al (1996) to as low as 27 in Lan et al (1998). Of the others one had 110 subjects and another 84, three others ranged between 58 and 68 subjects. It is quite surprising that of the three trials carried out using experienced Tai Chi Chuan practitioners in Korea and Hong Kong that they were unable to find more than 30 such people to use within their trials.
Sample size is important as a small subject group is less likely to show important therapeutic benefits that might be found in the trial (Crombie and Davies 1996, p135). How many subjects should be used in such trials? There is no clear indication of this but a total subject group should surely be of at least 100 in order to have enough information to show any reasonable results. Despite this the fact that small groups may mask / hide therapeutic benefits, the research papers all show positive results. Therefore larger group sizes may be able to demonstrate far more wide reaching results that will have a greater impact on society.
The papers reviewed here have identified both physiological and psychological benefits to Tai Chi Chuan; this review has focused on the physiological benefits. Not all of the papers suggested further research; this is unfortunate as this is a useful and necessary part of the paper, it not only means that the authors have identified an area that needed research but also they have identified where further research may be warranted and constructive.
Tai Chi Chuan has been practiced in China for many years and recently has spread worldwide. There is even a “World Tai Chi Day” that has been organised to increase public awareness to the joys and benefits of Tai Chi Chuan. As we have seen positive outcomes have been reported on; balance, strength, flexibility and in CABS. There are many more advantages that have been reported in other research papers found in abstract format but were unavailable in full text for this review. Yet it is reasonable to conclude that Tai Chi Chuan does have beneficial effects on the body. Also due to its modus operandi it can be practiced by anyone right through to and including their old age.
Research into Tai Chi Chuan seems to have begun in earnest from the early to mid 1990’s. The research by Wolf et al (1996) is one of the most quoted pieces of research on Tai Chi Chuan; almost every article uncovered in the researching of this review had a reference to this piece of work. It is one of the better examples of research in this area, which established both physiological and psychological benefits. Though this is not to imply that the other pieces of work are invalid or poor but there are definite areas where improvements can be made. The research would benefit greatly by having larger sample sizes and the wider use of RCT’s.
The latter being regarded as a rigorous research method and therefore will automatically command greater respect. It is interesting that five of the seven articles come from; Hong Kong (one of which was in collaboration with University College Worcester in Britain), Taiwan and South Korea three of these study the long term effects of Tai Chi Chuan. Only two of the Asian papers use the respected RCT method however the other three are using experienced subjects for their Tai Chi Chuan group so these subject arguably cannot be randomised into separate groups. Having said this it does not necessarily translate that these studies are any the less scientific or rigorous but it is something that will detract from their credibility.
It is already acknowledged in the West that exercise has an accumulative effect; just look at physical fitness the proverbial quote is “6 months to gain and 6 weeks to lose” (Scott, A. pers comms). So it would benefit the pool of knowledge to recognise some clearly defined aims with regards to long term practice of Tai Chi Chuan and set about doing some research with an appropriate sample size and an established scientific method throughout. Through this the full effects, advantages and disadvantages can be established and the information may help present and future generations for people of all ages in all societies. Perhaps also the research could encompass other gentle exercises like yoga or walking, not power walking but simple countryside walks. It is altogether possible that these too will have beneficial effects on health.
The research into the benefits of Tai Chi Chuan, should the results prove positive, has many implications. It may not only affect the elderly but a whole cross section of society from the young through to the old. Using Tai Chi Chuan as a regular therapy there could be some very positive gains in the realm of self treatment for condition such as; hypertension, osteoarthritis, mobility, cardiorespiratory, co ordination and psychological benefits. All of which could have wide reaching effects on the pharmaceutical industry.
These industries make not only a huge amount of drug therapies to help these conditions but also make a huge profit from the sale of those drugs. This potential threat to income goes right across the Complimentary and Alternative Medicine (CAM) therapies research as neither Tai Chi Chuan nor CAM offer any revenue for these companies.
There are also questions that need to be both asked and answered within “the alternatives to Drugs” field of research such as: Why in the CAM therapies field are so many negative research results published?
In contrast to this the pharmaceutical companies have a prevalence for publishing only positive research results. Perhaps the true purpose of the CAM therapy research is to prove it does not work or at best is a placebo. At this point it should be pointed out that CAM therapies fail to fit or fall into the Western medical research model and desperately need an acceptable research model of their own. Furthermore it is also interesting to note that the pharmaceutical companies have little desire to publish the negative findings. Despite the fact that these negative results can have as important an affect on further research as those of a positive nature.
In addition the subjects of research that CAM therapies are given to work on are subjects that have no recourse through Western medicine i.e. people who have been given up on by Western medicine and have no relief via any method for their pains e.g. “Acupuncture in patients with tension type headache: randomised controlled trial” (Melchart, et al 2005, p376-382). How should we go about examining such types of intervention, i.e. those not using drugs and the whole complementary field, as there is a definite need for an appropriate research model in this area and at least there should be ‘a level playing field’.
Articles / Journals
Deadman, P. (2005). “Treatment of patients with chronic headaches in a hospital for traditional Chinese medicine in Germany a randomised, waiting list controlled trial”. J.C.M. 77, p.72.
Harmer, P. Li, F. & Fisher, K. J. (2002) “Reducing Fear of Falling in the Elderly through Tai Chi” Medicine & Science in Sports & Exercise. 34 (5) supplement 1, pS29.
Hong, Y. L. & Robinson, P. D. (2000). “Balance control, flexibility and cardiorespiratory fitness among older Tai Chi practitioners” British Journal of Sports Medicine. 34, p29-34.
Jung, H. C. Jung, S. M. & Rhayun, S. (2005). “Effects of Sun-style Tai Chi exercise on physical fitness and fall prevention in fall-prone older adults” Journal of Advanced Nursing. 51, p150-157.
Lai, J. S. Lan, C. Wong, M. K. & Teng, S. H. (1995). “Two Year Trends in Cardiorespiratory Function Among Older Tai Chi Chuan Practitioners and Sedentary Subjects” The Journal of American Geriatrics Society. 43, p1222-1227.
Lan, C. Chen, S. Y. Lai, J. S. & Wong, M. K. (1998) “The effect of Tai Chi on cardiorespiratory function in patients with coronary artery bypass surgery.” Medicine & Science In Sports & Exercise. 31, p634-638.
Melchart, D. Streng, A Hoppe, A. Brinkhaus, B. Witt, C. Wagenpfeil, S. Pfaffenrath, V. Hammes, M. Hummelsberger, J. Irnich, D. Weidenhammer, W. Willich, S. N. & Linde, K. (2005) “Acupuncture in patients with tension type headache: randomised controlled trial” B.M.J. 331, p376-382.
Wang, C. C. Collet, J. P. & Lau, J. (2004). “The Effect of Tai Chi on Health Outcomes in Patients With Chronic Conditions A Systematic Review.” Arch Intern Med . 164, p493-501.
Wolf, S. L. Barnhart, H. X. Kutner, N. G. McNeely, E. Coolger, C. Xu, T. & the Frailty & Injuries Cooperative Studies of Intervention Techniques Group.(1996). “Reducing Frailty and Falls in Older Persons: An Investigation of Tai Chi and Computerised Balance Training” The Journal of American Geriatrics Society. 44, p489-497.
Wolfson, L. Whipple, R. Derby, C. Judge, J. King, M. Amerman, P. Schmidt, J. & Smyers, D. (1996) “Balance and Strength Training in Older Adults: Intervention Gains and Tai Chi Maintenance” The Journal of American Geriatrics Society. 44, p498-506.
Xu, D. Hong, Y. Li, J. & Chan, K. (2004). “Effects of Tai Chi exercise on proprioception of ankle and knee joints in old people” British Journal of Sports Medicine. 38, p50-54.
Anderson, D. M. (2002). Mosby’s Medical, Nursing & Allied Health Dictionary. (6th ed). United States America: Mosby’s Inc.
Black, N. (1998). Health services research methods: a guide to best practice. London: BMJ publishing group.
Crombie, I. K. with Davies, H. T. O. (1997). Research In Health Care design, conduct & interpretation of health services research. (2nd ed). New York: John Wiley & Sons.
Drummond, A. (1998). Research Methods For Therapists. (2nd ed). United Kingdom: Stanley Thornes Ltd.
Polgar, S. & Thomas, S. A. (1995). Introduction to research in the health sciences. (3rd ed). Melbourne: Churchill Livingstone.
Rand, R. (2004). Tai Chi Chuan A Comprehensive Training Manual. Great Britain: Crowood Press.
Torgerson, C. (2003). Systematic Reviews. London: Continuum International Publishing Group.
Wile, D. (1983). T’ai-chi Touchstones: Yang Family Secret Transmissions. (revised ed). New York: Sweet Ch’i press.
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