Trends in Tai Chi Therapy Practice and Research

 In a National Health Interview Survey from The U.S. that traced the trends of tai chi among U.S. adults (N=85,360 participants), the data spanning from 2007 to 2017 suggested that the use of tai chi had increased by 64% [1]. The demographic data revealed a reduction in health disparities including an increased use of tai chi among older adults, females, those with incomes less than $35,000 per year and physically inactive adults. Those with difficulty getting medical care were also more likely to engage in tai chi.

In a paper entitled “Bibliometric evaluation of global Tai chi research from 1980 to 2020”, 1078 publications were included [2]. The largest numbers of studies came from China (N=503) and from Harvard University (N=74). The research was oriented towards prevention and rehabilitation for depression, fall risk, cardiorespiratory disease, stroke, and Parkinson's. The publications appeared in journals on sports sciences, alternative medicine, geriatrics, gerontology and rehabilitation. The research weaknesses according to the authors related to imprecision and inconsistency of the intervention methods, samples, risk factors and research designs.

A similar bibliometric analysis of tai chi publications from 2010 to 2020 involved a search of five English and four Chinese language databases [3]. This literature search revealed 1018 publications on 987 studies which reputedly was a threefold increase from the previous decade. 56% of these were randomized controlled trials, 16% were systematic reviews, 15% non-randomized controlled trials and 13% case studies. 74% of these were from China, 13% from the U.S. and 2% from South Korea. 55% of the research included adults and 72% included older adults. The top ten diseases were hypertension, COPD, diabetes, knee osteoarthritis, heart failure, depression, osteoporosis, breast cancer, coronary heart disease and insomnia. 25% were healthy participants in which the research evaluated health promotion, balance/falls and physiological/biochemical outcomes. Yang style was the most popular style followed by Chen and Sun style. Most of the classes were face-to-face by tai chi instructors that took place in group settings for 60 minutes, three times a week for 12 weeks. 94% of the research groups reported at least one favorable outcome, and adverse events averaged 7%.  Over half of the studies fell short of expected intervention-reporting standards, suggesting the need for updating existing guidelines for tai chi research.

Slightly different distributions were noted in a paper entitled “Clinical evidence of Tai chi exercise prescriptions: a systematic review” [4]. In this paper, 139 articles were reviewed on disease populations (68%) and healthy samples (32%). The diseases were distributed 35% musculoskeletal, 23% circulatory, 13% mental and behavioral, 12% nervous system, 6% respiratory, 5% endocrine/nutritional or metabolic, 3% neoplasms, 1% injury/poisoning, 1% genitourinary and 1% diseases of the eyes. It is not clear whether this distribution reflected the use of tai chi by adults with these conditions or whether it represented the clinical interests of the researchers and the convenience of their samples. The most commonly applied tai chi style was, again, the Yang style (66%) typically featuring a moderate intensity, simplified 24-form (31%). The typical sessions were 60 minutes, two to three times per week for 12 and 24 weeks.

In still another review about trends in tai chi practice and research, 193 randomized controlled trials were selected from a group of 210 in the literature [5]. The trials were distributed 19% neurological, 15% falls/balance, 15% cardiovascular, 11% musculoskeletal, 7% cancer and 7% diabetes. Consistent positive effects were noted for Parkinson’s falls risk, knee osteoarthritis, low back pain, cerebrovascular and cardiovascular disease including hypertension. Except for stroke victims, no evidence was found for disease prevention.  Multiple outcomes were noted as well as risk factors. In terms of the research, effect (or reliability) estimates ranged from 7% high to 38% moderate to 32% low to 24% very low. These were related to the risk of bias (81%), imprecision (38%), inconsistency (33%) and publication bias (3%).

Despite these methodological limitations, there is some consistency across these reviews. They were all authored by research groups from China who suggested that Yang style was the most common tai chi style. In addition, the focus of most of the studies was centered on   problems/conditions that are most prevalent in older adults (although not necessarily unique to them) including depression, insomnia and falls risk and medical conditions including neurological, cardiovascular and musculoskeletal diseases. These trends have continued, as reflected in the current review, although fewer randomized controlled trials and more systematic review/meta-analyses have appeared in the recent literature reviewed here.

Tai Chi Therapy Research on Adult Problems and Conditions

The recent tai chi therapy research on adults has included a focus on many problems and conditions, as already mentioned. Three studies each have appeared on diabetes, hypertension and cardiovascular disease. Two publications have featured anxiety and depression as well as two for substance use and two for sleep problems. Lastly, one publication each has appeared for obesity and for bone mineral density (Table 1).

Table 1: Tai chi studies on problems/ conditions of adults.

Anxiety and Depression

In a systematic review and meta-analysis focused on studies of the mental and physical well-being in patients with depressive symptoms, 8 trials were reviewed [6]. Both anxiety and depression symptoms decreased following tai chi, and the quality of life improved.

In another systematic review and meta-analysis that was specifically focused on anxiety and depression in cancer, stroke, heart failure and COPD patients, 596 studies were located in the literature [7]. Only 25 of these studies were randomized controlled trials (RCTs). These RCTs collectively revealed that tai chi was followed by decreased depression in those experiencing stroke and heart failure and decreased anxiety in those experiencing stroke and cancer, but not heart failure or COPD. The comorbidity of anxiety and depression in these medical conditions is consistent with their comorbidity in the mental health literature. Interestingly, these changes in mental health symptoms have not been assessed in healthy individuals in this recent literature on tai chi except for a meta-analysis of studies on tai chi effects on the psychological status of adolescents.

In the meta-analysis of studies on adolescents’ psychological status, 7 English language and 3 Chinese databases were explored [8]. In the final analysis, 4 randomized controlled trials were included as well as 6 non-randomized controlled studies (N=1244 adolescents). Following a variety of tai chi programs, significant reductions were noted for anxiety, depression and cortisol levels in the adolescents. Surprisingly, no effects were noted on stress and self-esteem.

Substance Use

Tai chi has also been associated with decreased anxiety and depression in individuals diagnosed with drug addiction [9]. In this systematic review and meta-analysis on two randomized controlled trials and nine non-randomized comparison studies, both depression and anxiety were reduced and sleep quality and quality of life were improved. However, it’s not clear if any reduction occurred in substance use.

Other positive  effects of tai chi have been noted for adults with substance use disorders [10].  In this systematic review and meta-analysis of 16 randomized controlled trials, the participants experienced a decrease in systolic and diastolic blood pressure and in heart rate. In addition, they showed improved performance on the “one-leg stand with eyes closed” and the “seated forward bend”. No effects were noted on grip strength or body fat. The positive physical effects of tai chi on these individuals with substance abuse disorders would hopefully also lead to less substance use.

Sleep Problems

Sleep problems have also been reduced by tai chi.  Sleep quality was explored during COVID in a group of frontline healthcare workers from Shanghai (N=98) who were assigned to receive tai chi or relaxation for a two-week period [11]. The tai chi group had better scores than the relaxation group on the Pittsburgh Sleep Quality Index and on the Beck Anxiety Inventory.

In a systematic review and meta-analysis of randomized controlled trials, 24 of 25 high quality studies suggested moderate improvements in subjective sleep quality after 60-90-minute tai chi sessions [12]. Not surprisingly, greater sleep quality was noted among the healthy sample versus the clinical sample but it’s not clear why greater benefits were experienced by Asian versus American samples. Unfortunately, these studies were limited to subjective self-reports on sleep quality scales rather than actigraphy that could have effectively provided objective measures not only on sleep stages but also on physiology associated with improved sleep quality.

Obesity

In a paper entitled “Effects of Tai chi or conventional exercise on central obesity in middle- aged and older adults”, three groups were compared including a tai chi, an exercise (aerobic and strength training) and a control group (N = 543) [13]. After 12 weeks of participation, the outcomes were assessed at 12 and 38 weeks. Both the exercise and the tai chi groups showed decreased waist circumference and decreased weight, and those gains were maintained. However, the beneficial effect of reduced high-density lipoprotein-cholesterol was only maintained by the tai chi group.

Diabetes

Patients with pre-diabetes and diabetes, conditions that often follow obesity problems, have also been noted to benefit from tai chi. In a study on patients with pre-diabetes (N=40 each in the tai chi and in the control group), a 12-week intervention was provided [14]. The tai chi group showed not only decreased blood glucose and insulin resistance, but also a decrease in inflammation, body weight and blood pressure. Unfortunately, this sample of adults with pre-diabetes was not followed to determine whether tai chi practice was preventive of diabetes.

In a systematic review and meta-analysis, seven electronic databases were searched for the effects of tai chi on diabetes [15]. Nineteen randomized controlled trials were selected. Collectively, they suggested that tai chi led to a decrease in fasting blood glucose, glycosylated hemoglobin and triglycerides and an increase in high density lipoprotein-cholesterol.

  

Other benefits have been noted for those with diabetes. For example, in a review on 18 trials assessing the effects of tai chi on patients with type 2 diabetes, the body mass index decreased and quality of life improved [16].

Bone Mineral Density

In a paper entitled "Different training durations and frequencies of tai chi for bone mineral density improvement: a systematic review and meta-analysis”, 23 randomized controlled trials were selected (N=1582 patients) [17]. Bone mineral density improvement was noted in the lumbar spine, the femoral neck, and the femoral trochanter (the widest part of the hip bone) following a tai chi program of four days per week for more than 10 months. However, there was no greater improvement following tai chi when it was compared to other forms of exercise. The authors concluded that more research is needed on training frequencies and durations.

Hypertension

In a randomized trial of tai chi for preventing hypertension, 66 adults were randomly assigned to a Wu style tai chi group or a control group [18].The tai chi group met three times per week for six weeks. At the end of this period, low-density lipoprotein-cholesterol was decreased as was systolic blood pressure. It's not clear why diastolic blood pressure didn't change as systolic and diastolic blood pressure typically change together. 

In another randomized controlled trial, 99 patients with essential hypertension were randomly assigned to a tai chi or an exercise group [19]. After 12 weeks, both the exercise and tai chi groups showed decreased systolic and diastolic blood pressure. In addition, the tai chi group showed a decrease in angiotensin and an increase in nitric oxide (both of which have been associated with reduced blood pressure).

In a systematic review and meta-analysis of nine databases, randomized controlled trials collectively suggested that 60-minute tai chi sessions were needed more than five times a week for more than 12 weeks in order to show a decrease in systolic and diastolic blood pressure [20]. Increases were also noted in nitric oxide after only 12 weeks and high-density lipoprotein-cholesterol increased in less than 12 weeks of tai chi.

Cardiovascular Problems

In a paper entitled “Effects of tai chi exercise on cardiovascular disease risk factors", several risk factors were decreased [21]. These included a decrease in systolic blood pressure, diastolic blood pressure, triglycerides, low density lipoprotein-cholesterol and blood glucose.

In another study in which tai chi was compared to running exercises for 60 minutes a day, five days per week for 24 weeks, similar decreases were noted for both group [22]. These included decreased heart rate, diastolic blood pressure and low-density lipoprotein-cholesterol, as well as an increase in cardiorespiratory fitness and lean mass.

In a systematic review and meta-analysis on the effects of tai chi on adults with chronic heart failure, 15 studies were identified (N=1236) [23]. Tai chi plus usual care led to higher scores on the Minnesota Living with Heart Failure Questionnaire, improved performance on the six-minute walk test, increased left ventricular ejection fraction and reduced need of hospitalization for heart failure. In addition, scores on the Hamilton Depression Rating Scale decreased and sleep quality improved based on scores on the Pittsburgh Sleep Quality Index. As is typical of most studies, tai chi has resulted in positive effects for both psychological and physical variables. Unfortunately, the authors of this meta-analysis qualified their findings by saying that they were at risk of bias for inconsistency, imprecision and publication bias. 

Tai Chi Therapy Research on Older Adult Problems and Conditions

The recent tai chi therapy research literature on older adults has also focused on several problems and medical conditions. The most frequently studied problem in the recent tai chi literature has been cognitive function (10 papers). Although not as many studies were focused on balance as in previous literature, at least three were found in the current literature. Frailty and sleep problems were, surprisingly, only assessed in single studies. This was surprising given that the older adult problem literature has featured many studies on frailty and sleep problems. The diseases that were covered in this recent literature included knee osteoarthritis (3 papers), diabetes (1 paper), arteriosclerosis (1 paper), stroke (3 papers), and Parkinson’s (3 papers). Other papers included one each for social support and longevity (Table 2).

Table 2: Tai chi studies on problems/conditions of older adults.

Cognitive Function

As already mentioned, cognitive function has been the most frequently studied problem in the recent tai chi literature on older adults. In this recent literature search, six studies and four meta-analyses met the inclusion criteria.

In one study, tai chi was compared with walking in older adults and behavior and EEGs were recorded [24]. The older adults showed better recognition and memory of faces in both the tai chi and walking groups as compared to an inactive control group,

In contrast, in another study, tai chi had better effects than walking. In that study comparing brisk walking with tai chi on cognitive function in individuals age 60 and greater, three 60-minute training sessions per week were held for 10 weeks [25]. On The Montreal Cognitive Assessment the tai chi group showed better memory performance than the brisk walking group. Improved visual-spatial ability and attention performance occurred in both groups. Similar effects were noted after a 12-week tai chi and exercise comparison (N= 55) [26]. In that comparison, the tai chi group showed reduced response time and increased accuracy and visual memory.

In still another study, tai chi was again more effective than walking. In this study, adults greater than 60 years -old with cognitive impairment engaged in tai chi or walking 60 minutes three times a week for 24 weeks (N=328, mean age= 68) [27]. Once again, those in the tai chi group performed better than the walking group based on the Montreal Cognitive Assessment. These mixed results, suggesting that tai chi sometimes has better effects than walking and other times shows equivalent effects may relate to the use of different intensity exercise protocols or different outcome measures.

In yet another study on tai chi for cognitive function in older adults, the lessening of frailty following tai chi mediated the effects of tai chi on improved cognitive function [28].

Tai chi has also been said to enhance cognitive training effects on delayed cognitive decline and mild cognitive impairment [29].In this study, cognitive training plus tai chi was compared to cognitive training alone. Not surprisingly, the combination of tai chi and cognitive training led to greater regional activity on fMRIs. Over time that combination delayed the expected decline in global cognition and memory.

A few meta- analyses are also included in this literature on the effects of tai chi on cognitive function in older adults. The first of these yielded results that were similar to the previous study assessing the combination of cognitive training and tai chi. In this meta-analysis, searches were conducted on PubMed, Embase, PsycINFO and Web of Science [30]. This yielded 9 studies (N=1524) that suggested that the combination of tai chi and cognitive intervention led to increased memory (large gains) and better balance (small gains).

In another meta-analysis, 13 databases in English, Korean and Chinese were searched and 17 randomized controlled trials were entered into the meta-analysis (N= 2365, mean age =70) [31]. Tai chi had a significant effect on cognitive function after entering physical function as a moderator variable.

And in a third meta-analysis on older adults with cognitive impairment, nine studies were included (N=827) [32]. In this meta-analysis, the tai chi groups had better performance on at least four measures including a Mini-mental State Examination, the Montreal Cognitive Assessment, the Clinical Dementia Rating and digit span forward and backward.

In still another meta-analysis on 11 randomized controlled trials (N=1061), the tai chi groups were noted to have better performance on several measures [33].These included global cognitive function, memory, mental speed and attention, ideas, abstraction, figural creations, mental flexibility and visual spatial perception. Unfortunately, these meta-analyses did not include randomized controlled trials comparing tai chi with active control groups.

Balance

Balance has been the focus of many earlier tai chi studies, although only three could be found in the recent literature. Nonetheless, the results of the recent studies support the earlier findings including an increase in balance following tai chi practice. In a study entitled “Tai chi effects on balance in older adults: the role of sustained attention and myokines”, 30 individuals participated in a 10-week tai chi intervention [34]. The participants showed better performance on the “go/no go” task and they experienced an increase in brain-derived neurotrophic factors (one of the neurotrophic factors that support differentiation, maturation and survival of neurons in the nervous system) and irisin (that reduces inflammation and helps maintain the balance between resorption and bone formation). In addition, the research group reported that improved balance correlated with sustained attention and the production of myokines (cytokines that are produced by muscle fibers that help in immunomodulation and maintenance of healthy bodily functioning).

In a comparison of tai chi and Iyengar yoga, 16 weeks of tai chi or yoga were provided for a sample of 48 older adults [35]. Assessments were made of the “one legged stand with eyes closed”, the “eight feet up and go”, an isokinetic dynamometer measure and the Activities Specific Balance Competence scale. Tai chi was noted to increase knee flexor strength and extensor strength as well as scores on the Activities Specific Balance Competence scale. Iyengar yoga, on the other hand, increased static balance and dynamic balance. The better knee flexor and extensor strength in the tai chi group probably relates to the frequent bending and straightening the knees in that practice. The better performance on the balance measures by the Iyengar yoga participants probably relates to the prolonged poses that involve one leg stands in Iyengar yoga as in warrior three. The results of this study, surprisingly, revealed inconsistency between the subjective report of the tai chi participants suggesting better balance and the yoga group actually showing better balance.

In a systematic review and meta-analysis of studies on tai chi for improving balance and reducing falls, an increase in balance and a decrease in falls were noted in older people and  in older people with Parkinson's [36].The levels of evidence for the improved balance and the decreased fall rates were moderate to high for older people but low for Parkinson's patients. The authors qualified their results, as have many other tai chi researchers, by suggesting that there was imprecision, inconsistency and publication bias for the group of studies they reviewed.

Frailty

In a systematic review and meta-analysis on 11 randomized controlled trials from five countries, 5 non-exercise comparison studies were included and six exercise comparison studies [37]. The meta-analysis sample was comprised of 804 tai chi participants and 872 controls (mean age =71). The majority practiced Yang style (N= 9 studies) with the number of movements varying from 10-158, the sessions varying from 30 to 90 minutes, with two to seven sessions per week for 8-48 weeks. The follow-ups occurred at 8-48 weeks. The tai chi groups as compared to the non-exercise and exercise groups had greater performance on the “3-second chair stand” and the “timed up and go” tests and they had fewer falls and fears of falling. The tai chi group as compared to the non-exercise group also showed better performance on the “sit to stand” and the balance tests. Their scores were also more optimal on the mini- mental state, the depression and the quality-of-life measures.

This meta-analysis highlights the need for more research on standardized tai chi protocols. Nonetheless, as was noted for the adult tai chi studies, the data demonstrate that fewer differences are noted when tai chi is compared to exercise groups versus non-exercise control groups of older adults, likely because tai chi and exercise are eliciting similar movements of the limbs.

Insomnia

This result isfurther documented by a randomized controlled trial entitled “Effects of Tai chi or exercise on sleep in older adults with insomnia” [38]. In this trial, the effects of 12 weeks of tai chi were compared to 12 weeks of conventional exercise and a non-intervention control group. Both tai chi and exercise increased sleep efficiency and decreased wake time after sleep onset. Decreased awakenings were revealed by the more objective measure of actigraphy.

Diseases

Several studies have been published in the recent literature on tai chi for various diseases. They include knee osteoarthritis, diabetes, arteriosclerosis, stroke and Parkinson's.

Knee Osteoarthritis. In a randomized controlled trial on individuals with knee osteoarthritis, tai chi was provided for 24 weeks and that group was compared to a health education control group [39]. Not surprisingly, the tai chi group as compared to the inactive group showed improvement on ankle plantar flexion, ankle dorsiflexion and knee flexion.

In another study on older adults with mild degenerative knee osteoarthritis (N = 68), the tai chi group showed better performance on several measures [40]. These included the 30-second chair stand, the 30-second arm curl, the two-minute step, the “chair sit-and-reach”, the back scratch flexibility, the single leg stand, functional reach and the 10-meter walk. Although these reflect positive effects of tai chi, this study lacked an active control group and its statistical power was limited given the large number of measures for a relatively small sample size.

Nonetheless, similarly positive effects were noted in a systematic review and meta-analysis on 11 trials of tai chi exercise for knee osteoarthritis (N = 603 participants) [41]. The older adults who received tai chi performed better on the six-minute walk, the time “up and go”, posture control and the WOMAC physical function scale.

Diabetes. In a paper entitled "Tai chi program to improve glucose control and quality of life for the elderly with type two diabetes: a systematic review and meta-analysis", seven studies were included [42]. Collectively, the studies documented a decrease in glucose, as well as increased balance and improved single limb standing.

Arteriosclerosis.  In a study on arteriosclerosis and physical function in older people, tai chi had several positive effects (N=84) [43]. This included increased cardio-ankle vascular index, increased functional reach, gait speed, and “time up and go”. Unfortunately, the comparison group in this study was a non- active control group.

Stroke. A few studies have documented the positive effects of tai chi on various functions in stroke patients. Balance has been one of the beneficial effects of tai chi in stroke survivors (Hu et al, 2022). A meta-analysis has confirmed the improved balance following tai chi as well as exercise capacity among stroke patients [44]. In this systematic review and meta-analysis on 19 trials, several positive effects were documented including improved performance on the Berg Balance Function Scale, standing and walking, gravity swing area and gravity swing speed, as well as increased exercise capacity.

In another systematic review and meta-analysis based on 16 electronic databases in English, Korean and Chinese, 27 randomized controlled trials of tai chi were conducted over 12 weeks [45]. Collectively, they documented increased mobility (ability to walk) and dynamic balance. These effects occurred for short-term as well as long-term programs and when tai chi was compared with active controls. These findings are surprising inasmuch as tai chi has not differed from active control groups for some other conditions. It's also surprising that according to this research group, none of the randomized controlled trials had high bias.

Parkinson’s. At least two meta-analyses have been conducted on studies assessing the effects of tai chi on older adults with Parkinson's. In one meta-analysis, 17 randomized controlled trials were reviewed (N=951) [46].The results combined suggested increased gait velocity, better ratings on the Parkinson's Disease Rating Scale and improved motor activity. In addition, improvements were noted on specific balance activities and on the Berg Balance Scale. 

Similar findings were reported in a review of 28 studies on older adults with Parkinson's [47]. In this review, improved motor function and better balance were noted as well as fall prevention.

Social Support

In asystematic review entitled “Tai chi interventions promoting social support and interaction among older adults”, 4 studies based on social cognitive theory and successful aging were reviewed (Koren et al, 2021).  The tai chi groups experienced increased social support which, in turn, contributed to increased health benefits.

Longevity

In a study on an association between tai chi exercise and longevity as well as prevention of the need for long term care, greater survival duration and a longer period prior to the need for long-term care were noted in the tai chi participants [48].  These results were not surprising given the association between longevity and physical activity in centenarians [49]. It is surprising, however, that this recent literature did not feature more than one paper on longevity given the prevalence of tai chi practice among older adults and the association between longevity and physical activity.

Potential Underlying Biological Mechanisms for Tai Chi Therapy Effects

Underlying mechanism research suggests that tai chi is associated with increased connectivity of different brain regions, increased brain volume and decreased brain-derived neurotropic and inflammation factors.  Decreased inflammation was reported in a study on the effects of tai chi on lower limb osteoarthritis [50]. A significant decrease in inflammation and pro-inflammatory markers were thought to contribute to the improved condition noted for those with osteoarthritis.

In an fMRI study (N= 36), the authors suggested that tai chi was altering brain functional network plasticity including an increase in nodal clustering coefficient in the left thalamus [51].And, similarly, in a review on potential underlying mechanisms for the effects of tai chi, the authors suggested that tai chi activates the expression of signals in different brain regions, increasing their connectivity, increasing brain volume and decreasing brain-derived neurotrophic and inflammation factors [26].

In a systematic review and meta-analysis entitled “Effect of Tai chi on markers of oxidative stress”, five randomized controlled trials and five non-randomized controlled trials were included [52]. The authors reported several positive effects including an increase in superoxide dismutase (an enzyme that fights free radical cell damage) and catalase (an enzyme that protects cells from oxidative damage) and a reduction in lipoperoxide (which can lead to cell membrane rupture and cell death). However, unfortunately, only 2 of the 10 studies included active controls as comparison groups.

Another potential underlying mechanism is suggested by the similarity of the effects of  tai chi, running and walking in some of the activity comparison studies. Moving the skin of the feet would stimulate pressure receptors under the skin which leads to increased vagal activity [53].  This effectively slows the nervous system as in, for example, decreased heart rate and decreased cortisol. Increased serotonin also results from enhanced vagal activity. Serotonin, as the body’s natural anti-pain and anti-depression neurotransmitter, in turn, knocks down pain and depression This research group has reported that many of their studies have shown decreased cortisol as well as increased serotonin [54].This potential underlying mechanism has appeared in the yoga literature but not the tai chi literature. Additional mechanism studies are needed to compare those already suggested.

Methodological Limitations of this Recent Research

This literature on tai chi therapy research has differed from the research reviewed in 2020 by including primarily systematic reviews and meta-analyses instead of randomized controlled trials [55]. Although that suggests that a significant body of research has accumulated, many of the studies included in those reviews and meta-analyses were highly variable on the tai chi styles, the samples and the measures. Further, many were not randomized controlled trials. In addition, while some of those studies had active controls like walking, running or conventional exercise, most had inactive control groups. More randomized controlled trials are needed with tai chi being compared to active control groups to distinguish the effects of tai chi as compared to other forms of exercise. And, different types of tai chi need further comparison rather than Yang style being the most prevalent style practiced and researched. Further, comparisons are also needed to document the differential effects of the different tai chi exercises and forms within styles like the Yang style.

Most of the studies published between 2020 and 2023 were conducted before 2020 so they are not representative of the COVID online or the more current online tai chi therapy effects. In-person tai chi may be more therapeutic and online tai chi may be more accessible, more convenient and cost-effective. Long-term effects may be greater for online tai chi if it is more accessible, convenient and cost-effective and therefore more frequently practiced, but longitudinal comparisons have not appeared in this literature. 

Most of the research derives from Asian samples and is focused on highly experienced practitioners or clinical samples, suggesting that the data may not generalize to other samples.  These would seem to be convenience samples that can be readily recruited from hospitals and medical centers. As such, the findings have often been confounded by the greater experience of the tai chi practitioner in Asian countries or being an add-on therapy for the clinical samples. For example, tai chi for the older adults has frequently been added to physical or cognitive training. Without assessing these as separate therapy groups, the results are confounded.  In addition, the focus on clinical samples in tai chi research has led to tai chi being   a primarily interventive rather than preventive therapy. Tai chi instructors could be invited to collaborate with researchers as their classes could provide rich databases that would enable comparisons of students across varying levels of experience. That would also address the prevention effects of tai chi.

Despite these methodological limitations, this recent literature on tai chi therapy has supported the earlier research.  This review and earlier reviews highlight the positive effects of tai chi therapy.

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