Tai chi, in addition to other mind-body exercise programs such as yoga, have increasingly been advocated, and practiced in the United States in recent years. The article by Taylor-Piliae 1 in this issue of JCR reflects the increasing interest in this ancient form of exercise and its potential relevance for cardiac rehabilitation. The author provides support for the inclusion of tai chi in a comprehensive program of cardiac rehabilitation, and suggests that in developing countries, where resources may preclude traditional forms of exercise training, tai chi may assume a more central role in an exercise training paradigm. Readers of this article seek a better understanding of tai chi, and in that regard, the theoretical and physiologic rationale is well described. If the inclusion of tai chi were represented by a continuum, at one end one would find clinicians better informed but still unsure of the evidence for including tai chi, and at the opposite end there would be a group who expeditiously incorporate tai chi into their treatment regimens regardless of the evidence.

As usually is the case, a rational decision for inclusion probably lies somewhere in between, and reflects a function of the evidence, patient population, program philosophy, and clinician beliefs. The decision to include tai chi either as an adjunctive therapy or as an alternative to traditional training implies clinician acceptance, if not enthusiasm. Likewise, acceptance and enthusiasm to incorporate a new therapy must be grounded in evidence-based medicine, and Taylor-Piliae provides a detailed bibliography to support a variety of outcome measures affected by the practice of tai chi.

Clinicians are left to evaluate the available evidence in the context of their cardiac rehabilitation programs and associated patient outcome priorities. Logically, it seems that the evidence necessary to recommend tai chi as an adjunctive therapy need not rise to the level necessary to justify tai chi as an alternative to traditional exercise training. In consideration of the latter, the mandated outcome measures of morbidity and mortality have not been investigated in randomized studies of tai chi.

To be fair, traditional exercise training in cardiac rehabilitation preceded randomized, controlled trial evidence by a number of years. The rationale for cardiac rehabilitation in its early years was based on risk factor amelioration and improvement in physical fitness, with concomitant hypotheses of improved function and a reduction in morbidity and mortality. In that regard, traditional exercise training proved to be of considerable value, as evidenced in the 1995 Agency for Health Care Policy and Research Clinical Practice Guideline, 2 and in numerous subsequent studies. Taylor-Piliae 1 cites several studies that demonstrate improved hemodynamic and cardiorespiratory function after tai chi. In the context of patients with cardiovascular disease, two studies are reviewed. Channer et al 3 provided evidence of a trend for improved diastolic blood pressure improvement in a tai chi group, as compared with an aerobic exercise group (systolic response was similar), but it is important to note that the groups attended therapy just twice weekly for the first 3 weeks and once weekly for the remaining 5 weeks, for a total of 11 sessions. A more thorough evaluation of cardiorespiratory function is evident in the study of Lan et al, 4 which evaluated the status 20 patients after coronary artery bypass graft. These patients were randomized after a phase 2 cardiac rehabilitation program to a tai chi chuan exercise program or a home-based self-adjusted exercise program on the basis of their phase 2 exercise regimen. After 1 year of training, the tai chi chuan group exhibited a statistically significant improvement in peak oxygen uptake (P < .01) and work rate at the ventilatory threshold (P < .05). It is also important, however, to examine the magnitude of change because the measured improvement was approximately 10% and less than 1 metabolic equivalent (MET). Studies evaluating subjects without cardiovascular disease practicing various forms of tai chi have shown oxygen uptake costs as modest as 3 METs 5 and as high as 6 METs, 6,7 but were not evaluated in the context of a training study.

In summary, there seems to be little doubt that forms of tai chi provide a physiologic stimulus that yields a modest cardiovascular benefit. In that regard, tai chi would be a useful adjunct to a traditional exercise program. In considering tai chi as an alternative primary form of exercise training, clinicians should compare the foregoing evidence with that for existing aerobic conditioning programs, in which ample data indicate a variety of documented clinical and health outcomes, with an average increase in peak oxygen consumption closer to 25%. Indeed, although the debate continues regarding the volume and intensity of exercise necessary for optimal therapeutic benefit, recent compelling data from more than 44,000 subjects in a study by Tanasescu et al 8 suggest that higher-intensity aerobic exercise, and even resistive exercise, is strongly associated with reduced coronary heart disease mortality, considerably more so than lower-intensity exercise. Interestingly, the metabolic cost of moderate exercise in the Tanasescu et al 8 study was 4 to 6 METs, which could conceivably be achieved with tai chi according to the studies of Schneider and Leung 6 and Lan et al, 7 although this should logically be investigated in training studies for patients with cardiovascular disease. One of the poorest outcome measures in cardiac rehabilitation has been reduction in excess body mass. With a recognized need to increase exercise volume for patients with an elevated body mass index, clinicians need to evaluate prescribed adjunctive therapy carefully to ensure that caloric goals are met.

Patient population and program philosophy also may aid in the consideration of tai chi as an adjunctive form of exercise therapy. Taylor-Piliae provides evidence that a variety of other health-related outcome measures may be affected through tai chi including stress reduction, balance, postural stability, and fall prevention. Hong and Robinson 9 provide evidence of improved balance control with tai chi. As with measures of cardiorespiratory fitness, randomized controlled studies would strengthen this argument, although most clinicians likely would agree that the nature of tai chi exercise logically confers benefit in measures of balance and postural control. Thus, for patient subgroups in which higher-intensity exercise is contraindicated, or for older patients among whom a reduction in fall risks is of increasing importance, tai chi may well be a suitable adjunctive therapy. That said, there is an important, albeit often overlooked, distinction between improving a variable associated with falls (eg, balance) and an actual reduction in falls. Evidence showing the efficacy of tai chi exercise for these important outcome measures needs to be demonstrated in older patients with cardiovascular disease.

Clinicians should recognize the rise in the awareness and promotion of mind-body fitness. LaForge 10 provided a compelling argument that mind-body programs may be an important component of disease management models that focus on self-care, and ultimately, decreased healthcare use. The use of tai chi as an adjunct to cardiac rehabilitation programs should be evaluated on the basis of the needs among the patient population and in view of evolving scientific evidence, of which there is a clear need for additional data. Tai chi may well ameliorate recognized cardiovascular risk factors while providing other physical benefits, such as improved balance. As a form of mind-body exercise, it may confer additional benefit.

The potential for improved social interaction and better measures of mental health are emerging as critically important issues in contemporary cardiac rehabilitation. The compelling question remains as to what degree daily aerobic exercise should be modified to include tai chi. On the basis of available data, the combined caloric volume should approach 1500 kilocalories per week for optimum body mass management and cardiovascular health. Moreover, intensity of exercise does appear to matter, as evidenced by recent important studies by Tanasescu et al 8 and Myers et al. 11 The decision to include tai chi should be driven by this evidence in the context of individual patient needs. Chosen in that light, tai chi may well provide clinicians with an attractive adjunctive therapy. In the interim, clinicians and researchers are encouraged to investigate earnestly tai chi's effects on traditional cardiac rehabilitation outcome measures, and to provide insight as to its place in contemporary rehabilitative practice.

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