Tai-chi is recognized in the exercise market by its slow-motion movement. To my knowledge, there are no other slow-motion movement exercise routines. And to me, this is the central problem confronting Tai-chi research!
As seasoned internal martial art practitioners will tell you, not all slow-motion movement is Tai-chi and not all Tai-chi is slow-motion movement.
Most Tai-chi that is taught and practiced these days is nothing more than a slow-motion, choreographed dance or exercise routine; lacking the "internal" component.
For most people, it is primarily the variable of "movement speed" which differentiates Tai-chi from other exercises. And so, comparing Tai-chi to other exercises is like the proverbial "comparing apples and oranges". There is no basis for comparison.
Once the individual movement attributes are isolated, another research question arises: What is the effect on the variable being studied when one or more of these movement attributes are modified? What is the result when slow movement is interspersed with fast movement; flowing movement is interspersed with choppy movement; soft/relaxed interspersed with tension? Is it only the synergistic combination of these movement attributes that yield the observed result or does one attribute play a more dominant or significant role than the others?
Because the general population now tends to identify any slow motion, choreographed movement as being "Tai-chi, it should be rather easy to set-up a double-blind Tai-chi study where group "A" would learn a popular Tai-chi form and group "B" would learn the "placebo Tai-chi" form mentioned above.
I think that until Tai-chi research gets to the point of isolating and testing particular attributes in other "forms", attributes that are currently bundled in Tai-chi, then "science" is acting as little more than an ad campaign for this very complex and little understood art.
Finally, I have written the above based on my survey of Tai-chi research studies to date. If I've missed something, please let me know.
You can find research on Tai-chi by doing a search on Tai-chi at Pub Med or you can check out the Tai Chi Medical Research site which posts the latest studies and provides an easy to read summary.
Maybe it's all placebo? (August 24, 2010) by Josephine P. Briggs, M.D., Director, National Center for Complementary and Alternative Medicine, sharing her thoughts on the NEJM Fibromyalgia study that had just been published. Here's a portion of her comment:
"Tai chi is one CAM practice that clearly illustrates the challenge of conducting clinical research in CAM. As an accompanying editorial in NEJM notes, it is a complex intervention involving multiple components: exercise, breathing, meditation, relaxation, and a practitioner. How do you control for all of these variables when designing a study? Some CAM proponents will say that it is the combination that makes the intervention work; many conventional researchers will say you must isolate the components to identify the active “ingredient.” Critics will say it all just the placebo effect—you expect the intervention to work, and so it does."
"The written and oral tradition of taiji emphasizes that sitting and standing meditation (wuji) is the starting point for efficient taiji practice. You have to learn how to relax your mind and body in stillness before you can relax in form movement. You have to learn how to relax in form movement before you can relax while perturbed during push-hands.
Perhaps the most well-known saying in the internal martial art tradition of China is: lian quan bu lian gong, dao lao yi chang kung. (If you practice form, but not qigong, even if you practice your whole life, your art will be empty.) Very few research studies to date have mentioned this essential aspect of traditional taiji practice. The researchers and possibly the taiji instructors themselves are not yet sufficiently aware of this core tradition of the internal arts."
"The vast majority of taiji research studies to date, Dr. Yang said, have involved testing subjects who underwent only form training. This omits a crucial and once-secret part of traditional taiji training - the standing, sitting and lying-down qigong practice that builds internal energy and gong. When researchers omit this essential practice, they cannot investigate the full benefits of the art."