I would say that the degree of it “working” will depend what you are seeking for in tai chi, whether you are able to find the right teacher for you and the dedication of your practice.
I have done tai chi for over five years mainly under two masters (sifus). The reason I have two is because they both give me very different things. The first I do in a nearby housing estate with a big group in the mornings near my home in Hong Kong. My teacher there, Li sifu, is female, over 60 and the quality of her chi is amazing—very subtle, very beautiful. Although the practice is really about just doing the same sequences over and over again I am continuously amazed at how the practice deepens—how come I didn’t see this detail before?
As the practice deepens, the feeling of “chi” deepens into something tangible.
While obviously tai chi can work as a physical exercise to help one’s agility, flexibility, awareness of body and self, etc, to deepen it as a qigong practice one has to find the right teacher.
Anyway, here’s a page about tai chi and health I found just with a google search:
http://www.taichiacademy.com/scienceandtaichi.htm
There are tons of studies about the health benefits of tai chi.
Aside from health benefits, tai chi is also a communal activity here in Hong Kong. Because I am by far the youngest of that group, and I feel like I have a extended family of aunties and uncles and grandmothers. I am part of a lineage, not only in the tai chi practice, but in a wider community of collective wisdom (not unlike fluther!).
My other sifu is male; and he teaches tai chi in the martial arts tradition. So I train my strength and my sense of how to use tai chi in self defense. Despite the slowness you tend to see it done, tai chi is a martial art. All its movement phrases have its uses in defense or attack. And so learning it as a marital art teaches my reflexes, builds my strength, and its fun to be able to problem solve. As a dancer, the “pushing hands” tradition of tai chi also teaches me the skills of “listening” to ones partner (not unlike Contact improvisation)
My teacher grew up fighting on the streets of HK, and so yes, tai chi works as a martial arts technique.
Finally, I would say that tai chi will give you as much as you give to it. You can use it for health reasons (both of my sifus came to tai chi because they had severe health problems – one of them actually had a chronic back problem that had him in a hospital bed for months, but was cured by tai chi); you can use it as a energetic practice (chi), you can use it as a martial art practice. As a dancer, I use it as a movement + creative practice—I think it is always helpful for every artist to find a discipline to commit to, and mine happens to be tai chi. In HK, it can also be a communal practice…
So as you see, tai chi is working out very well for me.
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>> see tai chi related entries in my blog