Frank,
James (CD) is correct that there are tissues with high energy demands, like cardiac muscles (with regular and powerful contractions), that contain more mitochondria than tissues with less energy demands. But NO, there is no evidence that the slow and relaxed movements performed in solo TJQ forms practice would increase the number of mitochondria in the skeletal muscles of a TJQ practitioner. That is just speculative wishful thinking on his part – because of his “empirical experience” acquired from Tai Chi practice (i.e., he FEELS like he has more energy, and since ATP, which is a primary fuel for cellular activity, is synthesized in the mitochondria, he THINKS that TJQ MUST produce more mitochondria in the skeletal muscles of TJQ practitioners, because it is POSSIBLE for tissues to have more mitochondria...).
James does not even seem to realize that TJQ has fewer energy demands than for dancers, laborers, athletes, etc., but SOMEHOW [contrary to scientific expectations] TJQ would give practitioners more mitochondria (and therefore more ATP synthesis and therefore more energy reserves) in their skeletal muscles. [Since he cannot even see the contradictions in the information that he himself posts, I have lost hope that he will be capable of understanding. He seems to have gone too deeply into the mental web that he has woven for himself to be able to see clearly.]
Just focus on feeling the QI, fellow practitioners, and perhaps you can convince yourselves “empirically” that you have more energy because you have somehow gotten more mitochondria (even without having to work as hard as dancers, laborers or athletes), and produce more ATP (because you FEEL like you have more energy), but somehow require less oxygen because your heart can stay beating at a slower rate and therefore does not pump as much oxygen to the cells through the bloodstream... Just FEEL THE QI and you may be convinced that James is on to something. FEEL THE FORCE! (At this point, James’ ideas do seem to me more like Star Wars fiction.)
There is some evidence that ATP-synthase (located within the mitochondria, and which produces the ATP) may be slightly but significantly up-regulated (i.e., increased activity) by certain activities (the relaxation response was what the researchers specifically looked at). While this would not indicate more mitochondria, it would indicate that there may be more available ATP under those conditions. But James dismissed that study for some reason (it was not specific to TJQ?). But there is also contradictory evidence that treatments thought to increase ATP synthesis (e.g., as supplements for athletes) do not increase strength or endurance. So even with more available ATP, it does not seem to help athletic performance (but perhaps TJQ SOMEHOW is different?).
The evidence so far seems to contradict what James is hoping for (believes?). But it is possible that something could increase the available energy reserves in TJQ practitioners (i.e., his ideas have not been DISPROVEN, as far as I am aware). It is POSSIBLE but NOT PROBABLE.
Now, there are practices in TJQ that I do support, and that I do think would have significant benefits for practitioners:
1. Partner practice, where practitioners are practicing issuing and receiving against/from resistance by their partner/opponent.
2. “Moving through molasses” solo forms practice. See my article at the following link:
http://slantedflying.com/taijiquan-movi ... -molasses/
3. Super slow solo forms practice – i.e. moving at the nearly imperceptible speed analogous to the minute hand of a clock rather than the normal speed analogous to the second hand of the clock (the second hand can be perceived to be moving continuously whereas the minute hand is still moving continuously but appears to be stationary, it is imperceptible unless one looks away briefly and thereafter notices a change in position when looking back. Now that will really work your muscles and your balance, and you will be on one leg for minutes at a time rather than just seconds!
But TJQ is not commonly trained this way by modern practitioners, so I doubt that these practices are what James was referring to when mentioning TJQ practice, and especially not when mentioning slow and relaxed practice of solo forms. I am skeptical that even these more energy demanding ways of practicing TJQ would increase the number of mitochondria in the skeletal muscles of practitioners.
Edit: I should also note that mitochondria divide independently of the cell in which they reside, so it is possible for mitochondrial division to be triggered (e.g. by high energy demands?) to produce more mitochondria in the cells without being coupled to cell division (i.e., more mitochondria within individual cells, without requiring more cells).