I consider power stretching an essential practice for supporting tai chi practice or any other movement. Professional dancers, runners, swimmers, hikers, skiers, etc. know this of course, along with master martial artists. One thing I have learned about how people power stretch is that they over do it and can injure themselves, especially in the beginning of practice. They stretch when they are not warmed up, for example. Or they overstretch when it would be better to gradually work their muscles, tendons, ligaments and joints into more extension. They rip and tear, rather than coax and nurture. The older you get the more liable you are to do this if you are not mindful.
Power stretching is an essential part of practice if you want deeper benefits; but until you understand through practice over time, I suggest not over doing it when you add power stretching.
Chinese martial arts power stretching is different from other systems for the most part, but you do find things similar in other systems. One difference is how you incorporate your attention in the postures, which is more internal and energetic in nature. Some teachers offer detailed methods of observation to help sharpen our attention and our sensitivity to subtle changes in our bodies. I know my teachers and I do, anyway.
For older people who are beginning tai chi or have been practicing for a short time, stretch only as much as it is comfortable at first, then progress to more challenging extension. Most of us can go out of our comfort zone without harm. But if you are following a seasoned practitioner, don’t push yourself to match their effort and extension. You won’t be able to. However, allow them to challenge you a little. My teacher, George Xu (Guo Ming) once told me, “Go slow in the beginning. The master goes his speed, you go yours.”
We seldom push ourselves beyond our limits, or what appears to be limits. Most of us will stay where we are if it’s working for us. That’s not a bad thing, because it allows us to save energy for when we need it. It’s sort of a survival trigger, but you also risk complacency. It’s also true that the more we stretch beyond perceived limits, the more energetic capacity we develop. This is the essential tai chi principle: know your limits, but practice to go beyond them. Learn what they are, but overcome them through regular, consistent practice … alone and as part of a group. It will do wonders for you.