In my training guide, I have included yoga (yogasana) techniques for structural alignment. During the time when I first learned chi-kung as a young boy, people then liked to do moving forms more than (boring!) stationery stance. Some moving forms like the then popular He Xiang Zhuang 鶴翔樁 can indeed allow practitioners to generate chi rather quickly. The negative side is, in addition to its lack of mechanism to control the strong chi thus generated, it does no benefit to one's structural alignment.
To promote structural alignment, doing chi-kung in a stance is essential. As a pragmatic person, I never hesitate to add useful techniques to my own training system if they are beneficial. And yoga (or more correctly, yogasana) is definitely one good choice.
A few years ago, yoga gyms blossomed in Hong Kong. Overseas and local yoga teachers and organizations opened bigger and bigger gyms with main emphasis on yoga. In the last 12 months, many of them went bankrupt and those who paid annual fees complained of possible fraud. Why? Apart from the usual reason of fad and "mass psychosis", there were indeed many cases of students (and teachers) having injuries from doing the asanas. Isn't it yoga supposed to be contributing to better alignment rather than causing alignment related injuries?
Or rather the question should be: How to do proper yoga to avoid alignment related injuries?
A prominent yoga teacher in Taiwan by the name of Madam Chen wrote in her book "Positive yoga" complained that some teachers there were athletes and dancers who learned yoga for a couple of months and started teaching the stuff. Many who got injuries were actually those teachers! Her advice is, in addition to finding a good teacher, firstly one should first learn proper breathing techniques, secondly, one must not treat flexibility as competition, and thirdly, most importantly, one has to watch out for the alignment lines and points and to reach all alignment requirements as the progress guideline of each pose.
I certainly agree with yoga teacher madam Chen. I further suggest that as a foundation practice of doing proper and injury-free yoga, one should first practice a few session of standard zhan zhuang pose (embracing a tree). Once chi is activated in a practitioner's body, he can more easily feel whether or not he is aligned properly doing his yoga asanas. Moreover, his accumulating chi (assuming he continues with his practice of zhan zhuang) can give him more power to move into a well-aligned pose, and being safe in the process.