In the "transmission of the lamp" of Buddhism to China from India
among other things some postures(asanas), mudras and breath discipline
were transmitted. As happens in cultural adaptation different versions developed- some good some not so good .Same in Indian yoga too... lots of health club yoga teachers have a superficial understanding of yoga--- specially the role of the breath and different kinds of breathing. Hatha is only one kind of yoga---there are several kinds. And even variations in teaching hatha. Hatha is the joining (yoke) of ha and tha two complementary forms of energy....sun-moon, yin/yang etc.Yoga pre dates Buddhism in india but
the hindu Patnjali attempted to systematize yoga approx. in the second century BC. he did not "invent" it. Taoism and Buddhism sometimes have had a cooperative relationship and sometimes rivalry. But the breath principles are parallel. If you check good books including Yang Jwing-Mings on the subject in one final circulation around the stomach Buddhists and Taoists just differ on anti clock versus clockwise- the latter difference is not really
significant. Yoga like chi gung can be heath specific and martial specific. Not all yoga is static- astanga yoga isnt.
The chi in chi gong parallels prana. But chi as a word is used in many other contexts and should not be confused.
Some good martial arts sytems have chi gung built into it.
Like many good things- best to get an expert teacher.
yuanfen/joy
The breath discipline and the realted yoga