Zhan zhuang as PNF stretching

PNF stretching, or proprioceptive neuromuscular facilitation stretching, are stretching techniques commonly used in clinical environments to enhance both active and passive range of motion with the ultimate goal being to optimize motor performance and rehabilitation. The literature regarding PNF has made the technique the optimal stretching method when the aim is to increase range of motion, especially in short-term changes. Generally an active PNF stretch involves a shortening contraction of the opposing muscle to place the target muscle on stretch, this is followed by an isometric contraction of the target muscle. PNF can be used to supplement daily stretching and is employed to make quick gains in range of motion to help athletes improve performance. Aside from being safe and time efficient, the dramatic gains in range of motion seen in a short period of time may also promote compliance with the exercise and rehabilitation program. (Wikipedia)

Increase mobility is an important objective for athletes, middle-aged to advanced aged folks, and patients recovering from major disease.  The exercise that we normally called stretching is usually active stretching whereby a person tries to achieve a higher level of mobility through the method of directly pulling and lengthening one's muscles with or without making use of one's body weight.  It is the most inferior kind of stretching, worse some people in pursue of quick result might possibility damage their joints through ballistic, bouncing or kinetic mobility, in addition of getting poorer result.

With proper techniques and conscientious personal adjustments, the practice of zhan zhuang can be made to do PNF stretching for maximum mobility results.  Take embracing a tree as an example, assuming one has learned the art of zhan zhuang, one can first make embracing in or inward force as the dominant force (like 70% in-force, 30% out-force), hold isometric for a few breathes, relax, and do the reverse, i.e. like 70% out-force, 30% in-force), repeat.

"But you are only doing an increase in mobility at the very limited embracing frame?"  Good question!

The next step is conscientious personal adjustments.  A practitioner will need to go beyond his comfort zone of putting his arms around an imaginary tree or ball.  Where and how to extend his arms (and therefore the other parts of his body in concert) will depend firstly on his particular training objective (like whether or not he is an athlete, and what kind of athlete he is) and secondly on his individual bodily situations (like how is the difference in mobility of his left and right shoulder joints like, or does he suffer from tennis elbow? etc. etc.).  Whereas a seasoned practitioner will be able to adjust his own training method to suit his objective and bodily conditions, a beginning practitioner should better consult a knowledgeable coach rather than aimlessly pointing his arms and legs in all directions that might do harm to him instead of good.

PS: Guided partner assist or self-assist techniques can also be useful.

Partner assist PNF stretching