Particularly in the Soto School of Zen (Chan) the posture itself is the central teaching, the method and the fruition. Zen has the Zhenwu preliminary stage, it just isn't given any attention in the teaching, except to say, "sit still."
In Yiquan, Zhenwu becomes a barely active body. Thus students are instructed to wrap their arms around an imaginary tree and try to move it. This constant vigilance could also be called "stillness ready to pounce."
While it is entirely possible to just start practicing meditation with no instruction save a posture; meditation does require a certain kind of strength. Let's call it meditation muscle.Â Generally the Zen tradition helps people build this meditation muscle by having new students join a daily group of people who have already established a committed practice.
Willing oneself to "be still" by constantly resisting the urge to move has the same effect as the Yiquan approach of "stillness ready to pounce." Both approaches develop this meditation muscle. They are both pulling on the same "rope."
Since we are not actually Zhenwu (a permanently meditating war god ready at any moment to leap up and charge off into battle), all these methods give-in to something softer and weaker, they reveal our true nature--they are non-productive.