The Yoga teacher Richard Freeman, who I've had the opportunity to practice with for a number of years now, has a beautiful way of describing the relationship between opposing actions within an asana - how they can be invited and allowed to interpenetrate in a way that is mutually enhancing, instead of canceling each other out.
So for instance, there are inwardly-spiraling and externally-spiraling actions of the legs and arms. In a given asana, one of the two actions might be the primary one, but it's always possible, and desirable, to allow at least a hint of the opposite action, as a kind of tether, or context for the primary action. It's a practice in which we engage in a kind of rewiring of the nervous system - transforming a straight-up reciprocal-innervation sort of response system into one which functions more along the lines of the yin-yang symbol.
So for instance, when I contract my quadriceps (the large muscles on the front of the thigh), a reciprocal-innervation response would have me turning off my hamstrings (the muscles on the back of the thigh) completely. But if I maintain a micro-bend (as in, barely visible, but feel-able) at my knee, I can keep my hamstrings on-line, firing in at least a small way, even as I contract my quadriceps strongly.
It's a kind of Polarity Processing applied to our physical and energetic bodies. Little by little, we learn to allow both halves of a movement polarity to remain conscious. Eventually, as the structural patterns resolve into flow, there is a delicious feeling of the two dancing with each other: interpenetrating in a way that allows them to remain distinct, yet at the same time in communication with, and enhancing one another.
What emerges then is a deep sense of integrity and vibrancy within the given form: a stillness which remains fluid; a balance which never loses its love of play.