[PHOTO: Pose demonstrated by Yao Zongxun, father of my teacher Yao Chengguang]
I have emphasized the idea and practice of SLO in Tai Chi. SLO stands for 'Single Leg Operation'. I have focused the spotlight on a number of them from the standard ZMQ37 short Yang style form. These include: Golden Rooster on One Leg, Separate Feet, Lotus Kick, and a few others. These are postures in the form where you aren't just 100/0 (like Play Guitar), but even more explicit - in a real SLO, one foot is entirely lifted. So they are often static versions different types of kicks. In my tutorial film The Hot Zone, I show how you can integrate your practice of SLO's as single poses into the more natural flow of the full form. But you can also practice them in isolation.
I have also written about Yiquan, a derivative art from classical Xingyiquan. Yiquan is big on pure standing work, often accompanied by various quasi-internal techniques of small-scope movement and visualizations. Not to get into the entire art of Yiquan here, I want to point out that while there are actually very few true SLO's in Yiquan (and only a few kicks), in fact Yiquan is the proud possessor of one of the very best SLO's of all.
It is just called One Leg Standing. It looks extremely simple and basicaly it really is simple. I haven't called it out much because my focus is more on the other arts. Also, as a practical thing, this stance feels awkward, and will be perceived by people trying it out for the first time as mentally tedious and physically tiresome after say a minute or even less for most people. And, if you have no prior experiece with the sheer reality of the internal energy (from doing my other stuff), you probably won't feel the awesome charge that regular practice of this brings you.
But in the interest of completeness, I feel I should now call out this superb SLO. All you need to do is follow the picture above. Minimally try to do 2 minutes per side. If you follow this with (Xingyi foundational) Santishi as covered in my recent book AXE Advanced Xingyi Energetics, that's ideal.
Yes, at first this will feel goofy, awkward, tedious and pointless. So most of you will try it once for maybe 10 or 15 seconds and then give it up, never looking back. Which is fine. But a few of you will persist with it just enough to realize it's awesome potential. You'll get hooked and incorporate it into your practice, at least at the level of the 2 mins per side once or twice a day routine.
Over time you'll realize that it is packing and layering the internal power into your entire torso (with spread to all limbs of course). Just an awesome drill, another fruit of Wang Xiangzhai genius. You don't need to agonize much over every little detail of pose. Just work to the photo above and let it self correct. With these SLO's there's less chance of you getting it totally wrong than there is with 2-legged stances, because external conditions like balance and gravity generaly keep your wild misconceptions within realistic bounds. It's pretty much idiot proof. Just stand stably and calmly in the position shown. No special breathing, just breathe and stand calmly and naturally.