Warrior 2 is an interesting pose that involves the action of external rotation of the rear hip, even though the foot is angled towards the body. It flows well with reverse warrior and side-angle pose, as the leg and hip position remain largely unchanged throughout those poses. The most important consideration when doing any of these three poses, is to make sure your front knee is not caving inward. Most people can self-correct this in Warrior 2 when given an auditory cue, but as soon as they look upward and sweep their front arm overhead for reverse warrior, boom, their knee caves in (drifts inwards). It’s like there is a hard-wiring between the sweep-up and the cave-in. After years of studying the correct alignment, I still find that I have to be mindful of this every time I do reverse warrior… it’s just not one of those things (in my experience) that comes naturally.
When your knee is in correct alignment (over your ankle and not drifting inward), your knee is protected. When the inward drift occurs, the glute and hip muscles aren’t working hard enough and the ligaments of the medial knee take the brunt of your effort. Over time, this can lead to repetitive stress injuries of the knee. And what’s the point of doing yoga, if we’re going to leave with more injuries than we came in with?!
Photo attribution: http://creativecommons.org/licenses/by/2.0/deed.en: Lululemon Athletica