Why the emphasis on shoulders down the back?

Ever since I started taking yoga teachers have always emphasized bringing the shoulders down the back when you lift or extend your arms. This has always been a challenge, and in recent years it's occurred to me more and more that it's just unnatural. I've gotten to the point where I'm a little dubious about this dictate to keep the shoulders down when reaching up.

The most obvious and vexing example of this is warrior 1. If you press your palms together in front of you and try to lift your arms overhead while honestly keeping the shoulders all the way down, for most people you can't lift the arms any higher than 10 or 11 o'clock. But if you let the shoulders rise naturally, you can bring the hands straight overhead, arms alongside the ears, and maybe even behind the ears a bit.

Extended side angle is another pose where we extend the arm alongside the ear sometimes. And here too teachers are insistent on keeping the arm "plugged into the socket", as they frequently say.

What really got me thinking about this was swimming, and looking at pictures of swimmers. If you look at one of those classic underwater pictures of olympic swimmers reaching forward in the water, their shoulders are lifted way, way up alongside the ear. That extends the range of the stroke, and, just as important, it brings into play those big lattisumus dorsi muscles along the outside of the back, which pull the shoulder down. There's a lot of power in those muscles. But more importantly, on a totally intuitive level, the swimmer is just reaching as far as she can, and to do that, her shoulder lifts way up.

Well, I think that lifting the shoulder up towards the ear so that the arm comes alongside the ear is a part of our natural range of motion, and it's something we need to work with rather than inhibit. We go out of our way in yoga to extend our range of motion of everything else, so why not the lifting of the shoulders?

My guess is that it's an aesthetic thing more than anything else, and it comes from dance. Lots and lots of dancers end up as yoga teachers. And in dance, you want to keep the shoulders down and the arms away from the ears to frame the head and neck. So perhaps all these yoga teachers just remember years and years of "shoulders down" from dance, and come to believe that it's a biomechanical thing rather than an aesthetic thing.

I do think the situation is completely different when we're putting weight on the shoulders, pressing as in plank or chaturanga or vashistasana. This is completely different than in swimming crawl, where the shoulder is pulling, not pushing. When the shoulder is pushing as in the weight-bearing yoga poses mentioned, you want the shoulder down and back. This allows you to make more use of the much bigger muscles of the back and chest rather than the puny and delicate muscles of the rotator cuff. If you're supporting all your weight with those puny muscles, you've got a good chance of straining the muscles or more likely tendons.

So, my advice is to try lifting those shoulders, especially in Warrior 1 and parsvakonasana. You'll feel a nice stretch in your lats, and you'll find a rotation in the shoulder that you can't find otherwise. We want as much mobility as we can get in our shoulders, just as we do in our hips. But if you're putting weight on the arms, hold them down and back, and try to take that weight with the muscles of the trunk, not the shoulder.