A feat of biology!
This the shoulder, you probably have one, maybe even two. Three or more is unusual, in this case consider consulting your therapist.
We take for granted the incredible range of movement afforded to us by this crazily complex joint. Comprised of your collar bone, shoulder blade and upper arm (your clavical, scapula and humerus for our latin subscribers) the only point of solid articulation with the rest of the body is where the collar bone and breast bone meet. The rest just…hangs there. Well, not quite.
Your shoulder is held together by an awesome array of muscles and other soft tissues. It’s their job it is to allow you to literally scratch your own back whilst preventing the whole thing from dropping off. The precise set up of these structures means that modern humans have an advantage not afforded to our ancient hominid ancestors. Or indeed our closest evolutionary cousins such as apes and chimps – and that is the ability to throw
It’s at a funny angle…
The precise angles involved give us far greater range of movement than other mammals. Get your dog to throw his own ball for once. Opposable thumbs aside, his shoulders simply can’t do it. We all know that apes fling…stuff. But even against the least athletic of us, they’d never win at the coconut shy.
This specific range of movement translates beautifully into running as well. Being able to swing your arms parallel to your body in a nice low shoulder position counterbalances the momentum of your legs, providing stability. And a particularly odd study concluded that swinging your arms uses 3% less energy than keeping your hands behind your back. 9% less energy than folding your arms over your chest, and 13% less energy than running with your hands above your head…
Keeping ’em moving
So how do we keep our shoulders in tip top condition? By keeping them moving through full range and challenging the muscles involved to keep them strong and flexible. Restrictions of both your lats and your thoracic spine contributes to lack of shoulder mobility. Pain when lifting your arm out the side is commonly attributed to the rotator cuff being squashed or impinged in the joint. However new evidence is challenging this view.
Irrespective, the good news is that in both of these common issues, introducing dynamic stretching and resistance training can greatly increase range and decrease discomfort.