Body, that is.
The photo is from the photo shoot Interweave did for The Efficient Weaver.
One of the reasons I particularly wanted to do this DVD (now downloadable course) was to show proper position and posture at the loom.
I so often see photos on the internet of people sitting at the loom in a chair or on a bench that is too low for proper ergonomics. I wince. Because while it may not hurt today or even next week, over time sitting 'poorly' will hurt.
Generally speaking it is a bad idea to sit in an ordinary chair at the loom. (I don't care what people say, that you don't need a bench, I'm here to say that it's generally a bad idea.)
Most looms are tall enough that an ordinary chair is simply too low. Ordinary chairs are also generally raked to the back, putting your hips and knees into a 'bad' position relative to each other.
If you only have an ordinary chair, build it up with cushions. What to look for?
Elbows should be higher than the breast beam. Hips higher than knees. Sit forward so that you are perched on the edge of the bench, on your sitz bones. Sit up straight. Pivot from your hips. Engage your core muscles. Shoulders in neutral. Throw the shuttle with thumb up, not down.
Recently Beth Smith did a blog post where she talks about changing her shuttle handling.
Be kind to your body. Work ergonomically.