Observing other people in terms of their physique is fine, but there are two big problems. Firstly, we can't be absolutely sure of their type. Secondly, we can't generalise from one person. I was more thinking about adding or enhancing the Socionics physique descriptions. For example, www.socionics.com
says that "ISTjs often have a very firm, solid figure, especially males. They keep their feet rooted to the ground giving the impression that they are sturdy and secure. Their heads are firmly fixed squarely to their shoulders and are practically immovable. Their necks appear to be inflexible so when they turn their head their shoulders usually follow.
Could you possibly elaborate on this, or give examples for other types?