@prof
I try to show what I mean:
If you stand on one leg, you will always try to balance your weight on the engaged leg or standing leg. So the center of your bodyweight (big dot in my picture) will be over the foot of that leg.
If you put that leg outside your bodyweight, you will have a hard time to keep balance: quite uncomfortable.
Again: just get up your chair, stand next to a wall and try out both poses. You will naturally keep the one with the leg under your body, not the one where it is outside...
Sorry for thread-hijacking...
DV