Balancing on one-arm with the elbow on the ground requires a very precise perception of the base for the correct force line, otherwise it will shear off very quickly. What should not be underestimated also at this altitude. Therefore and also because the view to the flyer is very limited, the one-armed is shored in both positions.
However, special attention is always on the stability of the wrist, so the flyer does not have to stand uphill.
1. Lying sideways, the forearm is leaning at the back of the back and
2. Lying on the stomach, the hand shore itself at the head. Do not push your hand to the head, but lean your head against your hand to stabilize. This position is statically not so useful and is usually used only as an intermediate position in the spring roll (Chinese waltz, …).