TSA seems to have a requirement that when undergoing the intrusive physical search, the arms be extended straight out and the arms be rotated so that the palms are up. See accounts here, here, and here (in comments), and here.

Extending the arms full out and rotating the palms up becomes tiring and painful. It must be particularly so for older persons. It would be much easier to hold the palms down with the arms extended.

What is the point of requiring this particular posture?