I can't get enough of this pose and I don't know why. I get excited even when non-muscular girls do it.
I don't know your age John but I'm an old guy who grew up when girls wouldn't flex and any muscularity was due to being active. Girls just didn't lift weights wayyy back then. However, there were several girls with very nice arms and a few with great biceps. The hair brushing, tying back or tussling with their hair, was the only biceps show. It was a real treat!!!!