http://www.eijkhout.net/lead_follow/posture.html
2.4 On Posture
“*Maintain good dance position, good posture and… remain grounded.”
As for the bent forward posture used when dancing the Lindy Hop, Frankie Manning is on the video from “Can’t Top the Lindy Hop” specifically describing how he made a conscious decision to bend over, to change the look and line of the dance, to set him apart from other dancers. Note that he was still thinking like a dancer and performer, aware of the lines of the body. It wasn’t totally arbitrary; he knew the aesthetics. Arthur Murray and the ballroom crew disagree with that aesthetic, and impose a straight back. That’s a choice… their preference. On the posture “controversy”, Frankie Manning says “Straight can be okay. Stiff is wrong. I don’t teach people to bend over or straighten up–I teach people to relax. I tell them to, anyway…. You don’t stoop over ‘cause you’re old, you straighten up ‘cause you’re old. I can’t get over there like I used to!”