I'd love to jump in and give you an answer here, but I have no idea. I just wanted to say, however, that this series was one of my faves way back when before I lost it in a HD crash so cheers to you for posting it again.
The origin of the aerobics series is one of the great mysteries of the universe. I don't think even the person who originally posted it knows where it came from or what was really supposed to be going on in the scene. I've seen it pop up from time to time with explantions ranging from mind control to blackmail, but nothing really definitive.