This raises an interesting point though. I'm tired of hearing some coaches asking me to keep my legs together during the whole dolphin kick action. My ankles/feet are built in a way that at the peak of hyper extension, my feet both point toward the inside. There's nothing I can do about it. Therefore, instinctively, to get more extension my legs are not *tied* together on the downbeat.
Maglischo clearly says that in his opinion, the upbeat isn't propuslive. That, as of 2003, had not been demonstrated by science yet.
Me? I'm confuse. I feel some propulsion resulting from the upbeat. That is, if I go hard on the upbeat, it seems that it's getting me to move faster. But like you say, it could be a momentum issue. Energy is accumulating during the upbeat and the drastic shift from up to down may create a wip effect.... I really don't know I'm confused.
In other words, my turns suck, and with only 1 SDK * 7 turns, no wonder why my 200 is so bad.