What do they mean by Phelps taking a half stroke at the end to win his butterfly race by .01 seconds?

Question

Do they mean he didn't swing his arms all the way BACK before coming forward cause he knew he didn't have time to do that and it wasn't necessary, or do they mean it was a normal full stroke UNTIL his arm movement FORWARD was stopped by the wall, thereby making it less than a full stroke? I can't tell by the replay...it looks like a full swing and stroke forward if you ask me. But the analyst keeps calling it a half-stroke and it's driving me crazy. WHERE??? is the half stroke?

Answer 1

Actually the 1/2 stoke everyone is referring to is when he touches the wall, there are three phases to every stroke, the catch (when the hands come into the water to start to pull the water), the pull (or the power phase where the arms propel through the water creating motion) and the recovery (the arms recovering to position to start the catch again).  At the end of the 100m butterfly race Phelps just finished the recovery and was starting the catch when his hands touched the wall, therefore there was no pull portion of the stroke (I guess in reality it's more like a 2/3 stroke but that just doesn't sound right now does it).  This is why the announcer keeps referring to the finish as a half stroke.  

Answer 2

most swimmers just drift when they are really close to the wall, but the 1/2 stroke was really just him not drifting, but continuously moving his arms until the very end. hope this helps.

Answer 3

The 1/2 stroke that they are referring to, is when Phelps was a few feet from the wall, he took a short stroke.  In fly the finish of the stroke is  when the arms and hands are all the way down touching the thighs.  His last stroke was really short to get to the wall, he did not extend down all the way.  So the first one, that he didn't swing his arms all the way back before coming forward.