what is the difference between an open and a relay split in swimming?
I'm gonna guess that there's no reaction time in the relay split - the time goes from whenever they start moving...?[/quote]
A swimmer may start moving/their dive before the other swimmer touches the wall. However, the swimmer that is entering the water must still be touching the block (with their feet) until the other swimmer touches the wall. Thus, the 2nd, 3rd, and 4th swimmers get a 'moving start' to their relay legs. This is why you see faster split times (in general) for swimmers that are not starting the relay off.