Anyway, there was a post on the excellent Sweat Science blog (reading that blog just makes me want to give up because he does all this stuff so well!) which looked at a recent study about the impact of different warm up protocols on swimming performance - The ideal warm up for swimmers
It is well worth reading the post and it prompted me to search around because initially I could not find the study to which it referred. I did find the actual thesis from the student who did the work however.
What is interesting to me is that 37% of the sample performed best with no warm up whatsoever. It may be specific to the event that was being measured and I am sure that there are confounding factors in the study, but it is something to think on. I think the conclusion that they reach - individuals differed in their response to different warm-ups is probably pretty accurate!