t-and-f: aerobic vs. anaerobic

[Pat Crandall]

In the discussion of the 800m 'kickers' actually being the ones who slow down the least, where is the dividing line (for the majority) between aerobic and anaerobic races. I'm betting that a 1200 would still be a kicker's race so it must be right around 1000m. Any physiological evidence to answer this?