I could as easily believe there's widespread drug use by marathoners as the next guy, but does it not seem to you that some of today's really fast 10K runners have moved up to try 42K--and that could explain the fast times? Marathoners of the past were not typically competitive at 10K. (Zatopek was, Shorter was, and others you could name.)
Maybe "enduring speed," the way Coe did in the 800 meters, is an idea that's moving up to marathon running. Plodders (relatively speaking--no slur intended) may be uncompetitive at this point. Mitch
