the thing that i'm wondering is ....
can a guy that runs sub 3"50 mile, can he run a world class time in the marathon the same year? we are talking about a 2:04.
now my understanding is that you can't do it. the reason is energy distribution. you can't max out in a 4 minute run and a 2 hour run "simultaneously" or within the same calendar year at least.
this energy distribution thing is why good 1500m men really suffer in the 5000m. and this is why sebastian coe never really optimized at 1500m, he was too supercharged, most of his best years he was set to run 600m-1.2k really fast. i always say this guy could go 1:39 for the 800. i might as well add that rudisha's world record is worth 1:38 high though you'll never see rudi ever ever ever draft properly
that is without epo and other peds. drugs can change the metabolism unnaturally for sure. you know, set a pb in half marathon and two days later run a mile pb. or "jogging" a 332 1500 m heat, stupid stuff like that.