8 X 1200 in 3:09 is very believable to me, given Rupp's and Farah's PRs. However, I respectfully disagree with the poster who said that 4,500 feet "isn't that much" to athletes of that caliber. Actually, the reverse is true. Because world-class athletes have such a high stroke volume and their blood moves so quickly, it's harder for them to fully saturate their blood with oxygen than it is for average folks. Thus, world-class athletes see a *larger* drop-off in performance at altitude. For instance, an average person might be able to fully saturate his blood up to 3,000 feet, and wouldn't see the ill-effects of altitude until he exceeded that level. But a world-class athlete, who struggles to fully saturate his blood under the best of circumstances, might see his performance decrease at *any* altitude above sea level.