I've been genuinely curious about this for a long time. We have women who can run sub 14:40 for 5000m but struggle to break 4:00 for 1500m.
Dibaba has run sub 14:30 this year. I've never heard of a male sub 14:30 runner who couldn't run 3:55 any day of the week without much fanfare. And I've DEFINITELY never heard of a sub 8:17 runner who couldn't run 4:10 in the mile or under.
There was a time where I had slower 800m AND 5000m PRs than Simpson and Dibaba but could run 3:55-3:57 in every race. I just don't get it.
So the question remains, why is the 1500m so physiologically difficult for women? I'm genuinely curious in scientific answers since it seems like the fitness is definitely there.