Settle an argument: can a sub-5 mile be run with only aerobic training?
I think yes, and that guys like Jurek prove it. My friend claims that even the most extreme long-slow ultra guys do some faster work or have track backgrounds, and that if a random person would never get faster than low-5s if they only did long slow runs.
What's the fastest mile possible without any 200/400/800 intervals in training?