If you read the interview at the link, it seems that Joe Vigil is claiming that Deena has run a "tempo run" for 12 miles at 5:01 per mile pace. I know that's not possible, but it sure seems that's what he's saying... here's the confusing segment below and the entire interview is at the link. Somebody have a better understanding?
Another thing that makes our program different from, say, the programs of Jack Daniels, who's a brilliant physiologist and a decent coach, is that he doesn't believe in working the athletes for more than about 4 miles on their tempo runs. I have my athletes run from 4 miles all the way up to 12 miles on their tempo runs. That's where the strength comes from.
When you look at Deena's physiological tests and tempo-run paces over the last 4 years, here's what you see. Her tempo runs, and these are at an altitude of about 8000 feet, have gone from 5:24, to 5:11, to 5:04, to 5:01. I make her stick at that tempo-run pace for a full year, but during the year I ask her to build up the distance she can run at that pace. We start at about 4 miles and increase it all the way to 12 miles.