"The breakthrough comes when you train over a period of time," says Ron Warhurst, who coaches distance runners at the University of Michigan. "If you're an eight-minute miler running 40 miles a week, you should maintain that pace and mileage until your body feels comfortable with it.
"You might need three or four months or six to eight. Then add 15 to 20 miles a week, and you might break through to 7:30 pace."
No one really knows what brings about a breakthrough, but the following factors seem to be common to runners' reported experiences.
1. Breakthroughs do not happen arbitrarily or effortlessly, though they seem to. They result from hard work and months, maybe years, of training.
2. Although hard training is required to achieve a breakthrough, too much training is worse than not enough.
3. The breakthrough requires a well-balanced program of distance running, speedwork, rest and diet though even the most inspired and enterprising training can't guarantee a breakthrough.
4. Breakthroughs don't happen to everyone, and no two runners get there through the same set of variables.
5. A runner could come to a breakthrough alone, but you are more likely to reach one in the company of other runners providing competition, spirit and resolve.
6. After the first breakthrough, others follow, although subsequent breakthroughs are not nearly as exhilarating or inspiring.
"You have to train harder, but don't think that if 40 miles a week has you running eight-minute miles, then 60 miles will get you 6:30s," Warhurst said. "It doesn't work that way. With increasing mileage, you eventually come to a point of diminishing returns."