A talented runner can perform extremely well on 30mpw + estimated 10+ hours of cross training. As others have said, she probably gets more bang for her buck by arc training with resistance for 60+ minutes than a steady run. If an athlete knows how to work hard cross training it can be very effective.
Regarding Valby specifically, they have a formula that works. Hopefully she continues with a coach who understands and individualizes. On the other hand, she could join BTC, plug in to Jerry's methods and take advantage of their team discount on foot surgery within a year.
I don’t think we’re disputing that you can’t perform well or that it can’t be quite effective. The point is that you won’t reach the same level that you might otherwise reach if you could handle more running. Principle of specificity and the importance of running economy apply.
When I was in college, I rode one of those exercise bikes at the dorm one night. Another student working there said I should put it on the hardest setting. He knew I ran track and XC. It was no joke. I rode the bike for like 30 minutes. Completely drenched in sweat. It was a really good workout. Just imagine doing that on Arc Machine. I bet it easily replaces doing easy miles to ring up the mileage count. Not only that I believe Arc works your upper body too.
When I was in college, I rode one of those exercise bikes at the dorm one night. Another student working there said I should put it on the hardest setting. He knew I ran track and XC. It was no joke. I rode the bike for like 30 minutes. Completely drenched in sweat. It was a really good workout. Just imagine doing that on Arc Machine. I bet it easily replaces doing easy miles to ring up the mileage count. Not only that I believe Arc works your upper body too.
The issue is not whether there are any benefits from cross-training - there will be - but is it as good for a distance runner as training aimed specifically at that discipline? If not, it is only second best. But still, apparently, good enough for one athlete to whip all the best college athletes in the country.