AFIK, Manzano, Centrowitz, Jager, Murphy, and Brazier all trained below 60 miles a week in high school. Brazier and Murphy were more like 35 / wk from what I’ve read. They all have Olympic or World medals at the senior level. None of the “Big 3” have that.
For what it’s worth, I’m pretty sure Shorter and Rodgers trained modestly in high school. Few would deny that high mileage is necessary for success at the senior world class level in the 5k and above. However, there is little evidence that high mileage as a teenager is predictive or necessary for high level success at the senior level.
My question for advocates of high mileage in high school is to what end? A state championship, a scholarship, a US junior record? None of these accolades are worth the risk of serious future injury or burnout. I can’t say that Ritz’s hs training and approach to racing caused his battles with injury as an adult. However, I’m sure he would trade his junior world Xc medal in a heartbeat for a senior world/ Olympic medal. ( I don’t think his medal in the half-marathon”world championships rates with a main event medal or even a world xc podium)
If I were the coach of an obviously gifted mid-d or distance runner, I would encourage him to keep his mileage below 60 miles a week. A runner with pace control, decent speed and a baseline Vo2 max above 70 will have a very successful hs career off of moderate mileage. If he doesn’t have pace control, decent speed or high baseline Vo2 max all the mileage in the world won’t make any difference.
Once an Achilles is strained, bone density deficiencies, or race skittishness develop in a young runner, it is extremely difficult to right the ship. Don’t ruin a young athletes future career before they have matured and can make training decisions on their own.