I've never heard of a high school team having sophomores doing anywhere close to 100 mpw. While there were certainly individual guys who did 100+ (Hulst and co from the '70s come to mind), the notion that entire teams were doing that kind of mileage is ridiculous.
it's mostly mental wrote:
It's 20 miles per day or less than 2.5 hours in total work per day. Hard, but not exactly superhuman. Certain HS programs used to have guys as young as Sophomores run 100+ after only a year of running. It's not much of a stretch to get to 140 if you're a mature adult with more running experience. Go talk to athletes in other sports (swimming, cycling, tennis) and 2.5 hours per day doesn't seem unusual or even high.
Comparing the time spent running to time spent cycling or in the pool doesn't work; running is dramatically higher impact and while a swimmer or cyclist will often benefit from 3+ hours a day of pool or bike training, many runners will face either severely diminishing or negative returns at that volume.