My daughter will soon be joining a high school cross country team where they run 30 miles/wk through July and August. My first thought when I heard this was that it didn't sound like enough miles. For many years I ran 50 miles/wk and suffered no harmful effects. 30/wk sounds like nothing.
The last couple of years, my daughter came with me and she ran between 20 and 25 miles/wk because I was saving her legs for high school cross country and track. She ran a certified road race 5K in 18:32 and some 1600's in middle school track in upper 5:10's. Running is easy for her and I feel she can easily handle 40 miles/wk and might improve a ton if she did this. A lot of things I read say this much mileage is too much, but maybe that is just for the average runner, which she is not.
Right now, she looks totally normal height, weight, and development for her age. What do you think? Should I suggest she supplement the high school training with some extra miles on her own? Bring the 30 mpw up to 40?