I’m a runner, ran D3 in college so I understand some of what goes into training. My son decided to try club XC this spring as an 8th grader so he understands what running in HS would be like. The beginning of the season was going great, ran a 15:30 4k on a hard course but now he can barely run 17 minutes. His legs are heavy and he “can’t move them.” It’s only when he runs hard. His breathing is fine and he wants to run faster but his legs won’t let him. I’m curious if it’s over training on top of figuring out nutrition. Here’s a sample week of workouts from the club (all done on grass and hill loops):
Monday: 1100m repeats at tempo speed
Wednesday: huge hill (best sledding hill in the county) repeats with 400-600m loops fast
Friday: 600m fast repeats
Sunday: race day.
Sometimes he would had 3-4 miles easy on Tuesdays.

I feel like the focus is on too many hard days vs gradually increasing mileage with easy runs. He kind of jumped onto all of this at the start of the season with just running 3 days a week of 3-4 mile rules. He’s frustrated (we all are) and I’ve never seen him so excited about a sport so I don’t want him to give up. Any thoughts or advice would be much appreciated?

I’m 16, and my current XC 5K PR is 16:35. I’d love to qualify for Nike Cross Nationals or the Brooks Cross Country Championships next year. What can I do over the next year to give myself the best chance?

I know that’s a big jump, but I’m willing to put in the work. I'm also curious about what top national level competing runners do differently than an average runner like me does. Is it the milage or do they have access to "secret" workouts? Currently I run 35-40 miles a week.