There are differing theories about how many miles a kid can put in safely before doing long term damage to the body. I think this discussion is, to be blunt, not relevant. I have only seen kids doing excessive mileage on the same YouTube channels where I am watching many people doing many things excessively. That is addictive behavior, that is not running. At Middle School Cross Country kids learn what it is to organize their own body so it is capable of a long run. Too many miles, on my team, means miles that are dreaded or abused. Having kids enter the sport of distance running at the Middle School Cross Country level is a good way to keep the miles fun and to help kids regulate themselves by comparing themselves to others. Running in groups as a Middle Schooler is a healthy activity and a worthwhile pursuit. I am not anti-digital, but running lends itself to conversation and laughs that are not completely guided by a screen. I concede there are many ways to add screens to running, Strava, Zombi Run, etc. But for the most part, your eyes are on the trails and your running mates. These are easy miles and at this age should not exceed 6 miles, but should be more along the lines of 4 miles for "the long run". By 18 a runner can run a marathon, so between 12 and 18 years old, mileage can increase to fit the individual body and psyche. I have had several athletes really take to running as their fitness tool to not only get fit, but to relieve stress, think, be alone for a bit, challenge themselves, show off a little, or just run along with a parent or sibling. These are absolutely worthwhile and good pursuits. The long run may not be necessary to master in order to race the 2 miles that make up a Middle School Cross Country race, but it is useful and trains the body to sustain effort at a lower level than continuous speed preparation. Combining speed work, body fitness and the long run satisfies what most scholastic cross-country runners are seeking and set up for competitive success. Mental preparation is key to what a long run accomplishes. That long run encourages prolonged concentration as well as prepares a young athletes mind for lengthier pursuits that require work on their part, a book for school, writing a lengthy composition, learning complicated mathematics, an eventual marathon. There are so many ways the long run benefits young people, coaches will do well to teach it as an enjoyable and regular endeavor and find ways to plan organized weekend runs for their teams.