I'm a dad of three girls. 6 (1st grade), 10 (5th grade), and 11 (6th grade). The older two compete regularly in the 5k (mid 23 range) and are 1 and 2 on their middle school cross country team (middle school goes to 8th grade and so they should be tops for a few more years) and among the best in most inviationals (Finish in the top 5, often win). mid to low 6 for the mile.
The six year old is restricted to no more than a mile at time without stopping. See can rn about 7 1/2 for the mile. 78 for the quarter.
They love running and are very competitive, especially with each other. I'm 43 and in the 19 minute 5k range. So, I take them running seperately, can chew up 2 hours of an evening at times.
If you don't have kids, one thing you have to understand the unbelivable drive they can have. At times it's like restraining wild horses. They want to run 10 miles (we will not allow until until a year after their first period). We are part of a track work-out once a week. They love running 400 repeats (even the 6 year old). If you don't know the kids personally, do ASSUME the parents are tyrants living out some fanatasy of their own youth. Yes, even a 6 year old can decide they want to run and compete hard at it.
That said, I agree that the national youth records are held by a bunch of unknowns as they burnout early or get injured. That is why we are pulling back on their running. We are also very keen to their injuries. When they have any injury, we sit them until it passes. Now they keep it from us if they think they can fight through it. So you have to be preceptive.
I write this because a tone I picked up from this thread is its inhuman to have young kids run hard and compete hard. That is not true.
You are wrong to think you should call DCFS the next time you see a 6 year old running in the park with a parent.