-1.
I can be 13 and still faster than someone who is 18, for example, someone who doesn't partake in running / such. Kids are more use to running outside (barefoot even) and most of them would be faster than people older than them, I've seen it lots of times as I do track and field oocly and go to multiple meets.. Realistic? maybe, but someone being younger and still faster is still realistic loll. As Kana said, just run around as you play.