Iowa on the High
Not if it's good wrote:
It isn't just genetics. It can be coaching and mental care if things aren't always on the upswing. In good programs, the majority of girls continue to improve.
Some girls hips grow up to ten inches (without a change in diet) during puberty.
There was a female sprinter I knew who was good as a kid (12 high/13 low) between age 8-12 then as soon as she hit puberty breaking 15 is a task.