Sprinting Technique Help

I train a hockey player… when she sprints, she complains that her heels will hit her butt during her sprints.

Is this normal?
How can we fix this issue?

well im not sure about hockey, but try maybe to practice her on flexing her toes up all the time, and to get the heels in a straight line under the butt, while the toes are flexed.
i hope i make sense