Over-pronation of the feet

A degree of pronation is normal, as the foot needs to adapt to contact with the ground, however over-pronation occurs when the arch of the foot excessively flattens or 'collapses', the heel rolls inward and the soft tissues stretch. This is a common problem in dancers of many genres including jazz, modern and theatrical dance, but the problem is most pronounced in ballet dancers.

Going onto pointe

When I was learning to dance I couldn't wait to start pointe work - just like every other girl learning ballet. At my school we were allowed to go on pointe once we got into a certain class (I can't remember which one now, however most of us were between 11-13 years old). It was a rite of passage to start pointe, to get the beautiful, horribly painful shoes and begin weeks of tedious barre work that seemed to go on forever and somewhat killed the romantic notion I had of dancing on my tiptoes. It's such a big step for girls doing ballet that the last thing they're ever going to consider is whether their body is ready for it.

Ah nostalgia, my first ever pair of Swanildas

A colleague of mine did her MSc thesis looking at what criteria dance schools used to assess a girl's readiness to begin pointe work. The results were pretty depressing. Nearly every school used age (usually 12) as the determining factor. Some, like mine, used level. Which worked out about the same as age. Almost none even considered strength or physiology.