We have 40+ in Levels 6 and up. At one point this season, every single 12yo was injured, and most of the 13yos as well. Only one kid under 12 was injured, regardless of level. Some are out for the season, others have missed a meet or two. After they go through puberty, it seems rare for girls to compete a whole season without an injury. So, we have 10/11 yo L8's and L9's that are fine, and 13y0 L6's and L7's that are hurt. Rapid growth is a big risk in itself, and when you couple it with progression to harder skills, it's a recipe for injury. Thankfully, most of them aren't serious, and often they don't even happen at gym!