We also let our kids choose their own sports.  We did tell them that once you committed to a team, you were on it for the season (unless of course they became ill or injured).  Our son who does not have CAH played football, baseball, basketball, soccer and even tried gymnastics one year in middle school.  The worst injury came from basketball. He was either 7 or 8 (whatever the minimum age was) when he started football.  At that age, they basically are running up and down the field and not really blocking or tackling very much or very effectively.  They do wear all the safety equipment.  Our daughter who has SW-CAH has played basketball (but had to stop because it was too much for her and made her ill every time), softball, soccer, and rides horses.  Her worst injury came from falling off a horse (probably how she tore her hip cartilage).  My advise is to let the kids be kids and participate in whatever they like, but be there for practices and games and be prepared for an injury, illness, dehydration, etc.  Sports are good for kids in so many ways - physically, emotionally, etc.