The Diaphragm needs to be fitted by a doctor.
Answer: Crunches target the rectus abdominis and other abdominal muscles. An ab crunch machine is designed to strengthen the abdominal muscles. Wearing compression underwear can give the stomach a more toned appearance. Ab crunches are a great exercise for people looking to shed weight
Explanation:
1. Make sure the sport they are playing, that the item can't cause a real injury
2. Make sure the surrounding area is acceptable so like no slippery floor, or marble floor
3. Make sure every kid is doing the steps correctly or game, if not, then teach them and separate from kids doing good.
( I don't know if you meant ruled steps, so I made some, this is just what I think, hope it's what you want. )
Cardiovascular is probably your answer
Cardio- the heart
Vascular- vessels
Circulatory- blood
