It depends on the actual situation. it is safe to wear it if you have a normal exercise, like jogging, billiards, fitness, and so on; but you are not recommended to wear contacts while doing strenuous exercise, such as swimming, playing football, playing basketball etc. in order to protect eyes against dangers caused by blurry vision or competitive sports, people who have vision problems are recommended to wear prescription sports goggles that can make they see clearly and offer eye protection.
It is depends. If you the sports are not fierce, you can wear contact lenses because they are much comfortable than sports goggles when you play. However, if the sports you engaging is fierce, it would be dangerous of wearing contact lenses. If the fierce sports cause the contact lenses broken in your eyes, it will be very hurt to your eyes. If so, i prefer to wear prescription sports glasses.