I coached a rec league basketball team last year. My kids were 11 and 12 years old. One day while they were running wind sprints, one of my players stopped because he was having trouble breathing. He couldn't catch his breath.
I later learned that he has asthma. This was a really scary moment. I know all of the kids were required to have sports physicals before they joined a team, but no one had mentioned to me that I had a player who suffered from asthma.