Why might someone faint when playing sport?

Heart Dr. can check: While playing sports, a person could faint for several reasons. He could be overheated or maybe was not drinking enough fluids. In those two situations, he will feel faint while standing or when quickly rising to a standing position. He could have a heart malformation or an abnormal heart rhythm. In these two situations, the symptoms may occur more randomly. A cardiologist's evaluation is helpful.

Potentially serious: If you faint while playing it can can be something dangerous.If you faint while standing afterward, it is more likely dehydration, over-exertion. See your doctor.