Most soccer concussions are caused by hard falls to the ground or collisions with other players. Heading the ball is not a primary cause, studies have determined, because the impact is not of sufficient force to send the brain crashing into the skull.
Attempts at heading do engender many concussions, however, as players' heads collide in battles for the ball. This has led to the increased use of padded headbands designed to lessen the forces of many blows, but their effectiveness remains the subject of debate.
As Sherry Stohler watched from the stands, leaning forward slightly every time No. 22 hit the turf during a slide tackle or rough play, old images of her daughter lying motionless were superimposed over the new.
"As long as she gets up and keeps playing," the mother said with a sigh, "it's a good night."