There she became a symbol of the endurance athlete's unbreakable will to finish, and the reason why such athletes must be stopped when endangered by heat. (si.com)
To allow such an athlete to return to play risks not only cumulative brain injury, but also Second - Impact Syndrome (SIS), which occurs when an athlete who sustains a head injury - often a concussion or something worse, such as a cerebral contusion (bruised brain)- sustains a second head injury before symptoms associated with the first injury have cleared (i.e. healed). (MomsTeam.com)