That led to rule changes in the N.F.L., particularly the removal of players with any significant concussion symptom from that day's game or practice.
But the Yankees legend had a well-documented history of significant concussions on the baseball field, and perhaps others sustained as a battering-ram football halfback in high school and at Columbia University.
13 In a study of collegiate athletes, Collins et al. found a significant effect of concussion history on neuropsychological measures, and an interaction between multiple concussions and learning disabilities.
Mr. Coles is the third star receiver on the Jets to endure significant concussions; Al Toon retired in 1992 because of postconcussion syndrome, and Wayne Chrebet did the same two years ago.
"He's got multiple, significant concussions," on and off the football field, "and even probably multiple, subconcussive injuries playing football.… It really fits that picture".
"I'm doing this to raise awareness of concussion and the injury, because it's so misunderstood," said Parlow, 30, who competed in three Olympics and two World Cups for the United States team and now has severe headaches from two significant concussions.
It is interesting to note that in the most popular sport in the world we have observed a significant spike in concussion among the soccer population".
"For example, half our team is in the VSR-4 — and there is a significant reduction in concussion risk in newer helmets, so by fall ball we're going to be in new ones," Duma said of the Virginia Tech football team.
They also urged that "officials and coaches... ensure proper enforcement of the rules of the game," such as barring spear tackling in which the head is used as battering ram and which is the cause of "a significant number of concussions and catastrophic injuries".
