The NFL says reported concussions rose 58 percent in regular-season games to the highest number in any of the past four years.
The league issued its concussion data for 2015 on Friday, a little more than a week before the Super Bowl, and it showed that helmet-to-helmet hits were also way up.
Jeff Miller, the NFL's senior vice president of health and safety policy, said during a conference call the league will study what might have caused the incidence of head injuries to rise so much this season.
Among the possible explanations mentioned by Miller were a doubling in the number of players screened for possible concussions, "unprecedented levels of players reporting signs and signals of concussions," and the fact that trainers who work as spotters or independent neurologists on sidelines "are much more actively participating in identifying this injury.