Warren Sapp announced on The Players' Tribune on Tuesday that he will donate his brain to concussion research when he dies.
Four Congress members have asked the NFL for information about why it attempted to intervene in the selection of a Boston University researcher to lead a study on football and brain disease.
Cardinals coach Bruce Arians says people who won't let their kids play football "are fools."
Giants owner John Mara said the effects of concussions and the link between football and brain disease represent the most serious issues confronting NFL owners at the annual league meetings.
The NFL, for the first time, acknowledged there is a link between football-related head trauma and chronic traumatic encephalopathy, or CTE.
Packers president Mark Murphy, who is on the NFL competition committee, said support is growing around the league to reduce the preseason schedule to three games.
