President Barack Obama expressed concern about violence and injuries in professional and intercollegiate football, saying he would "think long and hard" if he had a son before allowing him to play.

Obama, an avowed sports fan and the father of two daughters, said in an interview with The New Republic magazine that the National Collegiate Athletic Association in particular should consider rules changes in view of emerging evidence on long-term health consequences of head blows suffered by players.

He said he is "more worried" about amateur college players than professional National Football League players who are "grown men" represented by a union and paid a salary.

"You read some of these stories about college players who undergo some of these same problems with concussions and so forth and then have nothing to fall back on," Obama said in the interview, to be published in the magazine's Feb. 11 issue. "That's something that I'd like to see the NCAA think about."