DETROIT — Detroit center Frank Ragnow, a 4-time Pro Bowl selection who was key to coach Dan Campbell's Lions revival, announced his retirement from the NFL on Monday after 7 seasons. Ragnow, 29, posted to social media that he has tried to convince himself he's feeling well enough to play, “but I'm not,” he said.

Detroit Lions center Frank Ragnow, who was key to coach Dan Campbell’s revival of the team, announced his retirement from the NFL after seven seasons.

Detroit Lions center Frank Ragnow, a four-time Pro Bowl selection, announced his retirement on social media on Monday. "These past couple of months have been very trying as I've come to the realization that my football journey is ending and I'm officially retiring from the NFL,