San Francisco 49ers linebacker Chris Borland told ESPN's "Outside the Lines" Monday that he is retiring following his standout rookie season because of concerns about head trauma.
The 49ers confirmed Borland had shared his intention with the team.
Borland, 24, led his team with 108 tackles in his rookie season, emerging as a standout on defense. He had a sack and two interceptions.
Borland told "Outside the Lines" he wants to do "what's best for my health."
The 49ers have taken several hits recently.
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Last week, five-time All Pro linebacker Patrick Willis announced his retirement. The team lost coach Jim Harbaugh after the season, then watched Frank Gore, Mike Iupati, Chris Culliver and Perrish Cox depart in free agency this past week.
AP contributed to this report.
