SAN FRANCISCO (Reuters) - San Francisco 49ers player Chris Borland, a leading rookie last season, is retiring from the NFL over health concerns related to repeated head trauma, ESPN and the team said on Monday.
"From speaking with Chris, it was evident that he had put a great deal of thought into this decision. He was a consummate professional from day one," 49ers general manager Trent Baalke said in a statement.
"While unexpected, we certainly respect Chris' decision," Baalke said.
The 49ers did not specify in its statement why Borland, 24, chose to leave. ESPN reported he was retiring over health concerns related to head trauma, an issue that has rattled the league and prompted a massive lawsuit against the NFL.
Borland, a linebacker, was a star in his only season with the team, registering a team-high 128 tackles and earning several rookie of the week and month honors.
"I just want to live a long, healthy life, and I don't want to have any neurological diseases or die younger than I would otherwise," Borland told ESPN's Outside the Lines program, adding that he has no ill will against the team.
A class-action lawsuit involving thousands of former players, filed in 2012, contended that the league hid the dangers of brain injury among players while profiting from the sport's violent physical contact.
There have been suicides in recent years by former NFL players, including Jovan Belcher, Junior Seau, Ray Easterling and Dave Duerson.
In February, a U.S. judge refused to accept a proposed settlement between the NFL and the players, saying payment should be expanded for some players and families among other concerns.
(Reporting by Curtis Skinner; Editing by Paul Tait)