Former UFC champ Carwin announces retirement



Shane Carwin, who held the UFC's interim heavyweight title while Brock Lesnar was on he sidelines in 2010, announces his retirement today on Twitter.

Carwin, 38, had been plauged by injuries the past two years since his second career loss to Junior Dos Santos in 2011.

Carwin was scheduled to return to face Roy Nelson this past December, but pulled out of the fight due to a knee injury.

When Brock Lesnar was out of action due to diverticulitis, UFC matched Carwin vs. Frank Mir on March 27, 2010, in Newark, NJ, for the interim heavyweight title. Carwin knocked Mir out in the first round.

Lesnar vs. Mir in the title unification match took place on July 3, 2010, in Las Vegas.  Carwin nearly knocked Lesnar out in the first round, until to hit a physical wall and his body locked up due to lactic acid and exhaustion.  Lesnar won the title, Carwin's first pro defeat, with an arm triangle in the second round.