It looks as though the impressive and decorated fighting career of Sean “The Muscle Shark” Sherk has come to an end at the age of 40. The former UFC lightweight champ has reportedly hung up the gloves after dealing with injuries, since he handed Evan Dunham a split decision loss at UFC 119 in September, 2010.

News of Sherk’s retirement was reported by MMA’s Ariel Helwani and Bleacher Report’s Damon Martin is also reporting that the fighter is calling it quits. Sherk has yet to make an announcement on his Twitter account of Facebook page (as of Tuesday AM).

So, if you’re new to this whole MMA thing, then Sherk may not ring a bell since he hasn’t fought in a couple of years, but the noted wrestler was one of the sport’s top fighters for some time. Sherk went undefeated in his first 20 bouts as a welterweight, before former UFC champ Matt Hughes defeated him by UD in April, 2003. After winning 12 more fights Sherk took on Georges St. Pierre at UFC 56 in 2005, but also came up short and lost by stoppage.

After moving to 155 pounds, Sherk secured the UFC Lightweight Championship in 206 by defeating Kenny Florian by UD. After defending the belt a few months later versus Hermes Franca, Sherk’s was stopped by BJ Penn in May, 2008, after he returned from a suspension for failing a post-fight drug test. Sherk went 2-1 in his next three fights with his only  loss coming to former lightweight champ Frankie Edgar.

Sherk made his pro debut way back in 1999 and will exit the sport with a record of 36-4-1. Not too shabby, especially when you consider the only men to defeat him were current or former champs.

Stay tuned to Caged for all your UFC news and coverage.

(Update: Sherk has confirmed his retirement via Twitter by stating: “Have to say thanks for all the great support I’ve had over the years. It’s been an honor and privilege fighting for UFC and all the fans.”)