Tim Kennedy announces retirement after 15 years in MMA

Tim Kennedy announced the end of his 15-year MMA career with a heartfelt message on his Facebook page Tuesday.

The 37-year-old UFC middleweight apparently decided to retire while in the emergency room following his recent loss to Kelvin Gastelum at UFC 206 in December. It was Kennedy's return to competition after a two-year hiatus, and he said it was the first time he'd ever felt tired during a fight.

"We had talked about it a lot over the past few years," Kennedy wrote. "I'd spoken to (friend) Nick (Palmisciano), to my wife Ginger, and to (coaches) Greg Jackson and Brandon Gibson ad nauseam about the coming end.

"No matter how hard I trained, I knew this ride wouldn't last forever. But saying it out loud definitely brought me both sadness that this chapter was complete and overwhelming relief that it's a decision I could make without worrying about taking care of my family."

Kennedy retired with an 18-6 professional record, including three wins in five UFC appearances. He faced several top contenders inside the Octagon, and in April 2014 picked up a unanimous decision win over future middleweight champion Michael Bisping.

An active member of the United States Army, Kennedy came to prominence in the California-based Strikeforce promotion, knocking off the likes of Robbie Lawler and Melvin Manhoef, and twice challenging for its 185-pound title.

He has been one of the most vocal athletes in MMA in regards to fighter treatment and compensation. This past November, he helped to form the Mixed Martial Arts Athletes Association, alongside former world champions Georges St-Pierre and Cain Velasquez. The MMAAA aims to level the playing field when it comes to contract negotiations between the UFC and its fighters.

"Someday the Kelvin Gastelums and the Yair Rodriguezes and the Paige VanZants will be sitting in their respective emergency rooms with their respective Nick's talking about it being over," Kennedy wrote. "And when that day comes, I want to make sure their future is secure."