Former UFC lightweight champion Sean “The Muscle Shark” Sherk (36-4-1 MMA, 8-4 UFC) announced his retirement from mixed martials arts today, as first reported on Ariel Helwani’s The MMA Hour. In an interview with BJ Penn Radio earlier this year, Sherk discussed what he would need to get back into the cage, and what is keeping him out. “Many, many […]