The Ultimate Fighting Championship flourished in the U.S. during the mid-'90s as a pay-per-view-fueled sport for bloodthirsty fans who found professional wrestling and boxing too genteel. Marketed largely on the basis of its novelty and brutality, the mixed-martial-arts sport was eventually banned from cable TV, which makes it somewhat ironic that The Smashing Machine, a bone-crunching documentary on extreme fighter Mark Kerr (who left the fading UFC for a Japanese rival), made its debut on HBO. A big man with big emotions, Kerr remains hopelessly addicted to the heady adrenaline rush of pulverizing an opponent in front of thousands of screaming fans. Unfortunately, he's also addicted to the painkillers that make it possible for him to endure seemingly superhuman punishment. The Smashing Machine features plenty of hypnotically brutal, intense fighting, but its single most harrowing image could be Kerr injecting drugs into a bruised and battered vein that, like his body, has taken far more abuse than it ever should. The film documents a particularly bleak period in Kerr's professional and personal life, following him as he wrestles with addiction and with various sweaty musclemen. After overdosing on painkillers, Kerr goes to rehab and kicks the habit. But his shaky grasp on sobriety is constantly threatened by his hard-drinking, hard-partying girlfriend, who supports his decision to go straight but can't bring herself to stop drinking. With its conflicted, sympathetic hero, sexy-but-dangerous love interest, brute physicality, and dramatic story arc, The Smashing Machine plays like a neo-realist version of professional wrestling, with all the escapism and fantasy stripped away to reveal a bleak, Darwinian reality. It's also about as homoerotic as a film can get without actually being gay porn: Much of the footage is devoted to fight scenes in which sweaty, half-naked men punch at each other while locked in tight horizontal clinches, enduring all the pain of the boxing and wrestling elite for a fraction of the fame, cash, and glory.