HBO has put in development Muscle, a single-camera comedy from Blue Valentine co-writer/director Derek Cianfrance about the subculture of contemporary professional bodybuilding. It is based on Sam Fussell’s memoir Muscle: Confessions of an Unlikely Bodybuilder, which chronicles his four-year stint as a full-time bodybuilder after graduating from Oxford. Cianfrance and Fussell will co-write the script, with Cianfrance attached to direct. Both will also co-executive produce, while Blue Valentine producer Jamie Patricof is executive producing with John Lesher and Adam Kassan. It took Cianfrance 12 years to bring Blue Valentine, a personal account of a failing marriage, to the screen. The film, Cianfrance’s second, opened last week with the highest gross among specialty releases. It has been garnering awards buzz, especially for stars Ryan Gosling and Michelle Williams.