All roles require preparation, but for an actor there seems to be special training required to play a boxer. Think Robert DeNiro for "Raging Bull," or Christian Bale as an ex-athlete for "The Fighter." For Seth Numrich, who's the spry Joe Bonaparte in Clifford Odets' "Golden Boy," no dramatic weight loss was required, but otherwise the regimen was rigorous. 

"As soon as I got cast in May," he told me the other day in his dressing room at the Belasco, "I went to the gym." And not just to any sweatbox: Gleason's in Brooklyn, which has seen its share of both fighters and the actors who aspire to portray them. "I worked with a couple of people there," said Numrich, who's familiar to LCT audiences as Albert in "War Horse," "and they taught me the basics." He didn't remain long at Gleason's, however, because he was on the road for part of the summer. 

"In 'Golden Boy,' Numrich explained, "when Joe is asked when he learned to box, he replies, 'The past two years, all over the city in the gyms.'" That would have been an easier assignment in 1937, the time of the play, when there were more than 100 boxing gyms in New York, than today. Outside the city, Numrich didn't let a paucity of pugilistic palaces get in the way of his training. 

"I trained at gyms in Chicago, Minneapolis, Los Angeles, and San Francisco," the actor said. It was in that last city that he spent his biggest chunk of summertime, in a three-week workshop of a new play by Daniel Talbott called "Afghanistan Zimbabwe America Kuwait." "We call the play 'Azak' for short," Numrich explained. "It takes place in the near future. It's going to be done in New York soon at the Rattlestick Theater." 

Along with his physical training, Numrich did intellectual prep for "Golden Boy." "I love to do research," he said. "It's one of my biggest passions." For the Odets, he watched such period boxing films as "Body and Soul" and "Cinderella Man." He absorbed a seven-part PBS documentary series about the history of New York in the first half of the twentieth century. He read about the Group Theater, of which Odets was a member, and about the playwright's life. 

"I had no problem relating to Odets' struggle between being an artist and craving commercial success," Numrich revealed. "My actor friends and I talk about that subject a lot. We're artists because we love doing the work but we also have this part of us that wants to be recognized and celebrated." 

Numrich had already had some other preparation a few years ago, when he was a second-year student at Juilliard. "We did 'Golden Boy' as a rehearsal project. I played Fuseli, the Italian gangster. It was a little ridiculous because I was just 17 at the time. But I fell in love with the play. Revisiting it, I feel so connected to what Joe is going through." 

None of Numrich's preparation, though, could have prepared him for the experience of performing "Golden Boy" every night on the very stage where it premiered 75 years ago. "I knew about that before we started rehearsing," he said, "but you still are constantly reminded of how special it is. Revivals, even on Broadway, are rarely produced in the same places they opened. Doing 'Golden Boy' at the Belasco is a little like doing a Shakespeare play at the original Globe. Can you imagine?" 

Brendan Lemon is the American theater critic for the Financial Times and the editor of lemonwade.com.