Stallone enters a new ring

American Media Inc., home to the National Enquirer tabloid and glossy celebrity weekly Star, said Monday that it would team with “Rocky” actor Sylvester Stallone to launch a fitness-focused magazine.

The monthly magazine will be called Sly, the Hollywood action star’s nickname, and will be aimed at men ages 35 to 54, American Media said. It will join other magazines -- such as Oprah Winfrey’s O, the Oprah Magazine and Martha Stewart Living -- that are named after their muses.

The magazine is set to hit newsstands in early January, coinciding with Stallone’s reality TV show about young boxers, “The Contender,” which will run on NBC.

Stallone, 58, “will be very hands on. He will be involved with the editorial direction of the magazine,” American Media spokesman Stuart Zakim said. Stallone will appear on the cover of the first issue, but it has not been decided if he will be on the cover of every issue, Zakim said.