There’s a lot of muscle in this gym war. Tim Boyce, the front-desk man at the David Barton Astor Place branch, has been let go because his body was featured in an ad for rival Equinox. Barton told us, “It’s such a compliment when other gyms try to hire our employees . . . If any other gyms need a hot-looking staff for their ads, we have 300 of the best-looking trainers in the world. Please contact me directly.” Boyce — whose bare chest appears in Equinox’s new campaign, but not his face — could not be reached. A source said, “He has a very distinctive tattoo on his arm — it isn’t hard to work out it is him.”