The "muscleman" in question
A muscleman, musclehead, or simply "the muscle", were terms used to describe a person who was muscular.
In 2267, Leonard McCoy used the term "muscleman" derogatorily, asking James T. Kirk to "get that muscleman (a security officer) out of my sickbay" so Lazarus could recuperate in peace. (TOS: "The Alternative Factor")
In 2381, after Carol Freeman instructed Jack Ransom to place the evil computer AGIMUS into a crate, AGIMUS attempted to appeal to Ransom, stating "So, you're the muscle, huh?", before it attempted to trick Ransom into throwing it towards a nearby computer console with a network port. (LD: "Where Pleasant Fountains Lie")