It was created for the low-budget Charlton Comics company by none other than Jerry Siegel, co-creator of Superman. The first issue, in 1956, was numbered #22 (talk about wishful thinking).
Former wrestler Brett Carson, the "world's most perfect man," was a blond Aryan demi-god in white shorts and a lavender vest, perfect not only in body but in soul: "A healthy physique breeds a healthy mind," he exclaims.
The school system in the 1950s would agree. Kids were being forced to do push-ups and sit-ups every morning before class, in the belief that exercise bred morality.
And they hated him, not because he worked for the forces of good, but because he was in shape.
Mr. Muscles only lasted for two issues, but he still had time to acquire a teenage sidekick, Kid Muscles, who dressed in a yellow singlet. All the time. Presumably at school, certainly while tooling around in his 1950s convertible.
There was also a Miss Muscles, but she ony appeared in one story.
The second and last issue was devoted to a new superhero named Steeplejack.
I guess it got too hard to pretend that Mr. Muscles was there for any other reason than to let kids gawk at his muscles.
See also: Charlton Comics.