Mike Marvel's Dynaflex course was promoted from the early 1960s to the mid 1980s and the adverts for it appeared on the back of Marvel Comics. It was one of the first courses to teach Power Flex Contractions.

It is not certain today whether he actually existed or, because of the Marvel name, he was a figment of someone's imagination and was placed on the back of the Marvel Comics as a copy of the style of Charles Atlas advertising. Certainly the Marvel course did contain some of the type of exercises that Atlas taught.