ACE and NASM both does a great job for the general population, but NASM puts a slight bit more emphasis on corrective exercise. However, any of the certifications you have mentioned will get your foot into the door.
Broadway theatre, commonly known as Broadway, refers to the theatrical performances presented in the 41 professional theatres with 500 or more seats located in the Theater District and Lincoln Center along Broadway, in Midtown Manhattan, New York City.
If the music itself isn't a patch on the originals, that doesn't matter so much. No wonder it became a hit. Grease went on to a run of 3,388 performances, making it the longest-running Broadway musical in history up to its time. In 1978, it was adapted into a movie.