1. muscle up - Noun
2. muscle up - Verb
(transitive, intransitive) To train the muscles for increased size and strength.
We spent the summer trying to muscle up for football next term.
(intransitive) To force one's way into or through.
(transitive, intransitive, figuratively) To make stronger or more powerful.
muscle-up (plural muscle-ups)
An exercise done for strengthening the arms and upper body, in which one lifts one's own weight while hanging from a bar to a position above the bar.
muscle-up