muscle up verb 3/ˈmʌs.əl.ʌp/ noun 1forms 4 verb3 •To train the muscles for increased size and strength.We spent the summer trying to muscle up for football next term. •(figurative) To make stronger or more powerful.Churchill had again thwarted the American impulse to muscle up in the Pacific theater at the expense of the Atlantic[…] — 2007 •To force one's way into or through.There are only about ten tables, so you'll probably have to wait — or just muscle up to the bar like everyone else. — 2007 muscle-up /ˈmʌs.əl.ʌp/ noun1 •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.The muscle-up starts from a hang with a high or false grip. — 1966 formsmuscled up · muscling up · muscles up · muscle-ups