The REAL Reason Muscle Ups Build A BIG Back Muscle ups, especially when done for reps are an explosive movement. Explosive movements predominantly work off the type two muscle fibers, which are most responsible for growth. Besides that, repping out muscle ups gives you high degrees of eccentric loading each repetition. Eccentric are known to cause the most muscle damage which in turn can promote good muscle growth. If you can’t do a muscle up, it’s about time you start to learn. For help with le