How long does it take for muscle atrophy to set in after a break in schedule? ADVERTISEMENT 974 viewsJune 10, 2015 0 Grace June 10, 2015 0 Comments 4 Answers ActiveVotedNewestOldest 0 NatalieSmith5 Posted 0 Comments Hello Grace Swartz, Muscles start to atrophy after 48 hours without eustress. Take care, Natalie aka NAPS 2 B Fit. You are viewing 1 out of 4 answers, click here to view all answers. Register or Login