PrimarySecondaryNot worked
This movement mainly trains traps, and also recruits Rear delts, Lats.
The shrug loads the upper trap in scapular elevation. It is one of the few muscles where usable load far exceeds what the range suggests: the path is short, the strength is large.
Eight to fifteen reps, with a pause at the top rather than a bounce. Straps become useful before the trap does: the grip gives out first, not the muscle.
Rolling the shoulders back at the top. The rotation adds nothing for the trap and takes the AC joint under load through a path it does not control.
The variants REPWIND's catalogue carries, under the name the app shows:
The journal, the anatomical map and all 257 catalogue exercises — free to start.