PrimarySecondaryNot worked
This movement mainly trains abs.
The side plank loads quadratus lumborum and the obliques isometrically, against gravity pulling the hip down. It is anti-lateral-flexion work, not a movement.
Sets of twenty to sixty seconds per side. Progress is measured in time held with alignment intact, not in time held.
Letting the hip sag through the set. The position degrades without you noticing, and the exercise stops loading what you are doing it for.
The variants REPWIND's catalogue carries, under the name the app shows:
No other variant of this movement in the catalogue.
The journal, the anatomical map and all 257 catalogue exercises — free to start.