Bulgarian split squat

Dumbbells

A rear-foot-elevated split squat. The front leg takes most of the load (roughly 80%); leaning the torso forward shifts emphasis toward the glutes.

What each muscle does in the Bulgarian split squat

Muscle	Role	Action
Quadriceps	Primary	Extends the knee; the rectus femoris also flexes the hip
Gluteus maximus	Primary	Extends and laterally rotates the hip
Hip adductors	Secondary	Adduct the hip; the adductor magnus also extends it
Gluteus medius	Secondary	Abducts the hip, its front fibres rotate it inward, and it keeps the pelvis level
Hamstrings	Secondary	Flex the knee and extend the hip

Primary muscles are the prime movers; secondary muscles assist or stabilise. The balance shifts with grip, stance, range of motion and technique.