Bulgarian split squat muscles worked

Every role here is for this technique: rear foot on a bench behind, dumbbells at the sides, front leg lowered until its thigh is parallel to the floor.

What muscles does the Bulgarian split squat work?

The prime movers of the Bulgarian split squat are the quadriceps, gluteus maximus and adductor magnus. They produce knee extension and hip extension. The synergists are the hamstrings and soleus. Twelve stabilizers hold joints and segments still, among them gluteus medius, gluteus minimus and tensor fasciae latae.

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Joint actions and their prime movers

The joint actions of the Bulgarian split squat and the prime movers that produce each
Joint action	Prime movers
Knee extension	The quadriceps
Hip extension	Gluteus maximus and adductor magnus

Every muscle by role

A prime mover produces the lift’s main joint action against the load; a synergist assists that action, or adds a secondary action the lift needs; a stabilizer contracts mostly isometrically to hold a joint or a segment still. A role describes what the muscle does in the technique above, not how hard it works or how much it grows.

The front leg does the lifting, so each muscle below names its side: the front leg, both sides, or the other side.

Prime movers 3

Prime movers in the Bulgarian split squat, with what each does
Muscle	What it does here	Side
Quadriceps	Knee extension of the front leg	Front leg
Gluteus maximus	Hip extension of the front leg	Front leg
Adductor magnus	Hip extension of the front leg	Front leg

Synergists 2

Synergists in the Bulgarian split squat, with what each does
Muscle	What it does here	Side
Hamstrings	Hip extension of the front leg	Front leg
Soleus	Controlling the forward lean of the front shin	Front leg

Stabilizers 12

Stabilizers in the Bulgarian split squat, with what each does
Muscle	What it does here	Side
Gluteus medius	Stopping the pelvis dropping on the unsupported side It is more active here than in a back squat, because one leg carries the load (McCurdy et al. 2010).	Front leg
Gluteus minimus	Stopping the pelvis dropping on the unsupported side	Front leg
Tensor fasciae latae	Steadying the hip in the frontal plane	Front leg
Adductor longus and brevis	Keeping the front knee tracking over the foot	Front leg
Quadratus lumborum	Holding the pelvis level against the spine	Both sides
Erector spinae	Holding the trunk upright	Both sides
Rectus abdominis	Bracing the trunk against the load	Both sides
External oblique	Bracing the trunk and resisting rotation	Both sides
Internal oblique	Bracing the trunk and resisting rotation	Both sides
Transversus abdominis	Raising abdominal pressure to stiffen the trunk	Both sides
Wrist and finger flexors	Gripping the dumbbells	Both sides
Upper trapezius	Holding up the shoulders under the dumbbells	Both sides

Lowering and lifting

What the prime movers of the Bulgarian split squat do in each half of a rep
Phase	What the prime movers do
Lowering	The front leg’s quadriceps and gluteus maximus lengthen under load
Rising	They shorten to extend the front knee and hip

Stretched but not loaded

The back leg’s hip flexors, iliopsoas and the rectus femoris of the quadriceps, are stretched rather than loaded.

The explorer’s map leaves them uncolored and names them on the card.

Where these prime movers also work

The quadriceps: prime mover in the back squat, front squat, leg press, conventional deadlift, sumo deadlift, walking lunge and leg extension; synergist in the barbell hip thrust and front plank.
Gluteus maximus: prime mover in the back squat, front squat, leg press, conventional deadlift, sumo deadlift, Romanian deadlift, barbell hip thrust and walking lunge.
Adductor magnus: prime mover in the back squat, front squat, leg press, conventional deadlift, sumo deadlift, Romanian deadlift and walking lunge; synergist in the barbell hip thrust.

Compared with the other lunge lifts

Walking lunge: the same prime movers; synergists only in the walking lunge, gastrocnemius; stabilizers only here, tensor fasciae latae, adductor longus and brevis, the wrist and finger flexors, and the upper trapezius.

Sources

Andersen et al. (2014), Int J Sports Med 35(14):1196
McCurdy et al. (2010), J Sport Rehabil 19(1):57
NSCA, Essentials of Strength Training and Conditioning, 4th ed. (2016)

The cited studies that measured muscle activity used electromyography, and a larger signal need not mean more force or more growth (Vigotsky et al. (2018), Front Physiol 8:985). The roles draw on those studies for which muscles a lift involves and how two lifts differ, never to rank one muscle against another.

See these muscles in 3D

Visualiser · Biology Muscles Worked by Exercise 3D Explorer Choose a lift and a real body lights its prime movers, synergists and stabilisers, front and back, with the same muscles in 3D. Visualiser · Biology Muscle Origin, Insertion and Action Explorer Paint a muscle’s origin and insertion on real 3D bones, or click a bone to see what attaches to it.