How To Do the Bulgarian Split Squat

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The Bulgarian split squat is a split squat with your back foot up on a bench behind you. One leg carries most of the load while the other one is mostly there for balance and support.

It is brutal, it exposes side-to-side differences, and it needs almost no equipment.

Short version: set your front foot far enough forward that your shin stays reasonably vertical at the bottom, decide whether you are leaning or staying tall, lower under control, and drive up through the front foot. The lean decision is the interesting part.

Trunk position is a dial, and it was measured

Twenty-one trained female athletes performed four variations while EMG recorded eight muscles: gluteus medius, gluteus maximus, vastus lateralis, rectus femoris, vastus medialis, semitendinosus, biceps femoris and erector spinae. The variables were trunk position, neutral versus flexed forward, and surface, ground versus suspension.

Trunk flexion increased activation in the gluteus maximus, biceps femoris and rectus femoris.

Suspension-based execution significantly increased erector spinae activation, p equals 0.046.

So leaning forward is not sloppy form. It shifts work toward the glutes and hamstrings. Staying tall keeps more of it on the quads. Both are legitimate, they just buy different things.

Twenty-one trained women, bodyweight-level variations. Directionally useful, and note the sample is single sex, which is unusual in this literature and worth having.

Your back leg is doing most of the resisting

This is the finding that changed how I think about the lift.

Nine trained men performed bodyweight Bulgarian split squats while researchers measured a rear leg-derived moment, a resistive force from the back leg working against the front leg's hip extensors. It had been theorised but never actually tested.

It ranged from 76 to 86 Nm in a wide stance and 49 to 71 Nm in a narrow stance. As a proportion of the total resistance on the front hip, that was 70 to 97 percent in the wide stance and 62 to 98 percent in the narrow stance.

Your back leg is supplying most of the resistance your front hip is fighting. It is not a kickstand.

Which also explains why stance width changes how hard this feels at the hip: a wider stance produced a larger rear leg moment.

Nine men, bodyweight only. Small, but it is the first empirical test of the effect.

Wobbling your back foot: more work, and not only where you want it

Twenty-three trained male football players did bodyweight Bulgarian split squats under four conditions: a stable platform, a BOSU ball, a Swiss ball, and TRX suspension.

During the ascent, activation was significantly greater for biceps femoris, semitendinosus, vastus lateralis, vastus medialis and gluteus maximus.

So instability does increase muscle activation on the way up, across hamstrings, quads and glutes.

Before you put your foot on a Swiss ball, hold the other finding next to it: the suspension version also raised erector spinae activation. More instability means more work for your lower back stabilisers too.

And more activation at bodyweight is not the same as more growth or more strength. Instability work usually means you can load far less. Use it for variety and control, not as a replacement for loading the pattern.

How to actually do it

Set your back foot on something roughly knee height. Higher is not better, it just tips you forward whether you wanted that or not.

Step far enough forward that at the bottom your front shin is close to vertical and your back knee travels toward the floor rather than jamming into it.

Decide your torso angle before the set. Leaning forward biases glutes and hamstrings, staying tall biases quads. Then keep that angle for every rep.

Lower under control. The bottom is where balance disappears, so do not fall into it.

Drive through your whole front foot.

Expect your back leg to work. That is the mechanism, not an error.

End the set when your torso angle starts drifting or you need the back leg to push you up. That drift is the exercise changing under you.