Both feet on the floor, all the single-leg punishment.
Drop straight down, not forward. Keep your front shin near vertical and torso tall.
With feet staggered and stationary, the front quad grinds through every rep without the step, catch and balance chaos of a lunge, which means more tension going exactly where you want it. The glutes assist through hip extension on the drive up. One leg finishes its full set before you switch, so the weaker side cannot hide behind the stronger one.
A lunge involves stepping into or out of position every rep, a split squat keeps the feet planted and just moves up and down. The static stance is easier to balance and keeps constant tension on the front leg.
The Bulgarian elevates the rear foot, which dumps even more load on the front leg and adds a bigger stretch, but it is harder to balance. The flat-footed split squat is the place to build the pattern and load heavy first.
Keep the majority of your weight through the front heel, with the back leg acting mostly as a stabiliser on its toes. If your back leg aches more than your front quad burns, shift forward.
