For quad growth
For quad growth, the two are close. Leg extension rates slightly higher: more of the work on the quads, easier to progress.
Front-foot-elevated split squat gives more stretch.
Both are good choices, and they train the quads differently. Using both across your week covers more of the muscle than either alone: in studies, varied exercises grew parts of a muscle that one exercise missed. (Fonseca et al., 2014; Costa et al., 2021)
The research score comes from these, scored by hand from the studies. Lifter scores appear once an exercise has 10 ratings. How scores work
Front-Foot-Elevated Split Squat. Raising the front foot buys extra depth, and the quads work hardest in that stretch.
Leg Extension. The only exercise that fully loads the rectus femoris: it grew all three of its regions in one trial, where Smith squats didn’t. Lean back to stretch it more.
For quad growth, the two are close. Leg extension rates slightly higher: more of the work on the quads, easier to progress. Front-foot-elevated split squat gives more stretch. Both are good choices, and they train the quads differently. Using both across your week covers more of the muscle than either alone: in studies, varied exercises grew parts of a muscle that one exercise missed.
About the same: both are easy to learn.
Front-foot-elevated split squat needs dumbbells and a weight plate, so a home gym covers it. Leg extension needs a machine, so for most people it’s a gym exercise.
About the same: both rate Strong for joint and recovery cost in our research rubric.