For quad growth
For quad growth, Smith machine squat rates higher on our research criteria: easier to progress, easier on the joints.
Sissy squat keeps more of the work on the quads.
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
Sissy Squat. The knees travel far forward and stretch the quads hard, but it’s tough to load and stresses the knees.
Smith Machine Squat. A squat on rails, so you can place your feet forward and push the quads hard without balancing a bar.
For quad growth, Smith machine squat rates higher on our research criteria: easier to progress, easier on the joints. Sissy squat keeps more of the work on the quads. 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.
Smith machine squat is easier: it’s easy to learn, while sissy squat takes some practice.
Sissy squat needs no equipment, so you can do it anywhere. Smith machine squat needs a Smith machine, so for most people it’s a gym exercise.
Smith machine squat: it rates Strong for joint and recovery cost in our research rubric, against Good for sissy squat.