The sissy squat is a bodyweight squat variation that involves letting the knees travel far over the toes, placing an extreme stretch on the quads. This movement targets the quad muscles directly and can be performed in partial or full ranges of motion based on knee health and pain.
Stretches and strengthens the quad muscles
Can improve active flexibility in the knees if your knees can handle the move
Can be performed in partial or full range of motion
Doesn't require added weight to be brutally intense