For hamstring growth
For hamstring growth, the two are close. Lying leg curl rates slightly higher: more of the work on the hamstrings, easier on the joints.
Stiff-leg deadlift gives more stretch.
Both are good choices, and they train the hamstrings 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
Lying Leg Curl. Still a strong choice; hips are extended, so the hamstrings are less stretched.
Stiff-Leg Deadlift. Like the Romanian deadlift with straighter legs: a big hamstring stretch, with similar lower-back fatigue.
For hamstring growth, the two are close. Lying leg curl rates slightly higher: more of the work on the hamstrings, easier on the joints. Stiff-leg deadlift gives more stretch. Both are good choices, and they train the hamstrings 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.
Lying leg curl is easier: it’s easy to learn, while stiff-leg deadlift takes some practice.
Lying leg curl needs a machine, so for most people it’s a gym exercise. Stiff-leg deadlift needs a barbell, so for most people it’s a gym exercise.
Lying leg curl: it rates Strong for joint and recovery cost in our research rubric, against Good for stiff-leg deadlift.