The SLDL, or stiff-legged deadlift, is a barbell or dumbbell exercise that targets the hamstrings, lower back, and glutes by having you hinge at the hips with your legs kept nearly straight. It’s one of the most effective posterior chain movements for building hamstring size and improving hip flexibility, and it’s a staple in both strength and bodybuilding programs.
Muscles Worked in the SLDL
The stiff-legged deadlift hits the entire backside of your body, but the emphasis shifts compared to a conventional deadlift. Because your knees stay nearly locked, your hamstrings do significantly more work. EMG research published in PLoS One found that the semitendinosus (the inner hamstring muscle) activates more than the biceps femoris (the outer hamstring) during the SLDL. This difference becomes even more pronounced when you perform the exercise on one leg.
Your lower back muscles, specifically the erector spinae, also work harder in the SLDL than in other deadlift variations. That same research found that erector spinae activation was highest during the stiff-legged deadlift compared to conventional deadlifts, Romanian deadlifts, and hex bar deadlifts. The deep spinal stabilizers along your lumbar spine fire hard as well. Your glutes contribute throughout the movement but take a secondary role to the hamstrings and lower back.
In short: if your goal is hamstring and lower back development specifically, the SLDL delivers more targeted stimulus than a conventional deadlift, which spreads the work more evenly across the quads, glutes, and back.
How to Perform the SLDL
Set up with your feet hip-width to shoulder-width apart, standing tall with the barbell in your hands or resting on the floor in front of you. Your knees should have only a slight bend, just enough to avoid locking them out completely. Keep your chin slightly tucked, your shoulders pulled back, and your core braced before you begin.
From here, hinge at the hips and push your glutes backward, allowing the bar to travel down toward the floor. Unlike a conventional deadlift where your knees bend and push forward over the bar, in the SLDL your knees stay in place (or even drift slightly backward) to clear a path for the barbell. The bar will naturally move slightly away from your legs and travel over your toes rather than scraping straight down your shins.
Lower until the bar reaches somewhere between just below your knees and mid-shin level. Where exactly you stop depends on your hamstring flexibility. You should feel a strong stretch in the backs of your thighs without your lower back rounding. At the bottom, your shins should be roughly vertical and your weight should sit in your midfoot and heels, with your toes still in contact with the ground.
To come back up, drive your hips forward and squeeze your glutes, returning to a fully upright position where your shoulders stack directly over your hips. That’s one rep. A narrower stance increases the range of motion and the stretch on your hamstrings, so adjust your foot width based on your mobility.
SLDL vs. Romanian Deadlift
These two exercises look similar and get confused constantly, but there are three meaningful differences.
First, knee position. The Romanian deadlift (RDL) keeps your knees noticeably bent throughout the movement, similar to the athletic position you’d use in a hang clean. The SLDL starts with nearly straight legs and only allows a slight bend as you descend. If you bend your knees too much during an SLDL, you’ve essentially turned it into a conventional deadlift.
Second, range of motion. The RDL typically stops at about shin level, with the plates hovering above the ground. The SLDL travels further, often going all the way down to the floor between reps. This greater range of motion is part of why it demands more hamstring flexibility.
Third, muscle emphasis. Both exercises hit the hamstrings and glutes, but the straighter knee position of the SLDL shifts more load onto the hamstrings and erector spinae. The RDL, with its deeper knee bend, tends to involve the glutes a bit more. Neither is objectively better. The RDL is often easier for people with limited hamstring flexibility, while the SLDL provides a more intense stretch and greater lower back involvement.
Flexibility and Readiness
The SLDL is more demanding on hamstring and hip mobility than most lower body exercises. If your hamstrings are tight, you’ll run out of range of motion quickly and your lower back will round to compensate. That rounding under load is the primary injury risk with this movement.
The National Federation of Professional Trainers recommends mastering the conventional deadlift before attempting the stiff-legged version. The conventional deadlift teaches you the hip hinge pattern with more knee bend, which is more forgiving. Once you can hinge with a flat back under load, transitioning to the straighter-leg version becomes much safer.
If you can’t touch your toes with straight legs and a flat back (no weight), you’ll likely need to work on hamstring flexibility before performing a full-range SLDL. In the meantime, you can reduce depth, stopping higher up, or widen your stance slightly to shorten the range of motion your hamstrings need to cover.
Barbell vs. Dumbbell SLDL
The barbell version lets you load the movement heavier, which makes it the better choice for building maximum strength and muscle mass. The fixed bar also keeps the weight in a predictable path, so you can focus on the hip hinge without worrying about balance.
Dumbbells offer more freedom of movement. You can position the weights to the sides of your legs or slightly in front, adjusting the path to suit your proportions. Dumbbells also challenge your grip and stabilizing muscles more and allow a slightly greater range of motion since there’s no bar hitting the floor. They’re a solid option for beginners learning the pattern or for anyone training at home without a barbell.
Sets, Reps, and Loading
How you program the SLDL depends on your goal:
- Strength: 3 to 5 sets of 4 to 6 reps with heavier weight. Keep rest periods longer (2 to 3 minutes) and focus on controlled form, since the lower back is under significant load.
- Muscle growth: 3 to 4 sets of 8 to 12 reps with moderate weight. This is the most common rep range for the SLDL and gives you enough time under tension to drive hamstring development.
- Flexibility and endurance: 2 to 3 sets of 12 to 15 reps with lighter weight. The higher rep count with a full range of motion doubles as active hamstring stretching.
Because the SLDL places sustained tension on the lower back, most people use it as an accessory exercise after their main compound lift (squats or conventional deadlifts) rather than as their primary heavy movement for the day. Starting lighter than you think you need and building up over several weeks gives your lower back time to adapt to the unique demands of the straight-leg position.