Stiff Leg Deadlift vs RDL: Differences, Muscles and Which to Pick

The quick answer: the Romanian deadlift (RDL) starts from standing, keeps a soft knee bend that stays fixed, and stops the moment your hips stop travelling backwards. The stiff leg deadlift (SLDL) straightens the knees further and is traditionally pulled from the floor, with the bar resetting on the ground every rep, so it covers more range, gives the hamstrings a deeper stretch and puts more demand on your lower back. If you only pick one, pick the RDL. If you want extra stretch and your hamstrings are flexible enough to use it, the stiff leg version is worth adding.

Both lifts have their own full technique guides on the site: the Romanian deadlift and the stiff legged deadlift. This page sits between them and deals with the choice.

Stiff leg deadlift vs RDL at a glance

	Romanian deadlift (RDL)	Stiff leg deadlift (SLDL)
Start position	Standing, bar taken from a rack or blocks	Traditionally from the floor, resetting each rep (can be done from standing)
Knee angle	Soft bend, about 15 degrees, set at the top and held	Nearly straight, 10 to 15 degrees at most
Range	Until the hips stop moving back, usually just below the knee to mid-shin	Mid-shin to the floor, flexibility permitting
Bar path	Pinned to the thighs and shins	Can drift slightly in front of the shins
Typical load	Moderate to heavy for a hinge	Light to moderate, often 40% to 50% of your deadlift
Main target	Hamstrings and glutes, with erectors holding position	Hamstrings at long lengths, glutes, more lower-back demand
Who it suits	Almost everyone, including beginners who've learned the hinge	Lifters with good hamstring flexibility and a confident neutral spine

The knee angle is the real dividing line. Bend the knees more and you've drifted towards a conventional deadlift; lock them harder and you're closer to a barbell good morning. Lifters argue about the labels on Reddit endlessly, but what matters is which position you hold and whether your back stays flat while you hold it.

How the RDL works

You set the bar at hip height in a rack, stand up with it and hinge from the top down. The cue is that your hips travel backwards like you're shutting a car door with your backside, while the knees soften once and then stay quiet. When your hips can't go any further back without your knees bending more or your back rounding, that's the bottom, and for most people it arrives somewhere between the kneecap and mid-shin.

Because the bar never touches down, the hamstrings stay under tension for the whole set. You also get to choose where the rep ends based on your own hinge rather than where the plates happen to meet the floor, which is why the RDL scales so well across different leg lengths and flexibility levels.

How the stiff leg deadlift works

The stiff leg deadlift asks you to keep the knees close to straight and reach further. In its traditional form you pull the bar from the floor, stand up, lower it back down until the plates touch, and start again from a dead stop. A 20kg Olympic bar loaded with full-size 45cm plates sits roughly 22cm off the ground (our guide to how much a barbell weighs covers the bar specs), so each rep finishes with your hands near the top of your feet. That's a long way down with straight legs.

The extra range is the appeal: the hamstrings are pulled to a longer length than in most RDLs. The cost is that your torso ends up nearer horizontal with the bar a little further in front of you, which lengthens the lever your lower back has to resist. If you can't reach the floor with a flat back, the honest fix is to raise the bar on blocks or start from standing, rather than letting your spine round to touch down.

What the research says about the muscles

The most direct comparison is a 2022 EMG study of the Romanian, step-Romanian and stiff-leg deadlift in ten competitive bodybuilders lifting 80% of their one-rep max. On the lifting phase, the RDL produced more semitendinosus activity than the stiff-leg deadlift, while the stiff-leg version produced more glute max activity. Standing on a step to extend the RDL's range lifted excitation across most of the posterior chain, including the lower-back longissimus. The lowering phase showed fewer differences. Ten people is a small sample, so read it as a hint, but it does undercut the gym claim that straighter knees automatically mean "more hamstrings".

A 2020 systematic review of deadlift EMG research adds context: across deadlift variants the erectors and quads tended to show higher activation than the glutes and biceps femoris, but the RDL was the exception, with lower erector activity than hamstring activity. That fits how the lift feels. The RDL is a hamstring lift first, and the lower back's job is mostly to hold still.

EMG only tells you how hard a muscle is working, not how much it will grow. The better guide for hypertrophy is the evidence on training muscles at long lengths. In a 12-week study of seated versus prone leg curls, the leg trained with the hip flexed (hamstrings lengthened) gained more whole-hamstring volume, around 14% against 9%. That wasn't a deadlift study, but it's the reason the stiff leg deadlift's extra stretch is attractive, and also why a deep, well-controlled RDL already does a lot of the same job.

Which should you pick?

For hypertrophy

The RDL is the better default. You can load it heavier, keep constant tension and run sets of 8 to 12 without the floor reset breaking up the rep. Add the stiff leg deadlift as a second hinge, or swap to it for a block, when you want more stretch and your flexibility allows it; dumbbells make that easier because they can travel beside your shins. Pair either with a knee-flexing move like a leg curl or Nordic, since neither hinge trains the hamstrings' knee-bending role. Our hamstring exercises guide has options.

For strength

If your goal is a bigger deadlift, the RDL carries over better. It trains the hip hinge and back position you need off the floor, and you can push it to moderately heavy loads with 5 to 8 reps. The stiff leg deadlift is a weaker strength lift because the straight-knee position caps the weight long before the hamstrings give out, so keep it light and treat it as an accessory.

For sport

Most coaches reach for the RDL or its single-leg version for runners and field-sport players, because it's easy to load progressively and the knee position looks more like sprinting and jumping. The stiff leg deadlift can work as a lighter, higher-rep option to build tolerance at long hamstring lengths, but it isn't a must-have.

How to programme them

Treat both as accessories that come after your main lift of the day, and count them as hamstring and lower-back volume.

• RDL as the main hinge: 3 to 4 sets of 6 to 10 reps, once or twice a week, leaving one or two reps in reserve. Rest about 2 minutes.
• SLDL as a secondary hinge: 2 to 3 sets of 8 to 12 at roughly 40% to 50% of your deadlift max, with a 2 to 3 second lowering. Once a week is plenty if you also deadlift heavy.
• Rotating blocks: run RDLs for 4 to 6 weeks, then stiff leg deadlifts for 4 to 6 weeks. The change of position keeps progress coming without adding total volume.

Avoid putting heavy conventional deadlifts, RDLs and stiff leg deadlifts in the same week at full volume. Your lower back recovers more slowly than your hamstrings, and it's usually the back that tells you you've overdone it.

If you train at home, a barbell, plates and a pair of blocks or a rack cover both lifts; the home gym hub has the kit worth buying.

Common mistakes when switching between them

Letting the RDL turn into a stiff leg deadlift by accident. Chasing depth with straighter knees and a rounding back just gives you a bad RDL. Decide which lift you're doing before the set.

Bending the knees more as you lower on an SLDL. Set the knee angle at the top and freeze it. If the knees keep softening you've changed the lift halfway down.

Loading the SLDL like an RDL. Expect to use noticeably less weight. Matching your RDL numbers is the quickest way to grind reps with a rounded spine.

Touching the floor at any cost. The floor is a target for flexible lifters, not a requirement. Raise the bar instead.

If neither lift sits right with your back or your setup, our list of Romanian deadlift alternatives covers hinges and hamstring moves that load the spine less, and a deficit deadlift is the other route for lifters who want more range off the floor.

Recommended reads

• Stiff legged deadlift: full form guide
• Romanian deadlift: how to do it and muscles worked
• Romanian deadlift alternatives
• How much does a barbell weigh?
• Home gym equipment