The Single-Leg RDL (single-leg Romanian deadlift) is one of the best moves for building strong, resilient hamstrings while exposing and fixing left-to-right imbalances a barbell can hide. Loaded with a single dumbbell, it forces the hamstring and glute of your standing leg to control both the descent and the return, all while your core and ankle fight to keep you stable. It's an intermediate exercise because the balance demand is real, but that's exactly why it carries over so well to running, jumping, and heavier bilateral deadlifts. Expect better hip-hinge mechanics, more athletic single-leg strength, and noticeably tighter hamstrings within a few weeks.
How to do the single-leg rdl
- Stand on one leg with a soft, unlocked knee, holding a dumbbell in the hand opposite your standing leg (this keeps your hips and spine square).
- Set your spine in a neutral position: chest tall, shoulder blades back, and a slight natural arch in the lower back.
- Initiate the movement by pushing your hips straight back, not by bending your knee — think of closing a car door with your butt.
- As you hinge, let your free leg extend straight behind you so your torso and back leg form one long line roughly parallel to the floor.
- Lower the dumbbell toward your mid-shin or the floor, keeping it close to your standing leg and stopping when you feel a strong stretch in the hamstring.
- Drive through the heel and mid-foot of your standing leg, squeezing the glute to pull your hips forward and return to a tall standing position.
- Tap the free foot down lightly to reset if needed, complete all reps, then switch legs.
Muscles worked
The primary muscle is the hamstrings of the standing leg, which lengthen under load as you hinge and then contract powerfully to extend the hip and pull you upright — the defining action of any Romanian deadlift. The glutes (especially gluteus maximus) act as a major hip extender alongside the hamstrings and also fire to keep the pelvis level against the rotational pull of the offset dumbbell. The core — deep stabilizers, obliques, and spinal erectors — works isometrically to resist trunk rotation and hold a neutral spine throughout. Smaller stabilizers in the standing-leg glute medius, ankle, and foot constantly fire to keep you balanced, which is why this lift builds athleticism, not just raw strength.
Benefits
- Builds hamstring and glute strength through a full stretched-to-shortened range, improving the hip hinge that powers deadlifts and sprints.
- Exposes and corrects left-to-right strength imbalances that bilateral lifts let you mask.
- Trains single-leg balance, ankle stability, and proprioception that carry over to running, jumping, and change-of-direction sport.
- Strengthens the hamstrings in a lengthened position, a key factor in reducing hamstring strain risk.
- Requires only one dumbbell and minimal space, making it easy to program at home or in a busy gym.
Common mistakes
- Twisting the hips open: keep both hipbones pointed at the floor by rotating the free-leg hip down, as if you had a headlight on each hip you must keep aimed straight ahead.
- Turning it into a squat: if your standing knee bends and tracks forward, you're squatting, not hinging — push the hips back instead and keep the shin nearly vertical.
- Rounding the lower back: chasing depth by curling the spine kills hamstring tension and stresses the discs; stop the descent when your back can no longer stay flat.
- Chasing the floor: you don't need to touch the ground — only go as low as you can keep a neutral spine and a strong hamstring stretch.
- Rushing and bouncing: yanking the weight up with momentum robs the hamstrings of work; control the lower for 2-3 seconds and pause briefly at the bottom.
- Locking the standing knee: a fully straight, rigid knee shifts load off the hamstring and stresses the joint — keep a soft bend the whole set.
Form tips
- Hold the dumbbell in the hand opposite the standing leg to keep your pelvis and spine square and maximize the anti-rotation challenge.
- Fix your eyes on a spot on the floor 3-4 feet ahead to steady your balance without dropping your head and rounding your neck.
- Drive the free heel toward the wall behind you to keep the back leg long and the hips level.
- Move slowly: a 2-3 second descent builds far more control and hamstring tension than dropping fast.
- If balance falls apart, lightly touch a wall or rack with your free hand at first, then wean off the support as you stabilize.
Sets & reps
For most lifters, 3 sets of 8-10 reps per leg with about 75 seconds of rest is an ideal starting point and matches FORMA's seed prescription. For hypertrophy, run 3-4 sets of 8-12 reps per leg with a controlled tempo and a deep stretch each rep. For strength and balance carryover, use slightly heavier loads for 3-4 sets of 6-8 reps, prioritizing flawless control over weight. For endurance, athletic conditioning, or rehab-style work, go lighter for 2-3 sets of 12-15 reps. Because it's unilateral, always match reps on both legs and start every session with your weaker side.
Frequently asked questions
Is the Single-Leg RDL good for building hamstrings?
Yes. It directly targets the hamstrings of the standing leg, loading them through a long stretch and forcing them to extend the hip on every rep. Because each leg works independently, it builds balanced hamstring strength and trains the muscle in a lengthened position, which supports both growth and injury resilience.
How is a Single-Leg RDL different from a regular RDL?
A standard RDL is a two-legged barbell hinge focused on maximal load. The Single-Leg RDL uses one leg and a dumbbell, so it uses lighter weight but adds a major balance and anti-rotation challenge. It exposes side-to-side imbalances and builds athletic single-leg stability that the bilateral version can't.
Why do I keep losing my balance during the Single-Leg RDL?
Wobbling is normal early on. Spread your toes and grip the floor, fix your gaze on a spot 3-4 feet ahead, and move slowly. Keeping a soft knee and driving the free heel straight back also stabilizes you. If needed, lightly touch a wall with your free hand until your stabilizers catch up.
How heavy should I go on the Single-Leg RDL?
Start lighter than your ego wants. Pick a dumbbell you can control through a full range with a flat back and no balance breakdown, typically in the 8-10 rep range. Master the movement and lengthened-stretch position before adding load; balance, not raw weight, is the limiting factor here.
Which hand should hold the dumbbell?
Hold the dumbbell in the hand opposite your standing leg (contralateral). This keeps your pelvis and spine square and increases the anti-rotation demand on your core and glutes. Holding it on the same side is also valid and slightly easier to balance, so beginners can start there and progress to the contralateral hold.
Is the Single-Leg RDL safe for my lower back?
When done with a neutral spine, it's back-friendly and can actually strengthen the posterior chain that protects your spine. The key is to hinge from the hips, keep the back flat, and stop the descent before your lower back rounds. Avoid chasing the floor, and reduce load if your form breaks down.