By Dr. Jerry Yoo, DPT, CSCS | NL Physio
I see a surge of runners come through Next Level Physio with the same complaint every training cycle: a nagging ache right at the sit bones, the origin point of the hamstrings. It shows up on long runs, it shows up climbing stairs the next morning, and it usually gets blamed on "just tight hamstrings" until it doesn't go away. If that sounds familiar, the single leg Romanian deadlift, or SL RDL, is one of the most effective tools I prescribe to fix it.
The Power of the Single Leg RDL
The single leg RDL isn't just another exercise I hand out because it looks good on a program. It's a core piece of Phase II, the Excel phase, in our MEI Method for getting runners back to full mileage. What makes the SL RDL different from a standard deadlift is that it trains each leg independently, which exposes and corrects the side-to-side imbalances a two-legged lift will always let you hide.
Why Single Leg RDLs?
- Enhanced Lower Body Strength and Power: The single leg RDL zeroes in on the hamstrings and glutes, the two muscle groups doing the most work every time your foot hits the ground. Strengthening them translates directly to better performance, whether you're grinding through a tempo run or pushing up a hill.
- Boosted Balance and Stability: Standing on one leg while hinging forward challenges balance and proprioception in a way bilateral lifts never will. That carries over to real running terrain, uneven trails, quick cuts, tired legs late in a race.
- Injury Resistance: I can't promise any exercise prevents every injury, there are too many variables outside anyone's control. But the SL RDL trains the hamstring's eccentric phase specifically, the lengthening-under-load action that's most often missing when a hamstring strain keeps recurring.
Muscles Worked
Here's exactly what's firing during a single leg RDL, since I get asked this constantly.
Hamstrings do the bulk of the work, specifically the biceps femoris, semitendinosus, and semimembranosus, the three muscles that make up the hamstring group and control that hip-hinge lowering phase.
Glutes, both the glute max and glute medius, are working just as hard, especially on the standing leg. The glute medius in particular is what's keeping your pelvis level while you're balanced on one foot, which is exactly the kind of stability a lot of runners are missing without realizing it.
Core and spinal stabilizers are active the entire rep too. Keeping a flat back through the hinge isn't just a form cue, it's your deep core and spinal stabilizers doing real work to protect your spine under load.
Executing the Single Leg RDL
- Begin standing, weight evenly distributed and knees slightly bent.
- Transfer your weight to one leg, maintaining the knee bend.
- Hinge at the hips, keeping your back straight and chest up, as you lean forward.
- Extend the free leg behind you, aiming for a straight line from head to heel.
- Lower until your hamstring stretches, then squeeze your glutes to return to the start.
- Complete your set before switching legs.
Pro Tips for Perfect Form
- Maintain a flat back to protect your spine.
- Focus on driving through the heel of your supporting leg.
- Ensure your shin remains vertical for optimal hamstring engagement.
- Lower your torso with control to maximize muscle work.
- Keep the weight close to your body for better stability.
SL RDL Programming: Reps, Sets & Progression
I typically start clients at 2 to 3 sets of 8 to 10 reps per leg, bodyweight only or holding a light dumbbell, focusing entirely on control and a level pelvis before adding load. Once that's clean, I'll progress to a moderate dumbbell or kettlebell for 3 sets of 6 to 8 reps per leg, prioritizing a slower eccentric, a 3 to 4 second lowering phase, since that's the part actually building hamstring resilience.
From there, load goes up gradually, same rep ranges, heavier weight, always with form staying identical to the lighter version. If form breaks down, the weight was too heavy that day. This isn't an exercise where grinding out an ugly rep does you any favors.
Common Mistakes
The three I correct most often in the clinic:
- Rounding the back. The moment the spine rounds instead of hinging at the hip, load shifts off the hamstring and onto the lower back, exactly where I don't want it going.
- Letting the hips open up. If your hips rotate outward mid-rep instead of staying square, you're losing the single-leg stability benefit entirely and putting uneven stress through the hip.
- Using momentum instead of control. Bouncing out of the bottom position or rushing the descent trades muscle tension for speed, which is the opposite of what this exercise is for.
This kind of hip and pelvic compensation doesn't always stay contained to the hamstring either. I regularly see it feed into hip pain and knee pain further down the chain, since a pelvis that isn't staying level under load has to get stabilized somewhere, and that's usually the joint above or below.
Variations
Once the standard SL RDL is dialed in, I'll often progress clients to a banded SL RDL for added resistance through the full range, or a kettlebell SL RDL for a lower center of gravity that's a little more forgiving on balance. Both are worth working into your rotation once bodyweight and basic loaded reps feel controlled.
Incorporating single leg Romanian deadlifts into your routine is one of the most reliable ways I know to resolve a persistent hamstring issue and build real running performance underneath it. That said, always consult with a physiotherapist before trying new exercises, especially if you're currently injured.
Need Help with Hamstring Pain?
If conventional methods haven't eased your hamstring pain, it's time for a tailored approach. Schedule your free Hamstring Pain Away Physio Assessment at Next Level Physio and get back to running without the pain.
