Stability Components of the 

Single-leg Romanian Deadlift

Single-leg strength training is beneficial for developing foot, ankle, hip, and spinal stability as well as core and unilateral strength. There are a lot of small muscles involved in keeping our bodies balanced while moving on one limb that are not as active when exercising on two feet. Single-leg training can also help identify and improve muscular imbalances on either side of the body.

The single-leg Romanian Deadlift (RDL) is my favorite single-leg exercise. I use it in my own personal weight training program and often prescribe it to my patients for a variety of reasons.

First and foremost: the RDL is a posterior chain strength exercise. The exercise targets the glutes, hamstrings, and back muscles. Performing the RDL on one leg instead of two still provides all the benefits of posterior chain strengthening while adding a multitude of stability components. When performed correctly, the single-leg RDL helps strengthen muscles of the foot, ankle, hip, core, and shoulder blade. 

Let’s break it down from the bottom up:

1. FOOT STABILITY

Activation of the muscles in the bottom of your foot is necessary to create a stable base to support for the rest of your body. Driving the big toe into the floor helps to lift the medial arch of your foot, creating a solid foundation. Without intrinsic foot activation, we see a collapse of the medial arch, contributing to ankle pronation. The demand of these muscles is significantly greater when standing on one foot compared to two feet. You may find that after a few repetitions the bottom of your foot is burning. Do not worry, these small muscles are just really tired from supporting all of your body weight without help from your other foot!

2. ANKLE STABILITY

A supple or dynamic ankle is necessary to maneuver through uneven terrain; however, a weak and unstable ankle increases your risk of injury in such situations. We must have a combination of mobility and stability for optimal function. When performing the single-leg RDL, an unstable ankle will roll in and out. This is called ankle pronation and supination. Ankle pronation, or inward rolling of the ankle, is often associated with collapse of the medial arch of the foot. Ankle pronation can affect joints further up the kinetic chain and can contribute to movement dysfunction at the knee, hip, and lower back. The ankle should remain in a neutral position while performing the single-leg RDL.

3. KNEE STABILITY

All joints are affected by function of the joints directly above and below them. Therefore, the knee is affected by what is occurring at the ankle and the hip. Ankle pronation and medial arch collapse can cause knee valgus, which is when the knee moves inside the foot towards midline. A strong foot and ankle will aid in keeping the knee in a neutral position. Refer to section 4. HIP STABILITY for how the knee is affected by hip dysfunction. 

4. HIP/PELVIC STABILITY

There are muscles in the back of the hip and side of the hip that contribute to knee stability. Weak hip muscles can lead to dynamic collapse in all of the joints below the hip, including knee valgus, ankle pronation, and medial arch collapse. 

Conditions associated with chronic and repetitive knee valgus during activity include:

• Patellofemoral pain (PFP) syndrome
• Iliotibial band (ITB) syndrome
• Medial collateral ligament (MCL) sprain
• Lateral meniscus tear
• Anterior cruciate ligament (ACL) sprain

Hip strength and stability are also required to keep a neutral pelvis throughout the hinge pattern. The two boney points in the front of your hip should point forward like headlights throughout the movement. A common mistake is for the hips to flare out or externally rotate. In this case, the headlight of the standing leg would be pointed toward the floor and the other would be pointing off to the side. 

5. SPINAL STABILITY

Ideally, the RDL is performed with a neutral spine. All of the muscles that surround the spine contract to prevent the lower back from rounding (flexing) or over arching (extending). Maintaining the natural curvature of the spine spine helps strengthen the lower back and core muscles and allows for greater force output from the glutes and hamstrings.

6. SCAPULAR STABILITY

The muscles that attach to your shoulder blade, or scapula, are responsible for holding and supporting the weight/resistance. Weak scapular muscles will allow the weight to pull your arm and shoulder away from the body and towards the floor. Scapular weakness is a common source of shoulder pain. 

The single-leg RDL is a complex exercise that should be prescribed with caution. There is a variety of ways to regress this exercise in order for beginners to master all key components. Stay tuned for a future blog post highlighting single-leg RDL progressions and teaching tools.

Questions? Comment below!

Written by Hannah Sweitzer, DPT, OCS, CSCS