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Why we do single-leg exercises

There's a reason behind all the unilateral movements you see in your training program.

Katie Ekema

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Do you ever wonder why we do single-leg exercises at the gym? Think about most of the movements you do outside of the gym. Walking, running, hiking, climbing stairs, getting out of a car, playing sports, and even simply stepping from one place to another. These movements all involve shifting your weight from one leg to the other.

Because so many everyday movements happen one leg at a time, it’s important that our training prepares us for it. That’s where single-leg, or unilateral, exercises come in.

What Is a Unilateral Exercise?

A unilateral exercise is an exercise where you primarily work one side of your body at a time. Some examples include:

  • Single-leg toe touches

  • Single-leg squats

  • Lunges

  • Step-ups

  • Split squats

  • Single-leg RDL’s

These are different from bilateral exercises, where both legs work together, such as squats, deadlifts, and RDLs.

Both types of exercises are valuable, and we need both in a well-rounded training program. Bilateral exercises allow you to move heavier loads and build overall strength, while unilateral exercises help address some things that two-legged exercises simply can't do as well.

They Mimic How We Actually Move

When you walk, run, hike, or climb stairs, you're constantly transferring your weight from one leg to the other. At some point during each step, one leg is responsible for supporting and controlling your body. Single-leg exercises help train your body to handle those same demands.

We don't want to be strong only when both feet are planted firmly on the ground. We also want to be strong, stable, and coordinated when we're standing on one leg, shifting our weight, or moving through space.

They Help Identify and Address Imbalances

Most of us have a dominant side. You may naturally favor your right leg when stepping up, pushing off, or balancing, compared to your left leg.

When performing a bilateral exercise like a squat, both legs are working together. However, your stronger side may naturally contribute a little more without you even realizing it. This can make it difficult to identify differences in strength or control between your left and right sides.

Single-leg exercises take away some of that compensation because each leg has to do its own work. By training one leg at a time, we can identify differences between sides and give the weaker or less coordinated side an opportunity to catch up. Over time, this can help create more balanced strength and control between your legs.

They Challenge Your Balance and Stability

Single-leg exercises make you work harder to stay stable.

When you're standing on two feet, you have a larger base of support. When you move to one leg, that base becomes much smaller, and your body has to work harder to keep you balanced. This challenges your proprioception, which is your body's ability to sense where it is in space and how it's moving without you having to look at it.

Single-leg exercises also require your ankles, hips, glutes, and core to work together to help stabilize your body. This type of stability is important not only for athletic performance, but also for everyday life. Being able to control your body on one leg becomes especially valuable as we get older and want to maintain balance, independence, and confidence in our movement.

Stronger Stabilizing Muscles = Better Control

Your larger muscles aren't the only muscles working during an exercise. Smaller muscles around your ankles, hips, and core also help keep your body in the proper position. When you're performing a single-leg exercise, these stabilizing muscles have to respond to small shifts in  balance and help keep you upright.

Single-leg exercises generally create a greater balance challenge than bilateral exercises, which gives these muscles and your nervous system a different stimulus. 

And remember: more isn't always better. Sometimes different is better. We're not doing single-leg exercises because two-legged exercises are bad. We're doing them because they train qualities that bilateral exercises don't emphasize as much.

They Can Be Helpful During Injury Recovery

Single-leg training can also be useful when someone is returning from an injury. There is a concept called the cross-education effect, where training one limb can help maintain or improve some strength in the opposite, untrained limb. For example, if someone is temporarily unable to train one leg because of an injury, appropriately prescribed strength training on the healthy leg may help reduce some of the strength loss in the injured leg.

Research supports this phenomenon. In a 2018 study, participants who performed six weeks of unilateral strength training experienced strength improvements not only in the trained limb, but also in the opposite, untrained limb. The researchers found a 13% increase in strength in the untrained leg after training.

A larger 2018 meta-analysis that looked at 96 studies also found evidence of the cross-education effect across young, older, and patient populations. This doesn't mean that training the healthy leg can heal an injured leg, but it does show that the nervous system can create adaptations that carry over to the opposite side. That's one reason unilateral training can be a useful tool during certain stages of rehabilitation. Of course, injury recovery should always be individualized and guided by a qualified healthcare professional when appropriate.

How Bilateral and Unilateral Exercises Work Together

Our bilateral exercises are the foundation for building overall strength. Our unilateral exercises are the supplement that helps us develop:

  • Side-to-side strength

  • Balance

  • Coordination

  • Stability

  • Proprioception

  • Single-leg control

  • More symmetrical movement

So the next time your coach gives you lunges, step-ups, or single-leg RDL’s… Think about everything that exercise is challenging you to do: control your body, balance on one leg, stabilize your hips and core, coordinate your movement, and make each leg work independently. 

We're not doing single-leg exercises just to make your workout harder. We're doing them because we want you to be strong and capable not only in the gym, but outside of it, too.

Want to learn more about Rise and our training philosophy? Head here to schedule a Free Fitness Consultation with our team - we’d love to meet you!