Unilateral vs. Bilateral Training: What It Is and When You Need Each

 

You’ve probably done exercises where you use one arm or one leg at a time. Exercises like step-ups, lunges, or single-arm rows. Then there are exercises where both sides work together, like squats or deadlifts. These are examples of unilateral vs bilateral training, and both have an important role in helping you move better, get stronger, and stay pain-free. At Pure Function Fitness, we use both approaches strategically to create well-rounded programs that support real-world strength, joint health, and long-term progress.

Why This Matters

If you’ve ever asked, “Why am I doing split squats instead of barbell back squats today?”, you’re not alone. Understanding the difference between unilateral vs bilateral training is key to building a body that not only looks strong, but also moves well, stays pain-free, and performs in the real world.

What’s the Difference?

Unilateral training means using one side of your body at a time.
Think: split squats, one-arm rows, single-leg RDLs. It’s about training each limb independently, which gives your body a chance to self-organize and expose what’s really going on under the surface.

Bilateral training means using both limbs together.
Think: squats, deadlifts, bench press. These are your classic “big lifts” where you move more weight and train your body as a unit.

Both types of training have benefits. But how and when you use them? That’s where the strategy comes in.

Benefits of Unilateral Training

This is where we usually start with new clients or anyone recovering from injury, dealing with pain, or trying to move better overall.

1. Corrects Strength Imbalances

Most people have one side that’s stronger or more coordinated. Unilateral training makes that obvious and gives you a chance to work on it.

2. Builds Core and Balance Without Crunches

When you’re standing on one leg or using one arm, your body has to stabilize. That’s real-world core work not just ab exercises. It teaches your system how to balance itself dynamically, which is huge for joint stability.

3. Improves Joint Mobility

With lighter loads and more control, unilateral exercises give joints like your hips, knees, and shoulders the space to move.

4. Encourages True Motion

This is a big one in our philosophy. Exercises like single-leg RDLs or one-arm presses help restore relative motion. That is, how your femur moves inside your pelvis or how your scapula glides over your rib cage. This matters whether you’re an athlete or just trying to get out of shoulder pain.

5. Less Load, More Stimulus

You don’t need a heavy barbell to get stronger. In fact, personal training for movement health often starts with lighter loads done well. Unilateral training lets you progress without overloading joints too early.

Benefits of Bilateral Training

Once we’ve built a solid foundation, bilateral strength training becomes a powerful tool.

1. Develops Maximum Strength

Bilateral lifts let you move more weight. This translates to power, performance, and resilience. Whether you’re lifting groceries or sprinting up stairs and strength helps.

2. Efficient Muscle Building

Want to build muscle? Compound bilateral movements like squats, presses, and deadlifts recruit more muscle groups and stimulate more growth.

3. Time-Saving

You hit both sides at once. It is really that simple. For clients with busy lives, bilateral lifts can deliver a lot of training effect in less time.

The SAID Principle: Why You Need Both

If you’ve ever wondered why we don’t just stick with one type of training, here’s the answer: your body adapts to exactly what you ask of it. That’s the SAID principle which stands for Specific Adaptations to Imposed Demands.

In other words:

What you train is what you get better at.

If you train with two legs, you’ll get stronger at two-leg movements. If you train one side at a time, you’ll get better at controlling each limb independently. That’s not a flaw in training, it’s how the body works.

What the Studies Say

• A 2023 meta-analysis found that unilateral training is more effective for improving sprinting, agility, and single-leg jumping. Meanwhile, bilateral training produced better results in two-leg jumping and maximum strength lifts like squats and deadlifts
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• Another study found that combining both training styles led to better improvements in strength and power across a variety of loads compared to bilateral-only training.
• This study found, in terms of hypertrophy (muscle growth), unilateral and bilateral training produced similar muscle size gains, but strength gains were highly specific to how you trained.

So if your goal is to move better, build balanced strength, and reduce injury risk, training both styles isn’t just helpful but its is quite essential.

When Should You Use Each?

The short answer: both have a place. But the order and focus depends on you and your goals, your body, and your training history.

Start with Unilateral Training if:

• You’re new to the gym or returning after a break
• You’re coming off injury or dealing with pain
• You’ve got visible movement issues or imbalances
• You want to improve joint mobility and coordination

Progress to Bilateral Training when:

• You’ve built stability and control
• Your movement patterns are clean and pain-free
• You’re ready to build maximum strength and power

Why We Start with Unilateral Work

Here’s the thing: bilateral lifts can mask problems. You can often “muscle through” a squat or deadlift using compensations you don’t even feel. But with unilateral work? There’s nowhere to hide.

That’s why we use these movements to gather feedback. They show us where your body lacks control, where you’re compensating, and where we need to focus to restore motion and reduce pain.

This approach helps us deliver better long-term results and whether you’re training for performance, trying to move better, or managing pain.

Sample Progression We Use

Here’s an example of how we often build a client’s training progression over time:

• Phase 1: Unilateral Focus

                   Split squats, single-leg RDLs, one-arm rows

• Phase 2: Transitional Patterns

                   Goblet squats, step-ups, push-ups

• Phase 3: Bilateral Strength Work

                   Barbell squats, Romanian deadlifts, bench press

Each phase builds on the last and no wasted movements, no rushing into loads your body isn’t ready for.

Want to Move Better, Feel Stronger, and Train Smarter?

Whether you’re dealing with pain, starting from scratch, or trying to break through a plateau, a smart program makes all the difference. At Pure Function Fitness, our team of personal trainers in Woodland Hills specializes in designing personalized programs that blend unilateral vs bilateral training to improve movement quality, build real-world strength, and help you reach your goals efficiently.

• Unilateral training for mobility and stability
• Bilateral strength training for power and performance
• Corrective exercise for real-life results

👉 Ready to feel the difference? [Book your free session today.] 

At the end of the day, it’s not about choosing between unilateral or bilateral training but it’s about knowing when and how to use each one. Both have their place, and when they’re programmed with intention, they can complement each other to build a stronger, more capable, and more resilient body. Whether you’re just getting started or looking to take your training to the next level, using the right tool at the right time makes all the difference. 

References

1. 1. Kassiano, W., Nunes, J. P., Costa, B., Ribeiro, A. S., Loenneke, J. P., & Cyrino, E. S. (2025). Comparison of Muscle Growth and Dynamic Strength Adaptations Induced by Unilateral and Bilateral Resistance Training: A Systematic Review and Meta-analysis. Sports medicine (Auckland, N.Z.), 55(4), 923–936. https://doi.org/10.1007/s40279-024-02169-z
   2. Liu, Y., Liu, X., & Geng, J. (2024). Effects of unilateral, bilateral, and combined unilateral+bilateral complex resistance training on bench press and squat strength in adolescent boxers. Frontiers in physiology, 15, 1321519. https://doi.org/10.3389/fphys.2024.1321519
   3. Zhang, W., Chen, X., Xu, K., Xie, H., Li, D., Ding, S., & Sun, J. (2023). Effect of unilateral training and bilateral training on physical performance: A meta-analysis. Frontiers in physiology, 14, 1128250. https://doi.org/10.3389/fphys.2023.1128250