Bilateral vs. Unilateral Strength for Athletes: Why Both Matter

 Coaches and trainers have long debated the best approaches to strength training, especially when it comes to bilateral versus unilateral exercises. Is it better for athletes to focus on lifting heavy with two legs or two arms at a time? Or should they prioritize unilateral work, which trains one limb at a time, for better balance and coordination?

The truth is, athletes need both bilateral and unilateral strength training to reach their full potential. Each method offers unique benefits that are essential for developing well-rounded strength, power, stability, and injury resilience.

In this article, we’ll break down the strengths of each approach, when and how to incorporate them, and why a variety of training stimuli is necessary to keep athletes performing at their best throughout the year.

Understanding Bilateral Strength Training

Bilateral strength training involves exercises where both limbs (either both legs or both arms) work together to produce force. Common bilateral movements include squats, deadlifts, bench presses, and overhead presses. These exercises are fundamental for building raw strength and are a staple in most strength and conditioning programs for good reason.

Benefits of Bilateral Training:

1. Maximal Load Capacity: Bilateral movements allow athletes to lift heavier weights because both limbs share the load. This helps develop maximum strength, which is critical for sports that demand explosive power, like football, basketball, or track and field.

2. Full Body Activation: Exercises like the squat and deadlift activate large muscle groups and stimulate the central nervous system. This not only builds muscle mass but also improves neuromuscular efficiency, enhancing overall athletic performance.

3. Foundational Movements: Bilateral movements mimic many natural, sport-specific actions like jumping, sprinting, and pushing or pulling. They build a base of strength that athletes can carry into more dynamic, sport-specific training.

Unilateral Strength Training: Why It's Equally Important

Unilateral strength training refers to exercises where one limb does the majority of the work. Examples include single-leg squats (pistols), lunges, step-ups, and single-arm presses or rows. While these movements don’t allow athletes to lift as heavy as their bilateral counterparts, they offer benefits that are crucial for athletic development and injury prevention.

Benefits of Unilateral Training:

1. Improves Balance and Coordination: Many sports, including soccer, tennis, and martial arts, require athletes to be stable and coordinated on one leg or arm. Unilateral exercises enhance proprioception, balance, and overall coordination, leading to better control of movement during competition.

2. Identifies and Corrects Imbalances: Everyone has strength imbalances between their limbs. Unilateral exercises expose and help correct these imbalances, reducing the risk of overuse injuries. Addressing weak points is key for keeping athletes healthy and performing at their best over the long term.

3. Builds Core Strength and Stability: Unilateral exercises inherently challenge the core to stabilize the body as one limb works. This leads to improved trunk stability, which is vital for transferring power through the body during dynamic movements like sprinting, cutting, or throwing.

Why Athletes Need Both: The Principle of Variety

Incorporating both bilateral and unilateral movements into an athlete’s training program is essential for a balanced approach to strength development. Variety is one of the core principles of effective training because it provides different stimuli that challenge the body in unique ways.

When we only train bilaterally or unilaterally, we limit the range of adaptations the body can make. Athletes who stick strictly to heavy bilateral movements might develop great strength but lack balance and coordination. On the other hand, athletes who focus solely on unilateral work might improve stability but never reach their full potential in terms of raw strength or power.

Strength Principles in Action:

1. Specific Adaptation to Imposed Demands (SAID Principle): The body adapts specifically to the types of stresses we place on it. To maximize athletic potential, we must expose athletes to both bilateral and unilateral stressors, ensuring they’re strong, stable, and coordinated in all movement patterns.

2. Progressive Overload: To build strength, athletes must progressively lift heavier loads. Bilateral movements allow for heavier weight, which is necessary to increase overall muscle mass and strength. Once that foundation is built, unilateral movements can refine balance and stability.

3. Periodization: Throughout the year, athletes should cycle between phases of training that emphasize different aspects of strength. A well-rounded program will include periods of bilateral strength work, followed by phases that focus more on unilateral stability and coordination to keep athletes progressing while avoiding burnout or injury.

Bilateral and Unilateral Exercises: When to Use Each

Understanding when to use bilateral versus unilateral exercises in a training program is key for coaches and trainers. Here’s a breakdown of how to implement each method throughout the training year:

1. Off-Season (General Strength and Hypertrophy):

   • Prioritize bilateral exercises to build a solid foundation of strength and muscle mass.
   • Use squats, deadlifts, and bench presses for maximal strength and hypertrophy gains.
   • Supplement with unilateral work to address any imbalances and improve stability in preparation for more dynamic movements.

2. Pre-Season (Power and Stability):

   • Shift towards more unilateral work, focusing on stability, coordination, and single-limb strength.
   • Include movements like lunges, step-ups, and single-leg squats to simulate sport-specific actions.
   • Continue using bilateral lifts but reduce the volume to prevent fatigue and ensure peak power development.

3. In-Season (Maintenance and Injury Prevention):

   • Use a mix of bilateral and unilateral movements to maintain strength while reducing the risk of injury.
   • Emphasize unilateral exercises to keep balance, coordination, and joint stability at peak levels.

4. Post-Season (Recovery and Rebuild):

   • Focus on unilateral exercises to address any lingering imbalances or weaknesses developed during competition.
   • Gradually reintroduce bilateral exercises as athletes recover and prepare for the next training cycle.

Influences from Various Training Styles

Many successful strength training programs for athletes borrow from a variety of disciplines. Coaches who blend different influences create more comprehensive training programs that yield better results.

• Powerlifting: Focuses heavily on bilateral strength (squats, deadlifts, bench press) for maximum strength development.
• Olympic Weightlifting: Incorporates bilateral power movements like cleans and snatches, which are key for explosive strength.
• Functional Training: Prioritizes unilateral exercises, core strength, and dynamic stability to mimic real-life or sport-specific movement patterns.
• Bodybuilding: Often includes unilateral work to isolate muscles and create symmetry, but bilateral lifts are the foundation for hypertrophy.

By incorporating the strengths of each style, athletes can maximize their potential. Bilateral lifts build the power needed for explosive sports performance, while unilateral exercises develop the stability and coordination required for complex, multi-directional movements.

Conclusion: Finding the Right Balance

Athletes and coaches don’t need to choose sides in the bilateral versus unilateral debate. Instead, they should understand how and when to incorporate each method into their training for optimal results. By embracing both approaches, athletes can build the strength, power, stability, and coordination necessary to reach their full athletic potential.

A varied training program that uses both bilateral and unilateral exercises ensures that athletes are prepared for whatever challenges their sport—and life—throws at them.

References:

1. Behm, D.G., et al. "The Effect of Unilateral and Bilateral Resistance Training on Strength, Imbalances, and Muscle Activation." Sports Medicine (2020).
2. McGill, S. "Core Stability and Athletic Performance: Evidence-Based Training Guidelines." Journal of Strength and Conditioning Research (2018).