What is Unilateral vs Bilateral Training? (Balance Your Strength)

Published: Exercise Biomechanics Guide

What Is Unilateral vs Bilateral Training?

Bilateral training involves using both limbs simultaneously during an exercise, such as a barbell back squat or conventional deadlift. Unilateral training involves working one limb at a time, such as single-leg squats, lunges, or single-arm rows. The distinction between these approaches has significant implications for strength development, muscle balance, injury prevention, and athletic performance.

While bilateral exercises allow you to move the most total weight and build maximum strength, unilateral exercises address side-to-side imbalances, improve stability, and develop functional strength patterns. The most effective training programs strategically incorporate both approaches to maximize results and minimize injury risk.

Understanding Bilateral Training

Bilateral exercises use both limbs working together to move a single load. These are the foundation of most strength training programs.

Examples of Bilateral Exercises

Lower Body: Back squat, front squat, conventional deadlift, sumo deadlift, leg press, Romanian deadlift, hip thrust, leg extension, leg curl

Upper Body Push: Barbell bench press, overhead press, dips (both arms), push-ups

Upper Body Pull: Barbell rows, pull-ups (both arms), lat pulldowns, cable rows

Advantages of Bilateral Training

  • Maximum load capacity: You can lift significantly more weight bilaterally than the sum of what each limb can do individually
  • Time efficiency: Train both sides simultaneously, reducing workout duration
  • Neuromuscular demand: Heavy bilateral lifts create strong adaptive stimulus for strength and power
  • Hormonal response: Large muscle mass exercises produce greater testosterone and growth hormone release
  • Sport-specific for some activities: Many sports require bilateral movement (jumping, tackling, rowing)

Limitations of Bilateral Training

  • Bilateral deficit: Your two limbs together don't produce force equal to the sum of their individual capacities
  • Strength imbalances: Dominant side can compensate for weaker side, masking and perpetuating asymmetries
  • Stability demands: Less challenge to single-leg balance and lateral stability
  • Injury risk from imbalances: Compensation patterns can lead to technique breakdown and injury

Understanding Unilateral Training

Unilateral exercises train one limb at a time, forcing each side to work independently without assistance from the other.

Examples of Unilateral Exercises

Lower Body: Bulgarian split squat, single-leg RDL, walking lunges, reverse lunges, single-leg press, step-ups, single-leg deadlift, pistol squat

Upper Body Push: Single-arm dumbbell press, single-arm overhead press, single-arm push-up variations

Upper Body Pull: Single-arm dumbbell row, single-arm cable row, single-arm lat pulldown, single-arm pull-up (assisted)

Advantages of Unilateral Training

  • Identifies and corrects imbalances: Exposes strength differences between sides and forces the weaker side to work without help
  • Improved balance and stability: Challenges proprioception and single-leg/arm stability
  • Greater core activation: Anti-rotation and anti-lateral flexion demands significantly increase core engagement
  • Sport-specific transfer: Most sports involve unilateral movements (running, cutting, throwing, kicking)
  • Injury prevention: Reduces compensation patterns and asymmetries that lead to injury
  • Lower spinal loading: Less total weight on spine while still challenging legs significantly
  • Work around injuries: Train healthy limb while injured limb recovers (helps maintain strength via cross-education effect)

Limitations of Unilateral Training

  • Lower absolute loads: Can't use as much total weight as bilateral exercises
  • Time consuming: Working each side separately doubles exercise duration
  • Less efficient for pure strength: Bilateral exercises superior for developing maximum force production
  • Learning curve: Balance component makes exercises more technically demanding initially

The Bilateral Deficit Phenomenon

An interesting phenomenon in strength science is the bilateral deficit: when both limbs work together, they produce less combined force than the sum of what each limb can produce individually.

Example of Bilateral Deficit

Single-leg press: Right leg = 150 lbs, Left leg = 150 lbs

Sum of individual legs: 150 + 150 = 300 lbs

Actual bilateral leg press: 250 lbs (not 300 lbs)

Bilateral deficit: 50 lbs (16.7%)

Why this matters: This demonstrates that unilateral training can actually produce greater total muscle activation and training stimulus than bilateral work, despite using less absolute weight. It also suggests that including both bilateral and unilateral work may optimize overall strength development.

The Science: Unilateral vs Bilateral for Muscle Growth

Research comparing unilateral and bilateral training for hypertrophy shows interesting findings:

Key Research Findings

Muscle growth: Both bilateral and unilateral training produce similar hypertrophy when volume and intensity are matched

Core activation: Unilateral exercises produce 20-40% greater oblique and transverse abdominis activation

Strength transfer: Bilateral training transfers poorly to unilateral movements, but unilateral training transfers reasonably well to bilateral

Balance improvement: Only unilateral training significantly improves single-leg balance and stability

Cross-education effect: Training one limb produces small strength gains (10-15%) in the untrained opposite limb

Bottom line: For pure muscle growth, both approaches work when programmed correctly. However, unilateral training provides additional benefits for balance, stability, and injury prevention that bilateral training alone cannot deliver.

How to Balance Bilateral and Unilateral Training

The optimal approach incorporates both training styles strategically based on your goals, training level, and sport demands:

For Powerlifting (Bilateral Priority)

Bilateral: 80-85% of total lower body volume

Unilateral: 15-20% as accessory work

Reasoning: Competition requires bilateral lifts; specificity demands prioritizing them

Example: Squat/deadlift variations as main work, Bulgarian split squats and single-leg RDLs as accessories

For Bodybuilding/Hypertrophy (Balanced)

Bilateral: 60-70% of total volume

Unilateral: 30-40% of total volume

Reasoning: Bilateral for maximum load and efficiency, unilateral for balance and complete development

Example: Squat + leg press (bilateral), then walking lunges + single-leg RDLs (unilateral)

For Athletes (Unilateral Priority)

Bilateral: 40-50% of total volume

Unilateral: 50-60% of total volume

Reasoning: Most sports involve unilateral force production (running, cutting, throwing, kicking)

Example: Trap bar deadlift + bench press (bilateral), then single-leg RDLs, split squats, single-arm rows (unilateral emphasis)

For General Fitness (Balanced with Unilateral Lean)

Bilateral: 50-60% of total volume

Unilateral: 40-50% of total volume

Reasoning: Balance strength development with functional movement and injury prevention

Example: Squat or deadlift variation plus one bilateral accessory, then lunges and single-leg work

Sample Workout Integration

Hypertrophy-Focused Leg Day

1. Back Squat (Bilateral): 4 sets × 6-8 reps

2. Romanian Deadlift (Bilateral): 3 sets × 8-10 reps

3. Bulgarian Split Squat (Unilateral): 3 sets × 10 reps/leg

4. Single-Leg RDL (Unilateral): 3 sets × 10 reps/leg

5. Leg Curl (Bilateral): 3 sets × 12-15 reps

Bilateral: ~60% | Unilateral: ~40%

Athletic Performance Leg Day

1. Trap Bar Deadlift (Bilateral): 4 sets × 5 reps

2. Single-Leg Squat to Box (Unilateral): 3 sets × 8 reps/leg

3. Walking Lunges (Unilateral): 3 sets × 12 reps/leg

4. Single-Leg RDL (Unilateral): 3 sets × 8 reps/leg

5. Lateral Lunge (Unilateral): 2 sets × 10 reps/leg

Bilateral: ~35% | Unilateral: ~65%

Upper Body Push Example

1. Barbell Bench Press (Bilateral): 4 sets × 6-8 reps

2. Single-Arm Dumbbell Press (Unilateral): 3 sets × 10 reps/arm

3. Overhead Press (Bilateral): 3 sets × 8 reps

4. Single-Arm Cable Flye (Unilateral): 3 sets × 12 reps/arm

Bilateral: ~55% | Unilateral: ~45%

Addressing Strength Imbalances

One of unilateral training's most valuable applications is identifying and correcting left-right strength discrepancies:

How to Identify Imbalances

  • Perform the same unilateral exercise on both sides (e.g., single-arm dumbbell rows)
  • Record the weight and reps achieved on each side
  • Calculate the difference: Imbalance % = [(Stronger - Weaker) / Stronger] × 100
  • Differences under 10% are normal; over 15% warrant targeted correction

How to Correct Imbalances

The "Weaker Side First" Method

1. Always perform your weaker side first when fresh

2. Do NOT exceed what your weaker side can do on your stronger side

3. Example: If left arm can do 10 reps with 40 lbs, only do 10 reps with right arm (even if you could do 12)

4. Over 4-8 weeks, the weaker side will catch up as it's no longer limited by being trained to match the stronger side

The "Extra Set" Method

1. Perform equal sets on both sides (e.g., 3 sets each)

2. Add 1-2 additional sets ONLY for the weaker side

3. Continue until the imbalance is reduced to under 10%

Common Mistakes With Unilateral Training

1. Completely Abandoning Bilateral Work

Problem: Only doing unilateral exercises limits absolute strength development and time efficiency.

Fix: Use bilateral exercises as your foundation, unilateral as valuable supplementation.

2. Letting Stronger Side Dictate Weaker Side Load

Problem: Using the weight your strong side can handle on both sides, causing the weaker side to cheat or fail.

Fix: Choose weight based on your weaker side's capacity, train both sides to that standard.

3. Poor Balance as an Excuse

Problem: Avoiding unilateral work because balance is challenging.

Fix: Start with easier variations (holding onto support, box for single-leg squats) and progress gradually. Poor balance is exactly why you need unilateral training.

4. Ignoring the Time Investment

Problem: Trying to do equal unilateral and bilateral volume without extending workout time.

Fix: Account for the fact that unilateral exercises take approximately twice as long. Adjust total exercise selection accordingly.

Warning: Don't Neglect Single-Leg Training

Many lifters avoid single-leg work because it's humbling—you can't use impressive weights, balance is challenging, and weaknesses are exposed. But this discomfort is precisely why it's valuable. Running, cutting, jumping, and most athletic movements happen on one leg. If you never train unilaterally, you're leaving massive performance gains and injury prevention on the table. Include at least 25-30% unilateral work in your program.

How FitnessRec Helps You Balance Training Styles

Effectively integrating bilateral and unilateral training requires proper exercise selection, imbalance tracking, and volume management. FitnessRec provides comprehensive tools to optimize your approach:

Exercise Library with Bilateral/Unilateral Classification

Find and organize exercises by training type:

  • Filter by type: Browse bilateral vs. unilateral exercises separately
  • Video demonstrations: Learn proper form for challenging unilateral movements
  • Progressive variations: Find easier and harder versions of single-leg/arm exercises
  • Exercise alternatives: Discover bilateral and unilateral options for the same muscle groups

Side-by-Side Performance Tracking

Monitor left vs. right strength and identify imbalances:

  • Per-limb logging: Record weight and reps separately for each side
  • Imbalance calculation: See percentage difference between sides automatically
  • Progress comparison: Track whether weaker side is catching up over time
  • Historical trends: View long-term balance improvements

Volume Distribution Analysis

Ensure proper bilateral/unilateral balance in your programming:

  • Training type breakdown: See what percentage of volume is bilateral vs. unilateral
  • Weekly patterns: Monitor if you're including enough unilateral work
  • Goal-aligned ratios: Verify your split matches your training objective
  • Exercise variety: Track diversity within bilateral and unilateral categories

Custom Workout Programs

Build balanced programs with strategic bilateral/unilateral integration:

  • Design workouts with appropriate bilateral foundation plus unilateral accessories
  • Create imbalance-correction programs emphasizing weaker side
  • Save templates with your optimal bilateral/unilateral ratio
  • Access pre-built programs with proven bilateral/unilateral balance

Personal Training Support

Work with trainers who understand bilateral and unilateral programming:

  • Imbalance assessment: Get professional evaluation of left-right discrepancies
  • Corrective programming: Receive customized plans to address asymmetries
  • Form coaching: Learn proper technique for challenging unilateral exercises
  • Goal-specific ratios: Get recommendations for bilateral/unilateral split based on your objectives

Pro Tip: The Quarterly Imbalance Check

Every 12 weeks, use FitnessRec to run a formal imbalance assessment. Test single-leg squat, single-arm row, and single-leg RDL on both sides. Record the maximum weight and reps for each. Calculate the percentage difference between sides. If any imbalance exceeds 15%, dedicate the next 4-6 weeks to corrective training using the "weaker side first" method. Track this in FitnessRec and retest to verify improvement.

Putting It All Together

Both bilateral and unilateral training have distinct advantages and limitations. The most effective approach strategically combines both to maximize strength, balance, and injury resilience. With FitnessRec, you can:

  • Track performance on both bilateral and unilateral exercises
  • Identify and monitor left-right strength imbalances
  • Ensure your program includes appropriate bilateral/unilateral balance
  • Progress systematically on challenging single-leg and single-arm movements
  • Access expert guidance on correcting asymmetries and optimizing training balance

Remember: Bilateral exercises build maximum strength efficiently, while unilateral exercises address imbalances, improve stability, and develop functional athleticism. Don't neglect either approach. Use bilateral movements as your foundation and unilateral work as essential supplementation. FitnessRec provides the tools to implement, track, and optimize this balanced approach for long-term success and injury-free training.