The Power of Single-Leg Training: Correcting Bilateral Imbalances and Enhancing Athletic Performance

Think about the endurance sports you engage in most often—running is a single-leg action, one foot after the other; cycling is an alternating push between the left and right legs; even the kick in swimming is an alternating single-leg effort. Yet, most athletes’ strength training focuses primarily on bilateral movements. This contradiction not only limits the transfer of strength but also masks bilateral imbalances that could lead to injury.

Bilateral Imbalance: The Hidden Performance Killer

Research shows that over 70% of endurance athletes have at least a 10% strength difference between their left and right legs. This discrepancy is not easily detected during bilateral squats or leg presses because the stronger leg automatically compensates for the weaker one. However, in actual sport, this imbalance has clear negative effects:

For cyclists: Power meter data frequently shows uneven power distribution between the left and right legs (e.g., 55/45 or even 60/40). The weaker leg not only contributes less force but also fatigues more quickly over long distances, forcing the other leg to overwork.

For runners: The weaker leg typically has a longer ground contact time and a shorter stride length. The body maintains stability through subtle compensatory strategies, but over time, these compensations accumulate and lead to overuse injuries in specific areas.

For triathletes: The imbalance compounds across all three disciplines. An uneven kick in the swim, a power deficit on the bike, and finally, it erupts in the run, amplified by fatigue.

How to Assess Your Bilateral Imbalance

Before starting training, understand your current status. Here are two simple assessment methods:

Assessment 1: Single-Leg Squat Test

Perform single-leg chair squats on each leg separately (squatting down to a chair height where the knee reaches 90 degrees), and record the maximum number of repetitions you can complete on each side. If the difference between sides exceeds 2 repetitions, it indicates an imbalance worth addressing.

Assessment 2: Single-Leg Glute Bridge Hold

Lie on your back and perform a glute bridge on one leg. Hold at the top while keeping your pelvis level, and record how long you can maintain the position on each side. A difference exceeding 10 seconds represents a significant imbalance in gluteal strength.

Eight Key Single-Leg Exercises

Beginner Exercises

1. Rear Foot Elevated Split Squat

Also known as the Bulgarian split squat. Place your rear foot on a bench 30 to 40 cm high, and step your front foot forward into a long stride. Keep your torso upright, bend your front knee and lower down until your rear knee nearly touches the ground.

• 3 sets x 8 to 12 reps per side
• Start with bodyweight, progress to holding dumbbells
• Focus: Your front knee tracks in line with your toes, avoiding inward collapse

2. Single-Leg Glute Bridge

Lie on your back with one leg bent and foot on the floor, the other leg extended or bent and lifted. Drive your pelvis upward using the gluteal strength of the planted leg, and hold at the top for 2 seconds, feeling a strong contraction in the gluteus maximus.

• 3 sets x 12 to 15 reps per side
• Progression: Place your shoulders on a bench and perform a single-leg hip thrust
• Key point: Keep your pelvis completely level, do not tilt to one side

3. Forward Lunge

From a standing position, take a large step forward. After your front foot lands, bend both knees to lower down, then push back up to return to the starting position.

• 3 sets x 10 reps per side
• Variations: Walking lunges, reverse lunges, lateral lunges
• Note: Stride length changes the training emphasis—a longer stride emphasizes the glutes and hamstrings more, while a shorter stride emphasizes the quadriceps more

Intermediate Exercises

4. Single-Leg Romanian Deadlift (Single-Leg RDL)

Stand on one leg, holding a dumbbell or kettlebell in the opposite hand. Keep a slight bend in the standing leg’s knee, hinge your torso forward while extending the rear leg backward, until your torso is nearly parallel to the ground. Return to an upright position using the strength of the glutes and hamstrings of the standing leg.

• 3 sets x 8 to 10 reps per side
• This is one of the most demanding exercises for balance and proprioception
• Tip: Kick the extended leg back forcefully, as if trying to kick open a door behind you—this helps activate the gluteus maximus

5. Lateral Step-Up

Stand sideways to a training bench (30 to 45 cm high) and place the foot closest to the bench on top. Use the strength of this leg to drive your body up onto the bench, without pushing off the ground with the other foot.

• 3 sets x 8 reps per side
• Key point: Use the strength of the top leg entirely; the bottom leg only touches the ground lightly
• Why it’s particularly good: Lateral step-ups elicit one of the highest levels of gluteus medius activation among most exercises

6. Single-Leg Calf Raise

Stand at the edge of a step and perform full-range single-leg calf raises. Lower your heel below the level of the step, then rise up onto your toes to the highest point.

• 3 sets x 15 to 20 reps per side
• Perform both a straight-knee version (gastrocnemius) and a slightly bent-knee version (soleus)
• Progression: Hold a dumbbell or wear a weighted vest

Advanced Exercises

7. Pistol Squat

This is the ultimate form of the single-leg squat. Stand on one leg with the other leg extended straight forward, squat down to the lowest point on one leg, then stand back up.

• 2 to 3 sets x 3 to 5 reps per side
• Assisted progression: Start by standing up from a seated position on a box, gradually lower the box height, and finally transition to unassisted
• Note: The pistol squat demands high ankle mobility. If mobility is insufficient, place your heel on a slant board

8. Single-Leg Box Jump

Standing on one leg, jump onto a box 20 to 30 cm high. Land with both feet on the box, then step down (do not jump down).

• 3 sets x 4 to 5 reps per side
• This is a key exercise for converting single-leg strength into explosive power
• Safety reminder: Ensure the box is stable and will not slide, start with a low box and gradually increase the height

Training Programming Strategies

The Golden Rule: Weak Side First

Always train your weaker leg first, and use the number of repetitions the weaker leg can complete as the training standard for both sides. This means your stronger leg may feel “underfed” during training, but this is exactly how you close the gap. Once the difference between sides narrows to within 5%, you can train each side at maximum capacity.

Weekly Programming Examples

Option A: Dedicated Single-Leg Training Day

Exercise	Sets x Reps
Bulgarian Split Squat	3x10 per side
Single-Leg RDL	3x8 per side
Lateral Step-Up	3x8 per side
Single-Leg Glute Bridge	3x12 per side
Single-Leg Calf Raise	3x15 per side

Option B: Integrated into Bilateral Training Day

Exercise	Sets x Reps
Back Squat	3x5
Bulgarian Split Squat	3x8 per side
Conventional Deadlift	3x5
Single-Leg RDL	3x8 per side
Plank	3x30 seconds

Option B is particularly suitable for athletes with limited time. After each bilateral main movement, follow it with a corresponding single-leg exercise to ensure bilateral balance receives attention.

Additional Benefits of Single-Leg Training

Beyond correcting bilateral imbalances, single-leg training offers the following unique benefits:

1. Higher core demands: When standing on one leg, the core must work harder to maintain pelvic stability. Research shows that core muscle activation during single-leg squats is 30% to 50% higher than during bilateral squats.

2. Lower spinal loading: Because lighter loads are used (typically 50% to 60% of bilateral movements), the compressive forces on the spine are significantly reduced. This is particularly friendly for athletes with lower back issues.

3. Better sport-specific transfer: The movement patterns of single-leg training more closely resemble actual athletic movements. A study on cyclists found that the single-leg training group showed greater power improvements in a 20-minute time trial than the bilateral training group.

4. Proprioception and balance: Single-leg standing training greatly improves proprioception at the ankle and knee joints. This is highly beneficial when running on uneven terrain or cornering on a bike.

Frequently Asked Questions

Q: Will single-leg training replace bilateral training?

A: No. Bilateral exercises (such as squats and deadlifts) remain more efficient for building maximal strength. The best strategy is to include both bilateral and single-leg movements in your training.

Q: Should the rear leg exert force during the Bulgarian split squat?

A: Ideally, the rear leg should rest lightly on the bench for balance support only, with all the workload performed by the front leg. If you find your rear leg pushing hard, it may indicate insufficient strength in the front leg—try reducing the weight.

Q: What should I do if I can’t stay balanced during single-leg RDLs?

A: In the early stages, you can lightly hold a wall or a support with one hand. Gradually reduce the support as your balance improves. Another tip is to train barefoot, allowing the soles of your feet to better “grip” the ground.

Conclusion

Single-leg training is not a supporting act in strength training—it is a core strategy for endurance athletes to enhance performance and prevent injuries. Your sport is inherently a series of alternating single-leg movements, and your training should reflect that fact. Starting today, add at least one single-leg exercise to every strength session, and after three months, use power meter or pace data to evaluate the results. You won’t be disappointed.

Related Reading

• Single-Leg and Asymmetric Load Training: Correcting Left-Right Imbalances and Functional Transfer in Endurance Athletes
• The Complete Guide to Unilateral Training: Where Left-Right Asymmetry Comes From, How to Assess It, and How to Train It
• Balance Training for Runners: Progressing from Single-Leg Stance to Dynamic Balance
• Strength Training for Triathletes — Core, Single-Leg, and Posterior Chain Training Prescriptions