Single-Leg Seated Leg Curl
The Single-Leg Seated Leg Curl is a machine-based unilateral hamstring isolation exercise that develops individual leg strength and addresses strength imbalances between legs. This movement is ideal for intermediate to advanced exercisers, athletes, and those seeking targeted hamstring development and injury prevention. The seated variation provides stability and safety while allowing substantial hamstring isolation and strength development.
NASM’s evidence-based approach recognizes unilateral training as essential for identifying asymmetries and building balanced muscular development. The single-leg seated leg curl improves hamstring strength, corrects strength imbalances, develops muscular endurance, and supports injury prevention for the knee and hamstring complex.
How to Perform a Single-Leg Seated Leg Curl
Step 1: Setup
Sit on the leg curl machine with your back firmly against the backrest and your seat adjusted so the pad sits just above your ankle. Position your feet on the platform with one foot while removing the other.
Step 2: Brace/Position
Position one leg under the pad with your knee bent at approximately 90 degrees. Engage your core and position your hands on the machine for stability and support.
Step 3: Execute/Drive
Curl the pad downward by flexing your hamstring, bringing your heel toward your glute while maintaining knee position. Focus on controlled movement and hamstring contraction throughout the exercise.
Step 4: Return/Descent
Extend your leg to return to the starting position with control, maintaining tension in the hamstring. Complete all repetitions on one leg before switching to the other leg.
Muscles Worked
Primary Muscles:
- Hamstring Group (Biceps Femoris, Semitendinosus, Semimembranosus) -- primary mover for knee flexion and hamstring curling motion
Secondary Muscles:
- Gastrocnemius
- Calf Muscles
Common Mistakes
- Using excessive weight that causes jerky movements or compensatory hip movement
- Not achieving full range of motion, which limits hamstring activation and strength development
- Allowing the knee to shift or rotate during the movement
- Moving too quickly without controlling both concentric and eccentric phases
- Failing to address bilateral asymmetries before progressing to heavier loads
Single-Leg Seated Leg Curl Variations
As part of NASM's evidence-based approach to movement and strength training, the single-leg seated leg curl reinforces proper movement mechanics essential to long-term performance and injury prevention. NASM-certified personal trainers use the Optimum Performance Training (OPT) model to integrate exercises like the single-leg seated leg curl into individualized programs based on each client's assessment results.
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FAQs
What weight should be used for single-leg leg curls relative to bilateral curls?
Single-leg loads should be approximately 40-60% of your bilateral leg curl weight. This ensures adequate challenge while maintaining proper form and preventing compensatory movement patterns.
How does seated leg curling compare to lying leg curl variations?
Seated leg curls provide more stability and back support, while lying variations allow greater range of motion and hip involvement. Both variations effectively target the hamstrings and should be incorporated based on training goals and available equipment.
How many repetitions and sets are appropriate for hamstring isolation work?
Perform 3 sets of 8-12 repetitions for hypertrophy and strength development, or 3 sets of 12-15 repetitions for muscular endurance. Adjust volume based on training phase and recovery capacity to maximize gains without overtraining.