Overview

The leg extension is a machine-based isolation exercise that targets the quadriceps by extending the knees against resistance. Performed seated with the padded bar across the lower shins, it provides focused quad activation, making it ideal for hypertrophy, strength imbalances, and finishing leg workouts.

Target Muscle Groups

• Primary: Quadriceps (rectus femoris, vastus lateralis, vastus medialis, vastus intermedius)

• Secondary: Hip flexors (during full extension)

How to Perform Leg Extension

Setup

1. Sit on leg extension machine with back flat against pad.

2. Adjust seat so knees align with machine pivot point (90° angle).

3. Position padded bar just above ankles, feet pointing forward.

4. Grip side handles for stability.

Execution Steps

1. Brace core, inhale, and extend legs upward until fully straight.

2. Squeeze quads hard at top for 1-2 seconds (avoid locking knees).

3. Exhale while slowly lowering pad in 2-3 second controlled eccentric.

4. Lower until knees reach 90° (never hyperextend).

5. Repeat without momentum.

Tips for Proper Form

• Keep back flat against pad throughout.

• Use full range but avoid locking knees at top.

• Control eccentric phase for maximum growth.

• Higher reps (12-20) optimize quad pump.

• Single-leg variation addresses imbalances.

Common Mistakes to Avoid

• Using momentum or swinging legs.

• Lowering past 90° knee angle (shear stress).

• Arching lower back off pad.

• Incomplete extension at top.

• Gripping handles too tightly (shifts tension).

Benefits

• Pure quad isolation without spinal loading.

• Targets all four quad heads effectively.

• Corrects leg strength imbalances.

• Joint-friendly for pre/post compound lifts.

• Excellent finisher for leg hypertrophy.