What should I feel during Leg extension (3s eccentric)?

Quad fires to full extension at the top; control the 3-second descent.

What are common mistakes with Leg extension (3s eccentric)?

Jerking to initiate; Cutting the eccentric short; Hip flexor driving the pad

How do I progress Leg extension (3s eccentric)?

Add load only after the 3-second eccentric is fully controlled.

What can I do instead of Leg extension (3s eccentric)?

Wall sit, Bulgarian split squat, Single-leg leg press

Leg extension (3s eccentric)

Pad just above ankles, back flat, knee joint aligned with machine pivot.

family=leg extension 3s eccentricpattern=machine squatforce=pushmechanic=compoundequipment=machine

Muscles

muscle emphasis · training guidance

quadsPRIME

Primary: quads
Supporting: None listed

Mechanics

Pattern: machine squat
Equipment: machine
Geometry: 90° Alignment
Target feel: Quad fires to full extension at the top; control the 3-second descent.
Progression: Add load only after the 3-second eccentric is fully controlled.
Regression: Reduce range of motion or switch to wall sit.

Common errors

Jerking to initiate
Cutting the eccentric short
Hip flexor driving the pad

Programming by goal

Goal	Sets × reps	Effort cap	Tempo
Strength	3 × 3-6	RPE ≤ 9	2-0-X-0
Muscle growth	3 × 8-12	RPE ≤ 8	3-1-1-0
Endurance	3 × 15-25	RPE ≤ 7	2-0-2-0

Engine defaults for one exercise. Adjust load so every rep stays within the listed effort cap.

Equipment context

The machine fixes the movement path, reducing stabilizer demand and letting you focus on the target muscle.

Substitutions

Wall sit
Bulgarian split squat
Single-leg leg press

Leg press Same pattern: machine squat · Shared equipment: machine
Pendulum squat Same pattern: machine squat · Shared equipment: machine
Lying leg curl Shared equipment: machine · Antagonist pairing: quads / hamstrings
Seated leg curl Shared equipment: machine · Antagonist pairing: quads / hamstrings
B-stance RDL Antagonist pairing: quads / hamstrings

See all 33 quads exercises in the Atlas

Progression ladder

Beginner / regression: Reduce range of motion or switch to wall sit.
Standard: Leg extension (3s eccentric)
Advanced / progression: Add load only after the 3-second eccentric is fully controlled.

Atlas metrics

Movement pattern: machine squat
Primary target: quads
Supporting muscles: None listed
Equipment: machine
Joint geometry: 90° Alignment
Alternatives: 3 substitutions

Evidence & limits

Last reviewed against peer-reviewed biomechanics references. Exercise descriptions are framed as training guidance, not medical advice.

Source: Schoenfeld BJ (2010). The mechanisms of muscle hypertrophy and their application to resistance training.

Eccentryx is fitness software. It is not a medical device and is not intended to diagnose, treat, cure, or prevent any disease, injury, or medical condition. Consult a licensed physician before beginning any exercise program.

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FAQ

How do I set up Leg extension (3s eccentric)?: Pad just above ankles, back flat, knee joint aligned with machine pivot.
What should I feel during Leg extension (3s eccentric)?: Quad fires to full extension at the top; control the 3-second descent.
What are common mistakes with Leg extension (3s eccentric)?: Jerking to initiate; Cutting the eccentric short; Hip flexor driving the pad
How do I progress Leg extension (3s eccentric)?: Add load only after the 3-second eccentric is fully controlled.
What can I do instead of Leg extension (3s eccentric)?: Wall sit, Bulgarian split squat, Single-leg leg press

Leg extension (3s eccentric) verified exercise line-art diagram.

The movement · Knee 116°→10°

Leg extension (3s eccentric): isolation pattern, 2200 ms rep trace, engine-derived.

Train Leg extension (3s eccentric) in Gym Mode → Browse the public Atlas →