Leg extension

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How to do it

Align the machine's axis with your knee; pause at the top and lower under control

Muscles worked

Mainly cuadriceps. Train it inside a balanced routine to progress safely.

Recommended sets and reps

As an isolation exercise, it works best in 3–4 sets of 10–15 reps with 0–2 RIR. Use it at the end of the session to add volume without systemic fatigue.

Common mistakes to avoid

• Letting the knees cave inward (valgus) when pushing, instead of keeping them tracking over the feet.
• Using too much weight at the cost of technique and full range of motion.
• Doing reps too fast, without controlling the eccentric (lowering) phase.

Alternative exercises

• Single-leg leg extension
• Back squat
• Front squat
• Goblet squat
• Leg press

Add it to your routine

FitnessAI can generate a personalized routine that includes Leg extension based on your level, goal and available days.

Frequently asked questions

What muscles does Leg extension work?

Leg extension mainly works the cuadriceps muscle group, plus synergist and stabilizer muscles depending on the variation.

How many sets of Leg extension should I do?

Between 3 and 5 sets per session, adjusting the total weekly volume for cuadriceps to your level (about 10–20 sets per muscle per week).

Is Leg extension good for building muscle?

Yes. Combined with progressive overload, good technique and enough rest, it's an effective tool to grow cuadriceps.

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