FitnessAILeg 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.
Technical sheet
- Movement pattern
- Isolation
- Minimum level
- Beginner
- Technical demand
- Basic
- Fatigue it generates
- Low (0.5 out of 2.2)
- Risk if technique breaks down
- Low
- Peak tension in the stretched position
These are the values the generator uses to decide where the exercise goes within the session.
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
More Isolation exercises
- Single-leg leg extension
- Overhead cable triceps extension
- Triceps pushdown
- Seated overhead dumbbell triceps extension
- Overhead dumbbell extension
Add it to your routine
FitnessAI can generate a personalized routine that includes Leg extension based on your level, goal and available days.
Build your Quads workout
Generate a full routine with the emphasis on Quads and Leg extension among your preferred exercises. Free, no sign-up.
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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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