Cable Leg Extension
The cable leg extension straightens one knee against a low cable strapped to your ankle, usually while seated with your back to the machine. It isolates the quadriceps, and the cable keeps tension on them from the bent-knee start to the straight-leg finish.
Also called: Cable Quad Extension, Ankle Strap Leg Extension, Cable Knee Extension, Ankle-Strap Cable Leg Extension · Equipment: cable · Pattern: squat
Step by step
- Attach an ankle strap to a low pulley and fasten it around one ankle. Sit on a bench or box with your back to the machine, far enough forward that the cable is taut with your knee bent to about 90°.
- Hold the sides of the bench and sit tall, with the working thigh supported on the bench and your other foot flat on the floor.
- Brace your trunk so the cable cannot pull you backwards.
- Straighten your knee to lift your foot up and forward until your leg is fully straight, keeping your thigh on the bench.
- Squeeze your quadriceps briefly with the leg straight.
- Bend your knee slowly back to about 90°, keeping the cable taut.
- Finish the reps, then move the strap to the other ankle.
- Thigh stays on the bench
- Only the knee moves
- Straighten fully and squeeze
- Slow on the way back
- Sit tall, hold the bench
In VALDA, these cues are one tap away on the exercise while you train.
What it trains
| Muscle | Role | Evidence |
|---|---|---|
| Quadriceps: vastus lateralis | Prime mover | C |
| Quadriceps: vastus medialis | Prime mover | C |
| Quadriceps: vastus intermedius | Prime mover | C |
| Quadriceps: rectus femoris | Secondary | C |
Evidence grades: A = strong research base · B = good · C = limited · D = coaching consensus.
What goes wrong, and the fix
Lifting the thigh off the bench
Fix: Keep your thigh pressed on the bench and move only below the knee.
Leaning or rocking the torso
Fix: Hold the bench and brace so your torso stays still.
Kicking the leg up
Fix: Straighten your knee smoothly and pause with the leg straight.
Letting the cable pull the foot back
Fix: Bend the knee back slowly, keeping the cable taut.
Cutting the range short
Fix: Move from about 90° of knee bend to fully straight on every rep.
What the research says
Muscle growthRehab & prehabGeneral fitnessEndurance
- Hip angle — A leg-extension trial found that a more reclined seat, with less hip bend, produced more rectus femoris growth, while vastus lateralis growth was similar at both hip angles.
- Range of motion — A knee-extension trial found that training the bent-knee half of the range produced growth equal to or greater than the full range, and more than training only the straight-leg half.
- Light loads and effort — A knee-extension study found that with light loads, sets taken to failure produced more quadriceps growth than sets finished short; with heavy loads, failure added nothing.
- Transfer — A 6-week trial found barbell squats improved squat strength and vertical jump more than knee-extension machine training.
Swap it mid-workout
With VALDA Pro, FLEX offers alternatives like these when you swap an exercise mid-workout.
Log the cable leg extension in VALDA, with these cues one tap away while you train and your history for it in one place.
General information about exercise technique, not medical advice. If you have an injury or a health condition, your healthcare provider is the right person to ask.