Single-Leg Extension
The leg extension done one leg at a time: seated in the machine, you straighten one knee against the roller and lower it slowly, training the quads of each leg on its own.
- Primary muscles
- Quads
- Difficulty
- Beginner
- Logged as
- Weight × reps
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Why do it
It suits anyone who wants to isolate the quads without loading the spine, and it's handy when one thigh is smaller or weaker than the other, since the stronger leg can't take over. Compared with the two-leg version you move a lighter stack and each set takes twice as long, so it's usually saved for accessory work after squats or presses. It also shows you quickly whether both legs can handle the same weight.
How to do it
Set the seat so the backs of your knees sit at the edge of the pad and the roller rests just above your foot.
Hook one leg under the roller, rest the other to the side and hold the handles.
Extend your working knee until your leg is straight and hold the top for a moment.
Lower slowly without letting the stack touch down, then finish all reps before switching legs.
Common mistakes
Kicking the leg up
Swinging the roller up fast lets momentum do the work instead of your quad. Extend smoothly and hold the top for a moment, as the steps describe.
Letting the stronger leg set the reps
If you start with your strong side, the weak side often can't match it. Start with the weaker leg and do the same reps on the other.
Hips twisting off the seat
With the load on one side, your pelvis tends to rotate and lift as the set gets hard. Hold the handles, keep both hips down, and lighten the stack if they move.
Resting the stack between reps
Letting the weights touch down at the bottom gives your quad a break every rep. Stop just short and start the next rep from there.
Sets, reps and progression
How many sets you do and how close to failure you take them depend on your goal and your week, not on the exercise. These guides cover it:
Alternatives that train the same thing
Same movement, a different angle or piece of equipment.
