Exercise · Legs and glutes · One side at a time
Single-leg extension on the machine
The single-leg extension on the machine isolates your quadriceps one side at a time. It’s useful to address a weaker side and to really feel the front of the thigh working. It works well at the end of a leg workout or when you want a simple quadriceps exercise.
Doable at all 76 gyms GoSet follows
The essentials
- Do all reps on one leg, then switch.
- Keep your hips seated.
Muscles worked
- Primary
- Quadriceps
How to do it
- Sit on the leg extension machine with your back against the pad and your hips firmly seated in the chair.
- Set the pad on the lower part of your shin, just above your foot, and pick a weight you can control.
- Keep both glutes on the seat, hold the handles, and bend both knees to start from the bottom position.
- Extend one leg at a time, controlling the way up for 1–2 seconds, until your knee is almost straight without forcefully locking it.
- Lower the leg back down over 2–3 seconds until you return to the starting position, without letting the weight drop.
- Do all reps on one leg, then switch sides and match the same number of reps with the other leg.
Common mistakes
Hips lifting off the seat
Instead : Sit all the way back and keep your hips seated the whole time. If they still lift, lower the weight or reduce the range of motion a bit.
Kicking the weight up too fast
Instead : Lift the leg in a controlled way and lower even slower. Aim for about 1–2 seconds up and 2–3 seconds down with no jerky motion.
Locking out the knee hard at the top
Instead : Stop just before your knee fully locks. Focus on tension in the quadriceps rather than snapping the joint straight.
Uneven work between legs
Instead : Count your reps and use the same weight and tempo on both legs. If one side is weaker, start your sets with that leg.
Coach tips
- Breathe out as you extend the leg, breathe in as you lower it. Keep the same rhythm for every rep.
- Adjust the seat so your knee lines up with the machine’s pivot point, this helps the movement feel smoother.
- If you’re new to this, start with a light weight and focus on feeling the quadriceps before adding more load.
- At the end of a set, you can slow down the lowering even more to keep tension when you’re getting tired.
Variations
- Start with your weaker leg first so it always gets the same work as the stronger side.
- Add a 1–2 second pause at the top to feel the quadriceps contraction more on each rep.
Sets and reps
Single-leg extensions are often done for 3–4 sets of 8–15 reps per side, usually in the middle or toward the end of a quadriceps-focused workout.
Equipment
Alternatives for the same muscles
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Common questions
I feel the work only on one leg, is that normal?
Yes, it’s a unilateral exercise, so each leg works on its own. Just make sure you use the same weight, reps, and speed on both sides to keep things balanced.
Do I need to fully straighten my knee?
You can go close to full extension, but stop just before you lock the knee hard. The goal is to keep tension in the quadriceps, not to force the joint.
What if I feel knee pain during the exercise?
Stop the set right away and don’t push through pain. Talk to a health professional before continuing with this exercise.
Can I replace squats with single-leg extensions?
Squats like barbell back squats, front squats, Bulgarian split squats, goblet squats, reverse lunges, and step-ups also train other muscles. The single-leg extension mainly isolates the quadriceps. Both types of exercises work well together in a program.