Leg Extensions
A beginner isolation strength exercise that works the quads, using a machine.
Starting position
End position
How to Do Leg Extensions
- For this exercise you will need to use a leg extension machine. First choose your weight and sit on the machine with your legs under the pad (feet pointed forward) and the hands holding the side bars. This will be your starting position. Tip: You will need to adjust the pad so that it falls on top of your lower leg (just above your feet). Also, make sure that your legs form a 90-degree angle between the lower and upper leg. If the angle is less than 90-degrees then that means the knee is over the toes which in turn creates undue stress at the knee joint. If the machine is designed that way, either look for another machine or just make sure that when you start executing the exercise you stop going down once you hit the 90-degree angle.
- Using your quadriceps, extend your legs to the maximum as you exhale. Ensure that the rest of the body remains stationary on the seat. Pause a second on the contracted position.
- Slowly lower the weight back to the original position as you inhale, ensuring that you do not go past the 90-degree angle limit.
- Repeat for the recommended amount of times.
Muscles Worked
Alternatives to Leg Extensions
10 movements that train the same primary muscle, closest substitutes first — same kind of training, then variations of the movement itself, then a similar difficulty.
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1
Single-Leg High Box Squat
A beginner compound strength exercise that works the quads.
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2
Leg Press
A beginner compound strength exercise that works the quads, using a machine.
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3
Single-Leg Leg Extension
A beginner isolation strength exercise that works the quads, using a machine.
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4
Smith Single-Leg Split Squat
A beginner compound strength exercise that works the quads, using a machine.
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5
Leg Raises
Leg raises target the often-neglected lower portion of the abdominals and hip flexors. They're one of the most effective exercises for building lower ab strength and definition.
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6
One Leg Barbell Squat
An advanced compound strength exercise that works the quads, using a barbell.
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7
Squats
The squat is the king of lower body exercises, targeting the quadriceps, glutes, and hamstrings while building core stability. It's a fundamental movement pattern that translates directly to everyday activities.
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8
Barbell Side Split Squat
A beginner compound strength exercise that works the quads, using a barbell.
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9
Barbell Squat
A beginner compound strength exercise that works the quads, using a barbell.
-
10
Barbell Walking Lunge
A beginner compound strength exercise that works the quads, using a barbell.
Frequently Asked Questions
What muscles do leg extensions work?
Leg Extensions primarily works the quads.
What equipment do I need for leg extensions?
Leg Extensions uses machines.
Leg Extensions: is it suitable for beginners?
Yes. Leg Extensions is rated beginner. Movements you can learn in a session, with a low skill floor and a forgiving failure mode.
What can I do instead of leg extensions?
Single-Leg High Box Squat, Leg Press, Single-Leg Leg Extension train the same primary muscles and are listed with 7 more alternatives above.
Can Fitnit count my leg extensions reps automatically?
Not automatically yet. Fitnit's AI rep counting covers push-ups, squats, dumbbell curls, crunches and pull-ups today; leg extensions can be logged manually in the app, and tracked movements are added over time.
Photographs and step-by-step instructions from free-exercise-db, a public-domain exercise dataset. Muscle mapping and alternatives by Fitnit.
Track Your Leg Extensions with AI
Fitnit automatically tracks push-ups, crunches, squats, pull-ups, and curls with advanced body tracking technology — and you can manually input any other workout too. Start free — Pro is $8.99/month.