Exercise Profile
  • Target Muscle Group
  • Exercise TypeStrength
  • Equipment RequiredMachine
  • MechanicsIsolation
  • Force TypePush (Bilateral)
  • Experience LevelBeginner
  • Secondary Muscles
Target Muscle Group


Quads Muscle Anatomy Diagram

Leg Extension Overview

The seated leg extension is an isolation exercise and one used to target the muscles of the quads.

This exercise can be particularly hard on the knees. So, for those with prior knee issues, it may be beneficial to stick with other movements, preferably compound, to target your quads.

The leg extension is a great exercise for quad development and may be beneficial to include in your workout routines if your goals are more aesthetics-driven.

The leg extension can be utilized in both leg workouts and full body workouts.

Leg Extension Instructions

  1. Select the desired resistance on the weight stack and insert the pin.
  2. Adjust the seat so that the knees are directly in line with the axis of the machine.
  3. Sit down and position your shins behind the pad at the base of the machine.
  4. Take a deep breath and extend your legs as you flex your quadriceps.
  5. As you lock out the knees, exhale to complete the repetition.
  6. Slowly lower your feet back to the starting position and repeat for the desired number of repetitions.

Leg Extension Tips

  1. Ensure the axis of rotation for the knee directly matches that of the machine. In other words, the point of rotation for the machine should be in line with your knee joint itself. If the knee is positioned too far in front or behind the axis of rotation, there will be excessive stress added to the joint which could cause significant injury.
  2. Typically extensions should not be done excessively heavy due to the lack of hamstring co-contraction with the quads. When one occurs in isolation it could present an injury risk to the knee if done with excessive weight.
  3. Pointing the toes can help to enhance mind muscle connection.
Anthony S
Posted on: Mon, 03/04/2024 - 06:54

I have a bad right knee from sports in high school. I've never had a knee problem doing leg extensions. What gives me knee soreness is squats and leg presses.

Gregory Cecere
Posted on: Tue, 12/14/2021 - 01:39

I Had significant (mystery) weight loss 2 years ago - lowest weight was 103 pounds for a 5'8' 75 year old senior.
While I gained weight back to 149 pounds, muscles loss was also significant.
I need a muscle gain in arms and legs...can only lift 3 pound weights.
If I get on the floor to do anything, I have a very difficult time getting back up without some support to pull myself up. Can you help me?

M&S Team Badge
Posted on: Thu, 12/16/2021 - 15:47

Hi, Gregory. Before I answer this in detail, have you been cleared to exercise by a doctor? If so, are there any other health or physical issues that are limiting you besides what you shared here?

Anthony pace
Posted on: Thu, 05/13/2021 - 14:14

Hi maybe this can help you guys..... for alternative exercise

Posted on: Sun, 01/13/2019 - 07:18

Is there an alternative to this exercise, that doesn't put so much stress on the knee?

Posted on: Thu, 02/22/2018 - 03:34

I like ur muscles baby

Raider Thomas
Posted on: Fri, 06/30/2017 - 12:16

Would useing a weighted plate work instead because i workout at home

Posted on: Thu, 02/22/2018 - 03:34

china isn't very heavy I would invest in saucepans

Posted on: Sun, 06/14/2015 - 14:53

Instead of this exercise you can do squats with the bar in front of your neck these are called front squats and isolate the quads

Posted on: Sat, 11/30/2013 - 09:06

I need an alternative to this. Have mainly free weights and simple machine.

Posted on: Wed, 10/23/2013 - 11:25

Is there any alternative to this exercise? I work out at home.

Posted on: Sun, 12/23/2012 - 09:24

I am also from India and just relying on your "12 day programme" for beginners and its helping me a lot. It has improved my knowledge of exercises as well as how to do the exercises in a correct way which is very important.
Thanxs :)

Posted on: Sun, 12/02/2012 - 16:39

for people thet are 200 cm tall and dont fit in the Machine :) what can we do instead ?

Posted on: Fri, 11/23/2012 - 13:42

How I can figure out what is the weight to start?

M&S Team Badge
Posted on: Thu, 11/29/2012 - 19:56

Hey Jose! Simply pick a weight that works for the rep range you are shooting for in each set. If you are unable to perform the desired reps, drop in weight. If it's easy to hit the rep mark, add weight.

Posted on: Mon, 10/22/2012 - 02:11

Hey Steve !I have recently found out this website.I am from India .I have already started this 4 day workout n finished day 2.I have seen good results.Thank you for ur article .My gym doesn't have this leg extension machine ,can u please suggest any alternative ..that will be truly helpful for me.Also I really wanna know if I can daily add 15-20mnts of skipping n ab workouts daily coz I want to desperately have flat abs..or may be ripped abs.I am man of 29 years .Hope u will help me Steve with may be any of ur recommended ab workout routines.Thanx man

Posted on: Wed, 10/13/2021 - 10:40

You have seen good results after 2 days lol?