Last month, I talked about how I re-incorporated weight machines into my strength training to good effect.
This year, we will be doing a few articles on how to properly use various weight machines. One of the benefits of using machines is that they have a much easier learning curve than lifting weights. But there are a few things you should know about using each in order to avoid pain and injury and use them most effectively for building size and strength.
First in these workouts is the leg extension machine, which targets your quadriceps and quadriceps only.
There is some folklore out there that the leg machine can cause injuries and put too much stress on the knees. But this is not borne out by research, which has found it Leg extensions are safe, including ACL rehabilitation.
There is also a myth that leg extensions are not functional. But quad strength translates into everything from walking to running, and especially explosive movements like jumping and section. Also, because people often use compensatory muscles when doing other leg exercises (especially if they’re dealing with injuries), leg extensions, by isolating the quadriceps, can help correct the strength imbalances created by these compensatory strategies. This is useful in preventing new injuries, as well as re-injury, particularly a second ACL tear.
Leg extensions are not only a safe strength-building exercise, but they also help you get defined and fleshy legs so you can confidently wear your short shorts around town. And, since you’re only moving one joint, they perform this function without requiring the kind of recovery you need after a squat or leg exercise.
But since leg extensions, like all exercises, are only safe if done correctly, let’s look at how to perform them correctly.
Setting up the machine
In my home gym, the leg plate machine doesn’t have as many adjustment options as you’d find in a commercial gym, so I couldn’t dial in my position as much as you could, but this is generally a good adjustment position.
The leg extension itself is a simple movement. The big thing to watch out for is setting up the machine before you start doing them.
There are several adjustments you should make to the machine before starting this exercise to ensure ergonomic comfort, maximize force-producing power, hypertrophy, and prevent undue pain and strain on your joints:
Weight stack/plates. There are different schools of thought on what weight to use for leg extensions. One is that you have to go with a lower weight because you’re only using one joint to move the weight and you can’t exert as much force without breaking form. To get the hypertrophic stimulus with lower weight, you’ll need to do high reps in the 15-20 range. If you’re going to go the high-rep route with leg extensions, perform them at the end of your workout so you don’t tire yourself for the main leg exercise like the squat.
The other school of thought is that as long as you can perform the reps with good form and without pain, you can stick to the traditional 8-12 rep range prescribed for hypertrophy and go heavy.
Experiment and find what works for you.
Seat back distance. The seat back can be adjusted forwards or backwards. Proper placement will minimize undue stress on your knees and allow you to produce maximum power. You want to move the seat back so that when you sit, your knees are neither too far forward of the edge of the seat base, nor too far back. Your knees should be in line with the pivot point of the leg bar. The folds at the back of the knees should touch the edge of the pillow.
Foot pad height. The pad that will sit over your feet can sometimes be adjusted up or down. The pad should rest where the ankle bends. Not up your shins or down towards your toes.
Leg bar range of motion. The foot bar can be adjusted to sit more or less below the seat base. The further back it sits, the greater the range of motion that will be possible in your leg extensions. Adjust the foot bar to full depth to maximize range of motion.
Sometimes there is also a pad that can be adjusted over the thighs to lock them in place. As your butt/legs should not lift if you are positioned correctly and doing the exercise correctly, this pad is not necessary.
Once you’ve made all of these settings, you may want to write down the numbered positions of each piece somewhere, so that the next time you use the machine, you won’t have to spend time struggling and making the settings through trial and error.
Doing leg extensions
Now that the machine is set up properly, it’s time to do a proper leg extension:
Slow and controlled. The big mistake people make with this exercise is to bounce/swing the leg bar up, use momentum, and let it drop back. Instead, you want to lift the bar and lower it in a slow and controlled manner. The path to hypertrophy is slow and controlled.
Raise the bar. As you lift the leg bar, you don’t lift your butt and hips up. You don’t rock back and forth. only your legs move, not the upper half of your body. The butt remains in contact with the seat base pad. The back remains in contact with the back of the seat. Lean back a little. Grab the handles to keep your butt down.
Steadily raise the bar until you reach full peak knee extension/contraction. Pause for one second during this top hold. Tightening. Feel and enjoy the burn.
Lower the bar. Much of the hypertrophy occurs during the eccentric phase of a lift, so lower the bar in the same slow and controlled manner as you raised it — its descent should take a full one to two seconds.
Instead of hitting back, the weight should just gently touch the weight stack as it returns. Once you hear it click, raise the bar again and do another rep.
The position of the fingers makes little difference. Keeping your toes straight forward as opposed to bending them slightly in or out can make slight differences in which parts of the quads work. But unless you’re an elite bodybuilder, this isn’t something you need to worry about. It’s good to keep your toes straight or slightly turned inward. Do whatever feels most comfortable for you as this will help you produce maximum power.
Go for full range of motion. Go all the way up and all the way down with each rep. If you can only lift the leg bar halfway up, the weight is too heavy.
Let’s go strong. Don’t just do leg extensions pointlessly, fitting them to the end of your workout without putting much effort into them. Just going through the motions won’t build muscle. You should do sets that get you within one to two repetitions of failure.
It sure hurts, but it hurts so good, baby.
Leg extensions can be done using only one leg at a time, which can be helpful in addressing strength imbalances.
Because leg extensions only work the quadriceps, they should be done in a program that includes other leg exercises such as squats, leg presses, and lunges.
