Leg Extensions

by JP – Updated: 09/24/2016

Muscles Used    •    Exercise Type    •    Form Instruction    •    Tips and Techniques    •    Recommended Reps    •    Common Variations    •    Substitutions    •    Equipment Needed

Bottom	Top

Primary Mover(s)	Muscles Used:	Secondary Mover(s)
Quads		None
		Other Mover(s)
		None

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Weight Training Exercises Database

– Leg Extensions –

Isolated Exercise, Push Movement

Seated on bench, place pads in front of and just above ankles, extend knees until legs are nearly straight, then lower back down.

Provided your machine has such adjustments, you want to adjust the back adjustment so your knees are comfortably over the bench. The hinge or lever of the machine should be in line with your knees. The ankle pad should be just over the top of your ankle.

Keep your butt down and back against the padding at all times. You are only moving at the knee joint.

Stop just short of lock out at the top of the exercise and just short of the weight plates clanking down at the bottom, keeping tension throughout the movement.

With your toes pointed in you are putting more emphasis on the outer quads and with them pointed out the emphasis moves to the inner quads. Pointed straight up you are emphasizing the middle quads. Keep the ankles tense, as opposed to dangling, to better isolate the quads.

At most, you want your leg forming a 90 degree angle at the bottom of the exercise. Anything more is putting too much stress on the knee and is not advisable. And going to 90 degrees is pretty controversial.

In fact, doing Leg Extensions at all is controversial. Many feel that they are simply too dangerous for the knee and not worth the risk. The movement is not thought to have much functional value. It can however have some value in terms of hypertrophy (increasing the size of the quads).

People with any knee problems should probably avoid the exercise altogether. It is a limited value exercise and won’t be missed.

Those with good knees who want to give it a try should be careful with it. Keep to good form, a smooth and controlled motion is critical to safe and effective leg extensions. Going too fast and involving momentum is a bad idea. Avoid going too heavy with it. Using the exercise as a pre or post exhaust exercise with higher reps (less load) is how many bodybuilders use it.

6-12 the majority of the time, trying higher or lower reps on occasion.

As mentioned, Leg Extensions aren’t a great exercise for mass gain but can be effective with pre and post-exhaustion techniques. For your main quad exercise, there are many quality alternatives. Squats would be your best bet. Leg Presses, Lunges, Machine Hack Squats and Dumbbell Step-Ups are other good alternatives.

Leg Press Machine, Weights