The leg extension machine might seem fairly straightforward to use, but if you don’t know how to set it up or use it correctly you could be getting just a fraction of the benefit for your efforts.
The leg extension machine works the muscles of thigh, which include the rectus femoris, vastus intermedius, vastus lateralis, and vastus medialis. Together they are more commonly known as the quadriceps or quads. The quads are mainly used as extensors of the knee joint, meaning they straighten the leg when walking, running or jumping. The rectus femoris is also used as a hip flexor movement, such as moving the leg forward when walking.
Despite there being different designs of leg extension machine they all tend to have the same adjustments and actions, so there a some common rules to bear in mind when using them.
Leg Extension Technique
1. Sit on the machine with your back against the pad and adjust the backrest so that your knees are in line with the pivot of the leg rest.
2. Next, if the leg extension machine you are using has an adjustment to alter the start position, move it so that your knees are at 90 degrees in the down phase. This is important if you are new to weight training to avoid any injuries to the knee area, but once you become used to it change it so your knees are bent as much as possible in the start position.
3. Next adjust the leg pad so that it is comfortably on the front of your ankles.
4. There are usually handles on either side of the leg extension. Use them. If you don’t you’ll find yourself lifted out of your seat as you exercise which will greatly affect your technique and therefore your results.
5. To start, just straighten your legs as much as you can. Note that the leg extension is one of the few exercises where you can do this. With most others your knees should never be fully straightened or “locked”, but because the weight is pushing against your legs here they are never actually locked.
6. Next bend your legs and lower the weight with control. Do this as far as you can without the weights touching the rest of the stack. The only time this should happen is when you have completed the set.
Leg Extension Notes
1. I’m sure I’m not the only one that’s seen someone several inches above the leg extension machine when they’re using it because they’re not using the handles. Not only does this look ridiculous, it reduces the range of motion and therefore the effectiveness of the exercise. It also makes it easier, which means adding more weight, which means an increased risk of injury.
2. Another thing you’ll often see with the leg extension machine is a lack of any control in the lowering (eccentric) phase. The weight is sometimes dropped and then caught at the end for another rep, or in extreme cases just dropped onto the rest of the stack. Instead you should lower the weight with control, whether this is 2 seconds or 10, otherwise you’re wasting half of every rep and increasing your risk of injury.
3. To train the muscle harder without the need to add more weight you can work it at its shortest point by sitting upright. Then at the end of the last set you can add a couple of extra reps by sitting back against the backrest, which should be slightly further away than you would normally have it. If you’re a beginner, have someone more experienced show you how to do this.
4. Doing the leg extension single leg is an effective (and safe) way to train the stabilising muscles and work on any strength imbalances. The method is exactly the same, but you should be even more aware of correct technique.
The leg extension machine is an excellent way to pre- or post- exhaust the quads, or if you’re a beginner and new to weight training, it’s a good introduction to working the legs.
As always, any questions or feedback leave a comment below.