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February 03, 2022 2 Comments
Leg extensions are a go-to exercise when it comes to directly targeting the quadriceps. It’s a killer way to finish a leg day. But, you may be wondering what your options are if your gym doesn’t have a leg extension machine (or it's often taken) or you’re working out from home with limited equipment? Well, you don’t need to let your leg gains suffer, there are plenty of other great alternatives to leg extensions that will hammer your quads (most even better!).
The key to substituting the leg extension machine is to use exercise variations that follow the same or similar biomechanics, completing a desired stimulus for the quadriceps according to your training program and applying exercise progressions over time.
To start, let's take a closer look at leg extensions...
Leg extensions performed on a leg extension machine start in a seated position where the back is resting against the seat and the hips and knees are in a flexed position. Both legs press against a weighted pad, positioned at the lower shin, into an extended position of the knees. The quadriceps repeatedly initiate knee flexion and extension. This action directly isolates the quadriceps muscles, located at the front part of the upper leg.
The quadriceps femoris muscle group consists of four individual muscles in the anterior compartment of the thigh; rectus femoris, vastus medialis, vastus lateralis and vastus intermedius. They originate at the ilium (upper hip bone) and femur (thigh bone) and come together and attach at the patella (kneecap) via the quadriceps tendon. The patella inserts in the tibia (shin bone) via the patella tendon. Out of all the quadriceps muscles, only rectus femoris crosses both at the hip joint and knee joint. The remaining three muscles just cross at the knee joint. Although these muscles have different origins, they share the same tendon that inserts in the patella. The quadriceps femoris extends the leg at the knee joint and flexes the thigh at the hip joint.
Here's a quick breakdown of the quadriceps muscles:
Leg extension takes place in the sagittal plane/medial plane. Primary movement takes place through the knee joint; a hinge joint. Hinge joints allow flexion and extension in one plane with limited degrees of motion in all other planes, we can compare the similarities of the knee joint to a hinge on a door.
The knee joint joins the femur (thigh bone) and tibia (shin bone) together, while the fibula (calf bone) and patella (knee cap) are smaller bones that make up the knee. Tendons connect the bones of the knee to surrounding leg muscles that move the knee joint. Ligaments join the knee bones and absorb shock and provide stability in the knee.
In the upward phase of leg extension, or the concentric contraction of the movement, rectus femoris, vastus medialis, vastus lateralis and vastus intermedius are engaged. During the downward phase, rectus femoris, vastus medialis, vastus lateralis and vastus intermedius cause flexion which eccentrically loads the muscle group.
Compound leg exercises such as squats, deadlifts and lunges all activate the quadriceps but do not isolate them. Exercises that solely isolate the quads, like leg extensions, load them directly and build strength. Not only do quad isolation exercises strengthen the quad muscles, the surrounding anatomy of the patellar tendon and quadriceps tendon build resilience to resistance.
Are leg extensions bad for your knees?
It is a common misunderstanding that leg extensions are bad for the knees when in fact, strong quadriceps lead to an increased stability of the knee joints. As long as quad isolation exercises follow consistent progressive overload with proper form, the final result of increased quad strength will follow.
But wait, there’s more to them then building strong knees...
Here are a few more benefits of quad-isolation exercises:
Don't forget your hamstrings - It is worth noting that most people are quad-dominant and an equal amount of training effort should be applied to training the posterior chain; back of the legs (hamstrings and glutes). A well-rounded program can help achieve well-rounded strength gains in all areas of the lower body.
If you do not have access to a leg extension machine or you simply want exercise variety, you can still replicate the leg extension in several different ways. Some alternatives are better suited than others according to your training goals, your physical capabilities and the progressions applied to the movement.
The three questions below are a great guide to help narrow down your most optimal leg extension alternative:
Does the exercise target the quads as best as possible?
If there are specific movement patterns that you struggle with, like lunges for instance, then look to simplify the movement. Instead of doing a full reverse lunge and feeling like you are losing balance, choose a split squat or an assisted split squat instead (meaning you can use one hand to hold onto something).
With movement patterns that we struggle with, there may not be a strong neuromuscular connection to the muscles involved. Most likely, the body is still trying to figure out the movement pattern itself and build practice through repetitions. In this case, choose movements that help you physically feel the isolation of just your quads. If you know that heel-elevated squats help you feel your quads the most, choose the squats and leave the lunges as practice for a standard leg day.
Does the exercise follow the same biomechanics?
The biomechanics of leg extensions are quite simple, the legs press the resistance away and come into a fully extended position at the top. Leg extensions are done in the sagittal plane and alternative movements should follow the same guideline.
A heel-elevated squat with a narrow stance is an appropriate alternative, the prime moving joints are the hips and knees while the legs move in the sagittal plane.
Now let’s take the sumo squat, you may feel activation in the quads but this position sets the hips in external rotation which switches the plane of motion from sagittal to transverse. The sumo squat incorporates a lot of adductor and glute activation and may not be the most optimal exercise to isolate the quads.
Can you progress this movement?
Progressions take time and can look very different for each exercise. Most progressions require equipment while others require using your own body to increase the difficulty of the movement.
Here is a list of progressions that can be incorporated for most leg extension alternatives:
Based on the above, here are the best alternatives that you can do at the gym if you have no leg extension machine or you want a variety/better options, and then several for if you are working out at home without any conventional equipment.
From the above list, let's breakdown our 5 favorites...
Difficulty Level: High
Ideal Reps: 10+ Reps Each Leg
Pro Tips: It may take some adjusting to find your starting position in the Bulgarian split squat. One hack is to position yourself in a secure bottom position (front thigh parallel to the ground, back thigh vertical and back foot pressing into the bench/step). From here, you’ll find stability in your form and will be able to press out of the bottom position and come up to standing without losing balance. Use anything that is stable in your surroundings to help you with balance if needed.
Progression: Eccentric Bulgarian Split Squat (slow down the negative movement)
Difficulty Level: Moderate
Ideal Reps: 8-15 Reps
Pro Tips: A narrow stance in the elevated heel squat helps maintain a more upright posture and direct focus on loading the quads. Elevating the heels may also increase the range of motion in your squat. Make sure to maintain tension through the movement, especially at the bottom of the squat. For a challenging progression, add a weight in the goblet position (at the chest).
Progression: Elevated Heel Squat with Pause (pause at the bottom of the rep)
Difficulty Level: Moderate
Ideal Reps: 10-12 Reps Each Leg
Pro Tips: Step ups in strength training are most efficient when negating any bouncing or momentum. It is common to see a bounce initiated when trying to step onto the bench. Instead, think about leaning and displacing your weight through the bench to help you stand in a vertical position. This activates the quads along with the glutes. A slow descent downwards will test your strength and balance. If you are training your right leg, make sure it stays on the bench the entire time so you benefit from the step up (concentric contraction) and step down (eccentric loading).
Progression: Eccentric Step Up
Difficulty Level: Low
Ideal Reps: 12-15 Reps Each Leg
Pro Tips: Focusing on one leg at a time for the banded leg extension can ensure that you keep balance on the bench and are able complete repetitions with proper form. If you’re ready to try looping both shins through the band to train both quads simultaneously, be prepared to engage your core to stay stable on the bench.
Progression: Standing Banded Leg Extensions
Buy Bands from SET FOR SET
Difficulty Level: Moderate
Ideal Reps: 10-12 Reps Each Leg
Pro Tips: Leaning the torso slightly forwards over the working leg, helps shift most of the weight into the front foot. This helps isolate the quads and helps the body find balance. Use anything that is stable in your surroundings to help you with balance if needed.
Progression: Front Foot Elevated Reverse Lunge
Set specific goals for your program. With quad isolation exercises, it is recommended to perform them after any compound lifts like barbell back squats. This way you can confidently fatigue the quads knowing most of your effort has been spent in the compound lift. An exercise like a seated cable leg extension requires significantly less neuromuscular control and full-body effort compared to a barbell back squat.
When it comes to sets and repetitions, quad isolation exercises fall in the category of 8-15 repetitions. This is dependent on the weight, stimulus goal and accessibility to equipment. If you are performing this at home with limited equipment, higher repetitions are a reasonable goal as long as you are able to maintain form and technique throughout those higher repetition ranges. If you have access to a gym with a broad selection of tools, play around with a variety of weights that complete the given stimulus with less repetitions. Example: Banded leg extensions fatigued at 18 reps vs. Cable leg extensions with moderate weight fatigued at 12 reps.
Choose quad isolation exercise alternatives that help you feel the most quad activation. Hone in on properly executing the form along with feeling the muscles activate through the given range of motion. Focus on physically squeezing your quadriceps through the movement. This will help build neuromuscular connection.
Don’t be shy to throw in progressions and a variety of exercise alternatives, but not all at once. It takes a fair amount of repetition to build proper patterning in the body while reaping the benefits of building strength. Slowly introduce a few variations or progressions of quad extension exercises to your training block and allow your body to adapt over time.
Example: My training block is 6 weeks. Throughout the 6 weeks I have banded leg extensions programmed. Week 3 and 4 I’ll supplement an eccentric banded leg extension and Weeks 5 and 6 I’ll incorporate high rep eccentric banded leg extensions. For the entire training block, leg extensions will be followed as prescribed. Weeks 4-6 introduces a progression to challenge the leg extension.
Leg extensions and the variations of leg extension exercises isolate the quadriceps muscles. The key to replicating leg extensions is choosing exercise variations that follow the same biomechanics, completing a desired stimulus according to your program goals and applying exercises that suit your abilities. Introducing a variety of leg extension alternatives incorporates new stimuli in a program and helps gain overall strength and neuromuscular connection. An important factor to keep in mind is to limit an overwhelming amount of variety or progressions in a training program block. Allow your body to reap the benefits by slowly introducing new quad isolation variations.
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