Are you tired of doing squats and deadlifts? Or are you struggling to isolate the muscles of the front and back of the legs? Then leg extensions and leg curls could be the answer for you. Both these exercises appear similar but work opposite muscle groups. The leg extension exercise trains the muscles of the front of the thigh or quads while the leg curl predominately trains the hamstrings at the back of the thigh.

What is a Leg Extension?

The leg extension exercise is an exercise that involves moving the knee from a bent position to a straight position. The primary aim of this exercise is to strengthen the quadricep muscles that are responsible for this movement. This movement around the knee involves the muscles of the quadriceps including -

• Rectus femoris

• Vastus lateralis

• Vastus medialis

• Vastus intermedius

The leg extension machine has a padded lever that you move with the lower part of your body from a seated position. This exercise is fantastic to strengthen the muscles and ligaments around the knee joint, help improve your squats and assist in the rehabilitation of an injury. It is possible to perform a single leg variation which helps to decrease muscle imbalance.

How to Perform a Leg Extension

• Start by having your back firmly against the backrest and your legs tucked below the padded lever so that the padded lever is against the lower part of your shin. Your knees should be bent at 90 degrees. Your knees should also line up with the fulcrum of the lever. Adjust the seat and lever if it is not.

• Grip the handles that are provided and brace your torso by tightening your core.

• Exhale and straighten your legs by squeezing the quads.

• Inhale and slowly lower the weight back to the starting position.

Common Leg Extension Mistakes

Locking the Knees

Don’t lock your knees at the top of the movement as this places strain on the knee joint.

Moving Too Fast

Moving too fast results in the level gathering momentum which results in the weight being unloaded from your legs at the top of the movement before swinging back down and creating excessive forces on the knee.

What is a Leg Curl?

The leg extension focuses on strengthening the muscles around the knee while straightening the knee. The leg curl focuses on muscles at the back of the leg that are involved with bending the foot back towards the glutes. These muscles include -

• Bicep femoris

• Semitendinosus

• Semimembranosus

• Gastrocnemius

• Soleus

The main aim of this exercise is to strengthen the hamstring group. This group of muscles tends to be weaker and more difficult to isolate and strengthen. While exercises such as the deadlift are excellent compound movements to strengthen your posterior chain, they lack the ability to isolate the hamstring, particularly if you are struggling with weak hamstrings.

How to Perform a Leg Curl

• Lie down on your stomach with the padded lever just above your heels and below your calves. Place your hands on the grips.

• Exhale and curl your feet towards your glutes, making sure that you don’t lift your hips from the bench.

• Inhale and slowly lower your feet back towards the starting point.

Common Leg Curl Mistakes

Leg Lever Too High

By having the lever too far up your calves, the range of motion will be limited and you will not get the desired training effects.

Moving Too Fast

Similar to the leg extension, if you are moving the lever too fast the lever will end up crashing back down into your ankles which results in a braking force on the tendons of your hamstrings and becomes an injury risk.

Should I Do Leg Extensions or Leg Curls?

When using the leg extension machine or leg curl machine, it is important to remember that you have to dedicate training time to both exercises. If one muscle group gets stronger than the other then you will become prone to lower limb injuries. Your hamstrings should be at a minimum of 50% of  your quads and even stronger if you are participating in sports.

Having two machines could take up a lot of space in your home gym. The solution is the Mirafit Leg Curl and Extension Machine. This product has dual function, allowing you to strengthen the quads and the hamstring with a single machine. It also has a smaller than usual footprint by saving on the space taken up with stacked weight rack by making use of weighted plates instead.

To set it up as a leg curl machine you just need to sit in the machine, adjust the backrest, place the lever on the front of your shins with your legs bent at 90 degrees and then straighten your legs against the resistance.

To then convert it to a leg curl machine, all you have to do is adjust the lever so that it is now behind your leg, just below your calf, and with your legs out straight at 180 degrees. You will then curl the lever underneath your glutes.

The glutes and hamstring muscles are two of the major muscle groups of the leg. While there is a range of different exercises you can do to strengthen them, when it comes to isolating them it is more difficult. The leg curl and leg extension exercises are the most useful exercises to isolate the hamstrings and quads, and machines that offer a dual function are ideal for smaller spaces and allow both exercises to be performed.

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Tags: Equipment > Gym Machines ; Exercise Type > Strength