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December 21, 2021 6 min read

The hamstrings are an important muscle group for walking, running, and maintaining posture. Located in the back of your  thighs, antagonist to the quadriceps, they are a part of the posterior chain. They're responsible for bending at the knee joint and hinging at the hips, movements we likely perform every day, so it should come as no surprise that keeping them strong is essential.

Exercises like the  deadlift and lunge rely heavily on the hamstrings, but they are compound exercises, so they may also rely on the glutes, quads, core, and calf muscles as well. Isolating a muscle group isn't just for bodybuilders trying to build muscle, but it can be important for athletes and the average gym-goer to help avoid imbalance throughout your body, build strength in your lower body, and help prevent injuries.

The leg curl machine, similarly known as the hamstring curl, is one of the better isolation exercises for the hamstrings. The lying leg curl works the hamstrings similarly, and the leg press is popular, but it's also a compound exercise.

There's nothing wrong with a good barbell exercise, but to target only the hamstrings, the leg curl is the way to go.

Watch this video to learn how to do leg curls properly, or read on for a written version.

Anatomy of the Hamstrings

In your upper leg, in between the hip and the knee are the hamstring muscles. They are composed of three muscles known as the biceps femoris, semitendinosus, and semimembranosus.

You may have noticed the similarity between the name of the biceps femoris and biceps brachii, the muscle in the anterior of your upper arm. That's because they both have two heads, a short and a long head, and they are both responsible for flexion. The biceps femoris is responsible for knee flexion, hip extension, and lateral rotation at the knee and hip.

The semitendinosus is located medially to the biceps femoris and helps flexion of the knee, an extension of the hip, as well as internal rotation of the leg.

Lastly, the semimembranosus is located underneath the semitendinosus and also helps flex the knee, extend the hip, and internal rotation.

The Leg Curl Machine Benefits

The seated leg curl machine helps to isolate the hamstrings, which can contribute to mass and strength in the lower body. This leg workout can be beneficial for anyone of any fitness level.

Help from a Machine

Machine exercises can be beneficial for athletes of all fitness levels because beginner lifters are able to control their movement pattern and range of motion and more advanced lifters can challenge themselves with heavier weight or slower reps.

Isolate Your Hamstrings

Isolation exercises can provide more strength and mass to a specific area. Compound exercises can accrue benefits of their own, but isolating a muscle group is important for those muscles that may get overcompensated by other muscles. If you have strong quads or glutes, that may be compensating for the hamstrings in lower body exercises. The quadriceps antagonize the hamstrings, and if either muscle is stronger than the other, it could lead to injury. Doing leg curls could help improve muscle imbalances in the lower body.

Improved Physical Performance

The hamstrings aid in high-speed running and sprinting, as they flex the knee and help control the swing of the leg. Athletes like football, basketball, and soccer players can be found running and jumping frequently in games or practice, and powerful hamstrings can help the power needed for speed and height.

Injury Prevention

Research suggests that common knee and hamstring injuries are  caused by hamstring weakness, and performing hamstring exercises, could help prevent them. It also suggests that the hamstrings produce enough force to counter the force of the quadriceps in physical activities. If your hamstrings are weaker than your quads, it could lead to injury, so by keeping a strong balanced body, you can help prevent it.


Physical benefits aside, the accessibility of the leg curl machine shouldn't be too difficult since you're likely to find one among the other gym equipment in commercial gyms. The great aspect of this exercise is that you can also still perform it without the exercise machine. If you have a dumbbell or a resistance band on hand, you're able to perform a similar motion.

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How to do the Leg Curl

Although the machine does provide assistance with the leg curl, it's important to know how to set the machine and how to perform it properly and safely. Follow this step-by-step guide for the leg curl machine:

Hamstring Leg Curl

Pro Tip: Before starting, consider trying a pre-workout like PUMPED-AF to feel essential nutrients shuttle in and out of your muscle bellies resulting in skin-bursting pumps and increased training capacity.

1. To ensure proper technique, align the point of rotation on the machine directly with your knees for a smooth and secure fit.

2. From that point, adjust the back support pad to fit snugly against your back so there is minimal to no space between your lower back and the corner edge of the seat. Fix the angle degree adjustment to a proper level (based on flexibility and experience). It’s always safest to drop it below an angle of 180 as to not hyperextend the joint while under tension.

3. Place the back of your lower leg on top of the padded working arm and secure the thigh pad against your thighs just above your knees (be mindful that the rotation point is still in line with the knee joint).

4. As you exhale, begin curling your legs as far as possible to the back of your thighs by flexing at your knees. Hold the contraction tight for a good 3 seconds and SLOWLY begin the negative portion of the exercise, lowering the weight back to starting position, as you keep your torso stationary. The working weights should never come into contact with the stack during the set as to keep a consistent working tension on the hamstrings for a fully engaged experience.

5. A final tip for getting a fully engaged hamstring contraction is to squeeze glutes in and thrust hips slightly forward into the thigh lock-in pad.

leg curl machine for hamstrings tip

Leg Curl Programming Recommendations

Depending on what your fitness goals are, you'll want to plan out the reps and sets for each leg exercise. This can help you stay on track, whether you're looking to bulk, lean, or just stay healthy. Below are just some training recommendations for the leg curl machine. It should be noted that this is not the only way to perform it and are the following are simply suggestions.

For Hypertrophy

Hypertrophy refers to an increase in muscle size. If you're looking to build muscle gains, you might be a bodybuilder or a regular gym enthusiast that wants that beach bod aesthetic.

To focus on hypertrophy, you'll want to perform higher reps. No, that doesn't mean you need to perform 20 reps of the leg curl. High reps could be anything from six to 12 repetitions or more. It's important to understand that with higher rep count comes fatigue, and with that can come suffered form. Lighten the weight if you're losing form or having trouble getting to the prescribed number of reps.

With the leg curl, unless you know exactly which weight is right for you, it might be trial and error. Start off with three sets of 10-12 reps with a lighter weight. If the resistance feels too light, you can add small increments of weight at a time and continue to shoot for 10 reps.

For Strength

The lower reps are often used by powerlifters and  Olympic lifters  to develop the strength required to perform a one-rep max in competition. So, if your goal is to build strength, keep your reps low and your weights heavy. Low reps could mean anything from a one-rep max to five reps.

Even though the low rep count encourages heavier weights, form is always the most important factor of a safe and efficient workout. Don't let your ego get in the way of a good lift.

To build strength with the leg curl, start off with a decently heavy weight. Again, it might take some trial and error to find which is appropriate for your fitness level. Perform five sets of five reps, and if you find the weight is too light, and you can maintain proper form, add small increments of weight at a time.

Final Word

Having strong hamstrings can contribute to lower body strength, which can help improve overall performance and your quality of life. It's essential to exercise for balance in the body and to know why balance is important.

A mix of isolation and compound exercises can be beneficial for building strength and mass, and implementing high and low rep counts into your workout split can help boost performance.