The leg curl is a monoarticular exercise to train the hamstring muscles composed of the hamstring, the semitendinosus, and the semimembranosus.
It can be performed in three different ways depending on the machinery used: standing, prone, and sitting.
For all three modalities, the movement is monoarticular and characterized by a pure flexion of the knee against resistance a condition that generates a posterior translation force of the tibial plateau in response to the force generated by the bearing placed behind the ankle.
The posterior ligament is opposed to this force in an incisive way which due to its anatomical position is used for this purpose.
In this article, we briefly analyze the methods of execution one by one, understanding their strengths and weaknesses and clarifying the correct execution and the mistakes to avoid.
Standing Leg Curl
Standing leg curl requires you to work alternately, first with one leg and then with the other.
Position yourself with your thigh supported and the pad on the back of the ankle. From this position, flex your knee up to 90 degrees.
This modality is not recommended for all those subjects with retracted rectus femoris a condition that could establish a compensation in lumbar hyperlordosis during knee flexion.
Seated Leg Curls
In the Seated Leg Curls position the legs with the pads resting on the front just below the knee and on the back of the ankle. From this position, flex both knees up to 90 degrees.
Due to its structure, the machinery in question is perhaps the one that exposes the most to the posterior translation of the tibial plateau to which the posterior cruciate opposes.
People with very retracted hamstrings may find it very difficult to maintain the sitting position without sending the pelvis into retroversion and thus reversing the lumbar lordosis.
Leg Curl Lying Down
The Lying Leg Curl is probably the best variant. The machinery must be structured in such a way that in the prone position the hips are slightly flexed so as to guarantee a more effective contraction of the hamstrings which, being biarticular muscles, will be defended at the hip and favored as well as knee flexors.
Position yourself prone on the machine, with the kneecaps just outside the support surface and the pad placed immediately above the heels: from this position, flex the knees up to 90 °.
Avoid forcing the knee flexion angle to close excessively to prevent the affected muscles from losing tension.
Leg Curls: Practical Considerations
Having analyzed the three variants we now come to practical and common-sense conclusions to insert this exercise in a rational way in the training cards.
When to perform the leg curl machine? And in what modality?
- The three modes must certainly be performed with slow and controlled movements without forcing that alter posture. Avoid jumps that use excessive inertia to perform the movement, decreasing muscle tension.
- These are exercises to be limited for all those subjects with retracted hamstrings, also taking into account that these muscles are effectively activated as hip extensors even in exercises such as squats and lunges. It will be good to evaluate for these people an optimal program of lengthening of the posterior chain and not of reinforcement in maximum shortening of the same.
- Instead, it is recommended to use leg curls as a complement after more functional exercises and not as the protagonist of the routines, especially for beginners. For the advanced with good flexibility of these muscles and looking for harmonious development and muscular details the prone variant with a slightly flexed hip is recommended.
- It is true that by its nature the leg curl puts tension on the posterior ligament. This ligament is much more robust and vascularized than the anterior cruciate colleague and if healthy it can easily and effectively counteract the posterior translation force inflicted on the tibia.
- Attention only in cases of the previous clinical history of injury or reconstruction of this ligament in these cases it will be essential to carefully evaluate case by case and it may be advisable to eliminate the exercise from the routine especially if it generates subjective symptoms of the painful knee.