By Jimmy Pena, MS, CSCS
Seated Leg Curl
Probably one of the most important and yet basic aspects to remember during the seated leg curl is to lock yourself into place extremely well. Many people fail to realize the leg curl is an isolation exercise, but when you’re seated like this, extra movement will detract from the effectiveness of the apparatus. The pad or belt should be so tight that you can’t move whatsoever. Also important is to make sure you don’t overextend at the top of the range of motion. You want to stop the movement an inch or so away from full knee extension to keep tension in the target muscles but also to avoid wear and tear on the knees. Although extending your legs completely is fine during leg extensions, here the weight is below the Achilles tendons and your upper legs are fixed. Not stopping the momentum could cause severe injury.
Both exercises work the hamstrings, but which is better at targeting the inner hamstrings?
Lying Leg Curl
Definitely the more popular of the two exercises, the lying leg curl should be a staple in your hamstrings repertoire. Make sure you keep your hips down as much as possible. A little body english toward the end of a working set is okay, but to fully maximize the movement and avoid injury, a strict hips-down approach is best. Another mistake you’ll often find is the tendency to raise your head and look up during the set, but this practice can put severe strain on your cervical spine. If you haven’t tried intensity techniques on the lying leg curl, a great one to use is the drop set. Pulling the pin and going a little lighter after an initial failure is quick and easy, a great aspect of selectorized machines.
ADVANTAGE: Seated Leg Curl
The hamstrings are composed of three major muscles. The first is the biceps femoris, which is the outer muscle with two heads. One crosses the hip joint and attaches to the pelvis, while the other attaches to the femur (thigh bone). The second and third muscles are the semitendinosus and the semimembranosus, which make up the inner portion of the hamstring. Both cross the hip joint.
When you’re doing a lying leg curl, your legs are relatively straight in relation to your torso. Research shows this body position causes the biceps femoris (outer hamstring) to get more emphasis. However, in seated leg curls your legs are bent at the hips about 90 degrees in relation to your torso. This bend stretches the semitendinosus and semimembranosus -- the inner hamstring -- with better success, so they get worked harder in this position. While we encourage you to do both seated and lying leg curls in your routines from week to week, if your inner hams are having trouble catching up, we suggest you take a seat so that they can.