Main muscles worked
hamstrings, lower back
Capsule description
with resistance against your heels, lift your heels toward your hips
The leg curl provides direct exercise for the hamstrings—the three muscles of the rear thighs. This is important for developing healthy, balanced musculature around the knees and hips. There are also aesthetic benefits—a curve to the rear thigh, which in turn helps offset the protrusion of the buttocks.
Set-up
Lie face-down on a leg curl bench. The bench shouldn’t be flat, but have a hump where your hips are placed. Place your heels beneath the resistance pad. It’s essential that you line your knees up correctly—center of your knees in line with the center of the pivot point of the machine. The correct set-up will have your kneecaps positioned just over the edge of the bench—not on the bench itself.
Where the resistance pads are positioned is adjustable on some machines. If you use an adjustable machine, set the resistance pads so that they are flush with your ankles when your knees are straight and in the correct position.
If you use a machine with a range-of-motion limitation control, set it at the fullest safe setting for you. You would need to experiment, with minimal resistance, to find what this range of motion is for you. If there’s no range-of-motion control, do it yourself—don’t lower your heels all the way down to the position of straight knees if that’s excessive for your knees. Instead, maintain a slight degree of flexion even at the bottom (starting) position—an inch or two short of your knees being straight.
If you use a selectorized leg curl machine you may be able to delimit the range of motion manually. Remove the pin from the weight stack, then grip the cable that’s attached to the guide rod that runs through the weight stack, and lift it. The top weight plate will rise alone, revealing the guide rod. Expose two holes on the rod, for example, then use the pin to select the required weight. The gap between the first and second weight plates indicates the reduction in range of motion. Fine-tune the extent of the reduction according to what’s required to produce the maximum safe range of motion for you. Make a note in your training log of the setting.
How to manually delimit the range of motion using a selectorized weight stack. See text.
The procedure for delimiting the range of motion in the leg curl can be used for other selectorized machines, when excessive stretching needs to be avoided, such as the machine pullover.
Performance
Grasp the handles or other gripping sites in a symmetrical manner, and hold them lightly—just sufficiently to stabilize yourself. Don’t involve your upper body in the leg curl. Keep your hips firmly against the bench, and lift your head and shoulders slightly off the bench. Face forward or to the floor—don’t turn your head to the side. Pull your toes toward your shins—opposite of pointing your toes—and keep them in that position throughout the set.
Slowly and smoothly lift your heels as far toward your hips as is comfortable. Hold the position of fullest contraction for a second, then smoothly lower your heels to the starting position. Pause for a second, then repeat. There must be no sudden or jerky movements. Move smoothly up, and smoothly down, about three seconds for each phase, plus a second for the pause at the top, and another second for the pause at the starting position. Exhale on the ascent, inhale on the descent.
During the ascent of your feet, your hips should come off the bench slightly, to permit full contraction of the hamstrings. Your hips should rise no more than one inch. Any more than that will overstress your lower back through excessive extension of your spine, which can cause injury. Excessive lifting of the hips also reduces the work done by your hamstrings.
The start of the rep must be done with great care—ease into it, don’t heave the weight. After the final rep, when lowering the weight to its resting place, place it gently.
Options for leg curl machines
Some manufacturers produce leg curl machines for seated or standing work, one leg at a time in some cases. Some provide work for both limbs simultaneously, but each thigh may have independent resistance so each would perform its full share of the work.
The standing leg curl is a unilateral movement that usually leads to technique flaws, including a torso twist, and uneven stresses on the spine and torso from the asymmetrical loading.
If there’s more than one leg curl machine where you train, find the one that feels best for you. For trainees with back problems, the prone and standing leg curls may irritate the back even when done with correct technique. Try the seated version instead. Generally, the seated leg curl is the pick of the machines—for comfort, maintenance of correct technique, and isolation of the hamstrings. During the seated leg curl, however, never press down on your thighs—there should be no exaggerated compression of your hamstrings.
Seated leg curl.
Adding weight
Selectorized cable units, and selectorized machines in general, commonly have weight increments of 10 pounds or 5 kilos, and larger in some cases. This is too much weight to progress by in a single jump. Where you train may have special weights of 5 pounds or 2.5 kilos—and perhaps smaller ones, too—designed to fit on the top of a weight stack. If it doesn‘t, you may be able to get your own from an exercise equipment store. Use them to help you to work from one pin setting to the next.
Alternatively, place the weight selection pin through a small barbell weight plate before the pin goes into the weight stack. Although a pin that holds a plate won’t go fully into the weight stack, it should go through enough to hold the plate securely and select the resistance, too.
Magnetic small plates are another option for adding small increments of weight to a stack.
Whichever option you choose, check that the set-up is secure before you perform a set.
Origin of “hamstrings”
The three thigh muscles of the posterior or rear thigh are usually referred to as the “hamstring” group. This is because tendons of those muscles are used by butchers to attach curing hams to meat hooks.