Most hardcore lifters have a decidedly sour opinion of leg curls, often penciling the various permutations of the exercise into their big book of lame exercises next to cable triceps kickbacks and the good-girl/bad girl machine.
The classic hip extension staples like the glute ham raise, back extension, and reverse hyperextension are nearer and dearer to most strong guys' hearts, but I'm here to argue that not all leg curls be reserved for the females and fancy boys. Fact is, with a few MacGyver tweaks, leg curls can deliver one whale of an ass whipping.
A year and a half ago, I co-wrote an article with Bret Contreras that discussed all things hamstring. We covered why they're so important, the functional anatomy, and different exercises you can employ to hammer them effectively and efficiently.
I'll spare you the rehashing, so here's the Cliff's notes version:
The hamstrings have two primary functions: hip extension and knee flexion. Machine leg curls focus solely on the knee flexion component of the hamstrings, and while I certainly don't think they'll hurt you, it's not the best use of your valuable training time.
I prefer the following leg curl variations instead because they train the hamstrings through both of their primary functions while working the glutes at the same time, giving you a far greater bang for your buck.
If you don't give a damn about function and just hope to fill out your jeans better and maybe get a few double takes from the occasional lonely housewife, these exercises are damn fine options as they also do a great job of accentuating the eccentric component of knee flexion.
I can personally attest that my hamstrings have grown quite a bit in the last year since adding these exercises into the mix. I resisted them at first as they seemed a little too much like something Anderson Cooper would do between sets of curls with a blow dryer, but once I got over myself and tried them, I knew right away that they'd become mainstays in my routine.
As an added bonus, they're also easy on the lower back and don't require a lot of expensive fancy equipment or machines.
All the exercises below share a few common form cues so I'll get those out of the way up front to avoid sounding like a broken record.
Lie supine on the floor with your knees bent at approximately a 90-degree angle. Push through your heels and bridge up until your body forms a straight line from your shoulders to your knees. It's crucial that you maintain this position for the entire set. The torso and hips should remain still while the primary movement comes from the knee joint.
This means that the glutes (and secondarily, the hamstrings) work to keep the hips extended while the hamstrings work concentrically to flex the knee and eccentrically to control knee extension.
If you're unable to keep the hips extended (i.e. you find your hips sagging), it's a sign that you should regress to an easier variation for the time being.
Likewise, if you're feeling it a lot in your lower back, you aren't using your glutes enough and are compensating by hyperextending at the lumbar spine. This may just be a form flaw that needs cueing, or it may mean that you need to regress to something a bit easier.
Don't let the thought of regressing drum up all sorts of painful childhood memories of being picked last in every pickup softball game. You're much better off stepping back and doing it right versus attempting something more difficult than what you're ready for.
Even if you think you're strong already, I still recommend starting with the more basic variations first, as these exercises will challenge your hamstrings in ways you've never felt before and will take some getting used to.
#1 – Valslide Leg Curls
Valslides are an economical, portable replacement for a slide-board. Since most commercial gyms won't have a slide-board readily available, this is something you can put in your gym bag and bring with you, or even use at home.
They'll work on turf, carpet, wood; pretty much any surface other than rubber. For you exceptionally cheap bastards, some furniture sliders will work similarly to the Valslides; just make sure they're at least big enough to cover your entire foot or else they won't glide as smoothly.
Cost aside, I like using the Valslides more for leg curls because there's more friction (meaning it's harder) and you can move your legs freely and independently of one another without being limited by the narrow width of the slide-board.
Starting in a supine bridge position with your tibia perpendicular to the floor and your heels on the center of the slide pads. Slowly slide your feet out until your legs are fully extended, making sure to keep your hips up as you lower down.
Once you reach full extension at the bottom, squeeze your glutes and pull through your heels to return to the starting position.
Another cool thing about this exercise is that it keeps constant tension on the hamstrings because you actively have to push out on the eccentric and pull back on the concentric.
If you find you aren't able to transition from the eccentric to the concentric without dipping your hips, regress to doing only the eccentric portion of the rep. This means you'd bridge up as normal, lower yourself down to full leg extension, touch your butt to the floor, slide your feet back up to the starting position, and repeat. When you can do a set of eight controlled eccentrics you should be able to handle the full version.
#2 – Resisted Valslide Leg Curls
Once you can comfortably knock out a few sets of 8-10 reps using the regular version, it's time to make it harder.
One simple way to do so is to put a weight plate on top of two Valslides to increase friction.
Place the slides parallel to each other as close to the edges of the plates as possible and position them so that they track straight out. While your feet will be on top of the plate, try to line them up with the pads underneath the plate as best you can to ensure the plate slides freely without rubbing against the floor. Here's what it looks like in action:
Another way to add resistance is to drape chains (or something similar) over your hips. Whereas putting plates over the slide pads increases the difficulty for the hamstrings, loading the hips increases the difficulty for the glutes by making it harder to maintain a good bridge position. It won't take much additional load to notice a big difference.
As always, it's important to keep the hips up throughout the set, so if that's not possible, the weight is too heavy. It should look like this:
If you're feeling particularly frisky and/or masochistic, you can also overload the hips with heavier weight and just perform the eccentric portion of the rep. I'll warn you right now though, these burn something crazy.
#3 – Valslide "V" Leg Curls
Another way to up the ante on Valslide leg curls without adding additional load is to perform them in a "V" fashion. I actually call these "Spread 'ems" in my training log, but I suspect that name won't find its way into your favorite mainstream fitness magazine. "Dirty Girls," however appropriate, likely won't make the cut either.
In any case, it's just like a regular Valslide leg curl, only rather than extending your legs straight out, you extend them out at an angle, again making sure to keep the hips elevated.
This introduces a frontal plane component to the exercise and fries the glutes through hip abduction. The further out to the sides you extend your legs, the more you'll feel your glutes, and the harder it'll be. Start with the feet closer together and gradually angle them out further as you get stronger. In other words, start with good girls before tackling the dirty girls.
Once you've got these down, try them "offset V" style where one leg extends straight ahead and the other goes out at an angle. I prefer to do these in alternating fashion switching sides between reps.
These smoke the glutes in much the same way as regular "V" curls with an added unilateral element that increases the rotary stability demands on the hips and core.
#4 – Single-Leg Valslide Leg Curls
This is an awesome exercise, but transitioning from the double-leg version to the single-leg is a big leap, so make sure you've mastered some of the more advanced bilateral variations before attempting them.
It may also be prudent to start with single-leg eccentrics first.
When you do finally make the plunge into the full single-leg version, the same rules apply. Keep the torso steady, the hips level and extended, and keep the reps under control (i.e. no jerking).
If these feel easy, you're probably doing them wrong. With the hips flexed slightly and a bit of momentum I can do these all day, but using good form with the hips extended is really freakin' tough and 10-12 reps is a tall order.
#5 – Bridge Rollouts
If you can't get access to sliders for whatever reason, this exercise just requires a foam roller.
This is very similar to the concept of Valslide leg curls, only you have to inch your way out and back gradually as opposed to sliding. It also introduces a unilateral element because only one foot is in contact with the roller at a time.
These may look a little weird, but I strongly urge you to try them before rushing to judgment. If you do them correctly with the hips up, your hamstrings will be begging for mercy after just a few reps.
#6 – Glute Bridge Walkouts
If the bridge rollouts are too much at first, try these. They literally require no equipment whatsoever, so you've got absolutely no excuse.
Just bridge up and walk your feet out until your legs are extended and then walk back in to the starting position, making sure to keep your glutes engaged as you move. Think Valslide leg curls, only without the Valslides.
To make it harder and work the glutes more, walk your legs out at an angled, "V" style.
#7 – Stability Ball Leg Curls
I don't use the stability ball for much other than leg curls (okay, nothing other than leg curls), but I do like it for this application.
To make the regular version even better, try doing them with your heels together and the soles of your shoes facing each other. From there, perform the leg curl as normal, but push your knees out as far as you can. Like the Valslide "V" leg curls, this will significantly increase glute involvement.
You can also do them one leg at a time. I much prefer using Valslides for the single-leg version because it feels more stable since you don't have to worry about the ball rolling around, but if the ball is all you have available to you, it's certainly better than nothing.
This is one of those exercises I see butchered all the time though, so if you're going to do it, make sure you at least do it well. Hips up, control the reps, yada yada yada.
Putting It to Use
It's my hope to one day help rid the world of weak posterior chains and flat, dimply ass cheeks that resemble a pair of freezer-burnt toaster waffles. Could this article be a small step in that direction? At the very least, I hope I've changed the way you think about leg curls.
Remember though, for optimal posterior chain development, it's best to include a wide variety of exercises, so for best results combine these leg curl exercises with deadlifting and bridging variations.
Don't let poor programming and exercise selection hamstring your hamstrings.