If your leg days are all about squats (and other quad-dominant exercises), listen up: You might be setting yourself up for an injury. Many of us pay too much attention to the muscles on the front of our legs while ignoring the backs of our thighs (aka our hamstrings). Problem is, this can lead to crappy stuff like muscle imbalances, compensations, and, eventually injury (especially because weak hamstrings can make you more prone to knee and hip problems). The solve? More lying hamstring curls.

It’s in your best interest to keep your leg muscles in proportion. To do that, you need to show your hammies some special TLC, and hamstring isolation exercises are the way to go. Arguably, there’s no better way to target these muscles than the lying hamstring curl.

We know it’s a bit old school, but trust us: it works. Here’s how lying leg curls can level up your lagging hamstrings (and your overall fitness).

How to do a lying hamstring curl with perfect form every time

1. 1.
   Load the machine with a weight that’s going to be challenging but doable for 8 to 10 reps.
2. 2.
   Lie face down on the machine with your legs stretched out fully. Place the roller pad a few inches above your heels on your lower calves. Hold the handgrips on each side of the machine for support.
3. 3.
   Exhale and bend your knees, pulling your feet as close to your butt as you can. Keep your hips square and glued to the bench.
4. 4.
   Hold at the top of the movement, squeezing your hamstrings briefly, then inhale as you slowly lower your feet to the starting position.

TIP

To really hit your hamstrings, flex your feet during the movement, curling them toward your shins.

Lying hamstring curls: muscles worked

As the name implies, the lying hamstring curl primarily strengthens the hamstrings, the group of muscles that run along back of your thigh from your hip to your knee, says Julianne Lane, PT, DPT, CSCS, a physical therapist at Bespoke Treatments in San Diego.

But they also work other big muscle groups in the posterior chain, says Brooke Van Paris, CPT, a personal trainer at Life Time Boca Raton. These include the:

• Gastrocnemius and soleus (aka your calves): when contracting (or lifting up the weight)
• Gluteus maximus (aka your butt): when lowering the weight

Who should (and shouldn’t) do lying hamstring curls

Lying hamstring curls are for you if you’re looking to improve:

• Muscular balance
• Speed
• Balance
• Movement patterns
• Range of motion
• Injury prevention
• Quality of life

In other words, just about anyone—from strength athletes to body builders and weekend warriors—could benefit from repping out lying leg curls, Dr. Lane and Van Paris agree.

That said, lying hamstring curls can be tricky (or even a tad troublesome) for certain people, according to Dr. Lane and Van Paris. Steer clear of the curl machine if you fall into any of these groups:

• People with pain, injury, or a recent surgery in the knees, hips, back, or neck
• Pregnant people

Still not sure whether it’s safe for you to crank out lying leg curls? Consult a professional. “Talking with your doctor before starting a weight training program is best,” Dr. Lane says. Likewise, “if you work with a physical therapist or trainer, check with them for guidance on using the lying hamstring curl machine.”

5 benefits of lying hamstring curls

If lying leg curls aren’t already part of your weekly workout routine, here are five solid reasons to put them into rotation.

1. Stronger, more flexible hamstrings

This one’s pretty obvious given the name of the exercise. Still, it bears mentioning because, honestly, you can’t overstate the importance of healthy hamstrings. You need them to walk, climb stairs, do squats, and execute countless other movements.

Lying hamstring curls put your hamstrings under constant load, targeting these muscles in two ways. First, “the concentric contraction (pull) helps promote muscle hypertrophy,” meaning it makes the muscle bigger, Dr. Lane says. Secondly, “the eccentric contraction (stretch) helps promote tissue lengthening,” she says. In other words, it builds long, limber, flexible muscles.

Van Paris agrees: The lying hamstring curl is a great way to lengthen and stretch the hamstrings, as it takes the muscles through their full range of motion. By improving flexibility, you also enable your hammies to activate through their entire range, she says.

That’s a big bonus: Most people struggle with “chronically shortened” hamstrings thanks to “prolonged sitting and lack of movement in our day-to-day lives,” Van Paris says. And when your hamstring muscles stay in a tightened, short position, it can lead to muscular imbalances, weaknesses, and, down the line, injury.

2. Enhanced sports performance

Want more speed and agility on the field or the court? Start cranking out lying hamstring curls.

“The hamstring muscles are crucial for explosive strength,” Dr. Lane says. That’s because they “help with sprinting acceleration, jumping, change of direction, and deceleration,” she says. Pretty much all the things you need to up your game whether you run, cycle, play tennis, soccer, pickleball, or any other sport.

Hamstring strength is also crucial to keep you sidelined from a sports injury. “Having strong and flexible hamstrings helps to prevent injury by slowing the leg in its eccentric movement phase of walking and running,” Van Paris says. Essentially, this “prepares the joints for contact with the ground,” she says. So whenever you need to pivot on a dime or stop short, you can do it without stressing out your joints or muscles.

3. Better balance

Facts: If you want to stay steady on your feet, you need strong, healthy hamstrings.

Balance may not be super sexy, but it is super important, especially as you get older and falls become more likely (every year, one in four older folks will take a tumble, and one-fifth of these falls will cause a serious injury, such as broken bones or a head trauma, per the Centers for Disease Control and Prevention).

So what’s the link between balance and hammies? “Hamstring strength aids in stabilizing the lower-body joints and improves reaction to quick changes in the environment,” Van Paris says.

Specifically, “the hamstrings help to improve balance by working synergistically with the quadricep muscles,” Dr. Lane says. By building your hammies with lying leg curls, you can “create more limb symmetry and stability” and “complement popular quad-dominant exercises such as leg presses and squats,” she says.

4. Improved posture

If you sit at a desk all day, odds are your posture needs a little love (no judgment, we’re in the same boat). Sitting for extended periods (especially if slouched or slumped) tends to put strain on your neck and back. Plus, it shortens your hip flexors. All of this is bad news for posture (not to contributes mention aches and pains).

Having healthy hamstrings can help offset some of these postural problems. Hamstring strength “aids in improving posture by increasing the alignment of the pelvis and spine,” Van Paris says.

For better posture (and less pain), it’s also a wise idea to stand, stretch, and take a quick stroll every half hour—your body will thank you.

5. Fewer knee and hip injuries

As we mentioned, strong, limber hammies can help prevent you from getting hurt. Together with the quadriceps, the hamstrings work to “help significantly stabilize the hip and knee joints,” Van Paris says.

By protecting your joints in this way, you “reduce the risk of soft tissue injury while accelerating, running, and decelerating at higher speeds,” Dr. Lane says. “In particular, the lateral hamstring, [the] biceps femoris, helps to reduce the risk of ACL injuries, knee shearing forces, and twisting,” Van Paris adds.

Old knee and hip pain and injuries can crop up as we get older, so you might want to start strengthening those hamstrings now by doing lying leg curls to nip future issues in the bud. As they say, an ounce of prevention is worth a pound of cure.

3 common mistakes when doing lying hamstring curls

Lying leg curls can help you build long, strong hamstrings, but only if you perform them with proper form. If you don’t do the exercise correctly, it won’t be as effective. “Without good form, you could be working a completely different muscle group than intended,” Van Paris says. Plus, you can end up in pain (or even injured).

Avoid these common mistakes when you use the lying hamstring curl machine.

1. Leg pad too high

When the machine’s ankle pad or roller is too high on your calves, “it will increase pressure on the Achilles tendon and reduce your range of motion,” Dr. Lane says. In other words, it will feel uncomfortable and won’t work your muscles in their full range. A double no-no.

So what’s the optimal place for the ankle pad? It should be “resting on the calf muscles a few inches above the heels,” she says.

To be sure you have the right positioning, you can always ask a fitness pro like a trainer or physical therapist at your gym. They can help adjust the pad if needed.

2. Pointed toes

If you trained in ballet or often do barre classes, you probably have a tendency to point your toes. But this habit won’t help you during lying leg curls. While pointed toes aren’t a bad thing, per se, this toe position will work your calves more than your hamstrings, Van Paris says. For the full hamstring effect, keep your toes flexed, she says.

3. Incorrect weight choice

“One of the most common mistakes people make is using too heavy of a weight,” Dr. Lane says. “This will cause the person to compensate by lifting their hips and potentially arching their back under load.” It might even lead to lower back pain.

“If you cannot reach 8 reps with good, controlled form, then you have gone way too heavy.”—Brooke Van Paris, CPT

So how heavy is too heavy? Van Paris recommends choosing a weight that you can lift for 8 to 12 reps per set. “If you cannot reach 8 reps with good, controlled form, then you have gone way too heavy,” she says.

On the other hand, “if you reach 12 to 15 reps, and you feel like it was pretty easy, and you have more gas still in the tank, you have gone too light with the weight,” Van Paris says.

Alternatives for lying hamstring curls

While the lying hamstring curl is a truly excellent hamstring exercise, it’s not advisable for certain peeps (like those with knee, hip, back, or neck problems and pregnant people). Even if you don’t fall into these groups, you might not love lying hamstring curls (hey, different strokes, right) or maybe you simply don’t have access to a machine. Luckily, there are plenty other options that target your hammies just fine. Try one of these alternatives.

1. Stability Ball Hamstring Curl

Balancing on a stability ball requires a lot of hip and core stability. Translation: Both your hammies and abs will be on fire.

1. 1.
   Lie on your back on a mat, placing your heels about hip-width apart on the stability ball and your toes pointing toward the ceiling.
2. 2.
   Brace your core muscles and extend your arms out to your sides with palms turned to the floor to help stabilize your body.
3. 3.
   Gently exhale and press your hips up off the floor, squeezing your glutes, until your legs and hips are in a straight line. At the same time, press your heels into the ball for additional stability.
4. 4.
   Exhale as you slowly move your heels toward your hips and raise your hips farther off the floor, pulling the ball toward you.
5. 5.
   Inhale and slowly reverse the movement, lowering yourself back toward your starting position.

2. Romanian Deadlift

Not only do RDLs hit your hamstrings, they also build back, core, and grip strength.

1. 1.
   Stand upright with your feet shoulder-width apart and hold a dumbbell in each hand at your sides.
2. 2.
   Start by bending your knees slightly. Keep your chest tall as you reach your hips back behind you. You should feel a stretch in your hamstrings. Keep the dumbbells close to your legs.
3. 3.
   Reach your hips back as far as you can without rounding your low back or your shoulders.
4. 4.
   Push through your feet and squeeze your glutes as return to the starting position.

3. Kickstand Deadlift

In this position, also known as a single-leg deadlift, you can isolate one leg at a time, which improves strength and balance.

1. 1.
   Start with your feet together, holding a dumbbell in each hand in front of your thighs.
2. 2.
   Step your right foot a few inches back so that your right toes are in line with your left heel but just a few inches to the right. You’ll use these toes for balance.
3. 3.
   Keeping your left knee slightly bent, hinge forward, pushing your hips backward.
4. 4.
   Continue lowering the dumbbells until your upper body is almost parallel to the floor.
5. 5.
   Keeping your back flat, brace your core and push through your left foot to return to standing.
6. 6.
   Do all your reps on one leg, then repeat on the opposite side.

4. Seated Hamstring Curl

Got back issues? The seated hamstring curl machine supports your lumbar spine and core much better than lying leg curls, Dr. Lane says.

1. 1.
   Sit in the leg curl machine with your feet hip-width apart and the ankle pad resting on your lower calves.
2. 2.
   Brace your core and lock your shoulder blades back and down, then squeeze the back of your legs as you drive your heels down as far as possible without arching your lower back.
3. 3.
   Reverse the movement slowly, returning to the starting position.

Frequently asked questions

Is the seated hamstring curl better than lying?

“No option is better or worse than another—both isolate the hamstrings and allow for knee flexion—but each have their benefits,” Van Paris says. It just depends on your goals. For example, if your aim is to build muscle, you may prefer seated leg curls.

“Research shows that for muscle hypertrophy (muscle growth), the seated hamstring curl reigns king,” Van Paris says. Dr. Lane agrees, citing an April 2021 study¹ in Medicine & Science in Sports & Exercise: The researchers “compared 20 healthy adults, who completed seated leg curls with one leg and lying leg curls with the other leg. The individuals performed 5 sets of 10 reps, twice a week for 12 weeks.” After the 12 weeks, they concluded that seated leg curls produced greater increases in muscle volume.

OK, but why are seated curls superior for muscle growth? “The seated hamstring curl machine trains the hamstring in a [more] lengthened position,” Dr. Lane says. “This puts the hamstring on stretch, which allows the muscle to contract through a larger range of motion.” The greater the range of motion, the greater the muscle activation, recruitment, and growth.

Still, Van Paris points to a few drawbacks of sitting: “In the seated position, the hip flexors are in that same chronically shortened position that we see in day-to-day life.” Whereas with lying leg curls, “the muscles and body can move more freely and naturally,” she says. Lying hamstring curls also offer more trunk stability and support, so they’re a better choice for people with low back issues, Dr. Lane adds.

Do lying hamstring curls hit the glutes?

Sure do. While prone leg curls primarily strengthen the hammies, they also put your butt muscles to work. Specifically, your gluteus maximus kicks in during the eccentric phase of the movement (when you lower the weight), Van Paris says.

What is a good weight for the lying hamstring curl?

This “will vary drastically depending on your athletic history, type of sport you are training for, and your body composition,” Dr. Lane says. For instance, if you’re a gym newbie, you might start with a lighter load. But if you already have baseline strength in your legs, you might go heavier. Either way, finding the right weight may “take some trial and error,” she says.

While everyone’s sweet spot will be different, here are a few guidelines to help you calculate how much you should lift on the lying leg curl machine, per Dr. Lane:

• To grow your muscle size (hypertrophy): You want to do 2 to 3 sets of 8 to 12 repetitions at 60 to 80 percent of your 1 repetition max (1RM), with the last 1 to 2 reps being close to failure.
• If you are an endurance athlete (running, biking, swimming, etc.): You want to do 2 to 3 sets of 12 to 15 reps below 60 percent of your 1RM, with the last 1 to 2 reps being close to failure.

But how much you lift is only part of the equation. “No matter what the weight,” the key is “keeping good form the entire way through” the exercise, Van Paris says. “If you cannot maintain good form and mind-to-muscle connection,” you need to drop a few plates, she says.

Here’s a quick way to assess whether you’re lifting the right amount, per Van Paris:

• If you can’t reach 8 reps with controlled form, your weight is too heavy.
• If you reach 12 to 55 reps and think, “piece of cake,” your weight is too light.