Lying Leg Curl vs Seated Leg Curl

You’re standing in the gym, looking at two different machines designed to do the same thing: work your hamstrings. One has you lie on your stomach, the other has you sit down. You’re probably wondering if it even matters which one you choose. The debate over the lying leg curl vs seated leg curl isn't just about comfort; one is significantly better for muscle growth.

Key Takeaways

• The seated leg curl is superior for hamstring growth, potentially building up to 50% more muscle mass than the lying version over time.
• This is because the seated position trains the hamstrings while they are stretched at the hip, a principle called lengthened-position training.
• The lying leg curl is still useful for targeting the outer part of the hamstring (biceps femoris short head) and can be more comfortable for people with lower back sensitivity.
• For maximum growth, start your workout with heavy seated leg curls for 3-4 sets of 6-10 reps.
• Use the lying leg curl as a secondary or finishing exercise for 2-3 sets of 10-15 reps to work the muscle from a different angle.
• You cannot fully develop your hamstrings with curls alone; you must also include a hip-hinge movement like a Romanian Deadlift (RDL).

What's the Real Difference? (It's All in Your Hips)

When comparing the lying leg curl vs seated leg curl, the seated version is definitively better for building bigger hamstrings-by as much as 50%-because it trains the muscle in a stretched position. It’s not about personal preference; it’s about biomechanics. The key difference isn't whether you're sitting or lying down, but the angle of your hips.

Your hamstrings are a group of three muscles on the back of your thigh. Two of these three muscles (the semitendinosus and semimembranosus, plus the long head of the biceps femoris) cross two joints: the knee and the hip. This means they perform two main actions: bending your knee (knee flexion) and extending your hip (pushing your hips forward).

Think of your hamstrings like a rubber band attached to your butt bone and the back of your knee.

On the seated leg curl machine, your hips are bent at a 90-degree angle. This position pulls the rubber band taut at the hip attachment point *before you even start curling*. You are training the muscle from a stretched, or lengthened, position. Training a muscle when it's under stretch creates more mechanical tension and has been shown to trigger significantly more muscle growth.

On the lying leg curl machine, your hips are flat (extended). This leaves slack in the rubber band at the hip attachment point. The muscle is in a shortened, or contracted, position at the hip. While it still works to bend your knee, it misses out on the powerful growth stimulus that comes from being trained under a deep stretch.

This is why you can often lift more weight on the lying leg curl. It's an easier position for the muscle. But easier doesn't mean better. The seated version forces the hamstrings to work harder through a more challenging range of motion, leading to better results.

Build stronger legs, workout by workout.

Track your leg day lifts. See your strength grow week by week.

Start your 7 day free trial

Why the Seated Leg Curl Is the Clear Winner for Growth

The science and real-world results are clear: if your primary goal is bigger hamstrings, the seated leg curl should be your priority. The principle is called hypertrophy in the lengthened position.

When you load a muscle while it's stretched, you create tiny micro-tears in the muscle fibers, particularly when you control the negative (the lowering phase of the rep). Your body responds to this by repairing the fibers and making them bigger and stronger to handle the stress next time. The deep stretch of the seated leg curl maximizes this process.

Here’s what that means for you in the gym:

1. More Mechanical Tension: The seated position puts the hamstrings under constant tension throughout the entire set. There's no resting point at the top or bottom, which forces more total work on the muscle.
2. Greater Muscle Activation: By starting from a stretched position, you recruit more muscle fibers from the very first rep. This leads to more effective sets and faster growth over time.
3. The Weight Feels Heavier (And That's Good): You will almost certainly have to use less weight on the seated leg curl than the lying version. Do not let your ego get in the way. This is a sign that you are placing more direct tension on the target muscle instead of using momentum or other muscle groups to help.

If your gym only has one of the two machines, you can still build great hamstrings. But if you have the choice, dedicating your primary effort to the seated leg curl will give you a much better return on your investment. A good target is to perform 3-4 sets in the 6-10 rep range, focusing on a slow, 3-second negative on each rep.

So, Is the Lying Leg Curl Useless?

Absolutely not. Just because the seated curl is superior for overall mass doesn't mean the lying leg curl has no place in your routine. It’s a different tool for a slightly different job. Think of it as a flathead screwdriver versus a Phillips head-both are useful, but you need the right one for the task.

Here are three specific situations where the lying leg curl is the better choice:

1. Targeting the Outer Hamstring

Your hamstring complex has multiple parts. The lying leg curl, with the hips in extension, allows for a slightly better contraction of the biceps femoris short head-the part of your hamstring on the outside of your leg. While the seated curl is king for overall mass, the lying curl can be a great accessory movement to ensure complete development.

2. When Your Lower Back Is an Issue

For some individuals, especially those with tight hip flexors, the 90-degree hip flexion of the seated curl can cause discomfort or pinching in the lower back. The lying leg curl keeps the spine in a more neutral position, taking the hips out of the equation. If you find the seated version consistently bothers your back, the lying curl is a perfectly effective alternative.

3. As a High-Rep Finisher

Because you can typically handle more weight and it’s a less neurologically demanding movement, the lying leg curl is an excellent exercise to finish your hamstring workout. After your heavy seated curls and RDLs, you can use the lying curl for higher reps (e.g., 2-3 sets of 12-20 reps) to chase a pump, flood the muscle with blood, and create metabolic stress-another driver of hypertrophy.

Don't think of it as lying vs. seated. Think of it as a 1-2 punch: seated for the heavy blow, and lying for the finishing touches.

Your leg day progress. All in one place.

Every set and rep logged. Proof your hamstrings are getting stronger.

Start your 7 day free trial

How to Program Both for Complete Hamstring Growth

Knowing the difference is one thing; putting it into practice is what gets you results. You don't have to choose one over the other forever. The best approach is to use both strategically within your training week.

Here is a simple, effective framework for building your hamstrings using both machines. This should be done 1-2 times per week, with at least 48-72 hours of rest in between.

Step 1: Start with the Growth Driver (Seated Leg Curls)

Begin your hamstring training with the seated leg curl. You are freshest at the start of the workout, so you can apply the most intensity to the exercise that delivers the most bang for your buck.

• Sets & Reps: 3-4 sets of 6-10 reps.
• Execution: Focus on the negative. Curl the weight up powerfully over 1 second, squeeze for 1 second at the peak contraction, and then lower it slowly over 3 seconds. Control is everything.
• Weight: Choose a weight that brings you to near-failure in the target rep range. The last 1-2 reps of each set should be a serious struggle.

Step 2: Add the Hip Hinge (Romanian Deadlifts)

Curls only train one function of the hamstring (knee flexion). To fully develop the muscle, you must also train hip extension. The Romanian Deadlift (RDL) is the best exercise for this.

• Sets & Reps: 3 sets of 8-12 reps.
• Execution: Keep a slight bend in your knees but don't turn it into a squat. Hinge at your hips, pushing your butt back while keeping your spine straight. Lower the weight until you feel a deep stretch in your hamstrings, then drive your hips forward to return to the start.

Step 3: Use the Finisher (Lying Leg Curls)

End your hamstring workout with lying leg curls. By now, your hamstrings will be fatigued from the heavy seated curls and RDLs. The goal here is not to lift heavy but to isolate the muscle and chase a pump.

• Sets & Reps: 2-3 sets of 12-20 reps.
• Execution: Focus purely on the mind-muscle connection. Squeeze your hamstrings as hard as possible at the top of each rep. Don't worry about a slow negative; the goal is blood flow and metabolic stress.
• Weight: Use a lighter weight that allows you to complete the high-rep sets with good form.

This three-exercise combination hits your hamstrings from all angles and with different mechanical principles, ensuring no stone is left unturned.

Frequently Asked Questions

Which is better for bad knees?

Both the seated and lying leg curl are generally safe for knees because they are isolation movements that don't put compressive force on the joint like a squat. The seated version provides more stability. The key is to start with very light weight and perform the movement slowly to ensure no pain.

Can I use a dumbbell instead?

Yes, the dumbbell leg curl is a great substitute for the lying leg curl, especially for home workouts. Lie face down on a flat bench and squeeze a single dumbbell vertically between your feet. It's more challenging to stabilize, but it effectively targets the hamstrings.

Should my toes be pointed or neutral?

Foot position can slightly change the emphasis. Pointing your toes inward (pigeon-toed) will target the inner hamstrings (semitendinosus/membranosus). Pointing your toes outward will target the outer hamstring (biceps femoris). For general development, start with a neutral foot position.

Why do I feel it in my lower back?

On lying leg curls, feeling it in your back is a classic sign your hips are lifting off the pad to cheat the weight up. This means the weight is too heavy. Lower the weight and focus on keeping your hips pressed firmly into the pad throughout the entire set.

How often should I train hamstrings?

For most people, training hamstrings directly 1-2 times per week is optimal. They are a large muscle group that receives some stimulus from squats and deadlifts, but they need direct work to grow. A single, intense session like the one outlined above is often enough for great results.

Conclusion

Stop thinking about it as an either/or choice. The seated leg curl is your primary tool for building mass, and the lying leg curl is your tool for adding detail and volume.

Use them both as intended, stay consistent, and your hamstrings will have no choice but to grow.