Leg curls are one of the best exercises to truly isolate the hamstrings, helping build strength, stability, and power in these posterior chain muscles.
But, you may want to know, how many leg curls should I do to build muscle? How many leg curls should I do to increase strength?
In this guide, we will discuss how to do leg curls, a good leg curl weight to use, leg curl alternatives to add to your lower-body workouts, and ultimately answer your question, how many leg curls should I do to see results?
Let’s dive in!
How to Do Leg Curls
Before we look at how many leg curls to do to build muscle, increase strength, increase muscular endurance, or other fitness goals, let’s discuss how to perform leg curls properly.
Leg curls is a general term that describes a hamstring exercise where you curl your leg (beginning with a straightened leg and then bending your knee) against some form of resistance.
Generally, when people are discussing how to do leg curls or how many leg curls to do and a workout, they are referring to hamstring leg curls using a weight machine.
The leg curl machine is a weight training machine found in the gym that can be used to strengthen your hamstring muscles without needing free weights.
There are two general types of hamstring leg curl weight machines: seated leg curls and prone leg curls (lying on your stomach).
Although the body position changes in each of these leg curl machines, the leg curls exercise is similar in either setup in terms of the muscles worked by leg curls and the number of seated leg curls versus lying leg curls reps you should do.
That said, we will provide step-by-step instructions for how to do seated leg curls and prone lying leg curls.
Here are the steps for performing this hamstring workout exercise:
Lying Leg Curls
- Lie on your stomach on the leg curl machine with the backs of your ankles slipped underneath the pad.
- Keep your core tight and press your hips down, making sure to only move your lower legs by contracting your hamstrings.
- Squeeze your hamstrings to curl the weight up towards your butt. Think about “gluing” your hips and upper body down so that you are only initiating and controlling the movement from your hamstrings.
- Squeeze your hamstrings in the top position when your heels or the pad of the machine is all the way up near your bottom.
- Hold for 2-3 seconds.
- Slowly lower back down, aiming to extend the eccentric (lowering) portion as long as possible.
Here is how to do seated weight machine leg curls:
Seated Leg Machine Curls
- Sit upright in the leg curl machine with your back supported by the backrest, your hands lightly gripping the hand grips on either side of your hips, your chest up, and your legs secured under the pads. You should have the leg press machine adjusted so that your knees are at the edge of the seat and your back is supported by the backrest. The lower pad should be just behind your ankles at the very bottom of your shins above your Achilles.
- In the starting position, your legs will be straightened out in front of you with your feet hanging off the end, with the pad supporting your lower legs and feet out in front of you.
- After selecting the correct weight, press your lower back and hips into the machine to ground yourself.
- Then, contract your hamstrings to bend your knees and curl the pad towards your butt underneath the seat of the leg curl machine. Think about engaging your abs and core muscles to stay pressed against the back of the seated leg press machine.
- Pause once your knees are flexed as much as possible, squeezing your hamstrings.
- Slowly extend1Schoenfeld, B. J., Ogborn, D. I., Vigotsky, A. D., Franchi, M. V., & Krieger, J. W. (2017). Hypertrophic Effects of Concentric vs. Eccentric Muscle Actions. Journal of Strength and Conditioning Research, 31(9), 2599–2608. https://doi.org/10.1519/jsc.000000000000198your legs back to the starting position by resisting the pull of the weight machine.
Unfortunately, hamstring leg curls are often done with poor form, which can increase the risk of injury and increase the effectiveness of the exercise.
You need to isolate the workload to your hamstrings by not using momentum and not arching your back.
Moreover, in order to maximize the effectiveness of your leg curls reps, you need to move through the entire range of motion, straightening your legs all the way out and then bending your knee to bring your heel all the way up to your butt.
Alternatives to Leg Curls
If you do not have access to a gym where you can use weight machines for leg curl workouts, it is possible to strengthen the same muscles worked by leg curl weight machines in a few different ways.
Here are some variations of leg curls:
Stability Ball Hamstring Curls
- Lie on your back with your legs straight and your heels up on a stability ball. Place your arms at your sides with your palms down on the floor.
- Engage your abs and glutes to lift your hips up so that your body is in a straight line from your heels to your head. Your shoulder blades should be on the floor.
- Engage your hamstrings and glutes and press your heels into the ball as you bend your knees to roll the ball in towards your butt.
- Return to the starting position. Move slowly and with control.
The Nordic hamstring curl is a bodyweight hamstring exercise that can work as an alternative to weight machine leg curls.
Studies have found2Al Attar, W. S. A., Soomro, N., Sinclair, P. J., Pappas, E., & Sanders, R. H. (2016). Effect of Injury Prevention Programs that Include the Nordic Hamstring Exercise on Hamstring Injury Rates in Soccer Players: A Systematic Review and Meta-Analysis. Sports Medicine, 47(5), 907–916.that Nordic hamstring curls are an effective exercise for hamstrings in terms of injury reduction.3Bourne, M. N., Timmins, R. G., Opar, D. A., Pizzari, T., Ruddy, J. D., Sims, C., Williams, M. D., & Shield, A. J. (2017). An Evidence-Based Framework for Strengthening Exercises to Prevent Hamstring Injury. Sports Medicine, 48(2), 251–267. https://doi.org/10.1007/s40279-017-0796-x
Therefore, adding the Nordic hamstring curl to your workouts for hamstrings can potentially help keep your hamstrings healthy.
Nordic Hamstring Curls
- Kneel down with an upright torso on a pad or cushioned weight bench to improve the comfort of your knees.
- Have a partner hold down your ankles and feet, or find a secure bar or weighted object to hook your heels under to keep your feet anchored down.
- Cross your arms over your chest. As you get stronger, you can hug a weight plate to your chest.
- Keep your hips fully extended so that your body is in a straight line from your knees to your head.
- Fall forward as a plank, meaning your entire body from the knees rather than just hinging at the hips (aim to move your body from the knees to the head as one solid plank).
- Try to “fall“ towards the floor in a slow and controlled manner. If you are not using a weight, you can use your hands to lightly touch the floor and help you press back upward. As you get stronger, just squeeze your hamstrings to reverse the motion and initiate the concentric contraction back up to the starting position.
Gradually increase the angle through which you are moving, bringing your chest much closer to the floor as your hamstrings strength increases.
How Many Leg Curls Should I Do To See Results?
Your training goal plays the most significant role in helping guide the number of sets and reps of leg curls you should do, along with how much weight to lift for weight curls.
The following table provides recommendations for how many reps to do and how much weight to lift for different strength training goals based on the average guidelines from the American Council on Exercise (ACE)4How Many Reps Should You Be Doing? (n.d.). Www.acefitness.org. https://www.acefitness.org/resources/everyone/blog/5867/how-many-reps-should-you-be-doing/and the National Strength and Conditioning Association.5Sands, W., Wurth, J., & Hewit, J. (2012). The National Strength and Conditioning Association’s (NSCA) BASICS OF STRENGTH AND CONDITIONING MANUAL. https://www.nsca.com/contentassets/116c55d64e1343d2b264e05aaf158a91/basics_of_strength_and_conditioning_manual.pdf
| Training Goal | Sets | Reps | Rest Period | Intensity |
| General Fitness | 1-3 | 12-15 | 30 to 90 seconds | Varies on exercise and ability level |
| Muscular Endurance | 3-4 | >15 | Up to 30 seconds | <67% of 1RM |
| Hypertrophy (building muscle mass) | 3-6 | 8-12 | 30 to 90 seconds | 67% to 85% of 1RM |
| Muscle strength | 4-6 | 3-6 | 2 to 5 minutes | >85% of 1RM |
| Power | 3-5 | 1-5 | 2 to 5 minutes | 85%–100% of 1RM |
So, when you want to do leg curls to increase hamstrings strength, work up to performing 4-6 sets with 3-5 leg curls reps per set, using at least 85% of your one-repetition maximum (1RM) for the load.
When your primary goal is hamstrings hypertrophy (muscle growth) with leg curls workouts, you should build up to performing at least three sets of each exercise, using loads that are 67 to 85% of your 1RM for 8 to 12 reps.
After your leg curls workouts, try our foam rolling leg exercises to loosen up your hamstrings. You can find our guide here.
