Seated Leg Curl: A Simple Trick To Maximize Hamstring Mass

August 25, 2021

You may have spotted this weird-looking machine at the gym. The only people you ever see using it are skinny non-lifters. Obviously, this machine won't get you jacked. So, you stick with your tried-and-true leg curls and stiff-legged deadlifts.

Of course, these are great exercises for hamstring mass. But avoiding the seated leg curl could be holding back your quest for drooping hamstrings. By identifying the main muscles worked in the seated leg curl, you will see why.

Seated Leg Curl Muscles Worked

The hamstrings consist of three main muscles:

  • Semitendinosus
  • Semimembranosus
  • Biceps femoris long head and short head

The semitendinosus is the innermost hamstring muscle while the biceps femoris is the outermost hamstring muscle. Leg curl hamstring exercises preferentially target the inner hamstring muscles [1]. While hip extension exercises (like the Romanian Deadlift) activate more of the biceps femoris.

However, the seated leg curl might be a different beast. The biceps femoris long head is a biarticular muscle. Meaning that it crosses two joints, the hip, and the knee. The outcome? The biceps femoris can be stretched much longer than the other muscle groups.

The seated leg curl does just this. With the hip flexed and the knee extended, the biceps femoris is put under extreme stretch. Think about the big stretch you get if you stand and put your foot up on a chair while bending forward. The same thing is happening but under load.

So while the leg curl action may activate the inner hamstrings, the huge stretch of the biceps femoris makes the seated leg curl a leg curl exercise that may also target the outer hamstrings.

How To Perform The Seated Leg Curl

Seated Leg Curl
  • Adjust the seated leg curl machine so it fits your body. To do this, sit in the machine and place your legs on top of the pad. The pad should sit at the bottom of your calves just above the back of your ankle bone.
  • The back support should be adjusted so you can sit in the seat comfortably while maintaining your leg position on the pad. Once comfortable, move the top pad support on top of your thighs so it’s tight.
  • Flex your knees as you bring your heel under your seat. While performing the curl, pull your foot towards you which will help reduce the involvement of the calf muscles.
  • Slowly return to the starting position in a controlled manner. 2-4 seconds is a good tempo for the eccentric phase.
  • Make sure you return all the way back until your legs are straight to get the biggest stretch on your hamstrings.

Common Seated Leg Curl Mistakes

As simple as the seated leg curl is, there are some mistakes commonly made by gym-goers on their quest for massive hamstrings.

Uncontrolled Swinging The Weight

This exercise becomes useless if you aren’t controlling the eccentric phase and just curling your legs as fast as possible. Keeping tension throughout the whole movement is what will maximize muscle growth.

Partial Reps

Partial range equals partial results. If you want to maximize hypertrophy, you need to maximize mechanical tension on the muscle. Meaning placing the hamstrings under load through the stretch.

How Many Sets And Reps Of The Seated Leg Curl

Generally, anywhere from 2-5 sets of 10-20 reps is a good range for maximizing the growth stimulus from the seated leg curl exercise.

A Simple Trick To Maximize Hamstring Growth With The Seated Leg Curl

Remember when I mentioned that the seated leg curl places the biceps femoris muscle under extreme stretch? What if I told you you can take this a step further and in doing so, you can enhance muscle growth to an even greater extent?

Rather than leaning back into the back support, lean forward and hold onto the top of the pad support. 

If you want to take this a step further, arch your back as much as possible (like you’re an Instagram model). Very rarely you’ll need to go to this extreme.

In fact, the seated leg curl has shown greater hypertrophy in the hamstrings compared to the lying leg curl due to being placed in these long muscle lengths [2].

You can see it in action in the video below.

Seated Leg Curl Alternative

There aren’t many alternatives to the seated leg curl as the seated leg curl is essentially the only leg curl exercise that places the hamstrings under these extreme muscle lengths. But there is one alternative.

Banded Seated Leg Curl

This is your next best option if you don’t have access to a seated leg curl machine (especially for those that train at home). Tie a band to a sturdy object like a rack. Sit on a bench facing the band and place the band around your Achilles tendon at the bottom of your calves.

You’ll need to place your hands on the bench next to you to counterbalance your legs. This variation will feel weird and you won't feel the same hamstring activation as the machine but it's a substitute you can use.

References

1. Bourne, M. N., Timmins, R. G., Opar, D. A., Pizzari, T., Ruddy, J. D., Sims, C., ... & Shield, A. J. (2018). An evidence-based framework for strengthening exercises to prevent hamstring injury. Sports Medicine, 48(2), 251-267.

2. Maeo, S., Huang, M., Wu, Y., Sakurai, H., Kusagawa, Y., Sugiyama, T., ... & Isaka, T. (2021). Greater hamstrings muscle hypertrophy but similar damage protection after training at long versus short muscle lengths. Medicine and science in sports and exercise, 53(4), 825.

About the Author

I am a professional strength & conditioning coach that works with professional and international teams and athletes. I am a published scientific researcher and have completed my Masters in Sport & Exercise Science. I've combined my knowledge of research and experience to bring you the most practical bites to be applied to your training.

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