How To Boost Muscle Activation By 25%

It's true! Romanian deadlifts (RDLs) only hit 75% of your hamstrings (3 of the 4 heads) but leg curls hit 100% of your hamstrings (4/4 heads). That's because one head (called the biceps femoris short head) doesn’t cross the hip joint. That means it physically CANNOT contribute to hip extension while you do a Romanian Deadlift. It can only bend the knee — that’s its only function. If you have a straight knee, it simply won’t be active.

And if you skip your leg curls, you’ll never grow this head. You’ll only ever hit 3 of the 4 heads.

So does this mean you should only do leg curls? Probably not.

You see, even though the leg curl hits all 4 heads, it targets the lower hamstrings a bit more than the upper hamstrings. So I think for the best overall hamstrings growth you need BOTH a leg curl exercise like a Nordic ham curl, glute ham raise or machine leg curl and a hip-hinge-exercise (like a good morning or a Romanian deadlift).

[NoName-]

I love how YouTube recommended me this right before going to my monthly leg day 🔥🔥

[KyleVolt]

No one used this machine in my gym for 3 years… now I’m fighting to get a set 😭

[headshotgamers]

Tip no. 69 : Multicolored hamstrings increases muscle activation and test by 777%

[Chrollo]

Bro you’re a life savor, I stopped doing meg curls for RDL thinking they were enough, leg curls are coming back in the routine.

[AE-ivje]

Glad you said the answer is both, couldn't agree more! RDL is compound too so you get the added benefit of picking up some glute and erector (plus grip) stimulus in addition to the heavy hip hinge hamstring work.

I would add in a lying leg curl as well for some mid to shortened length work though. I'm finding that doing that exercise single leg reduces load which makes it easier to stay attached to the bench while really focusing on the contraction one leg at a time - almost like a preacher curl for the hamstring. Doing lying leg curl at the end helps get the last juice out of your hamstrings, but also deprioritizes the mid to shortened range which I know you're a fan of. Hit the lengthened exercises early to bring more effort to the most effective exercises.

[Gingerly-]

Jeff is just the best. The quality is unmatched.

[Horse.]

I used to go to the gym very consistently and just recently I tore my acl playing soccer and can’t do any for year. All these workout videos on my for you page make realize how good I had it before.

[SeanK]

I was so wrong about seated hamstring curls and a lot about leg training in general. I always thought i had poor leg genetics, i now realize i was just training them wrong. This exercise is a must.

[BoerteI]

Rocking the OG Kobe’s too, shit my man is fresh. 😎💪🏼

[Evan-ptnr]

doing leg curls first and then doing rdl’s with low weight high reps is a game changer

[LittleDV]

I do both. Feels good after watching this

[briannconn]

Yep. Rdls and the leg curl are my go to :)

[harty]

Mad support and respect for you Jeff. So sorry about the attack, you didn't deserve that. Tbh it shows how amazing you are, people are so jealous and threatened by you. Keep showing up and doing what you're doing, we love you. You have helped to change my life. I've learned soo much from you!! ❤

[zbvirus]

This muscle is very important for your knee health. As well as bending your knees, it also keeps em from collapsing inwards (towards each other) while under load.

[rodolfotorres]

And that’s why I do both Romanian and leg curls. 👌🏽👍🏽

[PORTBOB]

had me at the making numbers up opening line

[G-ForceJoJo]

I hated the seated leg curls until I got a little knee injury/over usage, and now it feels really good to do them in the beginning of my leg days

[Tshedza_R]

Motivated to do more leg days, this is now part of my routine for the month.... stay strong and natural for your health guys we all just trying 💪🏽

[vnilladyyvnilladyy-fz]

This is such a helpful breakdown of hamstring activation. I've been focusing on RDLs but now I see how important leg curls are too. Thanks for the insight.

[BaraahaMalatov-tp]

For real, this video just made my day!