And the Lord said to Joshua, “Do not be afraid of them, for tomorrow at this time I will give over all of them, slain, to Israel. You shall hamstring their horses and burn their chariots with fire.”

I’m not opening this article with a biblical passage because I’m religious. Far from it (unless you count Star Wars as a religion).

This verse from Joshua 11:6 is here to illustrate that God knew a thing or two about how to cripple an enemy. 

Why would He tell Joshua and the Israelites to take their swords and cut the hamstrings of the Canaanites’ horses? Because there’s no more effective way to incapacitate an animal and render it as useless as a ballon in space than to take out its hamstrings.

Lions, wolves, cheetahs, and the best hunting animals on Earth know this. Without hamstrings, an animal can’t walk properly. And they become much easier prey.

Humans are no different. Without hamstrings, you wouldn’t be able to do much of anything except maybe sit around and play video games all day. 

If you want to maintain a strong lower body or even build a more muscular physique, do not skimp on training your hamstrings.

Plus strong hamstrings help prevent knee injuries. And you don’t want crappy knees in your later years, do you?

Everything You’ve Ever Wished to Know about Your Hamstrings

Your hamstrings are composed of three muscles:

  • Semitendinosus
  • Semimembranosus
  • Bicep femoris (long head and short head)


So why are they called “hamstrings” exactly? 

Well, my language-loving friend, the word “ham” comes from Old English; it could also be spelled or pronounced “hom”. And it meant “the hollow or bend of the knee.” 

And if you go back even farther to its Germanic roots, ham meant “crooked.” Somewhere around the 15th Century, “ham,” gained the meaning of ‘the leg of an animal.’ 

String is a reference to tendons. 

Thus: the hamstrings are string-like tendons on the back of your knees.

Your hamstrings cross two joints, the knee and the hip. And without these muscles, walking, jumping, running, or standing would be impossible. 

Each of the hamstring muscles can function in different ways. But overall, they’re responsible for: 

  • Flexing your knee (knee to butt)
  • Extending your hips (hips forward and back)
  • Stabilizing your pelvis (all the muscles that attach to your hips stabilize your hips in one way or another)

Here’s the super nerdy stuff each muscle does on its own:

The semitendinosus and semimembranosus both extend the hip when your torso is fixed. They also flex your knee and inwardly rotate* the lower leg when your knee is bent.

The long head of the biceps femoris extends the hip, i.e., when you start to walk. And both short and long heads flex the knee and outwardly rotate your lower leg when your knee is bent.

*Quick note on “rotation:” no muscle in the body actually rotates. Muscles move joints, either closer to one another or away if they cross joints. If they do not, then they stabilize prime movers like the pecs/lat/quads/hamstrings/etc. The big muscles can stabilize your body when you make rotational movements. But they do not function TO rotate; they can just go through that range of motion and function, but they may not function optimally.

Even the tiny muscles of the rotator cuff, for example, stabilize the movement of your arm to your shoulder blade. But they don’t actually rotate anything.

Your hamstrings primary function, and probably the most important, is to decelerate your forward motion. Think of them like the anti-lock brake system of your body.

Unless you want to go careening out of control on the road, you want good brakes on your car.

Your hamstrings are no different.

And it’s cliche as hell to say, but you’re only as strong as your weakest link. Weak hamstrings drastically limit the power you can produce in your lower body.

Even worse, not building strong hamstrings can lead to injury. Underworking your hamstrings can create an unbalanced quad-to-hamstring ratio. This can lead to knee pain and instability, and according to some studies, can increase ACL injuries.


I cannot stress this enough: if you want to live a longer and higher quality life with little to no knee or low back pain, build strong(er) hamstrings.

How to Build Stronger Hamstrings

Your hamstrings have two primary functions: hip extension and knee flexion. They stabilize your pelvis as well. (I’ll cover stabilization exercises in a bit.)

But first, let’s cover how you can build stronger hamstrings at the gym. Your exercise selection here is simple and kind of boring.

Knee Flexion:

  • Leg Curls*

*I will cover the different types and why you “should” use more than one* 

Hip Extension:

  • Romanian Deadlifts
  • Stiff-legged RDLs/Good Mornings
  • Hyperextensions

At the end of the day, this is how you strengthen your hamstrings. You pull your knee to your butt with whatever tool you have. Or you hip hinge — pushing your butt back and then thrust it forward rep after rep.

But no two gyms are the same. Some have lying leg curls. Others have seated. Some of no hamstring machines at all. 

And some are pieced together with random equipment — gyms like this may only have a rusty standing leg curl.

Know this: there are differences between these leg curl machines. 

Yes, they work your hamstrings. But they train them slightly differently. And I’ll cover that below.

Common Mistakes in Training Hamstrings

Lifting weights, in general, is simple. Pick the weight up, put it down, repeat. But there’s so much more to it than that.

And when it comes to training your hamstrings, boy, oh boy, are there a lot of mistakes that you can make.

So let’s get cracking on that whole how to feel your hamstring thing.

Problem: You Use More Calves than Hamstrings

Wait, what? How is that possible?

Most people who work out at gyms know very little about biomechanics. Wikipedia defines biomechanics as, “the study of the structure, function, and motion of the mechanical aspects of biological systems, at any level from whole organisms to organs, cells and cell organelles.”

And here’s a biomechanics aspect you probably don’t know: your calves also function to flex your knee.

When your leg is fully extended, like in a lying leg curl, your calf muscles carry out the first 10-15 degrees of knee flexion. Once you get beyond that 10-15 degrees, your hamstrings take over the leg curl.

And this is where millions of people make mistakes every day when they train their hamstrings in a lying leg curl.

If you slam the weight up from the bottom of a leg curl machine, using momentum to get your heels to your butt, and barely control the weight going back down, you didn’t (really) train your hamstrings.

What you did was launch the weight up with your calves, and then you never fought gravity on the way down. You’ve worked your calves. But left nearly everything on the table for your hamstrings. 

Solution: Be Slow & Controlled out of the Bottom

Start slow with your lying leg curls instead of propelling the weight up towards your butt. Once you reach the end of the 10-15 degree portion of the leg, curl where your calves work the most, then explode the weight towards your butt and finish with a hard squeeze of your hamstrings.

But don’t let the weight slam back down either. 

Control the lowering, eccentric phase, and return to the starting position.

Then you have two options: 

  1. You can decide to go all the way to the bottom so you get some calf work — for long-term calf and knee health, this is a good idea to do every few months.

  2. Or you can stop the lowering right before the calves take over and keep more tension on your hamstrings throughout your set.

Problem: You Aren’t Staying in the Squeeze Position Long Enough

Here’s why the lying leg curl is great. It’s the one machine where the work you’re doing is most challenging where your hamstrings are their shortest.

You can’t hit this position when working your hamstrings through hip extension. And not training a muscle through its entire range of contraction can lead to joint issues and strength imbalances.

Solution: Hold the Squeeze

This is why that top position of the lying leg curl, where your heels are pressed into your butt, and your hamstrings are screaming like a banshee coming at you in Mass Effect 3, is so vital.

So if you want to build bulletproof hamstrings, make sure you hold the short position, the squeeze, for more than 1 second when you use the lying leg curl.

Jam your heels as hard as you can into your butt. Then slowly release the weight back down; remember, your hamstrings are your brake system, so use your brakes and don’t let gravity win.

Because your hamstrings attach to your hips and stabilize your pelvis, your hamstrings are important antagonists to your quads.

Specifically, your rectus femoris — the only quad muscle that crosses the hip and knee joints.

If you sit at a desk or in a chair for long periods, using the lying leg curl and holding the squeeze position can help strengthen your hamstring in the short position. This allows the rectus femoris to fully lengthen and relax from its constant tight state.

Problem: You Only Ever Use the Lying Leg Curl

Oh man, I was this guy for years. The lying leg curl felt so good to me. I hated the seated leg curl. So I refused to use it.

Except there’s a problem in doing that.

The seated leg curl trains your hamstrings in their lengthened position. And it’s here, in the lengthened position of any muscle, where you create the greatest amount of hypertrophy.

Only choosing to use the lying leg curl will prevent you from building your hamstrings in the long run. But, and this is more important, skipping seated leg curls will cause you more issues down the line.

A strong and well-balanced muscle is trained to handle stress across all aspects of the strength curve.

Solution: Cycle the Seated and Lying Leg Curls in Your Training

You don’t need to do this every month or every six weeks. But every few months, spend a 4-6 week training cycle using the opposite leg curl machine.

Your hammies can handle a wide array of rep ranges too. So make sure you’re cycling rep ranges as well. 

Do lying leg curls for 6 weeks at 4 sets of 8 reps with a 2-3 second hold at the top of each rep. Then the next training cycle add in seated leg curls for 3-4 sets of 10-12 reps; then swap back to lying for some 15-20 rep action; then back to seated for some heavier low reps around 6 or so.

Vary your hamstring curl training, and you’ll not only build stronger and bigger hamstrings, but your joints will also be grateful that you did.

One small tidbit on seated leg curls. Couple of things you want to remember here:

  1. Make sure your ass stays on the seat for each rep. Grab those handles at the side and pull yourself down into the seat. Letting your butt hover decreases your pelvis’s stability and allows your low back to take over.

  2. Fully stretch your hamstrings on the seated leg curl by slightly hinging forward. You don’t want to round the low back. But a small hinge in the seated position helps you fully stretch those hammies even more.

See the pictures below.

Do not do this. This will DESTROY your low back
You want to pull your butt DOWN into the seat.
hamstring trainin
To fully shorten the hamstrings, after you’ve pulled your butt into the seat, hinge at the hips — do not round your low back to do this — to fully shorten your hammies. You won’t need much of a hinge.

It’s All in the Hips

Now, let’s move away from the leg curls and talk about the other primary function of the hamstrings, hip extension. 

Hip extension biases more of the semitendinosus and semimembranosus. The bicep femoris is engaged here but to a much lesser degree.

When it comes to exercise selection for hamstrings and hip extension, you’re really only looking at a few exercises:

  • Romanian Deadlifts
  • Stiff-legged Deadlifts
  • Good Mornings
  • Hyperextensions

Problem: Not Tucking Your Chin to Your Chest 

This is a super common mistake I see in gyms all the time. And it doesn’t sound like that big of a mistake because why does it matter where your head is?

Well it does. Where your cervical spine goes, so too goes your lumbar spine. 

If your cervical spine extends (head back, eyes up), then your lumbar follows and extends. And this places a lot more pressure on your lower spine and the surrounding muscles. It can dampen the activation of your glutes as well.

Solution: Tuck Your Chin

Tuck your chin to your chest and look down at the ground. Do not look up in the mirror or to the side. Eyes on the floor and chin tucked as if you’re making a double chin.

More on this in the video below.

Problem: Leaving Your Active Range of Motion

Let me be clear: it is not “unsafe” to go for a longer range of motion when you do an RDL. But what it changes is that the lower you go, the less hamstrings and glutes you get, and the more your low back comes into play.

There’s a time and a place for longer range of motion deadlifts. But you should master your active range before you attempt to go outside of that.

Solution: Forget Thinking “Up and Down” with RDLs; Think “Back and Forward”

When I first started coaching people to do RDLs (and their variations), I would tell clients to imagine they were shaving their legs with the dumbbells.

The idea is that they would keep the dumbbells closer to their legs and slide them up and down from the middle of their hips to below their knees. And this can be a good cue.

However, I found that most of the time, I said I was still dealing with too much low back rounding at the bottom. 

To stay in your active range of motion and hammer your hamstrings and glutes, think “back and forward” with your hips, not up and down.

And the best way to think about this is to imagine your butthole is Pac-Man and that you need to eat the wall behind you. Check out the video below from Instagram, where I cover these two points.

Problem: You Want Less Glute Activation and More Focus on Your Hamstrings

Your glutes work as hip extensors as well. And though you can bias your glutes more in things like hip thrusts, glute bridges, Kas Glute bridges, or kickbacks, those bad boys are still gonna work when you do RDLs.

However, you can decrease your glutes and increase the work on your hammies by doing stiff-leg RDLs or Good Mornings.

Solution: Stiffen Your Knees

The stiff-leg deadlift and the good morning are the same exercises. The only difference is where you place the load.

Stiff leg deadlifts require you to hold the weight in your hands (like RDLs), whereas good mornings are done with the bar on your back like in a back squat.

Both of these movements require you to minimally bend your knee. And I mean like barely. You “can” keep your knees locked out to do these. But only if you do not have an issue with hyperextending your knees.

The simple act of stiffening your knees decreases the load on your glutes and increases the tension on your semitendinosus and the semimembranosus.

My friend Brit Rand has a great graphic on the difference below.


View this post on Instagram


A post shared by Brit Rand (@brit_rand)

Hamstrings as Pelvic Stabilizers

Before I give you some final critical pointers on hamstring training, I need to cover the last function of your hamstrings. And it’s often forgotten.

Your hamstrings also function to stabilize your pelvis.

Some people will claim that they cannot feel their hamstrings. Often, all the other dozen or so muscles that come in contact with the pelvis are working harder than the hamstrings to stabilize your pelvis.

The 90/90 Hip Lift and Breathing exercise below is the one I will use with my clients to help teach them to re-engage their hamstrings as stabilizers. If your hamstrings aren’t shaking like Los Angeles during an 9-point earthquake, you’re not doing these right.

I could spend a few hundred more words on the hamstrings as pelvic stabilizers. And there are other exercises or modalities that dive into this like PRI. But that is super nerdy stuff that is best learned hands on.

The 90/90 Hip Lift and Breathing is a good place to start that anyone can do.

Alright, so we’re like 3,500+ words into this article. And that means it’s time to wrap it up.

If you want to build a stronger lower body that doesn’t succumb easily to injury, then you have to train your hamstrings. And you need to train them in all aspects of their function — RDL, leg curls, Good Mornings, and pelvic stabilization.

But I’m gonna leave you with a handful of some hamstring training tips you can apply to your workouts to take your hammies from those tiny tendrils you have now to thick and juicy pork strings.

9 More Hamstring Training Tips

  • Dorsiflex your feet for heavy loaded leg curls
  • Poliquin Leg Curls: dorsiflex on the curl up, then plantarflex on the lowering; this uses everything in the calves and hamstrings, but overloads the hammies eccentrically
  • Walking on inclines or hill sprints will also wreck your hamstrings
  • Use a wide array of rep ranges
  • Turning your toes out or toward each other do not hit your hammies different
  • Keep your feet still while leg curl, no dancing feet
  • If you don’t have access to lying leg curls, you can use Swiss Balls instead.
  • Nordic curls are great for training your hammies, but don’t do these without having worked up to doing full reps. And when you do find you can do these, remember to squeeze your obliques and core so they can stabilize the pelvis while the hamstrings work.
  • Train fast concentrics and slow eccentrics on leg curls a few times throughout the year.

1 Comment

  1. Louis Page July 23, 2022 at 9:53 pm

    Wreck your hamstrings I guess that doesn’t mean literally …?!


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