The Four Horsemen of The Spine

Kelly doing a hip opener to illustrate the four horseman of the spine

If you’ve been following The Ready State (or MobilityWOD), you’ve likely heard me talk about the Four horsemen of the spine. These are four big movers that, together, all support hip flexion or spinal extension. Now of course the body’s movement system is “slightly” more complex than just a few big muscles around the pelvis, but over the past few decades, we’ve discovered that these four muscles (and attendant connective tissues) can be a great place to start if you are experiencing low back pain or discomfort.  

The first of the four horsemen is the Rectus Femoris. This long muscle in the quadriceps connects the kneecap all the way up to your pelvis. So, this is a knee-to-pelvis connector.  It has a tendency to become stiff in a lot of people.  

The next is the Iliacus. This comes from inside the pelvic bowl to the femur. This muscle sits deep inside the pelvic bowl and just doesn’t often get much love when it comes to mobility. Though hard to reach, it’s not impossible, and we’ll discuss some great ways to get in there. 

The third is the psoas muscle, which connects the trunk to the femur and forms the iliopsoas system with the Iliacus. The psoas crosses a LOT of real estate and is a powerful hip flexor, or spine forward flexor, or spine extender.  It also swells to keep the spine stable.  I like to think of this amazing tissue as the quads of the low back. 

Last but not least is Quadratus Lumborum or QL, which connects the bottom of your rib cage to the top of my pelvis in the lower back. As I often say to athletes during mobs, “the QL is not a bone! No matter how much it feels like one.” The QL actually shares a common attachment to the psoas and can be considered the hamstrings of the spine (yes this is over-simplified).

While all of these four tissues have incredibly diverse functions, they all can potentially create an extension load on the spine.  This is one of the reasons why stiff quads can contribute to low back pain for example.  If you think about our world-famous couch stretch for a second, that position loads the iliacus, psoas, and rectus femoris by challenging hip extension, or three out of the four horsemen. When we are able to relieve some of the passive extension forces on the spine, we often see significant improvements in spinal/hip function and decreases in back pain. 

Mobilizing The Four Horsemen

I’ll get into detail on specific mobs during the rest of this article, but regardless, I recommend going through our four horsemen daily maintenance video once. It includes one mob for each of the four horsemen and will help you further identify and learn about these tissues. Think of it as required reading material, so to speak. 

The next sections simply describe each of these mobs in a bit more detail, as well as going into the function of each muscle and offering alternatives. If you take nothing else from this article, doing the four horsemen daily maintenance vid should be it. 


Addressing The Rectus Femoris 

 As we said earlier, the Rectus femoris is one of the four quad muscles and it connects your pelvis all the way through your patella. This tissue system can become especially fibrotic and jerky-like, and doesn’t typically respond as well to stretching. It’s hard to stretch jerky, but you can mobilize it.

To find the Rectus femoris, we’re going to mobilize in the same position as the basic quad smash on a roller, starting just above the knee. Lay down, belly facing the ground, and get your leg on that roller. Roll across that patch of tissue, looking for anything that feels tight and fibrotic. If you find a tissue that clunks back and forth each time you roll across it, that’s the Rectus femoris. We’re gonna go all the way up the quad, scrubbing across and focusing on that tissue. Don’t worry, the rest of the horsemen are less gnarly. 

Take this mob, moving and scrubbing, all the way up from just above your knee to just under the bottom of the pelvis. 

Reaching The Iliacus

The Iliacus sits deep inside the pelvic bowl, making it one of the most difficult muscles to reach with stretching or tissue mashing. It is simultaneously a major player in creating stability for your trunk and torso. My friend Dr. Christine Koth believes the iliacus is so integral and so neglected, she’s created her own mobility tool (the hip hook) just for reaching it. The iliacus can easily become the main contributor to immobility and pain, and I recommend checking out this tool if you feel you need to put special attention on this muscle. A lacrosse ball peanut works great, but I love a good mobilization tool.

For our purposes, a large, hardball like our supernova or even a kettlebell handle will do. We’re going after the iliacus by laying in the ball just on the inside of our hip bone. You can find this point by laying on the ball with the tip of your hip bone on either side and then just falling off it into the musculature on the inside of that pelvic bowl. We want to breathe and sink into these tissues, tracing the pelvic bone down towards the femur. 

Know that as you move towards your leg, you may run into the nerve and artery in your groin. You can stop when you feel it!

Rolling-Out The Psoas

Often people refer to the iliacus and psoas together as the iliopsoas, but these two muscles are different systems. The iliacus connects the pelvis to the femur whereas the psoas connects the spine to the femur, so though they do similar things, they are quite different in terms of connections. We’ve seen the psoas get some much-needed publicity in recent years with devices like the Pso-Rite, and these devices are a great and relatively inexpensive way to specifically address these muscles. That said, you can do a lot for this area with a foam roller or a ball with a kettlebell. 

 With a heavy ball, or a lacrosse ball, and a kettlebell for more pinpointed work, we can address the psoas while laying on our back instead of laying on top of the ball with our stomach. This lets us receive a different input and have access to hip flexion within the mobilization. 

To go at the psoas this way, lie on your back and take a lacrosse ball and press it into your gut about halfway between your bellybutton and your hip bone. Then put a kettlebell on top of the ball and hold the bell handle to press the lacrosse ball into your psoas. From here you can floss the muscle by flexing and extending your leg, and internally and externally rotating the hip in combination with that. Breathe into the mob and move the ball to different places in that system. We want to spend about 3-5 minutes per side if possible. 

The other mob I like for psoas work is to lay on a textured, hard foam roller and use it to scrub out these tissues. This looks similar to gut smashing on a roller, but we focus on the area at and below your hip bones right in that pelvic bowl. For 5 or 6 minutes, scrub back and forth, contract and relax, and think of cutting yourself in half over that roller. After you feel your tissues change, move down a notch towards the bottom of your pelvis. 

Talking to The QL 

The QL runs from your pelvis to the bottom of your ribs in the area of your lower back. In our athletes, this muscle can become so stiff and ropey that it feels like a bone. Instead, we should be able to feel the QL on our back with our fingers and even grip around it. If you try this you might find it like trying to press your fingers through a wall. 

To address the QL, we’ll use a favorite mob we got from Jill Miller. Using a larger soft or hard ball, we’re going to “bend” across these tissues. Sound horrendous? Don’t worry, this is actually one of the best feeling mobs we do and should feel like satisfying a deep itch. 

Grab a larger ball like the supernova or the larger mush ball, and place it away from your spine over towards your obliques, but below your bottom rib, on the right side of your low back. Laying on the ball in this position, bridge up and let your right leg fall to the side, knees bent and feet on the ground. In this position, breathe into that musculature and think of scraping across that QL muscle in your back slowly and with focus on taking full, deep breaths. Once you get to the other side of that sausage, reposition the ball back in the starting position but down a notch from your ribs towards your pelvis. Keep scraping across that QL all the way down to just above the pelvic bone. 

You don’t need fancy tools to get started on improving your Horses. However, there are some fun ways to punch up your mobility gains using some specialized tools.  

Barbell: Rectus Femoris

If you’ve got access to a barbell, this can be used to attack the Rectus femoris from above rather than laying in the tissue. This lets us work on the muscle from a position of hip flexion. To do this mob, sit with your legs straight out and drape one end of a barbell across your Rectus femoris. Use your hands to press the barbell into your leg whole you wobble your foot back and forth. As the tissue opens up, scoot forward a notch going from above the knee up to the pelvis over the course of about 5 minutes, then hit the other leg. 

Kabuki Strength Pain Pill, Boomstick, and Baby Boomer 

The guys over at Kabuki Strength by Chris Duffin are some of the strongest dudes on earth, and they’ve made tools reflecting their needs. The PainPill is a 45-pound stick used for mobility. You can use the point of it to dig into specific tissue spots or roll it over the top of your tissues. For the horsemen, the pain pill is a great alternative for addressing the rectus femoris. For the Iliacus and psoas, the lighter weight boomstick or baby boomer are great for pressing into these tissues with the points. 

You can also have a partner drag the point of any of these devices across your QL for you. 

Hip Hook by Aletha Health (for the Iliacus)

The hip hook, as we discussed earlier, is a pinpoint tool for addressing a stiff iliacus. If you feel that your iliacus is the main component in your pain or immobility, it may be worth investing in this tool. Instructional videos on using the hip hook can be easily found both at the Aletha health website (along with the product,) and on YouTube. Happy hooking. 

The Pso-rite (For Psoas)

The Pso-Rite is a relatively inexpensive tool for addressing both sides of the psoas at once. It resembles a sort of hard plastic skateboard half-pipe you can lie on to hit this region. It can also be used for other areas of your body, but the psoas is its specialty. 

Made popular by MMA fighters and then by Joe Rogan, there’s a reason this tool is all the rage. It’s not a bad addition to the arsenal if you suspect your pelvic bowl as a primary source of mobility restrictions. 

Happy mobilizing! I hope this helps you get into your Ready State! Get expert led training with our Movement & Mobility 101 and Movement & Mobility 102 courses.

3 thoughts on “The Four Horsemen of The Spine

  1. keenanerikssonfitness
    keenanerikssonfitness says:

    Hey James, I’ve done the four horsemen vid a few times and I use the large supernova. You could probably use the small though. I’m like 6 ft 4, so the large is better for hitting the QL for me. Sometimes I’ll use the small for hitting the illiacus, but I typically use the large for that too. Mine are pretty tight and the small is just too precise.

    I think in the vid Kelly uses the large too. Actually he might even use the large mush ball.

  2. Avatar
    sodivera28 says:

    Thank you for sharing this info! My pelvic floor PT mentioned that I under activate the posterior portion of my core when bracing and hope working on my QL will help with this. One question I have: is it normal to feel increased tenderness after working on the QL? I find that I will get tension relief and more mobility after a focused 5-10 min session but wake up the next day with more tenderness in the lower ribs and QL.

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