Understanding SI Joint Pain

Leslie Guerin • April 30, 2025

How It Mimics, Differs from, and Interacts with Sciatica


Understanding SI Joint Pain:

Subtitle:
When the Pain Isn’t Just in Your Head—or Your Back: How to Tell If It’s Your SI Joint, Sciatica, or Something Else Entirely

If you’ve ever experienced lower back pain that radiates down your leg, you're likely familiar with the term sciatica. But what if the pain isn’t coming from a herniated disc or nerve compression at all? What if it’s your sacroiliac joint—the often-overlooked yet essential connection point between your spine and pelvis?

In this post, we’ll break down the mystery of SI joint dysfunction, why it often gets confused with sciatica, how to start telling the difference, and what gentle, Pilates-based strategies and stretches might help you manage symptoms or support recovery.



The SI Joint: What (and Where) It Is

The sacroiliac (SI) joint is where your sacrum (the base of your spine) meets your ilium (the large bones of the pelvis). There’s one joint on each side of the body. These joints don’t move much, but they absorb and transfer load between the upper body and legs.

When the SI joint becomes dysfunctional—either too tight, too loose, or inflamed—it can cause localized pain, stiffness, and even radiating discomfort that mimics other conditions.



My Experience Working with Clients (And My Own Body)

In 2020, I dealt with a herniated L5-S1 disc that brought on intense sciatic pain—shooting down my leg to my toes. It was sharp, deep, and persistent. But over the years, as I’ve worked with clients, I’ve seen many people describe a similar kind of pain that didn’t turn out to be sciatica.

Instead, it was SI joint dysfunction.

A major difference I’ve noticed in clients with SI joint pain: they often can’t tolerate pelvic tilting at all. Especially posterior tilts—that motion you make to “tuck” the tailbone—can be unbearable. Where a spinal or nerve-related issue might allow for small movement, SI joint pain can feel like a brick wall. They freeze, flinch, or breathe sharply when asked to tilt the pelvis in either direction.

That tells me something deeper is going on—and often points to the SI joint.



SI Joint Dysfunction vs. Sciatica: Spot the Differences

Although the symptoms can overlap, here are a few general differences:

Symptom

SI Joint Dysfunction

Sciatica

Pain location

One side of lower back, buttock, can radiate to thigh (rarely past the knee)

Radiates from low back/buttocks down the leg, often to foot

Pain type

Dull, sharp, or stabbing—worse when sitting, climbing stairs, or standing unevenly

Burning, shooting, electric shock-like down the leg

Movements that worsen it

Pelvic tilting, standing on one leg, twisting

Forward bending, coughing/sneezing, prolonged sitting

Relief found through

Neutral spine, gentle stabilization, bilateral exercises

Extension (Swan), decompression, nerve flossing

Leg numbness or tingling

Rare

Common

These distinctions aren’t foolproof, but they’re a place to start. Proper diagnosis is crucial. If you're unsure whether you're dealing with sciatica, SI joint pain, or another form of back pain, you need to ask good questions—and so does your healthcare provider.



What to Ask Your Doctor or Physical Therapist

Here are a few helpful questions to bring into your next appointment:

  • Can you help me determine if this is disc-related, SI joint-related, or muscular?
  • Does this pain refer down my leg because of nerve irritation, or from joint dysfunction?
  • Can you check for sacroiliac instability or inflammation?
  • Are any of my muscles (glutes, hip flexors, pelvic floor) underactive or overactive?
  • Could my leg length, gait, or previous injury be affecting my SI joint?
  • What types of movement should I avoid—or include?

A qualified PT (Physical Therapist) will know how to test for SI joint involvement—often through palpation, movement tests like the FABER test, and simple load-bearing challenges. Many clients experience great relief through physical therapy, especially when manual therapy is combined with targeted strengthening.



What Causes SI Joint Pain?

The causes of SI joint dysfunction are varied but often come down to imbalance or instability:

  • Pregnancy or postpartum changes (ligament laxity)
  • Uneven leg length
  • Prior trauma or falls
  • Repetitive one-sided activities (think golf, tennis)
  • Weak glutes and deep core
  • Prolonged sitting or standing

When the support structures (like the glutes, pelvic floor, and transverse abdominis) don’t do their job, the SI joint takes on too much responsibility—and eventually fights back.



The Pilates Connection

I’ve worked with dozens of clients with SI joint issues who found relief not from aggressive treatment but from returning to mindful movement. Pilates, with its focus on alignment, breath, and core engagement, offers a powerful way to gently stabilize and support the area without aggravation.

Unlike traditional “core” exercises like crunches or planks, Pilates starts with the basics: finding neutral spine, breathing into the back ribs, and activating deep stabilizers without compression.

It also emphasizes bilateral work—meaning using both sides of the body evenly—which helps reduce SI joint irritation that can result from asymmetrical training or habits (like always crossing one leg or standing with weight on one side).



A Gentle Routine for SI Joint Relief

The following is a sample of Pilates-based movements and stretches I’ve seen help clients manage SI joint pain over time. These are not one-size-fits-all, and you should always consult with your provider before beginning any new movement if you're in pain.

1. Find Neutral Spine

Lying down:

  • Knees bent, feet flat, arms long by your sides.
  • Align the hip bones (ASIS) and pubic bone in the same horizontal plane.
  • This is your "home base"—come back to it often.

Why it helps: Reduces pressure on the SI joint and gives the spine a balanced starting point.



2. Pelvic Clock (Without Tilting)

  • Imagine your pelvis as a clock face.
  • Gently “roll” awareness from 12 o’clock (navel) to 6 o’clock (pubic bone), and side to side (3 and 9).
  • DO NOT exaggerate or push into the tilt. Keep the motion subtle and mostly mental.

Why it helps: Encourages subtle proprioception without stressing the joint.



3. Modified Swan (Elbows Down)

  • Lie on your belly with elbows under shoulders, forearms flat.
  • Gently press into forearms to lift the chest a few inches without tensing glutes or lower back.
  • Keep pubic bone grounded, shoulders wide.

Why it helps: Promotes spinal extension without spinal compression or sacral shearing.



4. Bridge with a Ball or Ring

  • Lie on back, feet flat, knees bent.
  • Place a small Pilates ball or pillow between the knees.
  • Squeeze gently and lift hips to a small hover—no need for a full bridge.
  • Focus on engaging glutes and inner thighs equally.

Why it helps: Recruits pelvic floor and stabilizing muscles in a symmetrical way.



5. Figure Four Stretch (With Caution)

  • Cross one ankle over the opposite thigh and gently pull the thigh toward your chest.
  • Only go as far as feels neutral—stop if any pelvic tilting brings on pain.
  • Keep pelvis as level as possible.

Why it helps: Opens tight glutes and piriformis without excessive spinal or SI movement.



6. Side-Lying Leg Lifts

  • Lie on one side, hips stacked, legs straight.
  • Lift the top leg a few inches and lower slowly.
  • Keep waist long and avoid rolling the pelvis back.

Why it helps: Strengthens glute medius and outer hip—crucial for SI joint support.



The Green, Yellow, and Red Light System

As I shared in my sciatica blog post, I often use a traffic light system to guide pain management in movement:

  • Green Light = Feels good or neutral → Keep going
  • Yellow Light = Some discomfort → Move mindfully, proceed with caution
  • Red Light = Sharp pain, instability → Stop immediately and reassess

Your job isn’t to push through pain—it’s to listen, adapt, and build trust with your body over time.



Final Thoughts: You're Not Alone

SI joint pain can be deeply frustrating. It’s not always visible. It’s often misunderstood. And it can feel like there’s no clear path to healing. But the truth is: you are not alone, and there are steps you can take to support your body.

From thoughtful Pilates movements to working with a skilled PT, relief is possible, and more often than not, it comes from tuning in—not tuning out.

Start with what you can do today: find your neutral, breathe into your ribs, and support your spine from the center outward.


By Leslie Guerin February 22, 2026
There is a common misunderstanding about Pilates that has grown louder over the years: that it is meant to be gentle, slow, soft and easy. A “nice” workout. But that was never the intention. Pilates was not created to be performative. It was created to be effective. Effectiveness in movement does not come from looking impressive. It comes from precision. Somewhere along the way, the visual of Pilates became louder than the method itself. Long limbs moving with beautiful choreography and endless repetitions. Classes that look like Pilates. But looking like Pilates, being called Pilates and being Pilates are not the same thing. And most people, including many teachers, skip the part that actually makes it work. Pilates Was Never Meant to Be Performative Joseph Pilates did not design a system that rewarded momentum. He designed a system that required attention. Not attention to how something looks, though that is how you can tell if the exercises is executed properly. The attention should ideally be to how something is done. Modern fitness culture thrives on performance. Movement is filmed, shared, and packaged visually. The more dynamic it looks, the more engaging it appears. The more repetitions, the more it seems productive. This is where Barre and Pilates differ. This is where those lines have blurred and I quietly hope Pilates can resists this fad. A well-taught Pilates class may look almost uneventful from the outside. To someone expecting entertainment, it can seem understated. To the nervous system, it is deeply demanding. Because Pilates was never designed to entertain the eye. It was designed to reorganize the body. It is art, but not for arts sake. Precision Requires Attention Precision creates actual change. When movement becomes rushed, the body defaults to habit. Stronger muscles take over. Momentum replaces control. Alignment becomes approximate instead of intentional. Slowing down in Pilates is not about being gentle. It is about being accurate. It allows the brain to register position, and control. It gives the body time to respond instead of react. Precision is not passive. It is neurologically active. Holding a half curl with the neck long, ribs quiet, and breath organized requires far more attention than swinging through ten repetitions with momentum. Performing a leg circle without pelvic movement demands significantly more control than making the circle bigger or faster. The difficulty in Pilates is rarely about load. It is about coordination. Coordination should not be rushed for the sake of getting in more repetitions. Many Classes Look Like Pilates, But Aren’t Being Taught to Bodies This is where the disconnect becomes most visible. Exercises are demonstrated, copied and followed. Social media has taken the see and steal culture to new lengths! This leads to the body in front of the teacher is not being taught properly. Clients are becoming carbon copies of braod movements seen online and just simply being asked to replicate. There is a difference between cueing choreography and teaching movement. When classes focus primarily on what the exercise should look like, participants often compensate without realizing it. The neck grips during abdominal work. The hip flexors dominate leg movements. The lower back absorbs what the abdominals were meant to support. From the outside, everything appears correct. From the inside, the wrong muscles are doing the work. I know this to be true, because I have definitely performed Pilates.. and on an off day... I am sure I will unfortunately do this again. This has allowed me to really see though, that Pilates teaching requires observation. It requires adjusting range of motion, tempo, setup, and intention based on the individual body, not the idealized version of the exercise. Because the goal of Pilates is not uniform movement. It is intelligent movement. Real Pilates Feels Quieter, and More Demanding Neurologically One of the most surprising experiences for clients transitioning from performative classes to precise Pilates is how “quiet” it feels. There is less rushing and far less choreography for the sake of variety. Yet, thes classes often feels more challenging. Not because it is harder in the traditional fitness sense. But because it requires sustained mental engagement. You cannot mentally check out during precise Pilates. You are asked to notice: Where your ribs are How your pelvis is responding Whether your neck is assisting unnecessarily If your breath is supporting or disrupting the movement Which muscles are initiating versus compensating This level of awareness increases the neurological demand significantly. The brain is actively mapping movement rather than passively repeating it. That is why Pilates can feel deceptively demanding even when the exercises appear small or controlled. It is not about exhaustion. It is about organization. Gentle Is Often a Misinterpretation of Control When Pilates is described as gentle, it is usually because it lacks impact, heavy loading, or aggressive pacing. But low impact does not equal low intensity. Holding alignment under control. Moving without compensation and maintaining precision through fatigue. These are not gentle skills. They are refined skills. In fact, when Pilates is taught with true precision, many clients realize they have been overworking the wrong areas for years. Their hip flexors tire quickly. Their neck becomes aware. Their deep abdominals fatigue in ways they never noticed before. Not because the workout is harsher. But because it is finally specific. Specificity feels different than intensity. Why Precision Gets Skipped Skipping precision is rarely intentional. It is often the result of: Large class sizes Fast-paced programming Overemphasis on choreography Teacher insecurity around slowing things down The pressure to make classes feel “worth it” through visible effort Precision requires time. It requires observation. It requires confidence in subtlety. And subtle teaching can feel risky in a culture that equates visible sweat with value. But when precision is skipped, the method gradually becomes diluted. Exercises become shapes instead of tools. Cueing becomes generalized instead of specific. And the neurological depth of Pilates is replaced with surface-level movement. Teaching Pilates to Bodies, Not to Exercises One of the most important shifts a teacher can make is moving from teaching exercises to teaching bodies. An exercise is not the goal. It is the vehicle. Two people performing the same movement may need entirely different cueing, range, and pacing to achieve the intended outcome. Precision means recognizing that and adjusting in real time. It means allowing fewer repetitions with better execution. It means refining setup before adding progression. It means valuing stillness as much as movement. And perhaps most importantly, it means being willing to make the class feel quieter in order to make it more effective. Because when the body is truly learning, it does not need constant spectacle. It needs clarity. The Quiet Demanding Nature of True Pilates Clients who experience precise Pilates often describe it the same way: “It felt small, but I was working so hard.” “I had to concentrate the whole time.” “It was harder than it looked.” This is not accidental. When the nervous system is fully engaged, even controlled movements require significant effort. The demand shifts from gross muscular output to refined neuromuscular coordination. That is the part most people skip. And it is also the part that creates lasting change. Not bigger movements. Better ones. A Method That Rewards Thoughtfulness Pilates does not reward rushing. It does not reward performance. It does not reward spectacle. It rewards attention. It rewards consistency. It rewards intelligent progression. It rewards teachers who are willing to observe rather than simply lead. And in a fitness landscape that increasingly prioritizes how movement looks on camera, this quiet precision becomes even more valuable. Because bodies do not improve through performance. They improve through accurate, repeated, intentional movement. Reclaiming Precision in Modern Pilates Reclaiming precision does not mean making Pilates rigid or overly clinical. It means returning to its original intelligence. It means: Teaching fewer exercises more effectively Slowing down when needed Cueing for sensation, not just shape Observing compensation patterns Prioritizing neurological engagement over visual intensity When this happens, Pilates stops feeling “gentle” in the dismissive sense and starts feeling deeply effective. Subtle. Focused. Demanding in the way that truly organized movement always is. And that is where the real method lives. Not in performance. Not in speed. Not in how impressive it appears. But in the precision that most people overlook. Pilates doesn’t need to be harder.
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