All about the Psoas Muscle

Originally published 09/11/2017

The following blog post on the psoas is primarily aimed at our current Teacher Trainee group and forms an integral part of the Teacher Training programme. However, those who have already qualified or anyone interested in anatomy may also find this blog interesting. While a comprehensive understanding of muscles and anatomy is not essential for all yoga teachers, I have found, based on my experience, that refreshing my knowledge of anatomy and staying updated with the latest research enables me to provide a more well-rounded service to my students.

Although academic knowledge of the body does not solely determine the ability to lead and teach effectively, it does support me in offering appropriate guidance to my students. For example, if a student requests a specific hip or lat stretch, I can draw upon my anatomy knowledge to prescribe the correct posture. However, I also agree that overly focusing on anatomy can sometimes lead to confusion and complicate the teaching process. As with everything, balance is key.

We study anatomy on our teacher trainings not to become experts or to impress with our knowledge, but because, fundamentally, it's a deeply yogic practice. Understanding anatomy can shift our focus inward to the remarkable inner machinery of the human body. It fosters an appreciation for the body's complex mechanisms 😯. While it certainly aids in guiding students, the true enchantment of studying anatomy lies in its ability to redirect our own attention (when we do Yoga) from external events to the messages our bodies convey from within.

Yoga at its core is a deeply personal practice. But I digress.

The main subject of this in-depth blog is the psoas muscle. In recent years, the psoas has become a popular topic of discussion among yoga teachers. Personally, I prefer a holistic approach that considers the entire body rather than breaking it down into isolated parts. Nevertheless, the increasing literature connecting a tight psoas to back pain has led to ongoing discussions about this muscle. Additionally, the psoas' relationship to the diaphragm, connected by fascia (connecting/connective tissue), suggests that a "tight" psoas may impact or restrict breathing. Therefore, let us delve into a more detailed exploration of the psoas.

Before we continue, you might be wondering why I put the word "tight" in quotation marks. Well, it's to offer you a different perspective—not necessarily right or wrong, just another way of looking at it. I believe that no muscles are truly tight, at least not in the way we commonly think. Instead of using the word tight, what if we replaced it with toned? When someone struggles with a particular movement, it’s often due to muscle tone creating restrictions, rather than actual tightness. I hope that makes sense. But anyway, back to the blog!

The psoas muscle (above in red) is a big deal in our body—it’s the largest muscle by cross-section at the lower levels of the lumbar spine. Picture this: it’s a long, strong muscle (up to 16 inches!) running along either side of your lumbar spine. It starts from the front of the lumbar vertebrae (specifically L5), joins the iliacus muscle in the pelvis, and inserts at the lesser trochanter of the femur (upper thigh bone).

I've seen the psoas in a cadaver (a body generously donated to science). It belonged to a 67-year-old woman who had been inactive for years, yet her psoas was still impressively thick and strong. That speaks volumes about just how powerful this muscle really is. The image below is not her! Its just Artwork.

In everyday life, the psoas is the muscle we call on for most movements—walking, bending over, climbing stairs. It’s the engine of our body’s forward momentum. Imagine walking up the stairs: it's our psoas that lifts your leg and allows you to take a step. It also works with the other hip flexors to bring the leg toward the chest or vice versa, depending on what’s fixed (legs or spine).

For the yogis out there, think about Boat Pose (Navasana). Many assume it’s all about the abdominals, but it’s actually the psoas that's driving that hip flexion to keep our legs lifted. The abs are more like our spinal stabilisers in that pose.

Image used courtesy of Ray Long, Yoga Mat Companion 2: Forward Bends & Hip Openers (2010)

Continuing on the yoga front, if the psoas works to flex or bend your hips, what action do we take to stretch this muscle? The opposite. Extension at the hip. Think lunge or back-bending (to simplify the psoas for a moment).

Try to visualise the psoas muscles elongating as you bend backward. A "Tight" or restricted psoas muscle would inhibit our ability to perform some of the back-bending yoga poses.

Images used courtesy of Ray Long, Yoga Mat Companion 3: Back Bends & Twists (2010)

The Psoas and Its Hip Flexor Team

The psoas is part of a larger group of muscles known as the hip flexors. Think of these muscles as a team that works together to help you lift your leg up, whether you’re walking up stairs, climbing hills, or even just marching on the spot. This team includes muscles like the rectus femoris and sartorius on the front of our thigh (among a few others). All these muscles lend a hand when we’re lifting our leg to about 90 degrees (or when your thigh is parallel to the floor).

Now, here’s where things get interesting: once your leg goes beyond 90 degrees, it’s as though the rest of the team steps back, and the psoas takes over as the star player. So, while the entire group works together to lift your leg initially, the psoas becomes the MVP when we're aiming higher.

The Psoas and the Spine: A Common Misunderstanding

There’s been some debate (in the anatomy world) about whether the psoas helps stabilise the lower spine. Imagine a sturdy tent with ropes. Some people think the psoas acts like one of those support ropes that hold the tent (our spine) steady. But according to Dr. Stuart McGill, a spine expert, this isn’t quite the case. He’s shown that the psoas is more like a powerful tugboat, pulling your leg forward and flexing the hip rather than steadying the spine. In fact, instead of stabilising the spine, the psoas can actually compress the lower back, especially when overworked in exercises like sit-ups or leg raises. So, it’s not exactly the rope holding things steady—it’s more like a muscle doing its own thing. Not that this matters to you as a yoga teacher but still. Good to know I took the time out to research this for you! 😄

The Iliopsoas Myth: Are the Psoas and Iliacus Best Friends or Just Acquaintances?

You might have heard the term "iliopsoas" thrown around, suggesting that the psoas and another muscle, the iliacus, are like two peas in a pod—working together as one mega-muscle. But that myth has also been somewhat busted. The experts says there’s no such thing as an "iliopsoas" muscle. Gasp!

While it’s true that the psoas and iliacus work closely together to flex the hip (imagine them as two colleagues working on the same project), they are still separate muscles with their own distinct origins and functions. It’s a bit like two teammates who play well together on the field, but when you look closely, they each bring something different to the game. The psoas starts up higher, connecting to the spine, while the iliacus hangs out lower, attaching to the pelvis. Sure, they meet up at the same place (the thigh) to flex the hip, but they’re functionally quite different.

Even though many anatomy books lump them together for convenience (because they have similar roles at the hip), some (but not all - just to be clear!) insist that these muscles should be seen as independent, each with its own job to do.

Hmmm. Welcome to the wonderful world of anatomy, where one year you think you are making headway in your understanding of the human body and the next year you are questioning everything you know. Anyway, let's move on.

Some of the daily movements and exercises that involve the psoas include:

• Walking

• Climbing stairs

• Running

• Cycling

• Sit-ups and crunches

  
  

Too much of these activities can lead to an overworked—and ultimately "tight"—psoas muscle, which can cause back pain and compensatory movement patterns. Liz Koch, author of The Psoas Book (2012), states:

“The only muscle to connect your spine to your leg, the psoas influences everything from low back pain and anxiety to full-body orgasms and pure pleasure.”

She also mentions:

“A tense psoas can disturb digestion, reproductive functioning, and create a host of other ailments.”

In a summary of Liz’s book, a tight or weak psoas has a profound effect on everyday movement and can contribute to pain, postural issues, and muscle imbalances. However, when flexible and strong, it supports healthy movement, recreation, and exercise.

I personally agree with much of what Liz Koch says. But some of her claims seem—well—wild. That’s not to say she’s wrong; I just don’t fully agree. However, the reason I’m including her perspective is to give you a broader view of how much emphasis is placed on this muscle.

Other experts have said...

• Dr. Alison Grimaldi, a renowned physiotherapist, emphasizes the psoas muscle's unique role: "No other hip flexors do what the iliopsoas does." She points out its critical functions, including providing dynamic anterior stability for the hip joint, supporting the lumbar spine, and facilitating inner-range hip flexion.

  Dralison Grimaldi

  
  

• Dr. Alexander M. Dydyk and Dr. Amit Sapra discuss the clinical implications of psoas syndrome, noting that "Psoas syndrome is a rare injury to the iliopsoas muscle, typically seen in athletes, often runners, dancers, and high jumpers." They highlight that overuse or trauma can lead to this condition, causing significant discomfort and mobility issues.

  NCBI

  
  

• Dr. Benedict Nwachukwu, an orthopedic hip specialist, addresses the consequences of psoas impingement: "An impinged psoas muscle can cause serious problems with posture and is often a cause of lordosis (overarching of the lumbar spine)." He emphasizes that this condition can lead to low back pain and stiffness, underscoring the importance of proper diagnosis and treatment.

  Manhattan Sports Doc

  
  

These perspectives underscore the psoas muscle's vital role in movement, stability, and overall musculoskeletal health.

A "Tight Psoas": The Overworked Muscle

Picture this: you spend a lot of time sitting—whether at a desk, in a car, or curled up on the sofa. Or maybe you do something great for your body, like lots of squats and deadlifts (both of which require hip flexion). What happens? Your psoas adapts to being in a shortened position. Over time, this conditions the muscle to stay prepped for those same movement patterns all day long, which creates the sensation of tightness.

When this so-called tight psoas pulls on the lumbar spine, it can (though not always, of course) tip the pelvis forward. This results in anterior pelvic tilt, which throws off the alignment of your spine. Think of your pelvis as a bowl—if it tips too far forward, everything spills out of balance. This forward tilt can lead to:

• Lower back pain – A tight psoas pulls on the lower back, creating compression in the lumbar spine. Over time, this constant pull can lead to discomfort, ranging from a dull, achy, tired feeling to full-blown chronic pain (Dydyk & Sapra, 2023).

• Postural issues – A tight psoas can contribute to a "swayback" posture, where the lower back arches more than it should. This doesn’t just affect the spine but also disrupts full-body alignment. Now, this won’t necessarily cause pain—our bodies are remarkably adaptive—but it does increase susceptibility to lower back issues (Grimaldi, 2022).

• Restricted hip mobility – With a tight psoas, the hips might feel locked up, limiting movement and making activities like lunging or walking uphill feel harder than they should. Again, this alone won’t create pain, but it definitely increases the risk of lower back strain and discomfort (Nwachukwu, 2024).

A Weak Psoas: The Underworked Muscle

On the other hand, a weak psoas is like that one muscle that’s never quite pulling its weight. You may not even realize it, since the psoas works so quietly behind the scenes, but if it’s weak, the consequences can really sneak up on you.

A weak psoas might show itself when:

• We struggle with balance – Since the psoas plays a key role in hip flexion (lifting the leg), weakness here can make balancing on one leg feel shaky or unstable (think Tree Pose). Research shows that reduced psoas strength can contribute to instability, particularly in older adults and athletes recovering from injuries (Dydyk & Sapra, 2023).

• We feel other muscles compensating – When the psoas isn’t doing its job properly, other muscles—like the quads, hip flexors, and lower back—can (theoretically at least) step in to pick up the slack. Over time, this theoretically lead to overuse injuries, tightness, or imbalances in these muscles (Nwachukwu, 2024).

• Our posture suffers – Just like a tight psoas, a weak psoas can mess with alignment. If it’s not engaging properly, our posture may collapse forward, or our hips may lose some of their natural stability. Poor psoas function has been linked to postural dysfunction, contributing to conditions like swayback or excessive lumbar lordosis (Grimaldi, 2022).

Can We Have Both a Tight and Weak Psoas?

Here’s the kicker: it’s entirely possible to have a tight and weak psoas at the same time (because, of course, our bodies love to be complicated!). Just because the psoas is "tight" doesn’t mean it’s strong. In fact, many people with a tight psoas also have a weak one. Imagine a rope pulled too taut but still flimsy—same concept.

When your psoas is both tight and weak, you get the perfect storm:

• Back pain – The tightness creates compression, while the weakness forces other muscles to overcompensate, putting even more stress on the back.

• Limited movement – Our body might feel stiff and restricted in hip mobility while also feeling unstable due to lack of support from the psoas.

• Hip imbalance – Without proper psoas strength, our hips may tilt unevenly, affecting everything from our gait to balance in yoga poses. This imbalance can increase the risk of hip, knee, and even ankle issues over time.

The Psoas: Strength, Flexibility, and Durability in Yoga

A Personal Perspective on the Psoas and Back Pain

From personal experience, the idea that a tight psoas always causes lower back pain isn’t entirely accurate. I’ve had back pain for most of my adult life, yet my own Thomas Test (a physical exam that determines Psoas fleibility) results indicate that my psoas isn’t tight. While it’s not exceptionally flexible, it’s certainly not tight enough to cause compensation patterns—or at least, none that I’m aware of.

So, does a tight psoas always cause lower back pain? No. But there’s a wealth of literature suggesting that it can contribute to it.

Dr. Stuart McGill (2016), a leading expert in spine biomechanics, warns that we need to be cautious when strengthening the psoas due to its role in spinal compression. Exercises like sit-ups, which engage the psoas to flex the spine, can place compressive loads on the lower back that exceed recommended guidelines. Even worse, leg raises—an even more psoas-dominant movement—create even greater spinal compression (McGill, 2016).

This aligns with my own perspective, that constantly doing sit-ups and leg raises may be more detrimental to spinal health than having a tight psoas.

I firmly believe (and this is my opinion based on 25 years in the game—driven by science) that no one really has a weak psoas. More often than not, people have a psoas that is overworked and simply needs to be reminded of its full-length capacity—which is where stretching comes in.

A muscle that contracts fully is also more energy-efficient. Trying to generate force from a shortened psoas? That’s just wasted effort. Think of it like trying to jump with your knees already half-bent—you’re working harder but getting less power.

Or… have I just lost you on that last part? 😆

The point is: stretching the psoas is both the solution and the remedy. Simple as that!

How to Stretch the Psoas in Yoga

There are countless articles online about “awakening” or “releasing” the psoas, but let’s keep things simple. If a tight psoas is potentially linked to lower back pain, what are the best yoga stretches to keep it supple and strong?

1. The Classic Lunge Stretch (with a Crucial Adjustment!)

If you do one thing for your psoas, make it a basic lunge stretch. It’s simple, accessible, and highly effective when done correctly.

✅ To enhance the stretch, I actively squeeze the glutes of my back leg. This sends a neurological signal to my hip flexors to relax (a principle called reciprocal inhibition).

✅ At the same time, I gently contract my deep abdominal muscles to support my lower back. This is key—without core engagement, the lumbar spine can collapse into hyperextension, which is especially uncomfortable for anyone with a history of back pain.

🔴 The most common mistake in psoas stretching is allowing the lower back to overarch. This is what happens when you simply drop into a lunge without engaging the core. Instead of stretching the psoas, you just end up putting strain on the lower back.

So don’t me that guy—use your abdominals to protect your spine!

The Video below is from our Youtube channel. Before you comment on my barnet, this video was filmed 4 years ago.

2. Psoas Stretching Through Backbends

Any backbend inherently stretches the psoas because they all take the hips into extension. Some of the best yoga postures for this include:

• Wheel Pose (Urdhva Dhanurasana)

• Bow Pose (Dhanurasana)

• Camel Pose (Ustrasana)

However, backbends must be executed correctly to truly target the psoas. Many practitioners, instead of opening the hips, rely on excessive lumbar extension—again, leading to compression in the lower back rather than an effective stretch.

✅ In Wheel Pose, focus on pressing the hips up and forward rather than just bending backward.

✅ In Bow Pose, kick the legs back while maintaining core engagement to avoid dumping into the lower spine.

✅ In Camel Pose, imagine your hips being pulled forward as you lift the chest, rather than just collapsing into the lumbar curve.

When these adjustments are made, the psoas is stretched effectively without compromising the health of the lower back.

3. Strengthening the Psoas Without Overloading the Spine

As McGill (2016) warns, psoas-dominant exercises like sit-ups and leg raises create excessive spinal compression. Instead, consider safer ways to strengthen the psoas without harming your back:

✅ Standing Knee Lifts – While standing, lift one knee toward your chest while keeping your spine neutral. This engages the psoas in a functional way without excessive lumbar load.

✅ Boat Pose (Navasana) with Bent Knees – Instead of full straight-legged Boat Pose (which heavily recruits the hip flexors), keep the knees bent to reduce spinal compression while still strengthening the psoas.

✅ Active Lunge Holds – Holding a lunge with core activation not only stretches the psoas but also strengthens it in a lengthened state, creating both flexibility and durability.

References:

• McGill, S. (2016). Back Mechanic: The secrets to a healthy spine your doctor isn’t telling you.

• Dydyk, A. & Sapra, A. (2023). Psoas Syndrome. National Center for Biotechnology Information. Link

• Grimaldi, A. (2022). The Case Against Iliopsoas Release. Link

• Nwachukwu, B. (2024). Psoas Impingement and Orthopedic Considerations. Link

Summary

Discussions about the psoas will undoubtedly continue as our understanding of the human body evolves. There will always be debates about the muscle’s secondary functions. We know it flexes the hip (McGill, 2016), but what other movements it assists with remain a topic of discussion.

At this point, you might be wondering—does it really matter? And honestly, I’d be inclined to agree. With every newly suggested secondary function of the psoas, there seems to be a corresponding influx of yoga pose variations designed to "target" these so-called functions. But do we really need more?

The art of Hatha yoga has already been intelligently and beautifully crafted. Do we need to keep reinventing poses, using anatomy as an excuse to justify our “creativity”? The foundational system taught by B.K.S. Iyengar is already a complete practice, one that effectively stretches, strengthens, and fine-tunes every muscle in the body.

If you're a budding yoga teacher, you don’t need to complicate things. Stick to the fundamental poses—as taught by Iyengar or Pattabhi Jois—and you can’t go wrong.

The Purpose of This Blog

So, why write this?

The goal was to give you a fundamental understanding of your psoas—what it does, how it works, and, most importantly, how to stretch it.

• What does the psoas do? It flexes the hip.

• How do you stretch it? Extend the hip.

That’s it. Simple.

So the next time a student asks how to stretch their hip flexors, you’ll have the confidence to explain the basics and suggest a few poses they can practice. And really, that’s all they need.

If you wish to learn more about the Psoas you can check out my Anatomy Made Easy online course.

A Final Word of Caution

If you just feel tight, you can’t go wrong with stretching or yoga. A good stretch will always help restore mobility and function.

However, if you feel pain in what you think is your psoas, it’s best to seek medical advice. Spasms are no joke (just ask Emma at the studio!), and in extremely rare cases, serious conditions like calcifications or tumors can develop in the psoas (Torres et al., 1995). These cases are rare, but it’s always better to be cautious if you experience persistent pain rather than just tightness.

So, listen to your body, stretch when needed, and when in doubt—get it checked out.

Zahir Akram - Eternal Seeker

---------------------------------

Interested in deepening your practice or teaching skills?

Our online training courses are now available, offering comprehensive content on anatomy, biomechanics, and yoga philosophy. These courses are designed to support students and yoga teachers in their continued development.

We also offer in-house Yoga Teacher Training here at our studio in Addlestone, Surrey, UK.

For more information on our online courses, mentoring or to book in-house training, email Zahir.

Zahir@AkramYoga.co.uk

Blog ref:

1.Alter, Michael J, 1996. Science of Flexibility. 2nd ed. U.S: Human Kinetics (ADVANTAGE)

2.Bianca Elizabeth Machliss, Simon Andrew Borg-Olivier, 2016. Applied Anatomy & Physiology of Yoga. 1st ed. U.K: Yoga Synergy Pty Ltd; 1st edition (1 July 2016).

3.Boyle, Michael. 2006. Understanding Hip Flexion. Available at: http://www.ptonthenet.com/articles/ understanding -hip- flexion- 2679.

4.Chila, Anthony G.; et al., eds. (2010). Foundations of Osteopathic Medicine. Published under the auspices of the American Osteopathic Association (3rd ed.). Lippincott Williams & Wilkins

5.Clare Frank, P., 2010. Assessment and Treatment of Muscle Imbalance by Phil Page, Clare Frank (2010). 1st ed. United Kingdom: B00NPNDGAA.

6.Ellgen, Pamela, 2015. Psoas Strength and Flexibility: Core Workouts to Increase Mobility, Reduce Injuries and End Back Pain. 1st ed. U.S: Ulysses Press; 1 edition (16 Feb. 2015).

7.Hugo, The Osteopathy Partnership. 2016. Look after your Psoas and your back pain. [ONLINE] Available at: http://www.osteopathypartnership.com/look-after-your-psoas-and-your-back-pain/. [Accessed 30 August 2017].

8.Jemmett RS, Macdonald DA, Agur AMMan Ther. 2004 Nov; 9(4):203-10.

9.Kent Stuber, BSc, DC, MSc2, Sandy Sajko, BPHE, DC, MSc,, 2009. 2009 Dec; 53(4): 311–318. Psoas Major: a case report and review of its anatomy, biomechanics, and clinical implications, [Online]. 1, 1. Available at: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2796950/ [Accessed 27 September 2017].

10.Koch, Liz, 2012. The Psoas Book. 1st ed. U.K: B00YDKEGIA.

11.Kiel, David, 2014. Functional Anatomy of Yoga: A Guide for Practitioners and Teachers. 1st ed. U.K: Lotus Publishing (31 July 2014).

12.McGill SM, Patt N, Norman RWJ Biomech. 1988; 21(4):329-41.

12.McGill, Dr. Stuart, 2016. Low Back Disorders-3rd Edition with Web Resource: Evidence-Based Prevention and Rehabilitation. 3rd ed. U.S: Human Kinetics Australia P/L; 3rd edition (10 Jan. 2016).

13.Nachemson AActa Orthop Scand. 1966; 37(2):177-90

14.National Academy of Sports Medicine, (., 2013. NASM Essentials Of Corrective Exercise Training. 2nd ed. U.S: Jones and Bartlett Publishers, Inc; Revised ed. edition (25 Jun. 2013).

15.National Academy of Sports Medicine, (., 2016. NASM Essentials Of Personal Fitness Training (National Academy of Sports Medicine). 5th ed. U.S: Jones and Bartlett Publishers, Inc; 5th Revised edition edition (23 Jun. 2016).

16. Nicpon-Marieb, Elaine, 2014. Human Anatomy and Physiology (The Benjamin/Cummings series in the life sciences). 3rd ed. U.K: Benjamin-Cummings Publishing Company, Subs of Addison Wesley Longman, Inc; 3rd Revised edition edition (30 Nov. 1994).

17.Sahrmann PT PhD FAPTA, Shirley, 2001. Diagnosis and Treatment of Movement Impairment Syndromes, 1e. 1st ed. U.K: Mosby (12 Sept. 2001).

18.Sajko S (2009) “Psoas Major: a case report and review of its anatomy, biomechanics, and clinical implications”. J Can Chiropr Assoc 53: 311-318.