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Friday, December 29, 2023

You Can Palpate the Psoas

You Can Palpate the Psoas
Brent Brookbush

Brent Brookbush


You Can Palpate the Psoas

by Dr. Brent Brookbush DPT, PT, MS, CPT, HMS, IMT


This idea that the psoas cannot be palpated is a relatively recent assertion and seems to be part of a "Nihilistic" or "contrarian" movement in the physical rehabilitation professions (PTs, PTAs, ATCs, DCs, etc.). These Nihilists seem dedicated to proving that nothing we do is effective. The answer to the question, "Can you palpate the psoas?", has become a sort of "stress test" to determine whether or not you are a "true believer" in this physical rehabilitation contrarian movement. However, similar to the flat Earth conspiracy, the conspirators are obviously wrong, because the theory can be easily tested and proven false. It is both possible and easy to test the accuracy of psoas palpation, and there are several randomized controlled trials (RCTs) demonstrating the efficacy of dry needling or manually releasing the psoas.


  • Individuals claiming that the psoas cannot be palpated, are using the "definition swap game" to alter the definition of "palpation" into a version that is easily attacked. This debate tactic is a variation of the logical fallacy known as a "straw man argument".
  • Based on the conventional use of the word palpation by health and medical professionals (e.g. "perceptible by the touch"), the psoas can be palpated.
  • There is an easy and effective method for testing the accuracy of psoas palpation (hip flexion). The technique for palpating, testing the accuracy of palpation, and manually releasing the psoas is covered below (including video).
  • Although the reliability of psoas palpation has not been specifically investigated in a peer-reviewed and published study, several studies (including several RCTs) have demonstrated the efficacy of psoas release techniques. This implies these techniques have at least some reliability, as a lack of reliability would result in inconsistent technique performance and inconsistent improvement in outcomes. Inconsistent improvements are likely to lead to insufficient average improvements to result in statistically significant outcomes in comparative studies.

The Word "Palpation", the "Definition Swap Game," and Straw Man Arguments:

The definition swap game is a strategy in which an alternative definition of a word is created or implied, to make it easier to attack the debater's position. For example, “heart attacks” don’t exist, because I have never seen a “heart being attacked.” Seriously, who or what is attacking the heart? Nothing… see, “heart attacks” don’t exist.

This is actually a clever version of a logical fallacy known as a “strawman argument”. A strawman argument creates a "strawman" or dummy subject by distorting, exaggerating, or creating an alternative reality (stand-up the straw man). The straw man looks or feels like the original argument, but is purposefully altered to make it vulnerable to attack. The "strawman" is then attacked (and not the original argument) to reduce the perceived strength of the debater's position (knock down the strawman). For example; taking a shower is not healthy, because hot water is damaging to your skin. In this example, "hot water" replaces the shower, creating a "strawman" to attack. By attacking the hot water, which is a distortion of a shower, there is a perception that all showers are not healthy. This is false because the water may need to be much hotter than generally experienced during a shower to be unhealthy for the skin, and/or showers may be taken with warm or cold water.

The colloquial understanding of the term "palpation" results in relatively vague definitions. This makes this term vulnerable to this "definition swap game", or "strawman argument" tactic. Does palpation mean to touch, apply pressure, hold in one's hand, or the ability to feel the object's surface? Does "touch" imply there can be no obstructions (e.g. layers of tissue) between the skin of the fingers and the object being palpated?

Etymology and Definition of Palpation:

  • Palpable: late 14c., "that can be felt, perceptible by the touch," from Late Latin palpabilis "that may be touched or felt," from Latin palpare "touch gently, stroke," a word de Vaan finds to be of no known etymology (rejecting the connection in Watkins, etc., to a reduplication of the PIE root *pal-, as in feel (v.), on phonetic grounds). Some sources suggest it is onomatopoeic. The figurative sense of "easily perceived, evident, clear, obvious" also is from late 14c., on the notion of "seeming as if it might be touched." Related: Palpably; palpability. (Etymonline )

The contrarians that claim the psoas cannot be palpated, are suggesting that due to the various layers of tissue between the abdomen and psoas, the psoas cannot be "touched". Some, have even gone so far as to post grainy ultrasound images or rally the support of abdominal surgeons to support their argument. Note, surgeons have no business commenting on the practice of manual therapists. They know less about manual therapy than physical rehabilitation professionals know about pharmacology, and we are not weighing in on drug recommendations. Further, implying a surgeon's opinion is support for an argument, is a logical fallacy known as an "appeal to authority". There are many layers of tissues between the fingertips of a manual practitioner and the psoas during palpation of the psoas, including the skin, the fascia of the semilunar lines, the peritoneal sac, the omentum and/or intestines, the thin anterior layer of the thoracolumbar fascia, and potentially some nerves and vessels. But, the question remains, "What is the definition of palpation?". Does feeling a marble under a pillow count as palpation, or is it necessary to lift or cut through the pillow and hold the marble in the hand? And, if it does require holding the marble in the hand, then what is it called when feeling a pulse (which involves palpating a rhythm through several layers of skin and connective tissue), or a physician's palpatory exam of the abdomen (e.g. palpation test for appendicitis), or releasing the piriformis through the thick gluteus maximus (e.g. foam rolling or manual ischemic compression)? At this point, it should be evident how the definition swap game is being used to create a strawman definition of psoas palpation, which is incongruent with how the term palpation is conventionally used in the health and medical professions.

From the definition above, "perceptible by the touch", is likely the definition that is most congruent with how it is used by health and medical professionals. Below, we demonstrate how to palpate the psoas and check the accuracy of the palpation. This is accomplished by feeling the psoas contract under the fingertips; that is, the contraction of the psoas is "perceptible by touch". Further, release techniques (static manual release, ischemic compression, pin-and-stretch, etc.), only require acute pressure to be effective. It is the compression of over-active/hyper-tonic fascicles that results in the neuromuscular reflex reducing activity, which is the intended result of these techniques. So, when manual therapists claim they can palpate the psoas, they are not claiming they can "hold" the psoas, they are only claiming that the psoas is perceptible enough through the layers of tissue (like a marble under a pillow), to apply compressive forces specifically to the muscle, and potentially parts of the muscles exhibiting altered activity (increased tissue density or sensitivity).

The psoas and muscles surrounding the lumbar spine.
Caption: The psoas and muscles surrounding the lumbar spine.

Palpation and Release of the Psoas


  • Apply pressure to the psoas with the intent of using "ischemic compression" to release trigger points and areas of increased tissue density or sensitivity. This technique may be indicated if a restriction is noted during lumbar rotation, hip extension, or hip internal rotation.

Palpation and Differentiation

  1. The psoas is a deep muscle, lying behind the abdominal muscles and viscera. With the patient in supine, ask them to adjust their clothing to reveal their abdominal region. With a little practice, this technique may be performed through thin clothing; however, for patient comfort, it may be better to move clothing and reduce the amount of friction between the skin, clothing, and the practitioner's fingers.
    Ask your patient to assume a "hook-lying" position with a slight posterior pelvic tilt to reduce tension in the abdominal wall muscles.
  2. Identify the anterior superior iliac spine (ASIS) and semilunar line (lateral border of the rectus abdominis). Place one hand over the other so that the extended fingers and distal interphalangeal joints (IPJs) are braced with the extended fingers of the other hand.
  3. Place the fingertips on the semilunar lines below the level of the umbilicus.
  4. Depress your fingers into the abdomen toward the lumbar spine.
  5. Author's note: The psoas originates on the lumbar spine and inserts into the lesser trochanter; the belly of the muscle is likely deep and/or medial to the semilunar lines. I often see this technique demonstrated as if the psoas were very lateral, abutting the external obliques. They do not! Although I appreciate the notion of "working around" the abdominal viscera, doing this technique inaccurately likely poses a larger risk than responsibly pressing into the viscera with as little additional "searching" or "pressure" as possible.
  6. To aid in reducing the discomfort of depressing into the abdominal contents and stretching skin, continue to adjust the skin on the fingertips to reduce tension, and try to press deeper during the client/patient's exhalations. Following the belly down during breathing makes this technique more comfortable.
  7. Look for a vertically oriented, tube-like structure that is a bit more dense than other soft tissues in the area.

Clinical Gems

  • Test the Accuracy of Psoas Palpation: Test the accuracy of psoas palpation by asking the patient to flex their hip (lift their foot off the table) after it is believed the psoas has been located. Hip flexion will cause the psoas to contact and feel as though it became denser, moved, or "jumped" into the fingers. Internal organs do not contract and generally do not move with hip flexion. If it is suspected that the contraction is the rectus abdominis, have the patient/client perform a crunch and then perform hip flexion. Although hip flexion may cause the rectus abdominis to contract to stabilize the pelvis, once a rectus abdominis contraction is felt and confirmed, differentiating between the superficial rectus abdominis and the deep psoas is not difficult. Additionally, the patient may be cued to perform hip flexion and lumbar extension ("lift their leg" while "arching their back") in an attempt to reciprocally inhibit the rectus abdominis while cuing a psoas contraction. Note, do not assume that any dense structure, or tube-shaped structure, is the psoas. Several structures may feel dense or tube-shaped when compressed, and some of these structures may be more vulnerable to tissue damage with careless compression or abrasion. The only abdominal structures that will contract with hip flexion are the psoas and iliacus (the iliacus is located on the internal face of the ilium). We check the accuracy of our palpation every time we perform this technique, and we recommend every professional adopt the same habit. After all, why not? This accuracy test is quick and easy.

Begin your release:

  • Locate the densist and/or most sensitive regions along the length of the psoas. Note, that it is unlikely specific fascicles or nodules within the psoas and iliacus can be identified. Hold consistent pressure until the dense region softens under the fingers, or tissue density/sensitivity is significantly reduced (generally 20 - 120 seconds).

Potentially Sensitive Tissues

  • This is an advanced palpation, primarily due to the potential to compress sensitive tissues. The kidneys, abdominal aorta, common iliac artery, femoral nerve, and abdominal viscera may be compressed during this technique. Although momentary, responsible amounts of compression likely pose little risk; aggressively rubbing across tissues or maintaining an unnecessary amount of compressive force could be harmful. And, if it pulses, numbs, tingles, or sharps, GET OFF IT!
  • Note, to date, no published cases of injury from manual release of the psoas have been located. Two case studies (see below) have reported complications from attempts to needle the psoas. However, based on the nature of the injuries (puncture of tissues), it is unlikely they could be replicated with manual techniques.

  • Ball, A. M., Finnegan, M., Koppenhaver, S., Freres, W., Dommerholt, J., Mayoral del Moral, O., … & Gaffeny, E. E. (2019). The relative risk to the femoral nerve as a function of patient positioning: potential implications for trigger point dry needling of the iliacus muscle. Journal of Manual & Manipulative Therapy, 1-10.
  • Kim, D. H., & Kim, H. S. (2007). Epidural and Psoas Abscesses Recognized after Paravertebral Trigger Point Injection - A case report. The Korean Journal of Pain, 20(1), 74-77.

Trigger Points

  • Common trigger points for the psoas muscles (that are reachable with manual therapy) are in the middle of the belly of the psoas.

The Efficacy of Psoas Release

Although the reliability of psoas palpation has not been specifically investigated in peer-reviewed and published studies, several studies (including several RCTs) have demonstrated the efficacy of psoas release techniques. This implies these techniques have at least some reliability, as a lack of reliability would result in inconsistent technique performance and inconsistent improvement in outcomes. Inconsistent improvements are likely to lead to insufficient average improvements to result in statistically significant outcomes in comparative studies. Needling studies were included below, both because of the scarcity of studies investigating manual psoas release, and because it is the author's opinion that reliably needling the psoas would be more challenging and pose a greater risk than manual techniques. That is, if psoas needling results in consistently better outcomes, some reliability of needling has been demonstrated, and the reliability of needling implies that reliable manual release and palpation is achievable. The annotated bibliography below includes all of the studies that could be located that specifically mention psoas dry needling or psoas manual release techniques as part of their methodology.


  • Double-blind and sham-controlled RCTs have demonstrated that needling including the psoas, both in isolation and when added to conventional therapy, may result in a significant reduction in pain, state anxiety, and improvement in function. Further, trigger point-based injection may be more effective than acupuncture-based injection, and injection with type-A botulinum toxin (BTX-A or Botox) may be more effective than injection with NaCl or bupivacaine.
  • An RCT and experimental study demonstrate that manual release including the psoas can significantly improve hip mobility of young elite athletes, as well as improve the rotational biomechanics (specifically downswing hip turn) of young elite golfers, and egg-beater endurance test performance of young elite water-polo players.

Annotated Bibliography: Psoas Release Randomized Controlled Trials (RCTs)


A double-blind RCT by De Andrés et al. compared 8 males and 20 females (age: 51 ± 12 years) diagnosed with chronic (mechanical) low back pain (CLBP) lasting 6 months or more with a failure to resolve following conventional treatment. Additionally, participants had to present with bilateral active trigger points in the psoas and/or quadratus lumborum (QL). With the aid of fluoroscopy-guided injection, one side was randomly selected for injection of type-A botulinum toxin (BTX-A) and the other side randomly received a solution including NaCl or bupivacaine. Outcome measures were recorded at baseline and 15, 30, and 90 days post-intervention. The findings demonstrated that injection resulted in a trend toward a reduction in pain and a decrease in Spielberger State-Trait Anxiety Index scores (visual analog scale). Only the BTX-A injection resulted in a statistically significant reduction in pain; however, the differences between injection groups were not significant. Injections did not result in a significant difference in daily activity and quality of life scores (Hospital Anxiety and Depression scale [HAD-A and HAD-D], Lattinen, and Oswestry).

Placing of Needle (Quoted from De Andrés): To place the needle within the psoas muscle, it was inserted in the middle point of an imaginary line connecting the distal end of the transverse processes of L3 and L4 (or L4 and L5) and advanced until its tip reached approximately the midline of the vertebral body in the lateral view. To locate the needle in the quadratus lumborum, it was inserted just above the middle point of the iliac crest and advanced up to the vertebral laminae (behind the transverse process) in the lateral view (Figs. 1 and 2).

  • De Andrés, J., Adsuara, V. M., Palmisani, S., Villanueva, V., & López-Alarcón, M. D. (2010). A double-blind, controlled, randomized trial to evaluate the efficacy of botulinum toxin for the treatment of lumbar myofascial pain in humans. Regional Anesthesia & Pain Medicine35(3), 255-260.
  • https://www.academia.edu/28020285/A_Double_Blind_Controlled_Randomized_Trial_to_Evaluate_the_Efficacy_of_Botulinum_Toxin_for_the_Treatment_of_Lumbar_Myofascial_Pain_in_Humans

An RCT by Itoh et al. (2008) compared 30 patients (27 women, 3 men; age: 61-82 years) with non-radiating knee osteoarthritis pain for at least 6 months and normal neurological examination, randomized to an acupuncture point needling group, a trigger point needling group, or a sham needling group. All participants were blindfolded during a total of 5 treatments, 1x/week, 30 minutes/session, with follow-up assessment immediately, 5 weeks, and 15 weeks post-intervention. Acupuncture included the most commonly cited trigger points in the literature for the lower extremity (e.g. ST34, ST35, ST36, SP 9, SP10, GB 34), using disposable stainless steel needles (0.2x40mm, Seirin Co, Japan), inserted into the muscle (10mm depth), followed by a 'sparrow pecking' technique (alternate pushing and pulling of the needle) until the participant felt dull pain (e.g. de qi). Then the needle was left in place for 10 more minutes. Trigger point needling included the "most important" muscles of the lumbar and lower extremity that elicited a twitch response (e.g. quadriceps, iliopsoas, sartorius, adductors, popliteus, gluteus minimus, hamstrings, and "other" ), using disposable stainless steel needles (0.2x50mm, Seirin), inserted into the muscle (0-30 mm depth) followed by a 'sparrow pecking' technique (alternate pushing and pulling of the needle) to elicit a twitch), and then the needle was left in place for 10 more minutes. The mean number of insertions was 3.3. The sham group received a session that mimicked the acupuncture protocol; however, the ends of the needles were cut and sanded so that pressure, but no skin penetration would occur. The findings demonstrated that acupuncture and trigger point needling when compared to pre-intervention values and sham acupuncture, exhibited significant improvement for both pain (visual analog scale) and function (Western Ontario and McMaster Universities Arthritis Index). Note, the trigger point group exhibited a significantly larger reduction in pain.

  • Itoh, K., Hirota, S., Katsumi, Y., Ochi, H., & Kitakoji, H. (2008). Trigger point acupuncture for treatment of knee osteoarthritis–a preliminary RCT for a pragmatic trial. Acupuncture in Medicine26(1), 17-26.
  • https://go.gale.com/ps/i.do?id=GALE%7CA177636083&sid=googleScholar&v=2.1&it=r&linkaccess=abs&issn=09645284&p=AONE&sw=w&userGroupName=nysl_oweb&isGeoAuthType=true&aty=geo

An RCT by Itoh et al. compared 26 consecutive out-patients (17 women, 9 men, age: 65–91 years) from the Department of Orthopaedic Surgery at Meiji University of Oriental Medicine, with at least 6 months of non-radiating low back pain and a normal neurological examination. Participants were randomized into 2 groups, 1 group receiving trigger point acupuncture first, the other group receiving sham acupuncture first, 3 weeks without an intervention, and then the other intervention. Acupuncture was performed at trigger point sites, which were identified in accessible muscles by the presence of taut bands, pain, or a local twitch response, and in less accessible muscles were identified by pain or tenderness during manual pressure or needling. The muscles assessed included the iliocostalis lumborum, quadratus lumborum, gluteus maximus, gluteus medius, gluteus minimus, piriformis, Iliopsoas, and "other" (only 2 times). Acupuncture was performed using disposable stainless steel needles (0.2x50mm, Seirin Co, Japan), inserted into the muscle (10-40 mm depth), followed by a 'sparrow pecking' technique (alternate pushing and pulling of the needle) until the participant felt dull pain (e.g. de qi). Then the needle was left in place for 10 more minutes. The sham group received a session that mimicked the acupuncture protocol; however, the ends of the needles were cut and sanded so that pressure, but no skin penetration would occur. The findings were based on 19 participants who completed the study, demonstrating that acupuncture, when compared to sham acupuncture, resulted in lower pain (VAS) and Roland Morris Questionnaire scores. Further, both groups exhibited significant improvements in pain following acupuncture, but not sham treatment.

  • Itoh, K., Katsumi, Y., Hirota, S., & Kitakoji, H. (2006). Effects of trigger point acupuncture on chronic low back pain in elderly patients–a sham-controlled randomized trial. Acupuncture in Medicine, 24(1), 5-12.

An RCT by Mahmoudzadeh et al. compared 58 participants (age: 20-50 years, control group age 35.6 ± 8.5 years; dry needling group age 36.1 ± 7.8 years ) with discogenic low back pain and radiating nerve pain into one or both legs, randomly assigned to a control group performing conventional physical therapy or an experimental group performing conventional physical therapy and dry needling. Conventional physical therapy included 10 sessions/10 days (45 min session/day) of a thermal modality, transcutaneous electrical nerve stimulation (TENS), ultrasound, and McKenzie stabilization exercises. Dry needling was performed 5 times/10 days, 15 min/every other day (e.g. 2nd day, 4th day, etc.) with 3–6 cm solid filament needles, directly into muscles exhibiting motor trigger points (MTPs) or taut bands, with accuracy confirmed via reproduction of pain or a local twitch response. Muscles assessed included the paraspinals (iliocostalis, longissimus), multifidus, quadratus lumborum, gluteus maximus, gluteus medius, gluteus minimus, piriformis, psoas major, hamstrings (semimembranosus, semitendinosus, biceps femoris), and the gastrocnemius. The findings demonstrated significant improvements in pain (visual analog scores) and Oswestry Disability Index (ODI) scores; however, the group that received dry needling exhibited significantly larger improvement both immediately following and 2 months post-intervention

  • Mahmoudzadeh, A., Rezaeian, Z. S., Karimi, A., & Dommerholt, J. (2016). The effect of dry needling on the radiating pain in subjects with discogenic low-back pain: a randomized control trial. Journal of research in medical sciences: the Official Journal of Isfahan University of Medical Sciences21.
  • https://www.researchgate.net/publication/311223662_The_effect_of_dry_needling_on_the_radiating_pain_in_subjects_with_discogenic_low-back_pain_A_randomized_control_trial.

Manual Release

An RCT by Quinn et al. recruited 100 golfers with a handicap of 6 or less (age 16 - 25 years), who exhibited restricted hip extension (positive modified Thomas Test) and were participating in golf-related training a minimum of 2 hours/week. Participants were randomly assigned to a control group (no additional activity), a trigger point therapy and home stretching group, and a trigger point therapy and ball exercise group. Trigger point therapy included 45 seconds of manual ischemic compression to an iliopsoas active trigger point (elicited a referral pattern and twitch response) immediately followed by 60 seconds of static manual hip flexor stretching in the Thomas test position. The participants in the stretching group were instructed to perform a kneeling hip flexor stretch every day for 7 days, 60 sec/side, 3 sessions/day. The participants in the ball group were instructed to perform a PNF diagonal ball chop pattern with a 4kg ball, every day for 7 days, 50 reps/side, 3 sessions/day. The findings demonstrated that trigger point therapy resulted in a significant improvement in hip flexor mobility and rotational biomechanics (specifically downswing hip turn), and biomechanics improved more following the chops program when compared to the kneeling hip flexor program.

  • Quinn, S. L., Olivier, B., & Wood, W. A. (2016). The short-term effects of trigger point therapy, stretching and medicine ball exercises on accuracy and back swing hip turn in elite, male golfers–A randomized controlled trial. Physical Therapy in Sport, 22, 16
  • 22.\https://pdfs.semanticscholar.org/35d7/a4d293fe6aa4bd8ef618ad1dfa5564d8e3bb.pdf

Mosler et al. compared 16 junior elite male water polo players (mean age: 17.6 years) with an absence of any musculoskeletal injuries that would prevent them from participating in any 2 consecutive training sessions during the study. Participants continued their normal training and practice regimen during the 12-week study period while being randomly assigned to 2 groups. The first group received 4 weeks of additional trigger point therapy, while the other group did not, followed by 4 weeks of neither group receiving trigger point therapy (wash-out period), followed by the other group receiving 4 weeks of additional trigger point therapy. Additional trigger point therapy included 4 weeks, 2 sessions/week, 45 minutes per session, of an evidence-based list of techniques that have demonstrated efficacy for improving ROM (1. compression of the tensor fascia latae, psoas, iliacus, adductors, and the gluteals; 2. passive tissue tension to gluteals and hip external rotators; 3. friction massage to iliolumbar ligament and L4-5 interspinous space; 4. stretches to the anterior hip joint capsule, gluteal and piriformis muscles; 5. lateral hip distraction with seat belt). The findings demonstrated that additional trigger point therapy resulted in a statistically significant improvement in hip ROM (internal rotation, external rotation, and total passive range of motion), but did not improve hip abduction ROM. Further, a trend was noted for increased time on the egg-beater endurance test and vertical test (water polo specific); however, the results failed to reach statistical significance.

  • Mosler, A. B., Blanch, P. D., & Hiskins, B. C. (2006). The effect of manual therapy on hip joint range of motion, pain and eggbeater kick performance in water polo players. Physical Therapy in Sport, 7(3), 128-136.

© 2023 Brent Brookbush (B2C Fitness, LLC d.b.a. Brookbush Institute )

Comments, critiques, and questions are welcome.