Psoas Muscle: Anatomy, Common Problems and Exercises

To learn more, consult the guide on Exercises and Stretching for Truck Drivers: 10-Minute Routine in Rest Areas. To learn more, consult the guide on Postural Gymnastics: Fundamental Exercises and Benefits. To learn more, consult the guide on Correct Posture: How to Evaluate and Improve It with Targeted Exercises.

The psoas muscle, often referred to as the “muscle of the soul” or the “deep core”, is an anatomical structure of fundamental importance for posture, movement, and the general well-being of the individual. Its strategic position and multiple connections make it a key player in various bodily functions, but also a potential source of pain and dysfunction if not kept in balance. Understanding the anatomy of this muscle, the common problems associated with it, and the importance of specific psoas muscle stretching exercises and strengthening is essential to effectively prevent and manage the issues that may arise. This article aims to explore the psoas muscle in depth, offering a comprehensive overview for professionals and patients.

Table of Contents

• Anatomy and Function of the Psoas Muscle
• The Psoas in Body Biomechanics
• Common Problems Associated with the Psoas Muscle
• Diagnosis of Psoas Problems
• Physiotherapy Treatment
• Specific Exercises for the Psoas Muscle
• Prevention of Psoas Problems
• Frequently Asked Questions (FAQ)
• Frequently Asked Questions
• Resources
• Sources and Scientific References

Anatomy and Function of the Psoas Muscle

The psoas muscle is a powerful hip flexor and a crucial component of the iliopsoas complex, which also includes the iliacus muscle. Although often generically referred to as the “psoas”, it is important to distinguish between the psoas major and psoas minor, even though the latter is absent in approximately 40% of the population.

Origin and Insertion

The psoas major is the larger and clinically more relevant of the two. It originates from the lateral surfaces of the vertebral bodies and transverse processes of the lumbar vertebrae (from T12 to L5). From there, its muscle fibers run inferiorly, passing anterior to the sacroiliac joint and the hip joint, then joining the iliacus muscle. Together, they form the iliopsoas tendon which inserts onto the lesser trochanter of the femur, a bony prominence located on the medial and posterior aspect of the upper portion of the femur.

The psoas minor, when present, is a smaller and thinner muscle that originates from the vertebral bodies of T12 and L1 and inserts onto the iliopectineal eminence and the iliac fascia. Its primary function is trunk flexion and it does not play a significant role in hip flexion.

Anatomical Relationships

The deep position of the psoas major places it in close relation with numerous vital structures:

• Nervous System: The lumbar plexus (which includes the femoral, obturator, and genitofemoral nerves) forms within or in close proximity to the psoas fibers. This explains why psoas dysfunction can sometimes radiate pain along the path of these nerves.
• Vascular System: The abdominal aorta and inferior vena cava run medially to the psoas.
• Internal Organs: The kidney, ureter, colon, and appendix (on the right) are in proximity to the muscle, which can make it difficult to distinguish between musculoskeletal and visceral pain.
• Diaphragm: There is a fascial and functional connection between the psoas and the diaphragm, influencing respiration and trunk stability.

Main Functions

The psoas major plays a crucial multifunctional role:

• Hip flexion: It is the most powerful hip flexor, bringing the thigh towards the trunk or the trunk towards the thigh (as in a sit-up).
• Lateral trunk flexion: It contributes to trunk flexion towards the ipsilateral side when acting unilaterally.
• External hip rotation: In some positions, it can contribute to external rotation of the femur.
• Lumbar stabilization: It acts as a stabilizer of the lumbar spine, especially during movement.
• Influence on lumbar lordosis: A shortened or overactive psoas can increase lumbar lordosis, while a weak psoas can contribute to a flattened posture.

The Psoas in Body Biomechanics

The psoas is a key muscle in the body’s kinetic chain, influencing posture, gait, and even respiration. Its action extends far beyond simple hip flexion.

During ambulation, the psoas is fundamental for the swing phase of the leg, lifting the knee and bringing the limb forward. A weak or inhibited psoas can alter the gait pattern, making it less efficient and increasing the load on other structures.

Its connection with the lumbar spine makes it a primary actor in maintaining postural balance. A tight or shortened psoas can pull the lumbar vertebrae forward, increasing lordosis and potentially compressing intervertebral discs and facet joints. Conversely, a hypotonic psoas can compromise trunk stability.

The fascial relationship with the diaphragm implies that tensions in the psoas can influence respiratory mechanics, and vice versa. Limited diaphragmatic breathing can contribute to psoas tension, and a tight psoas can hinder diaphragmatic excursion. This interconnection highlights the importance of a holistic approach in evaluation and treatment.

Common Problems Associated with the Psoas Muscle

Given its anatomical and functional complexity, the psoas is susceptible to various problems that can manifest with diverse and often misleading symptoms.

Psoas Syndrome

Psoas syndrome is a generic term describing a condition of pain and dysfunction associated with tension, shortening, or spasm of the psoas muscle.

• Causes:

• Prolonged sedentary lifestyle: Sitting for long periods keeps the psoas in a shortened position, promoting adaptation and stiffness.

• Sports activities: Sports requiring repeated hip flexion (soccer, running, dance, martial arts) can lead to overuse and shortening.

• Direct or indirect trauma: Falls, blows, or sudden movements can cause strains or contusions.

• Lower limb dysmetria or postural imbalances: Can induce the psoas to work compensatorily.

• Emotional stress: Some theories suggest a correlation between chronic stress and psoas tension, given its proximity to the autonomic nervous system.
• Symptoms:

• Pain in the lower lumbar region, often unilateral, which may radiate to the groin, anterior thigh, or buttock.

• Difficulty maintaining an upright position or fully extending the hip.

• Pain that worsens with resisted hip flexion or hip extension.

• Sensation of stiffness or “locking” in the lumbar or groin area.

• Altered gait.

• In some cases, neurological symptoms such as numbness or tingling in the anterior thigh (due to compression of the femoral or lateral femoral cutaneous nerve).

Iliopsoas Tendinopathy

Iliopsoas tendinopathy is an inflammation or degeneration of the iliopsoas tendon, often caused by overuse or repetitive movements.

• Causes: Sports activities involving kicking, sprinting, jumping, or repeated hip flexion movements (e.g., gymnastics, dance, athletics). It can also be associated with muscle imbalances or altered hip biomechanics.
• Symptoms:

• Acute or chronic pain in the groin region, which may radiate to the anterior thigh.

• Pain that worsens with physical activity, especially with resisted hip flexion or passive hip extension.

• Sensation of “snapping” or “clicking” in the hip during movement (internal coxa saltans), which may be audible or palpable. This is due to the tendon sliding over bony or ligamentous structures.

Iliopsoas Bursitis

The iliopsoas bursa is a fluid-filled sac located between the iliopsoas tendon and the hip joint capsule, with the function of reducing friction. Inflammation of this bursa is known as iliopsoas bursitis.

• Causes: Direct trauma, overuse, rheumatoid arthritis, or hip osteoarthritis.
• Symptoms:

• Deep, dull pain in the groin or anterior thigh.

• Pain that worsens with hip movement, particularly with flexion and internal rotation.

• Sometimes, a palpable mass or swelling in the groin region.

• Difficulty sleeping on the affected side.

Impact on Other Conditions

A dysfunctional psoas can contribute to or exacerbate other musculoskeletal conditions:

• Low back pain: A shortened psoas can increase compression on the lumbar discs and facet joints, contributing to chronic low back pain.
• Sciatica: Although not a direct cause, psoas tension can alter pelvic and lumbar biomechanics, indirectly affecting the sciatic nerves.
• Visceral problems: Proximity to abdominal organs can make differential diagnosis complex, and in rare cases, psoas dysfunction may be related to constipation or pelvic dysfunctions.

Diagnosis of Psoas Problems

Accurate diagnosis of psoas problems requires careful clinical evaluation, as symptoms can overlap with those of other lumbar, pelvic, or abdominal conditions.

Anamnesis (Medical History)

A detailed collection of the clinical history is the first step. The physical therapist or doctor will inquire about:

• Location, type, and intensity of pain.
• Aggravating and alleviating factors.
• Patient’s physical and work activities.
• History of trauma, surgeries, or pre-existing conditions.
• Any associated symptoms (e.g., tingling, weakness, digestive problems).

Physical Examination

Physical examination is crucial for identifying psoas dysfunction.

• Postural Assessment: Observation of posture in standing and sitting to identify imbalances, pelvic asymmetries, or excessive lumbar lordosis.
• Palpation: Deep palpation of the psoas (often difficult due to its deep position) to identify points of tension, spasm, or pain.
• Joint Mobility Tests: Assessment of hip and lumbar spine mobility, looking for limitations or pain.
• Specific Tests:

• Thomas Test: The patient lies supine on the edge of the examination table, with both knees to the chest. One leg is allowed to drop down. If the knee of the extended leg cannot touch the table and the hip flexes, it indicates a shortening of the psoas or rectus femoris.

• Modified Thomas Test: A variant that allows distinguishing between psoas and rectus femoris shortening.

• Resisted Hip Flexion Test: The patient flexes the hip against the therapist’s resistance. Pain or weakness may indicate tendinopathy or psoas weakness.

• Hip Extension Test: The patient extends the hip while the therapist applies resistance. Pain may indicate a psoas problem.

Instrumental Examinations

Instrumental examinations are not always necessary, but can be useful to confirm the diagnosis, rule out other pathologies, or assess the extent of the damage.

• X-ray: Useful for ruling out bone problems or hip/lumbar osteoarthritis.
• Ultrasound: Can visualize the iliopsoas tendon, iliopsoas bursa, and identify inflammation or effusions.
• Magnetic Resonance Imaging (MRI): Provides detailed images of soft tissues, including muscles, tendons, bursae, and nerves, and is often the gold standard for diagnosing tendinopathies, bursitis, or other psoas lesions.

Physiotherapy Treatment

Physiotherapy treatment for psoas problems is multimodal and aims to reduce pain, restore function, and prevent recurrence. A personalized approach based on the specific diagnosis and patient needs is fundamental.

Treatment Goals

• Reduction of pain and inflammation.
• Restoration of muscle length and flexibility.
• Improvement of muscle strength and endurance.
• Normalization of hip and lumbar spine biomechanics.
• Postural and movement re-education.
• Prevention of recurrence through patient education.

Phases of Treatment

• Acute Phase (Pain and Inflammation Management):

• Relative Rest: Avoid activities that aggravate pain.

• Cryotherapy: Application of ice to the affected area to reduce inflammation.

• Physical Therapies: Use of modalities such as TENS (transcutaneous electrical nerve stimulation) for pain control, ultrasound, or laser therapy to promote tissue healing (always under the physical therapist’s guidance).

• Medications: In some cases, the doctor may prescribe non-steroidal anti-inflammatory drugs (NSAIDs) or muscle relaxants.

• Subacute and Chronic Phase (Re-education and Functional Recovery):

• Manual Therapy:

• Myofascial Release Techniques: Deep massage and compression techniques to release tension in the psoas and surrounding muscles.

• Joint Mobilization: Techniques to improve hip and lumbar spine mobility.

• Passive and Assisted Active Stretching: The physical therapist guides the patient through stretching exercises to restore muscle length.

• Therapeutic Exercises:

• Specific Psoas Stretching: Targeted exercises to lengthen the muscle (described in detail in the next section).

• Muscle Strengthening: Exercises to strengthen the psoas, but also antagonist muscles (glutes, hamstrings) and core muscles to improve stability and balance.

• Motor Control: Exercises to improve coordination and correct muscle activation during functional movements.

• Postural Re-education: Teaching correct posture and ergonomic movement patterns to reduce stress on the psoas.

• Patient Education: Information on how to manage the condition, prevent recurrence, and maintain a healthy lifestyle.

Specific Exercises for the Psoas Muscle

Exercises are a fundamental component of treatment and prevention of psoas problems. It is essential to perform them correctly and progressively, always under the guidance of a physical therapist.

Psoas Stretching Exercises

Stretching is crucial to lengthen a shortened psoas and restore its optimal length. Hold each stretch for 20-30 seconds, repeating 2-3 times per side. Deep, relaxed breathing is essential during stretching.

• Kneeling Psoas Stretch (Kneeling Hip Flexor Stretch):

• Kneel on a mat, with one leg forward and the foot flat on the ground (lunge position).

• Ensure the front knee is aligned with the ankle.

• Keep the trunk upright and the pelvis in posterior tilt (slightly contract the glutes) to isolate the stretch on the psoas.

• Gently push the pelvis forward, maintaining the posterior tilt, until you feel a stretch in the front of the hip of the back leg.

• Avoid arching your back.

• For a more intense stretch, raise the arm ipsilateral to the back leg overhead and lean slightly to the opposite side.

• Standing Psoas Stretch (Standing Hip Flexor Stretch):

• Stand with one foot forward and the other back, as if in a lunge.

• Keep the trunk upright and the pelvis in posterior tilt.

• Slightly bend the front knee and push the pelvis forward, feeling the stretch in the front of the hip of the back leg.

• You can place a hand on a wall for balance.

• Supine Psoas Stretch (Supine Hip Flexor Stretch with leg off the table):

• Lie supine on an examination table or elevated surface, with your glutes at the edge.

• Bring one leg to your chest and hold it with your hands.

• Allow the other leg to drop off the edge of the table, keeping the knee bent and the foot relaxed.

• Feel the stretch in the front of the hip of the hanging leg. It is crucial to keep your back flat and pelvis stable.

Strengthening Exercises for the Psoas and Related Muscles

Strengthening is just as important as stretching to ensure muscle balance and adequate stability.

• Supine Leg Raises:

• Lie supine with legs extended.

• Keeping your back flat and core active, slowly raise one straight leg approximately 30-45 degrees from the floor, without arching your back.

• Hold the position for a moment and slowly lower.

• Perform 10-15 repetitions per leg.

• Marching in Place (Marching):

• Lie supine with knees bent and feet flat on the floor.

• Keeping your core active and pelvis stable, slowly lift one knee towards your chest, as if marching.

• Control the movement and slowly lower the leg.

• Alternate legs for 10-15 repetitions per side.

• Core Stability Exercises:

• Plank: Hold the plank position on your forearms and toes, keeping your body straight like a board, engaging your abs and glutes. Hold for 30-60 seconds.

• Bird-Dog: Position yourself on all fours. Simultaneously extend one arm forward and the opposite leg backward, keeping your trunk stable and pelvis in line. Hold for a few seconds and slowly return. Perform 10-15 repetitions per side.

• Antagonist Strengthening: Don’t forget to strengthen the antagonist muscles of the psoas, such as the glutes and hamstrings, for optimal muscle balance. Exercises like glute bridges and hip extensions are fundamental.

Motor Control and Functional Re-education Exercises

These exercises aim to integrate the strength and flexibility gained into daily and sports movements.

• Squats and Lunges: Perform with attention to form, ensuring the psoas is not overactive or limiting.
• Balance Exercises: Stand on one leg, with or without oscillations, to improve pelvic and core stability.
• Specific Movement Patterns: For athletes, gradually reintroduce sport-specific movements, ensuring the psoas works efficiently and without pain.

Prevention of Psoas Problems

Prevention is key to keeping the psoas healthy and functional.

• Maintain Good Posture: Be aware of your posture, especially during prolonged sitting. Use lumbar supports if necessary.
• Avoid Prolonged Sedentary Lifestyle: Get up and move regularly, take short breaks to walk or stretch every hour.
• Perform Regular Stretching: Include psoas stretching exercises in your daily routine, especially if you spend a lot of time sitting or engage in intense physical activity.
• Adequate Warm-up: Before any physical activity, perform a complete warm-up that includes joint mobility and dynamic stretching.
• Balanced Strengthening: Maintain a training program that includes strengthening the core, glutes, and hamstrings, in addition to the psoas, to prevent muscle imbalances.
• Workplace Ergonomics: Ensure your workstation is ergonomic to reduce stress on the spine and psoas.
• Stress Management: Relaxation practices such as meditation or yoga can help reduce general muscle tension, including that of the psoas.

Frequently Asked Questions (FAQ)