The psoas muscle is a deep muscle that connects the lower spine to the upper thigh and plays an essential role in walking, climbing stairs, lifting the legs, and maintaining an upright posture. It is also a key component of the hip flexor system, which helps move the thigh toward the torso. Although the psoas is often discussed in connection with tight hips and lower back pain, its anatomy and functions are more complex than simple hip flexion.
Understanding where the psoas is located, how it works with surrounding muscles, and how to strengthen or stretch it can help people make informed decisions about movement, exercise, and everyday physical activity.
Where is the psoas muscle located?
The psoas muscle lies deep within the abdomen and pelvis, close to the front of the lumbar spine. Unlike superficial muscles that can be easily seen or felt beneath the skin, the psoas is positioned underneath several layers of tissue and is not directly accessible through ordinary self-massage.
The psoas major, the principal muscle commonly meant by the term “psoas,” begins along the sides of the lower thoracic and lumbar vertebrae. It travels downward through the pelvis, passes in front of the hip joint, and attaches to the lesser trochanter, a small bony projection on the upper inner portion of the femur, or thighbone.
There is a psoas muscle on each side of the body. Together, these muscles help connect the trunk to the legs and coordinate movements between the spine, pelvis, and hips.
The psoas is closely associated with the iliacus, a broad, fan-shaped muscle that fills much of the inner surface of the pelvic bone. The psoas major and iliacus converge near the hip and share a common tendon at their attachment to the femur. Collectively, they are known as the iliopsoas, the primary hip flexor muscle complex.
Because the psoas is deep and closely related to other anatomical structures, discomfort in the front of the hip, groin, or lower back cannot automatically be attributed to this muscle. Several muscles, joints, nerves, and internal organs occupy nearby regions.
Psoas muscle anatomy
The psoas major is a long, thick muscle composed of skeletal muscle fibers, which contract under voluntary nervous system control. Its position allows it to influence both the lumbar spine and the hip joint.
The muscle originates from the sides of the bodies of the last thoracic vertebra and the lumbar vertebrae, as well as from connective tissue associated with the spaces between those vertebrae. Its fibers run downward and outward through the pelvis before joining the iliacus tendon near the hip.
This arrangement is important because the psoas crosses two major anatomical regions. At its upper end, it connects to the spine; at its lower end, it attaches to the femur. As a result, its effects depend partly on which part of the body is moving and which part is stabilized.
The psoas major is innervated primarily by direct branches of the lumbar spinal nerves. These nerves carry signals that allow the brain and spinal cord to coordinate muscle contraction. The muscle also contains sensory receptors that provide information about its length and tension, helping the nervous system regulate movement and posture.
A smaller muscle called the psoas minor is present in some people but absent in others. When present, it lies in front of the psoas major and generally attaches to connective tissue in the pelvic region rather than directly to the femur. It has a relatively minor role in movement compared with the psoas major.
The psoas major is also anatomically close to the kidneys, portions of the digestive tract, the lumbar plexus of nerves, and major blood vessels. This proximity helps explain why pain in the region can have different causes and why persistent or unexplained abdominal, groin, or back symptoms should not be assumed to originate from the muscle.
What does the psoas muscle do?
The psoas muscle contributes to several movements and stabilizing functions. Its most familiar role is hip flexion, but it also participates in controlling the relationship between the trunk, pelvis, and legs.
Hip flexion is the movement that brings the thigh toward the torso or the torso toward the thigh. The psoas contracts when lifting a knee, climbing a step, getting into a car, or bringing the legs upward during certain exercises. It also contributes to the controlled lowering of the leg after it has been lifted.
Trunk and spinal control are additional functions of the psoas. Because the muscle attaches to the lumbar vertebrae, it can help control movement in the lower spine. Depending on the position of the pelvis and the activity of surrounding muscles, it may contribute to bending the trunk forward or controlling spinal movement against external forces.
Postural support involves coordinated activity across many muscles rather than the action of one muscle alone. The psoas participates in this system by helping regulate the position and movement of the lumbar spine and hips. Its contribution changes with body position, task demands, and the forces acting on the body.
Walking and running also depend on the psoas. During walking, the hip flexors help advance the leg into the next step. During running, faster limb movement and greater demands on hip motion increase the importance of coordinated hip flexor activity. However, the psoas does not work alone: muscles such as the iliacus, rectus femoris, and sartorius also contribute to hip flexion.
The psoas may also contribute to pelvic and spinal control during activities that require the legs to move while the torso remains relatively stable. In these situations, the nervous system coordinates the psoas with the abdominal muscles, spinal muscles, gluteal muscles, and other parts of the trunk and hip musculature.
The psoas and lower back pain
The psoas is frequently mentioned in discussions of lower back pain, especially when people experience stiffness after prolonged sitting or discomfort during hip extension. Its attachments to the lumbar spine and femur make it a plausible contributor to some movement-related symptoms, but the relationship between the psoas and back pain is not straightforward.
A muscle can become sore after unfamiliar exercise, sustained loading, or a sudden increase in activity. The psoas can also be strained, although strains in this deep muscle may be difficult to distinguish from problems involving other hip flexors or nearby structures.
Hip position may influence how the psoas feels during movement. For example, extending the hip moves the thigh backward relative to the pelvis and lengthens the hip flexor complex. Some people find this movement uncomfortable when the muscles are sensitive or when the hip joint or surrounding tissues are irritated.
However, tightness does not necessarily mean that a muscle is physically shortened, weak, or damaged. A sensation of tightness can arise from increased sensitivity, fatigue, reduced tolerance for a particular position, or protective muscle activity. Likewise, lower back pain can result from many different factors, including spinal joints, discs, muscles, nerves, and other tissues.
Prolonged sitting is sometimes blamed for shortening the psoas. Sitting does place the hips in a flexed position, but it does not inevitably cause permanent muscle shortening or dysfunction. Movement habits, physical conditioning, individual anatomy, and the demands of daily activities all influence how the hips and back tolerate prolonged positions.
For many people, changing positions regularly, building general strength, and gradually increasing physical activity are more useful than assuming that every episode of back stiffness requires an aggressive psoas stretch.
Signs of a psoas muscle problem
Problems involving the psoas or the broader hip flexor complex may cause discomfort in the front of the hip, groin, or lower back. Symptoms can vary depending on whether the issue involves muscle soreness, a strain, irritation of nearby tissues, or another condition.
Possible signs include pain when lifting the knee against resistance, discomfort when bringing the thigh toward the torso, tenderness in the deep front hip region, or pain when extending the hip. Some people notice symptoms when climbing stairs, running, getting up from a chair, or moving from sitting to standing.
These symptoms are not specific to the psoas. Hip joint disorders, tendon problems, abdominal conditions, and nerve irritation can produce similar discomfort. Because the muscle lies deep within the body, pressing on the abdomen or groin is not a reliable way to diagnose a psoas problem.
A sudden injury accompanied by substantial pain, an inability to bear weight, fever, significant abdominal symptoms, or rapidly worsening symptoms warrants prompt medical assessment. Persistent pain, recurrent symptoms, or difficulty with normal activities also merits evaluation by a qualified health professional.
How to stretch the psoas muscle
Psoas stretching generally involves extending the hip while keeping the pelvis and lower back in a controlled position. Since the psoas crosses the hip joint, moving the thigh backward relative to the pelvis can lengthen it. The goal is a comfortable stretch at the front of the hip without forcing the lower back into excessive arching.
Stretching can improve tolerance for hip extension and may help people who have limited comfortable movement in that direction. However, stretching is not necessary for everyone, and it is not a universal treatment for lower back pain. The appropriate approach depends on the person’s mobility, symptoms, and activity goals.
Half-kneeling hip flexor stretch
The half-kneeling stretch is a practical way to target the hip flexors.
- Kneel on one knee, with the other foot planted in front of you and the front knee bent approximately 90 degrees.
- Keep your torso upright and gently tighten the abdominal muscles.
- Slightly tuck the pelvis by bringing the front of the pelvis upward and reducing the arch in the lower back.
- Shift your pelvis forward a small amount until you feel a mild stretch at the front of the hip on the kneeling side.
- Hold the position while breathing normally, then release and repeat on the other side.
Keep the movement small and controlled. Moving the pelvis forward without controlling the lower back can create an exaggerated arch, reducing the usefulness of the stretch and potentially irritating the back.
Start with a comfortable hold of about 15 to 30 seconds and repeat as tolerated. The stretch should feel mild rather than sharp, pinching, or painful.
Standing hip flexor stretch
A standing variation can be useful when kneeling is uncomfortable.
Stand with one foot slightly behind the other. Bend both knees a little, keep the torso upright, and gently tuck the pelvis. Shift your weight forward just enough to feel a mild stretch at the front of the hip on the back leg.
Use a wall or sturdy chair for balance if needed. Avoid leaning backward or pushing the hips forward aggressively. If the stretch produces groin pinching or back pain, reduce the range of motion or stop.
Bridge exercise for hip and trunk control
A bridge is not a direct psoas stretch, but it strengthens the gluteal muscles and helps develop control of the pelvis and hips.
Lie on your back with your knees bent and your feet flat on the floor. Keep your arms relaxed beside you. Tighten the abdominal muscles gently, then lift your hips until your shoulders, hips, and knees form a roughly straight line. Pause briefly and lower with control.
Avoid lifting the hips so high that the lower back arches excessively. Begin with 8 to 12 repetitions if comfortable, adjusting the number to your fitness level.
Exercises to strengthen the psoas
Strengthening the hip flexors can improve their capacity to lift the legs and tolerate repeated movement. The most appropriate exercises depend on a person’s current strength, mobility, and symptoms. Beginners can start with low-resistance movements and gradually increase difficulty as control improves.
Supine marching
Supine marching provides a controlled introduction to hip flexor strengthening.
Lie on your back with your knees bent and your feet flat on the floor. Gently brace the abdominal muscles to keep the pelvis steady. Slowly lift one foot a few inches from the floor, then lower it and repeat on the other side.
Focus on moving the leg without allowing the pelvis to rock or the lower back to arch excessively. Begin with 8 to 12 repetitions per side, or fewer if maintaining control is difficult.
As strength improves, you can progress to lifting the knee higher or starting with the hips and knees bent to 90 degrees. The more demanding variation should be attempted only if you can maintain a comfortable, controlled position.
Seated knee raises
Seated knee raises emphasize hip flexion while the trunk remains upright.
Sit near the front of a sturdy chair with both feet on the floor. Keeping your torso steady, lift one knee toward your chest as far as is comfortable. Lower the foot slowly and alternate sides.
Start with 8 to 12 repetitions per leg. Avoid leaning backward to lift the knee higher, since this shifts some of the movement to the trunk rather than requiring the hip flexors to do the work.
To increase the challenge, pause briefly at the top or add light resistance around the foot or ankle. Resistance should be introduced gradually and should not cause pain or loss of control.
Standing resisted hip flexion
A resistance band can add load to hip flexion.
Secure a suitable resistance band according to its instructions and attach it to the ankle of the working leg. Stand in a stable position, using a support for balance if needed. Lift the knee forward against the band’s resistance, then return to the starting position slowly.
Keep the pelvis level and avoid leaning backward. Begin with light resistance and a small, comfortable range of motion. Perform a manageable number of controlled repetitions before increasing resistance or volume.
This exercise trains the hip flexor group, including the psoas, but it does not isolate the psoas completely. Multiple muscles contribute to lifting the thigh.
Supine straight-leg raises
Straight-leg raises train the hip flexors while requiring the abdominal muscles to help control the pelvis.
Lie on your back with one knee bent and the other leg straight. Gently brace your abdomen and lift the straight leg to approximately the height of the opposite knee, or lower if that is more comfortable. Lower the leg slowly without allowing the lower back to arch excessively.
Start with a small number of repetitions and increase gradually. If the exercise causes back pain, groin pinching, or difficulty controlling the pelvis, stop and choose an easier variation.
This exercise can be demanding because the long, straight leg creates greater leverage at the hip. Supine marching is often a better starting point for people who are new to strengthening their hip flexors.
How to build a safe psoas exercise routine
A balanced routine should account for the psoas’s role in a larger movement system. Training only the hip flexors may overlook the gluteal muscles, abdominal muscles, and other muscles that help control the pelvis and spine.
For a general starting routine, choose one gentle hip flexor stretch and two strengthening exercises, such as supine marching and seated knee raises. Perform the movements slowly, prioritize good technique, and stop before fatigue causes you to lose control of the pelvis or lower back.
Two or three sessions per week can provide a practical starting point for strength training, provided the exercises are well tolerated and allow adequate recovery. People who are already active may need a different schedule depending on their other workouts.
Progress gradually by adding repetitions, increasing the range of motion, or introducing modest resistance rather than changing everything at once. Mild muscular effort is expected during strengthening, but sharp pain, increasing groin discomfort, or symptoms that persist or worsen after exercise are reasons to stop and reassess the routine.
There is no single ideal psoas exercise for everyone. A runner who wants to improve leg drive, a person recovering from a hip flexor strain, and someone who experiences discomfort after sitting for long periods may have different needs. A physical therapist can assess hip motion, muscle strength, movement patterns, and possible alternative causes of pain to help determine an appropriate plan.
Psoas muscle health in everyday life
Maintaining a healthy psoas does not require constant stretching, specialized equipment, or frequent attempts to release the muscle manually. Regular physical activity, progressive strength training, comfortable hip mobility, and variation in body position all support the broader system in which the psoas works.
People who sit for long periods may benefit from taking movement breaks, walking regularly, and occasionally moving their hips through a comfortable range of motion. Those who run, cycle, dance, or participate in sports can benefit from conditioning the hip flexors alongside the gluteal muscles, trunk muscles, and other muscles used in their activities.
The psoas should be understood as both a hip flexor and a muscle that contributes to spinal and pelvic control. Its performance depends on coordination with neighboring muscles and the nervous system, not simply on whether it feels tight or relaxed.
The most effective approach is therefore to focus on function: comfortable hip movement, adequate strength, good control, and the ability to perform daily activities without persistent symptoms. When pain or restricted movement continues despite reasonable adjustments, professional assessment is more useful than assuming the psoas is the sole cause.