The Hip Flexor Complex: Focus on the Psoas

Hip Flexor Complex

You may, at some point, have heard about hip flexors. This is an encompassing term that describes a group of muscles that help you lift your knee to your chest, and that allow you to bend at your waist. Although that is their main function, an issue with these muscles can cause some very real problems. If you are experiencing chronic back pain, leg rotation, sciatic pain, issues with your posture, bloating and constipation, or many other core issues, it could very well be a problem with your hip flexors.

Hip flexor muscles include the Psoas Major, the Iliacus, the Sartorius, and the Rectus Femoris. You might have heard the Psoas and Iliacus referred to as the Iliopsoas. These two muscles work together most times to create proper movement mechanics in the front of the hip. They are, however, two different muscles, and they act only at the hip. The Sartorius and the Rectus Femoris, however act at the hip and also at the knee.

Rectus Femoris

The Rectus Femoris is one of the four muscles in the quadriceps. It is in the middle of the front of the thigh, and is responsible for extension of the knee and flexion of the hip and thigh. This is the most superficial of the four quadriceps muscle. It is long and connects, along with the other four at the same point on the patella, or knee cap, as the quadriceps tendon. Its final insertion point is on the tibia. Out of the four muscles, the Rectus Femoris is the most commonly injured. It is a weak hip flexor, and like the Sartorius, does most of its work at the knee.

The National Center for Biotechnology Information (NCBI) finds, “During intense exercise or trauma, the rectus femoris can tear at either the proximal or distal end, resulting in a debilitating injury that causes severe pain. This injury can either be a partial tear of the tendon at the patella or the muscle itself. This type of strain injury may occur during sprinting, kicking, or jumping. When strain injury occurs, patients typically present with moderate to severe pain in the groin or anterior aspect of the hip and swelling surrounding the affected area. The patient may also be unable to extend the knee.”


Sartorius is a very long narrow muscle that lies outside all the others. It is the longest muscle in the human body. It runs in a spiral that starts at the anterior superior iliac spine, and ends up down on the tibia. Sartorius assists in flexing the hip and helps produce lateral rotation and helps with abduction, albeit very weakly, at the hip. At the knee, it assists in flexing the leg. When the knee is flexed, it also rotates the leg medially. The Sartorius plays an important part in stabilisation of the pelvis—especially in women.

It is much more common for quadriceps muscles to be injured than for the Sartorius to become injured, however, it can happen. Sartorius muscles can become injured when, during a movement, muscles of the anterior upper leg get overly extended and then large loads are put on it. This can lead to Sartorius and other muscles being overstretched together. Smaller or bigger muscle fiber ruptures can also occur when the muscle gets strained and overstretched, but again, this is much more rare than other injuries to the upper thigh. The best way to handle any overstretching of muscles of the hip flexor complex is to practice regular strengthening exercises and stretching the tissue, which can be helped by massage therapy. If you are having hip pain, you can book a Massage Therapy session here.


The Iliacus is a large triangle shaped muscle that is flat and fans perfectly over the curved part of the pelvic bone, the iliac fossa. It is connected to the Psoas Major by a tendon that merges the two and runs down to the lateral aspect of the inguinal ligament and inserts on the lesser trochanter of the femur. The Iliacus is responsible for flexion and medial rotation of the thigh. It is important to note this muscle in its difference, though, when dealing with injury, because many different nerves run over it. This can play a large part in how we read pain. Nerves that run over this muscle can radiate pain in many different areas if the muscle is strained or otherwise injured in a way that causes pressure on the nerves. Nerves of the lumbar plexus that pass over the anterior surface of the Iliacus include:


The Psoas are long muscles that run from the sides of the lumbar region of the vertebral column to the pelvis, connecting to the tendon that merges it with the Iliacus. The Psoas Major is a fusiform muscle, which means that the muscle fibers are parallel to each other, like the biceps muscles. What this means is that the muscle is long, wider in the middle and slims out toward the end connection points. This type of muscle is responsible for a wide range of quick motion, but is not especially powerful in comparison to penniform muscles. The Psoas are made up of both fast twitch fibers and slow twitch fibers, making this a versatile type of muscle that is responsible for contraction in the hip.

The Psoas muscles are responsible for the vital movements in running, walking, sitting, and other movements that are part of daily life. It is the main connection between the trunk of the body and the lower limbs. The Psoas helps stabilise the spine and maintain posture. It is also responsible for flexion of the thigh at the hip joint, and it has a bit of a part to play in the lateral rotation and abduction of the thigh.

The Psoas is emphasized in many clinical settings due to its unique location in the human body. It may not seem as important as it really is, but the Psoas is the deepest core muscle in the body, and it is the only muscle that directly connects the trunk of the body to the lower limbs. Its positioning makes it a key player in the way the human body is stabilised and balanced. Without the Psoas, we would have a difficult time standing or walking, let alone performing more athletic functions. Anyone who has had an injury to the Psoas can attest to this. Many times, an injury to the Psoas muscle can present itself as lower back pain. You can learn more about Medical Massage Therapy and how it can help lower back pain here.

The Psoas is vitally important for balance and stability, but it also supports internal organs and acts as a sort of pump that allows blood and lymph to properly move through the body. The kidneys and adrenal rest on the muscular shelf that is provided by the muscle. The diaphragm massages the muscle and nearby organs, stimulating blood flow during breathing. As a result of where the muscle is placed and how it functions, when the Psoas is not able to properly function, the organs in the body are affected. This can result in physical and emotional exhaustion, which is why this muscle, in particular, is very important to Massage Therapists and Yoga Instructors. Postural alignment, balance, flexibility, joint mobility, functional organs, and walking depend on the Psoas, making it a small but very important muscle to keep in good, working health!

Conditions and injuries that involve the Psoas are relatively uncommon. When issues do occur in the Psoas or Iliacus, they are typically due to trauma and overuse, and are sometimes as a result of surgical procedures. The most common injuries in the area, again, due to overuse or trauma, are abscesses, hemorrhage, lesions, tears, and strains.

Psoas Syndrome and Iliopsoas Tendinitis

Psoas syndrome and Iliopsoas tendinitis are serious issues, but are less common conditions. Due to this, they often go misdiagnosed. Symptoms can include pain in the lower back, groin pain, pain that shoots to the knee, difficulty walking, and difficulty standing with proper posture. Psoas Syndrome and Ilopsoas tendinitis are most commonly found as a result of overuse in people who partake in athletic activities such as running, jumping, dancing, extreme hiking, and other activities of this nature.

Psoas Syndrome can be exacerbated by prolonged sitting. Sitting for long periods of time creates a situation where the Psoas is in a constant shortened state. The muscle becomes tight, and then constant movement may cause overuse symptoms, and the muscle is more easily injured. This can be an issue that spreads further, because the Psoas is a major flexor. A weakened Psoas muscle will cause the muscles around it to work harder to compensate, and they can then be harmed by overuse. When this happens, it can be the cause of low back pain, whether the Psoas is too tight, or if it is overstretched. It is important to keep the muscle strong and flexible, both, in order to maintain proper health.

Iliopsoas tendinitis may cause snapping hip syndrome. This is a painful issue. A person with snapping hip syndrome will feel the snap, and may even hear it while they are walking. Tendinitis causes inflammation, and that will create an issue where muscle tendons will rub over the hip socket. This is also an overuse problem, and the constant rubbing of the tendon keeps the issue going, as it continues to cause inflammation. This happens more often in young athletes than in any other group because the tendons become tight during growth spurts. To read more about the different types of snapping hip, check out this article by Sports Health:

Massage Therapy and the Hip Flexor Complex

Massage Therapy can be an integral part of the continuing health of the Hip Flexor Complex and and/or rehabilitating injured muscles of the Hip Flexor Complex. The benefits of Therapeutic Massage are astounding, and you can read more about them here. It is important to note that this type of Massage Therapy is useful for stretching the muscles and can assist in improving performance through using the modalities, Myofascial Release and Trigger Point therapy.

Sports Massage and Sports Injury Massage are also extremely beneficial for people who are having issues with the Hip Flexor Complex. Here is some information from our Sports Massage vs. Sports Injury Massage Blog that may help you decide if this is what is right for you, and which you would prefer to book, should you decide to add Massage Therapy to your routine!

Benefits of a Sports Massage

Reduce muscle tension

Sports Injury Massage reduces muscle tension by working on adhesions in the muscles that may feel like knots or guitar strings. Knots are balls of fiber that need to be smoothed out. Guitar strings need to be flattened out so they are smooth and flow with the other muscles. This is working on a specific muscle to help it work better with the rest of the muscle group.

Increase range of motion

When you relax all of the muscles that move your shoulder, you are able to move it further than before. This is the case with any joint in the human body. This is more about focusing on a group of muscles to work better together, rather than a specific muscle. It is the whole group, all of the muscles around a joint, that allow it to move to its fullest ability. This is what would increase flexibility. Passive stretching is a great addition to Sports Injury Massage, as both can help increase range of motion.

Enhance athletic performance

When an athlete has full range of motion and relaxed muscles they are able to run longer, throw better, and keep this up for a longer amount of time without fatigue, strain or injury. Think of it like a spaghetti noodle. If the noodle is dry it will break easier. If the noodle is wet (has blood flow), then the noodle moves easier and risk of injury is decreased.

Improve soft tissue function

Ease of movement is important in soft tissue function, and that is what Sports Injury Massage is useful in improving. Blood flow is also important in how soft tissue functions. The Massage Therapist applies pressure in a way that causes blood to flow. This allows muscles to become warmer. By stretching the tissues and working out adhesions Sports Massage Therapists flush out swelling in joints and allow soft tissue function to return to normal as a result.

Decrease muscle stiffness and fatigue

Sports Injury Massage keeps muscles from locking up after extended use. Cramping is a major issue in every athletic endeavor. Cramps effectively stop the ability of the muscle to work properly. Sports Injury Massage increases blood flow, thereby increasing the amount of oxygen that is delivered. This decreases fatigue and enhances muscle recovery. Sports Injury Massage’s ability to increase blood flow to the area also keeps inflammation down so muscles can recover faster.