Lower back pain can affect more than just your back. The muscles around your hips, pelvis, and lumbar spine all work together to help you stand, walk, bend, and maintain stability.
One muscle that often gets attention when discussing lower back and hip movement is the psoas. However, understanding the psoas requires looking at the bigger picture, including muscle strength, pelvic control, movement patterns, and the nervous system.
What Is the Psoas Muscle?
The psoas is a deep muscle located toward the front of the body. It connects the lumbar region of the spine to the femur, or thigh bone, and is an important hip flexor.
Because of its location, the psoas is involved in movements such as lifting your leg, walking, climbing stairs, getting up from a chair, and maintaining coordination between the spine and hips.
The psoas does not work alone. It works together with other muscles, including the iliacus, abdominal muscles, glutes, and muscles surrounding the hip and pelvis. Because of this, stretching or treating the psoas should not automatically be considered a solution for every type of lower back pain.
Why Can One Leg Feel Different From the Other?
During a physical examination, a healthcare professional may compare strength and movement on both sides of the body.
For example, a person may be asked to lift a bent leg while the examiner applies gentle resistance. If one side appears noticeably weaker, it may indicate a difference in muscle strength, motor control, pain inhibition, joint mobility, coordination, or nerve function.
A strength difference does not automatically mean that there is a nerve problem. Many different factors can affect how strongly someone can perform a movement.
A proper neurological examination may include testing muscle strength, reflexes, sensation, coordination, and other movements to determine whether a neurological structure may be involved.
What Do the L2 and L3 Nerve Roots Have to Do With It?
The L2 and L3 nerve roots are part of the lumbar portion of the nervous system and contribute to sensation and motor function involving the hip and thigh.
When evaluating someone with lower back pain and weakness, a healthcare professional may consider whether neurological structures could be contributing to the symptoms.
However, a single leg-lifting test performed at home cannot diagnose an L2 or L3 nerve-root problem. Similar symptoms can occur for many different reasons, which is why a complete assessment is important.
How the Psoas May Relate to Lower Back Movement
Because the psoas connects the lumbar spine and crosses the hip, it can influence how the hip and trunk move together.
If someone has altered movement mechanics, spends extended periods sitting, or has pain that changes their normal movement patterns, the muscles around the hip and pelvis may adapt.
However, a tight or sensitive psoas is not necessarily the cause of someone’s back pain.
Lower back pain can involve many different factors, including muscles, joints, discs, nerves, physical workload, movement habits, and other health factors. The goal should be to understand the individual rather than automatically identify one muscle as the source of the problem.
A Gentle Psoas Mobility Exercise
One way to gently work on the front of the hip is with a half-kneeling hip-flexor stretch.
Start in a half-kneeling position with one knee on the floor. Keep your torso relatively upright and gently bring your pelvis forward without forcing the movement. If comfortable, reach your arms overhead and add a gentle side bend.
Breathe slowly throughout the movement and stay within a comfortable range.
You should feel a gentle stretch rather than sharp pain, tingling, or worsening symptoms.
More is not always better. Aggressively stretching or pressing into a painful area does not necessarily make the exercise more effective.
Can Breathing Help During a Stretch?
Breathing can be a useful part of mobility work because it encourages you to slow down and reduce unnecessary tension.
Try inhaling for four seconds and then slowly exhaling for eight seconds. Repeat for several comfortable breaths while maintaining a relaxed position.
The goal is not to force the muscle to release. Instead, slow breathing can help you remain relaxed and avoid unnecessary bracing or holding your breath while stretching.
Don’t Forget Your Pelvis
Your pelvis plays an important role in how your hips and lower back move.
Rather than trying to force yourself into a specific “perfect posture,” focus on developing controlled and comfortable movement.
For example, constantly standing with an exaggerated arch or pushing the hips backward may not be helpful for everyone. The goal is to develop better awareness and control instead of constantly trying to correct yourself into one rigid position.
Your pelvis, trunk, hips, and lower body need to work together during everyday movements such as walking, standing, bending, and exercising.
Why Retesting Can Be Useful
An important part of a physical examination is comparing movement before and after an intervention.
A clinician may assess a particular movement, apply an appropriate mobility or manual technique, and then reassess the movement to see whether anything has changed.
If strength or movement improves immediately, that provides useful information about how the person’s nervous system and musculoskeletal system are responding.
However, an immediate improvement does not necessarily prove that a particular muscle or structure was the original cause of the pain. It is simply another piece of information that can help guide the overall assessment.
When Should You Get Your Back Pain Evaluated?
Most episodes of back pain are not emergencies, but certain symptoms deserve professional evaluation.
You should seek medical attention if you experience significant or progressive leg weakness, worsening numbness, severe or persistent pain, difficulty walking, new bowel or bladder control problems, numbness around the groin or saddle region, back pain following significant trauma, or other symptoms that concern you.
A healthcare professional can determine whether your symptoms are primarily related to the muscles and joints or whether further neurological or medical evaluation may be appropriate.
The Bottom Line
Lower back pain is not always simply a “tight psoas” problem.
Your lower back, hips, pelvis, muscles, and nervous system work together as a movement system. The psoas is an important muscle because it connects the lumbar spine and hip and contributes to hip movement and trunk stability.
However, addressing lower back pain requires looking at the whole person rather than focusing on one muscle.
Depending on the individual, gentle mobility, controlled breathing, strength training, and improved movement awareness may all have a role in improving movement and function.
Listen to your body, avoid forcing painful movements, and consider an individualized assessment when symptoms persist or neurological symptoms are present.
Medical Disclaimer
This article is intended for educational and informational purposes only and does not constitute medical advice, diagnosis, or treatment. The exercises and information discussed may not be appropriate for everyone. If you have persistent pain, significant weakness, numbness, or other concerning symptoms, consult a qualified healthcare professional for an individualized evaluation.