Los Angeles Rams receiver Puka Nacua left a joint practice with the Dallas Cowboys on Aug. 11 and did not get a full session back for nearly three weeks. Two days later, head coach Sean McVay named the muscle involved: the psoas. ESPN reported the problem as soreness in the psoas, presenting as groin pain.
Nacua returned to a full practice session on Aug. 30, having missed the Rams' joint work with both the Cowboys and the Saints along with most of the month's practices. He is not expected to miss regular season time. But the length of the absence, for what was publicly described as soreness, is a useful window into a muscle that almost never gets named in an injury report and that sports medicine physicians treat with unusual respect.
The Only Muscle That Connects Your Spine Directly to Your Leg
The psoas major originates on the last thoracic vertebra and the upper four lumbar vertebrae, runs down through the pelvis, and inserts on the lesser trochanter of the femur. Alongside the iliacus, which arises from the iliac fossa on the inner surface of the pelvis, it forms the iliopsoas unit.
That anatomy is unusual. According to StatPearls' reference on the iliopsoas unit, the iliopsoas is the primary flexor of the thigh at the hip and also contributes to external rotation and to stabilization of both the hip and the lumbar spine. The psoas muscles receive their nerve supply from the L1 to L3 branches of the lumbar plexus; the iliacus is supplied by the femoral nerve.
Practically, it is the muscle that drives the knee upward, and it does so while helping hold the low back steady. Nothing else in the body spans that distance in a single line of pull.
Why It Shows Up as Groin Pain and Gets Misfiled
The slippage in the early Nacua reports, from groin to psoas, is the normal presentation rather than a reporting error. The iliopsoas tendon passes under the inguinal ligament on its way to the femur, so irritation refers pain into the front of the hip and the groin. Athletes usually describe it as a deep ache they cannot locate with a fingertip.
StatPearls notes that psoas syndrome commonly occurs in runners, dancers, and jumpers, typically from overuse or trauma, and that iliopsoas problems turn up on MRI in about 21 percent of athletes evaluated for groin pain. Its true frequency in the general population is unknown, largely because the condition is often misdiagnosed and shares symptoms with other conditions.
For a receiver, the mechanism describes the job. Every acceleration out of a stance, every sharp break on a route, every plant and redirect loads the hip flexors while the trunk is being held rigid.
The Reason Coaches Get Cautious About Soft Tissue
McVay told reporters in mid August that the team was being smart with Nacua and expected him back the following week. That caution is not specific to the Rams, and it is not mainly about this one muscle.
Soft tissue injuries share a frustrating property: symptoms resolve faster than tissue heals. Pain and range of motion can look normal while the muscle-tendon unit is still remodeling and cannot yet tolerate maximal load as it lengthens under tension. Sprinting and cutting are exactly the demands that expose that gap. The clinical consequence is that a strain rushed back can turn into a longer, more stubborn problem.
The psoas adds a wrinkle. Because it also stabilizes the lumbar spine, an athlete guarding it will subtly change how the pelvis and low back move, which shifts load elsewhere. Trainers watch for that pattern as much as for the pain itself.
What Recovery Actually Involves
Management is unglamorous and mostly conservative. First-line care described in the StatPearls entry on psoas syndrome centers on rest and physical therapy: stretching the iliopsoas group, strengthening the surrounding spinal and hip musculature, and identifying what in the training routine contributed to the problem. Anti-inflammatory medication is sometimes added, and most patients respond without surgery.
Imaging is not automatic. In a straightforward hip flexor strain, the diagnosis is usually clinical, and scans are reserved for cases that do not follow the expected course or that raise suspicion of something other than muscle. Return to play typically proceeds through a graded progression, from pain free range of motion to loaded hip flexion to straight line running to change of direction at full speed.
For a professional franchise with a season opener approaching, the calculation is simply whether the last steps of that progression can be completed before the games count. Nacua getting a full practice in on Aug. 30 suggests the answer was yes.
It is worth being clear about what this story is and is not. Everything known publicly about Nacua's injury comes from team comments and beat reporting, not from a medical record. The value here is not a diagnosis of one athlete. It is that a muscle most people have never heard of, one that quietly connects the spine to the leg, is capable of sidelining an elite professional for the better part of a month.
Anyone dealing with persistent deep hip or groin pain that worsens with stairs, sprinting, or getting out of a low chair should be evaluated by a clinician rather than assuming it is a simple strain.
Key Questions Answered
What is the psoas muscle? It is a deep muscle running from the lower spine through the pelvis to the top of the thigh bone. with the iliacus it forms the iliopsoas, the main hip flexor.
Why was the injury first described as groin pain? The iliopsoas tendon passes under the inguinal ligament, so irritation typically refers pain into the front of the hip and groin rather than to the muscle itself.
Who tends to get psoas injuries? Athletes whose sports require repeated forceful hip flexion, including runners, jumpers, and dancers. Sedentary people and those with hip flexion contractures can also be affected.
How is it usually treated? Conservatively. Rest and physical therapy focused on stretching the hip flexors, strengthening surrounding hip and spinal muscles, and correcting training factors that contributed to it.
Does this kind of injury require an MRI? Not routinely. A straightforward hip flexor strain is usually diagnosed clinically, with imaging reserved for cases that fail to improve as expected or suggest a cause other than muscle.
Why do teams move slowly with soft tissue injuries? Symptoms tend to resolve before the tissue can tolerate maximal load, so an athlete can feel ready while still carrying elevated risk of reinjury.
Is Nacua's season in doubt because of this injury? Based on public reporting, no. He returned to practice on Aug. 30 and has not been reported as at risk of missing regular-season games because of the psoas issue.
