The quadratus lumborum (often shortened to “QL”) is a deep muscle in your lower back that runs on both sides of the spine, connecting your pelvis to your lowest rib and the upper lumbar vertebrae. It plays a central role in stabilizing your trunk, bending sideways, and even helping you breathe. It’s also one of the most frequently overlooked sources of low back pain.
Where the QL Sits in Your Body
The quadratus lumborum is a flat, rectangular muscle that sits deep beneath the more superficial back muscles you can feel when you press along your spine. It originates at the inner lip of the iliac crest (the top rim of your pelvis) and the iliolumbar ligament, then fans upward to attach on the inside surface of the 12th rib and the side projections of the first four lumbar vertebrae (L1 through L4).
Because it connects the pelvis directly to the ribcage and lower spine, the QL essentially forms a muscular bridge across the gap between your hip bone and your lowest rib on each side. It sits behind the kidneys and intestines but in front of the large erector spinae muscles that run along the spine. This deep positioning is one reason QL problems often feel like they’re coming from “inside” the back rather than from a surface muscle.
What the QL Does
The quadratus lumborum has three main jobs. First, it laterally flexes the spine, meaning it bends your trunk to the side. When the QL on your right side contracts, your torso tilts right. Second, it stabilizes the lumbar spine and pelvis during movement. Every time you walk, the QL on one side activates to keep your pelvis level while the opposite leg swings forward. Without it, your hip would drop with every step.
Third, the QL plays a supporting role in breathing. Because it anchors the 12th rib in place, it provides a stable base for the diaphragm to pull against during inhalation. This makes the QL an accessory muscle of respiration, particularly important during deep or forceful breathing like exercise or coughing. When both sides contract together, the QL also helps extend (straighten) the lower spine.
Why the QL Is a Common Source of Back Pain
Myofascial pain originating from the quadratus lumborum is one of the most common musculoskeletal causes of low back and buttock pain, yet it’s frequently missed in clinical evaluations. The muscle can develop trigger points (tight, irritable knots) that refer pain in patterns easily confused with other conditions. QL trigger points can send pain into the hip, the buttock, and down the leg, creating what’s sometimes called “pseudo-sciatica” because it mimics the shooting leg pain of a compressed sciatic nerve.
Several factors make the QL vulnerable to strain and chronic tightness:
- Prolonged sitting. Sitting for hours, especially with poor posture or in a slouched position, keeps the QL in a shortened state. Over time this leads to stiffness, weakness, and trigger point formation.
- Leg length discrepancy. When one leg is even slightly shorter than the other, the QL on the shorter side works harder to level the pelvis. Research using electromyography (which measures electrical activity in muscles) has shown significantly increased QL activation in people with leg length differences, even during rest.
- Repetitive bending or twisting. Activities that involve frequent side-bending or rotational movements, like shoveling, golf, or certain manual labor tasks, can overload the QL.
- Weak core muscles. When the deeper abdominal and pelvic stabilizers aren’t pulling their weight, the QL compensates, often becoming chronically overworked.
In some cases, QL dysfunction contributes to failed back surgery syndrome, where patients continue experiencing pain after spinal procedures. This happens because the surgery addresses a structural issue like a herniated disc, but the muscular trigger points in the QL (and sometimes the gluteal muscles or sacroiliac joint) remain untreated and continue generating pain.
What QL Pain Feels Like
QL pain typically presents as a deep ache in the lower back, just above the pelvis and to one side of the spine. It often worsens when you transition from sitting to standing, roll over in bed, or cough or sneeze (because the rib attachment gets tugged). Many people describe it as a stiffness that makes it hard to stand fully upright after sitting for a while.
The pain can spread to the hip, the upper buttock, and the front of the thigh. When trigger points are particularly active, the referred pain pattern can wrap around toward the lower abdomen or sacroiliac area. This broad referral pattern is part of what makes QL problems tricky to diagnose, since the pain doesn’t always stay where the muscle is.
QL Pain vs. Kidney Pain
Because the kidneys sit directly in front of the quadratus lumborum, pain from either source can feel remarkably similar. Both produce discomfort in the area below the ribs and above the pelvis. A few key differences help distinguish them.
QL pain is muscular: it changes with movement, gets worse when you bend or twist, and often improves (or at least shifts) with stretching or pressure. Kidney pain tends to feel deeper, as though it originates from inside the body rather than from the muscles. Kidney stones cause sharp, intense pain that worsens as a stone moves through the urinary tract, and the pain often radiates toward the groin. Kidney infections typically produce a dull, persistent ache along with systemic symptoms like fever, nausea, painful urination, or cloudy or bloody urine. If you have back pain combined with any urinary changes, fever, or nausea, that points toward a kidney issue rather than a muscle problem.
How QL Problems Are Treated
Most QL pain responds well to conservative treatment. Targeted stretching is the first line of approach. Side-lying stretches, child’s pose variations with a lateral lean, and standing side bends with an overhead reach all help lengthen the muscle. Foam rolling or placing a lacrosse ball against the QL while lying on the floor can release superficial trigger points, though the muscle’s depth means you sometimes need firm, sustained pressure to reach it.
Strengthening the broader core, particularly the obliques and deep spinal stabilizers, reduces the load on the QL over time. Exercises like side planks, bird-dogs, and single-leg deadlifts train the stabilization patterns that prevent the QL from doing all the work. If a leg length discrepancy is contributing, a heel lift in one shoe can reduce the asymmetric demand on the muscle.
For persistent pain that doesn’t respond to stretching and strengthening, clinicians may use trigger point injections or a procedure called a quadratus lumborum block, where a local anesthetic is placed near the muscle to interrupt pain signaling. QL blocks are more commonly used for post-surgical pain after abdominal, pelvic, or hip procedures, but they also have applications for chronic QL-specific pain. The block typically numbs a broad area from the mid-back down to the upper hip region.
Recovery timelines vary. A mild QL strain from an awkward movement may resolve in one to three weeks with rest, ice, and gentle stretching. Chronic QL tightness driven by postural habits or structural issues tends to be a longer project, often requiring several weeks of consistent stretching and strengthening before the pain meaningfully improves.