One-Sided Low Back Pain: A 4-Step QL (Quadratus Lumborum) Release Routine

You've probably woken up with just one side of your low back pulling tight while the other side felt fine. Standing up from a chair, that same side catches for a split second. Standing for a while, you notice you keep shifting your weight onto one leg without meaning to, letting the other hip drift up. Check your waistline in a mirror and one hip sits visibly higher, with a shallower crease along that side compared to the other. General back stretches from a video, done evenly on both sides, often leave the sore side exactly as tight as before.

The reason is straightforward. Most low back stretches target muscles like the multifidus or erector spinae, which run symmetrically along the spine and flex or extend the whole back. What's usually happening here is different: it's a one-sided problem in the quadratus lumborum (QL), a muscle buried deep in the flank between your lowest rib and the top of your pelvis. Each side of the QL works independently, connecting the ribcage to the pelvis on its own side. When one side gets overworked or shortens, it hikes that hip upward and produces the lopsided ache described above. Standing with your weight shifted to one leg for long stretches, carrying a bag on the same shoulder every day, a small leg-length difference, or quietly protecting one side after an old strain — the causes vary, but the outcome is the same: one QL stays short and guarded, and stretching both sides equally never actually reaches the imbalance.

This guide skips the symmetrical back routine and works through four steps aimed squarely at the one QL that's giving you trouble. It starts with a gentle traction-style release, moves to targeted ball work, adds a standing functional stretch, and finishes with a side plank to retrain active control of that muscle. Two pieces of research covered further down explain why this particular order makes sense.

One thing worth flagging before you start: the flank area where the QL sits overlaps with where your kidney sits. If you have fever or chills alongside the pain, blood in your urine, or pain that doesn't ease no matter how you move and comes in waves, that points toward a kidney stone or infection rather than a muscle problem, and you should see a doctor instead of working through this routine. The self-check section below covers this distinction in more detail. If none of that applies and this looks like a straightforward muscular issue, start with the self-check below. For a more general routine covering the whole low back, our lower back stretching routine is a useful companion.

Before You Start: Finding Which Side Is the Problem

QL release is not something you do evenly on both sides — it's something you weight toward the sore side. That means figuring out which side is actually shortened comes first.

What the Quadratus Lumborum Actually Does

The quadratus lumborum connects your lowest rib, the back of your pelvis, and the side processes of your lumbar vertebrae, with each side attached independently. Working together, both sides help extend your low back and anchor your ribcage down when you exhale. Working alone, one side hikes that hip upward and tilts your torso sideways. When you stand with your weight off one leg, the hip on the unweighted side rises partly because that side's QL is doing exactly this job. The trouble is that once this becomes a habit, that QL stays shortened, and a shortened muscle keeps pulling the hip upward, which reinforces the very posture that caused it — a loop where the pain and the habit feed each other. Breaking that loop takes two things: lengthening the shortened muscle, and retraining its ability to control that side of your trunk again. The four stages below are ordered to do exactly that.

Standing Side-to-Side Comparison Test

Stand with your feet about hip-width apart. Slide your right hand down the outside of your right thigh toward your knee as far as comfortable, bending your trunk to that side, and note where it stops and where you first feel a pulling or blocked sensation in your flank. Repeat on the left and compare how far each hand traveled and how each side felt. If one side reaches noticeably less, or the flank on the opposite side pulls tight early, the tight quadratus lumborum is usually on the side opposite the direction you bent. If your flank pulls tight on the left while bending right, the left QL is the shortened one.

Checking Hip Height and Waist Crease in a Mirror

Stand naturally facing a mirror. Compare the height of both hip bones and the depth of the crease along each side of your waist. The side with a shortened QL commonly shows a hip pulled upward and a shallower, shorter waist crease than the other side. If your pants or skirt waistband always rides up on one side, that's the same signal.

Finding the Tender Spot by Hand

Place both hands on the soft tissue in your flank, between your lowest rib and the top of your pelvis, roughly three or four finger-widths out from your spine, and press gently. The side that feels noticeably more tender, or that reproduces your familiar ache when pressed, is the one to prioritize today. If both tests point to the same side, that's a clear answer; if they disagree, go with whichever side reproduces the familiar pain under hand pressure.

Equipment by Stage

Stage 1 only needs a rolled towel or a small-diameter foam roller. From Stage 2 you'll want a lacrosse ball or tennis ball — switch to something softer if the pressure feels too intense at first. Stage 3 needs a doorframe or sturdy post, and Stage 4 just needs a mat.

Warning Signs to Check Before You Start

If any of the following applies to you today, hold off on this routine and see a doctor first.

• Fever, chills, or general body aches alongside the flank pain
• Blood in your urine, burning when you urinate, or unusually cloudy or foul-smelling urine
• Pain that doesn't ease at all with position changes and comes in waves (a classic kidney stone pattern)
• Low back or hip pain that radiates down into a leg
• Pain following a recent fall or impact where a fracture is a concern
• You are pregnant and this is a new, strong one-sided pain you haven't felt before

If none of these apply, work through the four stages below in order. Don't jump straight to the Stage 3 standing stretch or Stage 4 side plank. Loading an acutely short, sensitized muscle with a strong stretch right away tends to make the protective spasm worse, so the gentle release in Stages 1 and 2 is there to calm that sensitivity down first.

Timing and Frequency

Right after long sitting, or before bed, are good windows to feel the effect. In the acute early days, Stages 1 and 2 can be split into two sessions a day; as symptoms ease, drop to once daily, then to an as-needed basis once the ache mostly settles.

Stage 1: Gentle Side-Lying QL Release

Starting Position

Lie on your side with the painful side against the floor. Place a rolled towel or small foam roller under your waist, right at the tender spot you found between your lowest rib and the top of your pelvis. Bend your knees slightly for stability, and rest your bottom arm comfortably, either supporting your head or extended along the floor.

Movement Sequence

1) Once positioned, let your full weight settle onto the roll for 10-15 seconds without doing anything else, letting gravity slowly open the space between rib and pelvis. 2) If that feels comfortable, slowly reach your top arm overhead toward the floor in front of your face, adding a very light stretch through the flank line — go only about halfway on your first attempts rather than reaching all the way. 3) Hold while breathing steadily, then roll off the towel slowly when your time is up.

Breathing

Rather than shallow chest breathing, aim to breathe into your flank, inhaling slowly and letting the tension settle a little further on each exhale. Don't force a deep stretch — let the release follow the exhale on its own.

Sets, Time, and Frequency

30-45 seconds per hold, 2-3 sets, focused entirely on the painful side. Skip the other side, or give it just one light check. Twice a day while acute, dropping to once daily as it settles.

Common Mistakes and Fixes

The most common mistake is positioning the roll too high, directly under the rib itself, or too low, on the pelvic bone itself. Pressure directly on bone just hurts without releasing anything, so adjust the position a few times until it lands on that same soft spot you found by hand earlier. The second mistake is reaching the top arm all the way overhead on the very first session — loading sensitized tissue with a strong stretch right away tends to make it clamp down further. Skip the arm reach for your first two or three sessions and let gravity alone do the work. The third is doing the same thing on the non-painful side out of habit — this stage is one-sided by design, not a symmetrical exercise.

Signals to Stop

If you feel an electric, shooting pain or numbness spreading down a leg, stop immediately and get up slowly. If the roll height feels like too much for where you are today, fold the towel flatter and try again, or skip ahead to Stage 2 ball work for this session instead.

Stage 2: Ball Work to Release the QL

Starting Position

Stand with your back or flank against a wall, or lie on the floor, and place a lacrosse ball or tennis ball at the tender spot (between your lowest rib and pelvis, three or four finger-widths out from the spine). Standing against a wall makes pressure easier to control and is the safer starting point.

Movement Sequence

1) Lean your weight into the wall to load the ball and find the most tender point. 2) Hold steady pressure there for 20-30 seconds while breathing, letting the tissue soften gradually. 3) While keeping the pressure, add small movement — a slight knee bend and straighten, or a small hip sway — to work the tissue actively. 4) Shift the ball an inch or two to check one or two nearby tender spots as well.

Breathing

It's instinctive to hold your breath the moment pressure hits a tender spot, but breathing slowly and steadily through it sends your nervous system a signal that it's safe, which helps the protective guarding ease faster than holding your breath does.

Sets, Time, and Frequency

20-30 seconds per point, working through 2-3 points for about 60-90 seconds total per session. Once a day is the default; on especially sore days, split it into a morning and evening session rather than repeating the same spot back-to-back.

Common Mistakes and Fixes

The most common mistake is starting with a hard lacrosse ball and gritting through intense pain right away. If it feels like too much, switch to a softer tennis ball and reduce the lean angle to lower pressure first. The second is resting the ball directly on a rib or hip bone, which produces pain without any release — shift it slightly onto the soft muscle tissue instead. The third is assuming more pressure is always better when you find a tender point — giving it time tends to work better than grinding harder.

Signals to Stop

If numbness or tingling spreads toward a leg, if sharp pain persists past 30 seconds without easing through breathing, or if the spot still feels bruised the next day, back off the intensity and take this stage off for the rest of the week.

Stage 3: Standing Doorframe QL Stretch

Starting Position

Stand beside a doorframe or a sturdy post, about an arm's length away, with your painful side facing the frame. Cross the far leg in front of the near leg, shifting your hips slightly away from the frame, and reach your near-side (painful side) arm overhead to hold the doorframe or a sturdy shelf.

Movement Sequence

1) Keeping the gripping arm long, slowly shift your hips away from the frame, feeling a stretch line running from your hip up through your ribs on the gripping side. 2) Hold at a point of comfortable pulling, not pain. 3) When your time is up, slowly bring your hips back to center and uncross your legs.

Breathing

Exhale as you shift your hips away to deepen the stretch slightly, and keep breathing continuously through the hold rather than holding your breath. It's easy to tense up and stop breathing while balancing, so pay attention to keeping it going.

Sets, Time, and Frequency

20-30 seconds per hold, 3-4 sets on the painful side, versus just 1-2 light sets on the other side to check balance — the volume is intentionally lopsided. Once or twice a day, especially right after long sitting.

Common Mistakes and Fixes

The most common mistake is rotating the torso forward or backward instead of bending purely sideways. Check in a mirror that your shoulder line stays level and untwisted, and correct toward a pure side bend. The second is loading your full body weight into the stretch suddenly — shift your hips gradually and build intensity over the hold instead. The third is gripping too high, which shifts strain to the shoulder instead of the flank; lower your grip point so the stretch line runs through your side.

Signals to Stop

If you feel numbness or tingling spreading down a leg, or the stretch feels like a fixed pain that doesn't ease at all after 10 seconds of holding, reduce your leg-cross angle or go back to Stages 1 and 2 for the day.

Stage 4: Side Plank to Rebuild Control

Starting Position

Lie on your side with the painful side down, forearm positioned directly under your shoulder. Start with the beginner version, knees bent with shins on the floor, and move to a full straight-leg side plank once that feels stable.

Movement Sequence

1) Brace through your abs and flank, then lift your hips to form a straight line from head to knee (or head to ankle). 2) Hold that line without letting your hips sag down or pike upward. 3) Lower with control, either stopping just short of the floor for another rep or lowering fully to rest.

Breathing

Keep breathing normally throughout the hold rather than holding your breath. It's natural to want to hold your breath while bracing hard, but a broken breath actually makes the position less stable, not more.

Sets, Time, and Frequency

10-15 seconds per hold, 3-4 sets on the painful side to start — short, repeated holds rather than one long one, since this muscle has likely been under-used and guarded for a while. Keep the other side at a similar or slightly lower volume, and add 5 seconds per hold each week once you complete a full week pain-free. Three to four sessions a week is enough.

Common Mistakes and Fixes

The most common mistake is rushing to the full straight-leg version before the bent-knee version is stable. Stay with bent knees until your hips hold level without sagging. The second is gripping tension into your neck and shoulders to hold the position — drop your shoulder away from your ear and refocus the effort into your abs and flank. The third is trying for one long hold right away; several short sets work better at this stage than one long one.

Signals to Stop

If your original, familiar pain gets reproduced, if you feel your flank suddenly give way rather than ordinary muscle fatigue, or if pain carries into the next day, drop back to Stage 3 stretching only for a few more days before trying again.

Week-by-Week Progression Chart

An EMG study by McGill, Juker, and Kropf, published in Clinical Biomechanics in 1996, used fine-wire intramuscular electrodes to measure how the quadratus lumborum and several other trunk muscles activated across a wide range of tasks — sitting, walking, sit-ups, leg raises, an isometric side support position, and carrying an asymmetric load in one hand. The quadratus lumborum showed notably high activation during tasks that involved side-bending the spine or resisting a lopsided load, such as the side support position and the one-sided carry, supporting the idea that the QL functions less as a muscle that flexes and extends the whole spine and more as an independent stabilizer holding each side of the trunk in place. This was a single-session lab study on a small group of pain-free participants, so it does not directly test whether the staged release and stabilization routine here reduces pain, but it is the reasoning behind why this guide finishes with one-sided support work (Stages 3 and 4) rather than stopping at symmetrical stretching.

Research on one-sided low back pain itself is also worth weighing in. Barker, Shamley, and Jackson, published in Spine in 2004, used MRI to measure the cross-sectional area of the multifidus and psoas muscles on both sides in patients with chronic unilateral low back pain, comparing the painful side to the pain-free side. Multifidus cross-sectional area was significantly smaller on the painful side than the pain-free side, and this side-to-side difference correlated with pain and disability scores. This study did not measure the quadratus lumborum directly, and being a cross-sectional design, it cannot establish whether the smaller muscle caused the pain or resulted from favoring that side once pain began. Even so, it's a useful reference point showing that in unilateral low back pain, the painful and pain-free sides genuinely differ at the muscle level — which lines up with why this guide loads release and retraining volume toward the painful side rather than splitting it evenly. The chart below draws on both studies plus the four stages above as a general progression guide; it's normal to need extra days at any stage depending on how quickly your own symptoms settle.

Don't advance to the next stage just because a week has passed if you haven't met the criteria above. Adding a stronger Stage 3 stretch on top of a tender spot that hasn't calmed down in Stages 1-2 can bring the protective tightness right back.

Still Asymmetric After Several Weeks?

If the side-to-side comparison test still shows a clear gap after three or four weeks, check three things. First, is the habit of standing with your weight shifted to one leg, or carrying a bag on the same shoulder every day, still present? Second, could there be an actual leg-length difference (one shoe sole wearing down noticeably faster than the other is a possible clue)? Third, is your pelvis itself rotated or shifted to one side? If the third applies, our pelvic tilt correction routine is worth adding alongside this one. If there's still no improvement after that, a hands-on assessment of your posture and leg length from a physical therapist is the more efficient next step.

Warning Signs and When to Skip This

Stop Immediately If You Notice (Red Flags)

• Numbness or a shooting pain spreading down a leg during the movement (radicular pain)
• A new, sharp, electric-feeling pain
• Your leg suddenly feeling like it's giving out during a stretch or during pressure work
• Pain that keeps worsening the next day rather than settling down
• Your original pain getting reproduced during a more demanding stage, like the side plank

When to Skip This Routine and See a Doctor First

• Fever or chills alongside the flank pain, or blood in your urine (possible kidney stone or infection)
• Pain that comes in waves and doesn't ease no matter how you change position (a different pattern than musculoskeletal pain)
• Radiating leg pain from an acute disc herniation
• Pain following a recent fall or impact where a rib or pelvic fracture is a concern
• Osteoporosis or reduced bone density where the ball work or side plank's loading is a concern (in this case, stay mainly with Stage 1 traction and keep intensity low)
• You are pregnant and this is a new, strong one-sided pain (check with your OB-GYN first)

This routine does not replace a hands-on diagnosis or guidance from a physician or physical therapist. Keep in mind that flank pain sits right where muscular and kidney issues overlap, and don't push the intensity up on your own judgment if any item above applies to you.

Can I Combine This With Other Low Back and Core Work?

This routine isn't mutually exclusive with hinge movements like deadlifts or squats, but on days with a heavy hinge session, keep the side plank volume light for better recovery. Pairing this with our glute bridge progression, which stabilizes the pelvis symmetrically, helps reduce the habit of loading one QL more than the other. Once the Stage 4 side plank feels comfortable, our side plank progression is a good next step for building broader core strength through the flank.