The quadratus lumborum is the muscle that gets brought up every time lower back pain is on one side only and does not go away. The story told is always the same: you sit too much, it shortens, it tightens up, and by stretching it the pain disappears.
It is a coherent story. The problem is that when someone went to measure the stiffness of that muscle in people with chronic low back pain, they found the opposite of what they expected. It is worth telling it properly, because it changes the way these exercises should be used: not whether they should be done, but what to expect from them.
⚠ Important: read this before continuing
The exercises and advice in this article are general indications and may not be suitable for your situation. Every person has a unique clinical history: what works for others could be counterproductive for you.
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Before the exercises: when lower back pain is not muscular
Low back pain is almost always benign and goes away. Some pictures, however, have nothing to do with a flank muscle, and recognising them matters more than any stretch.
A systematic review of 22 studies and 41,320 patients who arrived at the emergency department with back pain estimated the frequency of serious causes: the conditions that required immediate or urgent treatment were 2.5-5.1% in prospective studies and 0.7-7.4% in retrospective ones, with vertebral fractures up to 7.2%, spinal tumours up to 2.1%, infections up to 1.9%, compression of the spinal cord or cauda equina between 0.1% and 1.9%, and vascular causes up to 0.9%. Two clarifications from the authors themselves: in the emergency department these percentages are higher than with the family doctor, and the accuracy of most warning signs has been reported by only one study, so it still needs to be confirmed.
That said, the reasons to be seen straight away rather than lying on the floor stretching are:
- fever, shivers or a recent infection;
- unintended weight loss or a history of cancer;
- difficulty controlling bladder or bowel, or numbness in the saddle area of the perineum;
- loss of strength in one leg, a foot that gives way, tingling that does not shift when you change position;
- a recent trauma, a fall, or a diagnosis of osteoporosis with pain that appeared suddenly;
- pain that does not change in any position, or that wakes you systematically at night.
One of these points does not mean you have something serious: it means you need a doctor, not an article. If none of this applies to you, the muscle can be considered.
What the quadratus lumborum is and what it really does
The quadratus lumborum, QL in the acronyms you find online, is a deep muscle, hidden under the back extensors, stretched between the iliac crest, the transverse processes of the lumbar vertebrae and the edge of the twelfth rib. It tilts the trunk sideways, takes part in extension of the spine and stabilises the pelvis when you walk or stand on one leg. The page dedicated to the lumbar region frames the other structures that can cause pain there.
There is one finding that deserves attention, because it explains why this muscle is of such interest. An electromyography study on thirteen healthy men recorded the activation of eight trunk muscles during a rapid shoulder abduction: the anterior and posterior layers of the quadratus lumborum, together with the transversus abdominis, switched on significantly earlier than the internal oblique, external oblique, lumbar multifidus and erector spinae (p < 0.01). According to the authors, it plays a role in controlling the centre of gravity and stabilising the spine in the frontal plane.
Put plainly: the quadratus lumborum is not a muscle that pulls, it is a muscle that anticipates. This is an argument for training it, not for stretching it, and in fact this is the point where the common narrative starts to creak.
The finding that contradicts the "contracted muscle"
Here is the part that almost no article tells.
In 2025 a Spanish group measured with shear wave elastography, an ultrasound technique that quantifies how stiff a tissue is, the quadratus lumborum of 40 people with chronic non-specific low back pain and 40 people without pain. The declared expectation was to find more stiffness in the patients, given the prevalence of trigger points in this population. The result was the opposite: the stiffness of the quadratus lumborum was significantly lower in the patients (shear wave speed p = 0.010; Young's modulus p = 0.008). Moreover, there was no difference between the right and left side in either group (p > 0.05).
The second piece comes from the same group, on 76 patients with chronic low back pain: the stiffness of the quadratus lumborum was negatively correlated with pain intensity and with symptoms of central sensitisation (both p < 0.01), and positively with physical quality of life (p < 0.01). That is: softer muscle, stronger pain. In their conclusions the authors write that greater softness of the muscle is associated with more intense pain and worse physical quality of life.
Now the honest part, which is needed so as not to overturn one dogma with another. These are cross-sectional studies: they photograph one moment, they do not demonstrate that the soft muscle causes the pain or the reverse. It could very well be the pain, and the consequent reduction in activity, that makes that muscle less stiff. And in the first study the elastography, although showing statistically significant differences, had a poor ability to distinguish sick from healthy (area under the curve below 0.7, with sensitivity of 70% and 75% and specificity of 97.5% and 50% depending on the metric): it is not a usable diagnostic test.
What these data say with reasonable solidity is more modest and more useful: the image of a quadratus lumborum that is stiff, shortened and asymmetric and causes your back pain is not confirmed when it is actually measured. If the muscle of the patients is not stiffer than that of healthy people, and the two sides do not differ, the idea of "stretching the contracted side" loses its mechanism.
"I feel it's tight on this side": why a finger is not enough
The natural objection is: I feel it, and the physiotherapist finds it. Here too there is a measurement.
A systematic review with meta-analysis gathered studies on the agreement between different examiners in identifying myofascial trigger points by palpation: 6 studies with 363 patients, with an overall kappa of 0.452 (95% confidence interval from 0.364 to 0.540). The most reliable criteria were localised tenderness (κ = 0.676) and the patient's recognition of their own pain (κ = 0.575). The authors' conclusion is clear: manual palpation to identify trigger points is unreliable.
Be careful about what this does and does not mean. It does not mean that what you feel does not exist: localised tenderness is precisely the criterion that holds up best, and the fact that pressing on a point you recognise "your" pain is genuine clinical information. It means that moving from "it hurts here" to "the culprit is that deep muscle" is a leap that fingers cannot guarantee, neither mine nor yours. In an area where joints, discs, the sacroiliac joint and muscles lie a few centimetres from one another, attributing the pain to a single deep muscle is a hypothesis, not a finding.
And sitting down? Here too the evidence disappoints
The other pillar of the story is that sitting shortens the quadratus lumborum. On the first link of the chain, sitting causes back pain, there is a systematic review built precisely to assess causality according to the Bradford-Hill criteria: 2,766 references screened, 24 studies included, 5 of high quality. The result was strong and consistent evidence of no association between sitting at work and low back pain, moderate evidence of no dose-response relationship, and non-significant risk estimates on the temporal criterion. The authors' conclusion: occupational sitting is unlikely to be by itself a cause of back pain in the worker populations studied.
The limit to keep in mind: we are talking about occupational sitting in cohorts of workers, not every form of sedentary behaviour, and it is not an encouragement to stay still for eight hours. But if sitting is not found to cause low back pain, the next link, "and therefore you must stretch the QL", hangs on nothing. If your problem flares after hours at the desk, the issue is probably the lack of variation rather than a shortened muscle: we discuss it in the article on back pain from sitting.
What the studies say about stretching for back pain
Here the picture is precise, and it must be reported in full because it is ambivalent.
The largest network meta-analysis on exercise in chronic low back pain included 118 randomised studies for 9,710 participants. The result: compared with control, all types of physical exercise were effective in improving pain and disability, with two exceptions: stretching for pain reduction and the McKenzie method for disability reduction. The most effective interventions on pain were Pilates, mind-body approaches and core exercises; on disability, Pilates, strengthening and core exercises.
It must be read precisely, in both directions. Stretching was not ineffective across the board: it did not beat control on pain, but it does fall among the interventions that improved disability. And it is not a comparison against absolute nothing: it is a comparison against control conditions, within a network in which almost everything else performed better.
The general context is favourable to movement. The Cochrane review on exercise for chronic low back pain included 249 studies and found moderate-certainty evidence that exercise is more effective than no treatment, usual care or placebo for pain at first assessment (mean difference -15.2 points out of 100, 95% confidence interval from -18.3 to -12.2), a clinically important difference. For function, however, the same review reports -6.8 points (from -8.3 to -5.3): a result that does not reach the threshold of clinical importance the authors had set. And compared with other conservative treatments, the advantage of exercise, though present, remained below that threshold.
The American College of Physicians guideline goes in the same direction: for chronic low back pain the first choice is non-pharmacological and includes exercise, multidisciplinary rehabilitation, acupuncture and mindfulness-based stress reduction (moderate-quality evidence), plus tai chi, yoga, motor control exercises, progressive relaxation, electromyographic biofeedback, low-level laser, operant therapy, cognitive behavioural therapy and spinal manipulation (low-quality evidence). Stretching on its own appears in neither list.
Taken together: moving works, stretching the quadratus lumborum as a treatment for pain is not what makes the difference. That is a different conclusion from "it is of no use at all".
An important tip: before trying these exercises, make sure you have received a correct diagnosis. People often think they have one problem, but the real cause of the pain is another. Doing the wrong exercises can make the situation worse instead of better.
Five exercises, used for what they are
Five sensible movements remain, which take the flank, pelvis and spine to the end of their range and carry very little risk. The correct way to use them is as an opening: two or three minutes before the part that matters, which is strengthening. Not as the cure.
A note on timing, so as not to present numbers dressed up as dosages. The meta-analysis on prolonged static stretching found a moderate reduction in muscle stiffness after 3-12 weeks of practice (effect size -0.749; p < 0.001), but no significant relationship between the total duration of stretching and the change in stiffness (p = 0.881), and across ten studies whose measured outcome was the stiffness of the muscle, not low back pain. The 30-60 seconds you read everywhere are therefore a reasonable convention, not a proven dose: consistency over the weeks matters more than the seconds of a single stretch.
1. Standing side bend. Standing, raise one arm overhead and lean towards the opposite side, without rotating the trunk and without pushing the pelvis sideways. You feel the stretch along the flank of the raised arm. It is the simplest, can be done anywhere, even at the office.
2. Side-lying child's pose. From the child's pose, sitting back on the heels with the trunk forward, walk your hands towards one side while keeping the buttocks in contact with the heels. The tension shifts to the opposite flank. On the floor it is easier to let the muscles go, because you do not have to manage balance.
3. Lying 90-90. Lying on your back, knees above the hips and legs bent at ninety degrees. Let the knees fall towards one side while keeping both shoulders in contact with the floor. It adds a rotational component to the side bend, and it is the one that is usually felt as most releasing.
4. Foam roller on the side. Lying on one side, the roller in the space between the last rib and the iliac crest. Roll slowly and stop where you find resistance. What to expect, honestly: the meta-analysis on foam rolling found a large effect on range of motion (d = 0.76, 95% confidence interval from 0.55 to 0.98, across 13 studies for 18 data groups) and no harmful effect, but those studies concern sporting populations and performance measures, not low back pain. It is a good way to gain mobility before training; it is not a treatment for back pain. If it is very uncomfortable, reduce the pressure: there is no proven advantage in doing it badly.
5. Thread the needle. On all fours, pass one arm under the body towards the opposite side, letting the shoulder and head descend towards the floor. It involves the flank, the obliques and the dorsal area. It is the gentlest of the five and often the most welcome in the morning.
Stop if a movement causes sharp pain, if the discomfort travels below the knee or if tingling appears. Stretching harder does not shorten the timescales.
When to do them, and what to add afterwards
The best moment is the one you can maintain: in the meta-analysis on static stretching the reduction in stiffness appears after weeks of repeated practice (3-12), while the total accumulated duration of stretching does not explain the result (p = 0.881). That said, three placements make sense.
Before training, as preparation: this is the use for which the evidence is most solid, given that the documented effect of stretching and rolling is on range of motion.
During the day's breaks, not because it "shortens" when you sit, since we have seen that this link does not hold, but because standing up and taking the trunk to the end of its range breaks up immobility, which is a different thing altogether.
In the evening, if it helps you unwind. Here we are in the realm of personal preference: I am not aware of studies showing an advantage of evening timing for back pain.
And then the part that really weighs. After the stretching, devote most of the time to what came top in the network meta-analysis: Pilates, core exercises, strengthening. For this muscle the opposite of what common sense suggests makes sense: train it in its lateral stabilising role, with exercises such as the side plank and walks with load on one side only, instead of limiting yourself to stretching it. If you want a progression already set up, you will find it in the exercises for lower back pain; if the pain has been going on for months, the pathway is the one described for chronic low back pain.
If the pain really is on one side only
Lower back pain on one side only is common. Attributing it to the quadratus lumborum is convenient because it gives the thing a name, but we have seen that this attribution holds up neither to palpation (agreement between examiners κ = 0.452) nor to instrument measurement (diagnostic accuracy below 0.7).
What to do, then, in practical terms: try and observe. If after two or three weeks of daily stretching the pain on that side is the same, the answer is not to insist harder: it is that you were working on the wrong lever. At that point it is worth looking elsewhere: tolerance to load, the strength of the hip and buttocks, the way you distribute weight when standing for a long time, sleep, periods of stress. Another low-cost route, if the sensation is one of compression, is decompression by hanging, which we discussed in the article on hanging from a bar.
When it makes sense to be assessed
A physiotherapist will not tell you with certainty that the culprit is the quadratus lumborum: nobody can, and anyone who does is going beyond what clinical tools allow. They can, however, do what an article cannot: watch you move, understand which movements reproduce the pain and which switch it off, rule out the causes that deserve a doctor and build a load progression tailored to you, which is the part with the best evidence.
With Ri-Hub the assessment is done by video call, at 29,90€ per session, with the physiotherapist following you in the weeks when the programme needs adjusting, which is in fact the phase where most people stop.
Conclusion
The quadratus lumborum is an important muscle: it activates before the others to stabilise the spine in the frontal plane, and this is documented. What is not documented is the story built on top of it. When its stiffness was measured in people with chronic low back pain it was lower, not higher, and there were no differences between the two sides; palpation is not reliable enough to crown it the culprit; and stretching, in the broadest meta-analysis available, is the only type of exercise that did not beat control on pain, although it improved disability.
The honest way to use this information: keep these five movements as an opening, not as a cure. Rule out the signals described at the beginning first. And put most of your time where the numbers are better, into strengthening and regular movement. If you have been stretching the quadratus lumborum for weeks without any change, you are not short on consistency: you are short on the right lever.
You might also be interested in:
Getting Started with Exercise: A Complete Beginner's Guide Left Shoulder Pain: Causes, When to Worry and Remedies Sciatica Exercises: The Best Movements to Free You from Pain
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Sources
- Quadratus lumborum muscle stiffness in chronic non-specific low back pain: a diagnostic accuracy study, European Spine Journal, 2025
- Association of Quadratus Lumborum Muscle Stiffness with Chronic Low Back Pain Features: An Observational Study, Medicina (Kaunas), 2025
- Best Exercise Options for Reducing Pain and Disability in Adults With Chronic Low Back Pain: Pilates, Strength, Core-Based, and Mind-Body. A Network Meta-analysis, Journal of Orthopaedic & Sports Physical Therapy, 2022
- Exercise therapy for chronic low back pain, Cochrane Database of Systematic Reviews, 2021
- Interrater Agreement of Manual Palpation for Identification of Myofascial Trigger Points: A Systematic Review and Meta-Analysis, The Clinical Journal of Pain, 2017
- Low Back Pain in the Emergency Department: Prevalence of Serious Spinal Pathologies and Diagnostic Accuracy of Red Flags, The American Journal of Medicine, 2020
- Causal assessment of occupational sitting and low back pain: results of a systematic review, The Spine Journal, 2010
- Long-term static stretching can decrease muscle stiffness: A systematic review and meta-analysis, Scandinavian Journal of Medicine & Science in Sports, 2023
- A systematic review and meta-analysis of the effects of foam rolling on range of motion, recovery and markers of athletic performance, Journal of Bodywork and Movement Therapies, 2020
- Feedforward activation of the quadratus lumborum during rapid shoulder joint abduction, Journal of Electromyography and Kinesiology, 2020
- Noninvasive Treatments for Acute, Subacute, and Chronic Low Back Pain: A Clinical Practice Guideline From the American College of Physicians, Annals of Internal Medicine, 2017
Last source check: August 2026.
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