The Missing Movement Behind Your Back Pain

Across two systematic reviews, that's the movement that keeps turning up alongside low back pain. And it isn't a spinal movement at all. It's hip internal rotation. Lose it, and your lumbar spine starts doing a job it wasn't built for. Every rep.

This Isn't Just a Clinical Hunch

In 2024, Pizol and colleagues published a systematic review of hip biomechanics in people with non-specific low back pain — 54 observational studies, screened from 338 articles, covering range of motion, kinematics, strength and muscle activation. Most rated moderate on their appraisal tool, a handful high, none poor — though moderate there means mid-range, not near the top of it.

The single most consistent finding across the whole body of work: total hip rotation is reduced in people with low back pain, and internal rotation is the most restricted direction of all. One included study found the reverse in people with acute pain. That's the exception.

Five years earlier, Avman and colleagues had run a narrower review looking only at hip range of motion, across six databases. Their conclusion landed in the same place: of every direction they examined, internal rotation was the one that mattered — the main direction worth assessing in someone with non-specific low back pain.

Two research groups, different databases, five years apart, same movement. That's worth something. It isn't proof.

Avman graded the evidence behind their own finding very low quality and said the association should be viewed with caution. That matters, because the two reviews aren't equal weight. Pizol is broad — it maps what's been measured. Avman looked hardest at this exact question and came away unconvinced.

And every study in both is observational. They can show that the restriction and the pain turn up together. None of them can show which arrived first.

The obvious challenge is that pain makes people guard, and guarding costs range — so the restriction could be the consequence rather than the cause. That's a fair reading, and the data can't rule it out. What it doesn't explain is the number of people I test who have the restriction and no pain at all. They're not guarding anything. It's already there, waiting, however it does in my experience go hand in hand with increased compression.

And here's where I'll go further than the research does, and say so plainly. Nobody in those 54 studies was loaded. They were measured on plinths and in gait labs, moving at their own pace. My position — from clinic, not from the literature — is that a restricted hip magnifies spinal compensations with movement requiring IR at the hip and even more so when you put weight on it. Add a bar and a hinge, and the range has to come from somewhere. That's when the lumbar spine makes up the difference, and when the restriction stops being a finding and starts being a cause.

That's a claim about mechanism, and the reviews neither support it nor test it. Take it as clinical reasoning, and test the restriction yourself.

The Rest of What They Found

Range of motion was one of four categories. The other three are more interesting.

Strength: hip abductors and extensors test weak in people with low back pain, in isolated testing and in functional tasks alike.

Muscle activation: the same population shows greater glute max and hamstring activation than healthy controls, with increased posterior sling activity during hip extension.

Read those two together. Weak on testing, working harder in life. The activation findings are mixed across studies, but that combination is what I see in clinic constantly — a muscle already ‘on’, holding a position rather than producing movement.

Kinematics: altered lumbopelvic motion, slower execution of everyday tasks, and modified joint coordination under repetitive lifting. Read together, that's a system organised around not moving the painful segment.

IR and ER Are Not Opposites

Internal and external rotation aren't two movements the hip picks between. Both are available at once, and the only question is how much of each you've got.

When enough compression builds up within and around the hip joint — reducing joint space — rotation in both directions becomes restricted. Both reviews found exactly that, incidentally: external rotation was also reduced, just less consistently than internal.

Test It Now — Two Simple Checks

Seated hip internal rotation. Sit on the edge of a chair, hips and knees at 90 degrees, feet flat. Without moving your knee, let one foot swing outward — that's the femur rotating inward. You're looking for roughly 35–45 degrees each side. Test both, and note any real difference between them.

Prone hip internal rotation. Lie face down, knees bent to 90 degrees. Let both feet fall outward together. Same target range. If your feet barely move from vertical, or one side drops noticeably less than the other, you have your answer.

If both are limited and your lower back is the thing that keeps complaining, that's not a coincidence to ignore.

What It Does to Your Training

In a hinge in particular, you need hip internal rotation. Without it, the range comes from the lumbar spine instead.

It's also why "strengthen your glutes" so rarely fixes a back. Those muscles are already working overtime. Loading them harder entrenches the position.

The Bottom Line

Loss of hip internal rotation is close to universal in people who train hard, and it travels with low back pain often enough that two reviews landed on it.

It isn't a flexibility problem, which is why the stretch you've been doing for two years hasn't touched it. It isn't a strength problem either — the muscles involved are already working overtime. It's a pressure and position/centre of mass problem.

Run the two tests. If you're restricted, you now know something about your back pain that you can address.

What changes it is position/centre of mass, breath and load, in that order — and which positions depends entirely on how you're built and what you're currently compensating with. Get that wrong and nothing moves. Get it right and the test can change inside a session.

That part is an assessment, not an article. It's what I spend my time on week after week, in the clinic and in the programmes I write. Give the hip its range back and the spine stops covering for it.

References

Pizol GZ, Miyamoto GC, Cabral CMN. Hip biomechanics in patients with low back pain, what do we know? A systematic review. BMC Musculoskeletal Disorders. 2024;25(1):415.

Avman MA, Osmotherly PG, Snodgrass S, Rivett DA. Is there an association between hip range of motion and nonspecific low back pain? A systematic review. Musculoskeletal Science and Practice. 2019;42:38–51.

Luke Sanders is an osteopath and strength coach based in London. He works with lifters, athletes and people who want to train without paying for it later.