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The 60-second test that reveals why your back pain keeps coming back

Why core strengthening isn’t the fix, and what actually is.

Rick Olderman, MSPT
 ·  13 min read
 ·  Updated September 2026

Licensed orthopedic physical therapist, 30 years of clinical experience. Former clinic owner,
author of Pain Patterns, winner of the 2025 NIEA Award, and creator of a systems-based
approach to chronic pain used in his APTA-approved continuing education course.

Low back pain affected 619 million people worldwide in 2020, and that number is projected to climb to 843 million by 2050 as the population ages.¹

It’s tempting to write that off as “well, people just get older.” But age by itself doesn’t cause back pain. Age is what gives the wrong movement patterns more time to compound. More years spent doing the wrong things, more accumulated strain on the same tissues. More years doing the right things, and that same time span works for you instead of against you.

Many of you reading this will say that you know exactly why you have low back pain — your MRI scan told you so. I especially hope, if this describes you, that you continue to read on, because there’s a great deal of evidence, both clinical and research, that doesn’t support that conclusion.⁷

So what’s actually going on with low back pain? After 30 years as an orthopedic physical therapist, here’s what I’ve found: almost all chronic back pain comes down to one or two things happening in your spine.

• Too much arching, or too little.
• An uneven pelvis and rib cage that’s driving the pain to one side.

You’ll learn how to test for both of these in this article.

The first cause: too much arch, or too little

The short version: if your back feels better with your knees bent, you may have an extension problem. If it feels better with your legs straight, you may have a flexion problem. If your pain is mainly one-sided, a sidebending problem may also be involved. Below, you’ll test yourself for each.

Let’s break down the first cause. For most people, chronic back pain traces to one of two patterns.

An extension problem means your low back is too arched, or too many forces are pulling it into an arch. This is by far the more common pattern in chronic back pain.

A flexion problem means your low back is too flat and wants more arch. This one is rare in chronic cases, but common in acute disc-related back pain. Interestingly, most generic solutions for back pain that you see on the internet and in clinics fall into this category — bird dog, cobra pose, upward dog, and so on.

So first, let’s find out which camp you fall into. Below is the simple test that answers that question.

The 60-second test: extension or flexion?

If your back felt better with legs bent, you likely have an extension problem. In my clinical experience, this fits about 99% of the people I’ve seen for low back pain. That means you have too much arch, or too many forces trying to arch your back further. The degree matters too: if a small knee bend was enough to reduce your pain, the forces pulling your back into extension are relatively mild. If you needed your knees all the way to your chest to feel relief, you have larger forces acting on your spine.

Conversely, if your back felt better with legs straight, you likely have a flexion problem. In my experience this is rare with chronic back pain — I see perhaps one case a year — but it’s a very common pattern in acute, disc-related pain (more on that distinction below).

A note on false answers. Many people assume they should feel better with their legs straight, so they talk themselves into that answer instead of feeling what’s actually true. Take the full 60 seconds and pay attention to your body, not your assumption.

Why this works as a diagnostic. In the minute it takes to do this test, nothing about the structural findings on your MRI has changed. No disc bulge or herniation has suddenly disappeared, no joint has healed, no muscle or ligament has been repaired. What changed is the force acting on your spine. If your pain changes that fast, the mechanics loading your spine matter as much as — or more than — whatever a scan found.²

Watch: Back pain from an L4-5 disc bulge? — a bonus segment from Bob & Brad, applying this test to a real MRI report, live.

The second cause: a sidebending problem

If your pain is mainly one-sided, an uneven pelvis and rib cage — what I call a sidebending problem — is often involved too.

I go into this pattern in full depth — including the photo test, the quick “reaching while walking” fix, and why it’s so often misdiagnosed as a leg length discrepancy — in my sciatica article, since it’s the primary driver behind most one-sided sciatic pain. Everything there applies just as much to one-sided back pain.

Why isn’t this just “core strength”?

Watch: Is core strength critical for chronic back pain?

At the risk of creating an uproar on the internet: a stronger core doesn’t fix either of these problems. If a stronger core were the answer, you’d never see anyone with a six-pack in back pain. But plenty of people with visibly strong abs have chronic back, sciatic, or SI joint pain, and plenty of people who can’t do a single sit-up don’t. Abdominal or core strength isn’t the variable that’s failing.

What the research backs, and what it doesn’t

The whole idea of “core stability” traces to a single, much narrower finding: two deep muscles — the transversus abdominis and multifidus — activate slightly slower in people with low back pain. Not weaker. Slower.³ That’s a timing problem, not a strength problem, and timing and strength call for very different fixes. But be clear that this doesn’t necessarily mean the slower firing pattern is causing back pain. It could just as easily mean the back pain is causing the muscles to fire more slowly — pain commonly inhibits muscle function.

Even researchers can’t agree on what “core” means. Definitions in the literature range from “the abdominal and lumbopelvic region” to “the neuromuscular system’s ability to control and protect the spine.”⁴ If the field can’t agree on the target, it’s no surprise the outcomes are inconsistent.

A Cochrane review — the highest standard of evidence synthesis in medicine — found core-specific exercise is not superior to general exercise for chronic low back pain.⁵ Both beat doing nothing. Neither beats the other.

What I’ve also noticed is that most of these trials don’t isolate the muscles they claim to test. Their own descriptions show programs progressing to more complex and functional tasks that integrate deep and global trunk muscles along with everything else — meaning the intervention broadens into general movement almost immediately. That makes it hard to credit any improvement specifically to “the core” rather than to the general movement retraining riding along with it.

One exception: acute, disc-related back pain. When a disc is freshly irritated, inflamed, or bulging, some spinal stabilization can help by reducing motion at the injured level.⁶ As that acute episode resolves, core work becomes less and less relevant — and for the chronic pain most people are searching for answers about, it was never the primary lever to begin with.

Here’s how I think about it. Our bodies have multiple lever arms acting on the low back: tight thigh muscles, a locked-knee walking habit, an old injury you’ve been unconsciously compensating around for years, pelvic dysfunction. All of it comes from the lower body operating on the pelvis and, consequently, the low back. The core sits at the junction of those lever arms.

Fixing an extension problem

Watch: Hidden posture habits causing your back pain

Someone with an extension problem needs to reduce the degree of arching in their lower spine. Here are a couple of ways to do that.

Unlock your knees

Stand for three minutes and you’ll notice you start locking one or both knees backward within about a minute. It conserves energy by resting on the joint instead of the muscle. Locking the knee also tilts the pelvis forward, which increases the arch in your low back — exactly what you don’t want if an extension problem is feeding your low back pain.

The fix: simply unlock your knees, just slightly, when standing or walking. Because this is a subconscious habit, a small piece of tape on the back of each knee works as a physical reminder every time you lock them. In my clinical experience, most people notice reduced pain within 24 hours and have the habit changed within three to five days of consistent attention.

This is the same locked-knee habit that shuts off your glutes and drives hip pain. I cover the fuller mechanism and a more active fix — tiptoe walking — in my hip pain series.

Relax the “perfect posture” habit

Locking the knees is often part of a larger postural pattern, where people believe the more erect you are, the better your posture is. That pattern strongly contributes to an extension problem. See for yourself: stand as tall and erect as you can, and you’ll notice your knees lock to achieve it. You’ll also notice your low back muscles contracting significantly. So start relaxing your posture while unlocking your knees a little.

Fixing a flexion problem

Back pain from a flexion problem needs more arching in the lower spine, not less. This is where those exercises I mentioned earlier come in — the bird dog, the cobra, upward dog. They promote more arching. But I’ve found a general lack of postural effort in people with flexion problems. Essentially, they need to become more erect in their posture. I’ve developed a simple method for achieving this, called lifting the rib cage.

The acute disc exception

It’s possible to have both patterns at different times. A chronic extension problem can be temporarily overridden by an acute disc episode, which behaves like a flexion problem while it’s inflamed. During that acute phase, lying on your stomach with a pillow under your chest, or doing the cobra or bird dog — all of which encourage more arch — can ease disc-related pain, even though that same position would aggravate a typical chronic extension problem. As the acute episode calms down over days to a week, the amount of extension needed decreases, and you’re usually left with your underlying extension problem to address.

Putting it all together

One of my patients, a very active man in his late 50s, had right-sided back pain for over 20 years, including a disc surgery and multiple cortisone shots that never solved it. His exam showed an extension problem, a right sidebending problem, poor gluteal activation while walking, tighter thigh muscles on the right, and retroverted femurs — five separate contributors stacked on top of each other. The gluteal and femoral shape pieces are patterns worth understanding on their own; I cover them in full in my hip pain series.

Unlocking his knees, reaching while walking, and stretching his thighs brought 75% relief in the first week alone. The remaining piece turned out to be tension patterns held throughout his body, so he used my somatics lessons to resolve the rest.

That’s usually how it goes: several of these patterns compounding at once, not one isolated cause. The body doesn’t lie about what’s actually happening, even when a diagnosis, a scan, or years of treatment pointed somewhere else. Fix the components of the pattern, and in my clinical experience the pain usually follows fairly quickly — no matter how long it’s been there, or what your imaging shows.

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