(And Why “Just Do Sit-Ups” Isn’t the Answer)
If you’ve ever dealt with low back pain, there’s a good chance someone — a friend, a family member, maybe even a healthcare provider — told you to strengthen your core. It’s common advice. But for a lot of people, it raises more questions than it answers. What exactly is the core? How do you strengthen it? And why does it matter so much for back pain?
Let’s break it down.
Your Core Is a Cylinder, Not a Six-Pack
When most people think of the core, they picture the rectus abdominis — the muscle responsible for that six-pack look running down the front of your abdomen. It’s part of the picture, but only a small one.
A more accurate way to think about your core is as a cylinder — a pressurized canister sitting in the centre of your body, with walls on every side working together to keep you stable and supported.
Here’s how that cylinder breaks down:
- The front and sides are formed by three layers of abdominal muscle: the rectus abdominis (your six-pack), the obliques (your rotational muscles on either side), and the transversus abdominis — often called the “corset” muscle because it wraps all the way around your trunk and is one of the deepest and most important stabilizers in the group.
- The back of the cylinder is supported by the deep muscles of the lumbar spine, which help control and stabilize spinal movement during everything from lifting to simply sitting upright for long periods.
- The roof is your diaphragm — yes, the same muscle you use to breathe. It plays a more active role in core stability than most people realize.
- The floor is your pelvic floor (how fitting), a group of muscles that form a supportive sling at the base of your pelvis, spanning from your pubic bone at the front to your tailbone at the back, and from one sit bone to the other.
All four parts work together. Weakness or poor coordination in any one of them can affect the whole system.
How the Core Actually Works: Pressure, Not Just Strength
Understanding what the core is made of is one thing. Understanding how it functions is where things get really interesting — and where a lot of generic core advice falls short.
Your core stabilizes your spine primarily through the regulation of intra-abdominal pressure. Think of it like inflating a balloon inside a tube — when the pressure inside increases, the tube becomes more rigid and resistant to buckling.
Here’s where breathing comes in. During inhalation, your diaphragm descends toward your abdomen while your pelvic floor gently lengthens and relaxes to accommodate the pressure change. During exhalation, your diaphragm domes back upward while your pelvic floor gently lifts and contracts. This coordinated rhythm — happening thousands of times a day without you thinking about it — is the foundation of core function.
When this system works efficiently, your core can respond dynamically to the demands of movement: supporting your spine when you lift something heavy, stabilizing your pelvis when you walk, and absorbing load when you land from a jump. When the coordination breaks down — whether from injury, pain, pregnancy, surgery, or just long periods of inactivity — other muscles start compensating, and that’s often where pain and dysfunction creep in.
This is also why sit-ups alone aren’t a great solution for low back pain. They train the rectus abdominis in isolation, often with significant spinal flexion load, without addressing the deeper stabilizing system underneath. For someone already dealing with back pain, that can often make things worse.
So What Should You Do Instead?
The good news is that the core responds well to targeted, thoughtful training — you just need to work with the whole system rather than one piece of it.
Dr. Stuart McGill, a leading spine researcher from the University of Waterloo, developed what he calls the “Big Three” — a set of exercises specifically designed to build core endurance and stability while minimizing stress on the spine. They’re a well-researched starting point that many physiotherapists and chiropractors still use today.
That said, the Big Three are a framework, not a prescription. What works well for one person may not be appropriate for another, especially if you’re dealing with specific pain patterns, hypermobility, postpartum recovery, or conditions like arthritis. The most effective core training is the kind that’s matched to your body, your history, and your goals.
When to Get Help
If you’ve been trying to “strengthen your core” on your own without much success — or if exercise is making your pain worse rather than better — it may be time to look a little deeper. A thorough assessment can identify which parts of your core aren’t pulling their weight, what movement patterns might be contributing to your pain, and what exercises are actually appropriate for where you’re at right now.
As a chiropractor at Acacia Health, this is exactly the kind of thing I love digging into with patients. I look at not just strength, but how your whole system is coordinating and moving — assessing the spine, pelvis, and nervous system alongside your movement patterns so that any core work we do together is connected to the bigger picture of how your body functions.
I also offer Clinical Pilates at Acacia Health, which brings that same assessment-driven approach into a movement-based setting. If you’re curious about what that looks like, you can read more on our Clinical Pilates service page or have a look at my intro to Clinical Pilates post for a deeper dive into the approach.
Not sure whether chiropractic or Clinical Pilates is the right starting point for you? That’s a completely normal question — and one I’m happy to help answer. Book a free 15-minute visit and we’ll figure it out together.
