Flexion Isn’t the Enemy: What Most People Get Wrong About the Spine

The Problem with “Protect Your Spine”

Over the last decade, spinal flexion has quietly become the villain of the fitness industry.

You’ll hear it everywhere, keep a neutral spine, don’t round your back, protect your discs. It’s repeated with enough confidence that it starts to feel like fact. Much of that thinking traces back to the work of Dr Stuart McGill, whose research into spinal biomechanics has shaped how coaches approach the lower back.

The issue isn’t that his work is wrong. It’s that it’s been simplified, stripped of context, and applied as a rule rather than understood as a model.

That distinction matters.

What McGill Actually Showed

McGill’s research demonstrated that repeated spinal flexion under load particularly when combined with fatigue can create the conditions for disc injury. Mechanically, it makes sense. Flexion shifts pressure within the disc, increases strain on the posterior structures, and over time, repeated cycles can lead to failure.

In a controlled setting, this is both measurable and repeatable.

From a risk management perspective, especially in rehabilitation, that insight is valuable. If someone presents with a flexion-intolerant spine, repeatedly exposing them to the exact mechanism that provokes their symptoms is unlikely to be productive.

So yes, flexion under load can be problematic.

But that’s not the same as saying flexion is inherently dangerous.

The Leap Most People Make

Somewhere along the line, a specific observation became a universal rule.

Flexion went from being a potential contributor to injury under certain conditions, to something people were told to avoid entirely. That’s where the message loses accuracy.

Because if flexion was fundamentally harmful, the human body would be remarkably poorly designed.

You bend your spine constantly. Sitting, tying your shoes, picking something up from the floor—these are all forms of spinal flexion. Not occasionally, but thousands of times a week. And yet most people don’t develop disc injuries as a result.

That alone tells you the problem isn’t the movement itself.

It’s how, when, and under what conditions it’s loaded.

Adaptation, Not Avoidance

Another common oversimplification is the idea that discs don’t adapt.

It’s often framed as a hard contrast—muscle and bone respond to training, discs do not. That’s convenient, but it isn’t entirely accurate. Discs are slower to adapt and less metabolically active, but they are still responsive to load and movement over time.

They develop tolerance.

Not in the same way as muscle, and not at the same rate, but enough that complete avoidance is neither necessary nor helpful.

In fact, avoidance tends to create the opposite effect. When people are taught to fear movement, they reduce exposure, become more rigid, and gradually lose the very capacity they’re trying to protect.

That’s where chronic issues begin to take hold.

Neutral Spine: Useful, Not Absolute

The idea of maintaining a neutral spine sits at the centre of this conversation. It’s one of the most widely used cues in strength training, and for good reason. Under heavy load, particularly in inexperienced lifters, it provides a consistent and relatively safe default.

But it was never meant to be absolute.

Even well-trained athletes don’t maintain perfect neutrality. The spine moves. Slightly, but inevitably. And in many cases, that movement is well tolerated.

Neutral isn’t about eliminating motion. It’s about managing it.

It’s a strategy—one that becomes more or less relevant depending on the individual, the load, and the context.

What Actually Drives Injury

In practice, injuries rarely come down to a single movement pattern.

They emerge from a mismatch between what the body is prepared to tolerate and what it’s asked to do.

Too much load, too quickly. Too much repetition without recovery. Poor control under fatigue. Inadequate exposure to certain positions over time. These are the factors that matter.

Flexion becomes a problem when it exceeds capacity, not when it exists.

That distinction is where most online content falls short.

A More Useful Way to Think About It

Rather than asking whether a movement is safe or unsafe, the better question is whether it’s appropriate.

Appropriate for the person in front of you. Appropriate for their current level of conditioning. Appropriate for the load, the volume, and the stage of training.

That’s how you actually manage risk.

It requires structure, progression, and coaching—not blanket rules.

The Takeaway

Spinal flexion isn’t something to eliminate. It’s something to understand.

McGill’s work gives us a clear model of how certain types of loading can lead to injury. That’s valuable. But it’s only part of the picture.

Long-term resilience doesn’t come from avoiding movement. It comes from gradually building the capacity to tolerate it.

How We Approach It at Poseidon Performance

At Poseidon, we don’t coach people to move less.

We coach them to move better—and to handle load with control.

That means building strength through progressive exposure, refining technique under increasing demand, and adapting the approach to the individual rather than forcing them into a rigid model.

Because the goal isn’t just to protect the spine.

It’s to make it capable.

Train with structure. Build real capacity.
Book a coached session at Poseidon Performance.