'Anatomical possibilism' has become a serious problem.

If you have ever been to a musculoskeletal health professional (physio, osteopath, physical therapist etc.), a personal trainer, or consumed any kind of online training information, there is a good chance that you will have been exposed to anatomical possibilism.

And if you are the kind of person prone to catastrophising or overthinking, it may very well have wreaked havoc on your rehab and training.

What is it?

Anatomical possibilism is the imagined, exaggerated, implausible and unproven relationships which are claimed to exist between anatomical structures.

If you have ever been told that 'structure x' is the "root cause" for your pain in 'structure y', then you've been possibilism'd.

Common examples would include:

• "Weak glutes cause your knee pain"

• "Tight pecs cause your shoulder pain"

• "Forward head posture causes your back pain"

These are some of the more plausible examples. Some more 'alternative' professionals will try to claim that anatomy as distal as your tongue or big toe can be to blame for pain in knees, shoulders, back etc.

It's all connected... Just not like that.

There are several serious issues with anatomical possibilism.

To start, it places a huge emphasis on the role of biomechanics in pain. This has also been dubbed the 'kinesiopathological model'. This paradigm has a heavy bias towards viewing pain through a lens of perfect neutral alignment, symmetry and the aesthetics of movement.

You will know you are dealing with a physio or coach operating within this paradigm if they are constantly using terms like 'root cause' and 'it's all connected' with respect to how different structures affect each other's risk for injury.

However biomechanics is just one of many dozens of risk factors that research has identified for pain. The image below is a meta model constructed from expert opinion on the contributing factors for lower back pain.

The irony here is that I think biomechanics lovers are actually correct to say "it's all connected". Where we disagree is:

1. Just how many factors 'all' truly encompasses, and...

2. What the negative effects of a hyperfixation on biomechanics can have on our other risk factors

The Biopsychosocial Model

While the kinesiopath model reduces pain and injury to a purely biomechanical explanation, the biopsychosocial model acknowledges the influence all of the other factors like: social, psychological, behavioural etc.

Pain onset and severity can be influenced by a myriad of things including:

• Work and relationship stress

• Beliefs around pain

• Previous injury

• Muscle strength

• Sleep

• Depression

• Diet

• Family injury history

As you can see, pain is highly complex. The idea of reducing every case of knee pain to someone's tight hip flexors or weak glutes is hopefully starting to seem a bit ridiculous.

When possibilism becomes damaging

The other somewhat sinister side effect of possibilism is the narrative that accompanies it. Too often, people are told that they have to stop moving a certain way or doing a certain activity because of some assumed 'muscle imbalance' or asymmetry. This creates a narrative of our bodies being highly fragile things that can break easily if not kept in perfect alignment.

What do you think happens when a passionate runner comes to a physio and is told that they need to stop running, because their fragile little body is an asymmetrical, unbalanced mess? Many of the contributing factors can become worse:

• Fear of pain and movement - "Moving wrong will make it worse"

• Negative outlook and beliefs - "I might never run again"

• Increased sensitisation - "I'm so conscious of my knee know"

• Reduced physical activity - "I've stopped running until I'm fixed"

• Loss of autonomy - "I have to see the physio twice a week to get better"

While it's not fair to say the above happens to everyone who is exposed to kinesiopathic thinking, it is likely that there is a great deal of survivorship bias occurring. In other words, we are more likely to hear and see stories about the people who had success with this model, than the ones who got no results or got worse. We've all heard the miracle rehab recovery story, but it's much less likely for someone to publicise to friends and family that they spent time and money on something that didn't work.

Biomechanics is not useless

The BPS model is likely not the final and most accurate paradigm to view pain and injury through. There may very well be an even better model in 20 years that makes BPS seem ridiculous. It is merely a useful model that seems to be more accurate and helpful than pure biomechanics.

However, biomechanics is a significant component of the BPS model, so it is worth figuring out when and how biomechanics does need changing in order for us to get better.

One way of approaching this could be to view biomechanics as just another way of manipulating load. For example, knee pain when squatting could be alleviated by reducing the weight on the bar. But we also have the biomechanical options of reducing the range of motion, or shifting to a more hip dominant squatting pattern, both of which will reduce the load on the knee. Certainly if I'm coaching someone with severe back pain, I'd recommend they temporarily try lift things close to their centre of gravity, to shorten the lever arm, and thus the amount of work on the back.

We might also reduce our risk of injury for very high load tasks by spreading the workload more evenly amongst many muscles. For example: utilising hip, knee, and ankle flexion when landing from a tall jump might be less likely to injure our ankles than if we landed with straight legs.

As for posture, it's not completely impossible that weakness or stiffness in one are could lead to a movement compensation that puts more work through a certain area, leading to pain in that tissue. The classic example of this is the idea that people with a weak upper back slouch more, and that this leads to more strain on their lower back and neck, resulting in pain. But you probably don't need to do upper back training to change this, rather you could just decide to sit up straighter and pull your shoulders back. Additionally, you're now just putting the workload into your upper back, which might just be playing pass the parcel with our pain. Sitting for long periods of time in the same posture seems a more likely root cause.

Closing thoughts

Anatomical possibilsm is likely effective at helping people get short term results. The simple actionable advice, paired with an explanation that makes sense to people, is certainly a strength of this approach. E.g. "Your knees hurt because your glutes are weak. Do 3x15 glute bridges every day for the next week". Great, no more thinking required.

On the surface this is a great hack for driving people into action, and we know enough about the general healing and analgesic effects of exercise to know that it's likely that a lot of people will find that approach helps their pain.

The problem comes in when they don't get better, and are now sent down a rabbit hole of troubleshooting dysfunctions that don't exist. Or maybe they do get better, but now believe that they have to keep doing glute bridges every day to stop their body falling apart.

These are all the unspoken evils of a narrative that explains pain through fragility. The BPS model offers the ability to still deliver a simple and actionable plan, but without scaring the crap out of people. Instead we can empower people to know they have many options, and that their body is highly capable when it's given the chance to be.