She came to me for gut issues. Bloating, irregular bowels, low energy after eating — the usual pattern. But before I got to the GI-MAP results, I wanted to see her move.
I asked her to run in place. High knees, arms swinging, the basic drill. Ten seconds.
She went splat.
Not literally — she didn’t fall. But the coordination collapsed almost immediately. Arms and legs on the same side moving together instead of in opposition. Knees barely lifting. The whole thing asymmetric, effortful, disconnected. She laughed it off. “I’ve never been coordinated.”
I’ve heard that sentence hundreds of times over the past thirty-seven years. It’s never true. People aren’t born without coordination. They lose it — or more precisely, they fail to develop the neural architecture that supports it, and then spend decades in movement patterns that never rebuild it.
The question I want to address in this post is what that actually means. Not just for how you move, but for how you think.
The architecture of coordinated movement
When a healthy infant develops, movement follows a precise sequence that is not accidental. Tummy time, rolling, crawling, creeping on all fours, pulling to stand, walking — each stage builds on the last. Paul Chek, whose infant development work has been formative in how I approach movement assessment, describes this sequence as the foundation of the nervous system’s wiring.
The critical pattern in that developmental sequence is contralateral movement — opposite arm and opposite leg working together. Right arm, left leg. Left arm, right leg. The marching pattern. The crawling pattern. The walking pattern, when it’s working properly.
This cross-crawl movement does something specific neurologically. It drives communication between the left and right hemispheres of the brain through the corpus callosum — the dense band of nerve fibres that connects them. Every time your right arm and left leg coordinate in opposition, you are running a bilateral integration loop that keeps both hemispheres talking to each other.
Children who skip the crawling stage — pulled to standing early, walked with push-alongs before the creeping pattern was established — sometimes show developmental consequences: reading difficulties, attention problems, coordination challenges. This is not coincidence. The movement pattern and the brain architecture are building at the same time. Skip the pattern, and you may compromise the architecture.
“The body is the unconscious mind.”
Paul Chek — How to Eat, Move and Be HealthyThe running drill as a clinical assessment
When I ask a client to run in place, I’m not testing their fitness. I’m looking at whether their nervous system can still coordinate contralateral movement under mild challenge.
A high proportion of the people who sit in front of me — educated, intelligent, successful professionals — can’t do it cleanly. Not because they are unfit. Many of them exercise regularly. They cycle, they go to the gym, they do yoga. But bilateral, cross-body, rhythmic coordination? Often fragmented or absent.
The pattern I see most commonly: ipsilateral collapse. Same-side arm and leg moving together, like a bear. It’s the movement pattern of a very young child before the corpus callosum has fully myelinated. In an adult, seeing it tells me something about how the nervous system is running — specifically, that the two hemispheres are not integrating efficiently under load.
I also use a dual-task version of this assessment, borrowed from NLP and sports performance work. I ask the person to march in place — deliberately, exaggerating the opposite arm swing — while simultaneously counting backwards from one hundred in sevens. Or reciting the alphabet in reverse. Or holding a short conversation.
What happens when you add a cognitive task to a movement task tells you a great deal. In a well-integrated nervous system, both run in parallel without either degrading. In a less integrated system, one or the other — usually both — falls apart. The marching goes ipsilateral. The counting stops. The conversation comes in halting fragments.
This is not a party trick. It’s a window into how the brain allocates resources between simultaneous demands — and how much of that is being handled below the level of conscious effort.
What the brain actually needs from your core
In 2019, a study published in Nature Neuroscience identified a mechanism that most people in the movement world hadn’t previously considered: the role of the body’s rhythmic movements — walking, running, breathing — in driving the flow of cerebrospinal fluid (CSF) through the brain.
CSF is not simply protective fluid that cushions the brain against impact. It is the brain’s waste clearance system. During sleep, the glymphatic system — the brain’s lymphatic equivalent — drives CSF through the interstitial spaces of brain tissue, flushing out metabolic byproducts including amyloid-beta and tau proteins, both of which accumulate in Alzheimer’s disease. The quality of this clearance is closely linked to the quality of sleep, particularly slow-wave sleep.
What the Nature Neuroscience research added to this picture is that rhythmic body movement — including the oscillations generated by walking and running — directly drives CSF pulsatility. The mechanical rhythm of movement creates pressure waves that actively pump CSF through the brain and spinal cord. The core musculature, by generating intra-abdominal pressure with every step and breath, is part of this pump mechanism.
Fultz et al. (2019) in Science demonstrated that neural, vascular, and CSF signals in the brain oscillate in a coupled rhythm during sleep, with CSF flow driven by slow neural and haemodynamic waves. Subsequent work has extended this to waking movement, identifying locomotion-driven CSF oscillations as a distinct clearance mechanism operating alongside sleep-based glymphatic function.
Keifer et al. (2020) in the British Journal of Sports Medicine reviewed coordination-based exercise interventions and found consistent improvements not only in motor function but in attention, working memory, and processing speed — effects that appeared to exceed those seen with aerobic exercise alone, suggesting the cognitive benefit comes specifically from the coordination challenge, not just the cardiovascular load.
Put simply: your brain expects to be moved. Not just exercised — moved rhythmically, coordinately, with the core engaged and the contralateral pattern intact. When that doesn’t happen, waste clearance is compromised, hemispheric integration is reduced, and the brain operates in a lower-resource state.
This is not a small consideration. It has implications for fatigue, for brain fog, for mood, for cognitive decline — and, as I’ll come to, for ADHD.
The ADHD connection
The relationship between movement and attention has been documented for long enough that it should no longer be controversial — and yet it is still routinely underappreciated in clinical practice, where the default response to an ADHD diagnosis remains pharmaceutical.
Children with ADHD consistently show deficits in motor coordination compared to neurotypical peers. This is not secondary or incidental. The same prefrontal-cerebellar circuits that support executive function, impulse control, and sustained attention are the circuits that support timing, sequencing, and coordinated movement. They are the same architecture. Damage or under-develop one side of it, and you see dysfunction on both.
Several trials have now demonstrated that coordination-based exercise — not just running or swimming, but activities requiring timing, sequencing, and bilateral integration: juggling, martial arts, dance, cross-crawl drills — produces measurable improvements in attention, working memory, and impulse control in children with ADHD. The effect sizes are not trivial.
In adults, the picture is similar. Attention difficulties, poor working memory, difficulty sustaining focus on single tasks — these frequently improve with structured coordination work in ways that general aerobic exercise does not fully replicate.
The brain doesn’t distinguish between a movement problem and a thinking problem. To the nervous system, coordination and cognition are expressions of the same underlying capacity.
The working hypothesis is relatively straightforward: cross-lateral, rhythmic, timed movement drives exactly the bilateral hemispheric integration and prefrontal activation that ADHD brains struggle to maintain. You are, in a quite literal sense, exercising the attentional architecture when you do coordination work. Aerobic exercise increases BDNF and blood flow — both important. But coordination exercise does something additional: it trains the sequencing and integration circuits themselves.
Back to the consulting room
My client with the gut issues. She couldn’t run in place cleanly. She’d never been a runner. She spent most of her working day at a desk, drove to work, used the lift, took exercise classes at the gym that involved a lot of bilateral symmetrical movement — both arms together, both legs together — but very little cross-body coordination.
She also had brain fog. Mentioned it in passing, as if it were just the cost of being forty-seven and busy. Difficulty concentrating in the afternoon. Words that wouldn’t come. The feeling, she said, of her brain running through treacle.
I’ve learned not to treat these as separate presenting complaints. The gut and the brain share a bidirectional nervous system. Movement — or the absence of it — affects both. The cross-crawl pattern that’s absent in the running drill is absent in daily life. The CSF clearance that should be happening with every walk to the car isn’t happening if the walk is shuffled, asymmetric, and disconnected from any genuine core engagement.
We ran the tests. The GI-MAP findings were significant. But alongside the clinical nutrition work, I gave her five minutes of cross-crawl drills, morning and evening. Slow, deliberate, exaggerated. Opposite arm to opposite knee. Eyes open, then eyes closed. Then adding the counting task.
Six weeks later, the brain fog was the first thing to lift. Before the gut symptoms had fully resolved. Before the diet changes had fully taken hold. The treacle feeling went — and she noticed it going before she noticed anything else changing.
I can’t give you a randomised controlled trial of one person. But I’ve seen this enough times that I’ve built it into the foundation of everything I do with clients in the Move Well First programme — before supplements, before dietary overhaul, before any of the more complex interventions. If the movement architecture isn’t in place, everything else is working against the grain.
What this looks like in practice
You don’t need a gym or a programme to begin reconnecting this system. The drills are simple. What they require is attention — which is, in a way, exactly the point.
Cross-crawl march: Standing, bring your right knee up while your left arm swings forward and your right arm swings back. Then left knee, right arm forward. Slow and deliberate to start. Exaggerate the rotation through the trunk. Two minutes, twice daily.
Dual-task version: Same drill, but simultaneously recite something that requires mild cognitive effort. The alphabet backwards. A times table you don’t know well. A phone number in reverse. If both the movement and the cognition degrade simultaneously, that’s the integration challenge you’re training.
Eyes closed: Adding vestibular challenge by removing visual input forces the nervous system to rely on proprioceptive and vestibular signals — the same signals that are being underused in sedentary, screen-heavy environments.
Walking with intention: On your next walk, pay attention to the arm swing. Opposite arm to opposite leg, consistently, without thinking about it. Most people will find this requires conscious effort for the first few minutes before it automates. That deliberate effort period is integration work.
Cross-crawl integration is one of the foundational movement assessments in the Move Well First programme — the movement system built into the Detective Health clinical approach. It sits alongside breathing mechanics, hip hinge pattern, overhead mobility, and single-leg stability as the five things I want to establish before adding complexity or load.
If you’re working through the TDG Five-Test Programme, movement assessment is part of the initial intake process — not as an add-on, but as a clinical baseline. What the body does under mild challenge tells you things the tests can’t.
The bigger picture
Functional medicine has done important work in expanding what we measure — hormones, gut microbiome, organic acids, inflammatory markers, genetic variants. I’ve spent thirty-seven years building that testing framework and I believe in it.
But there is a category of clinical information that doesn’t show up on any test panel: how a person moves. How their nervous system integrates under demand. Whether the basic bilateral architecture that was supposed to develop between the ages of one and four is actually doing its job.
Ask your client to run in place. Watch what happens.
If the arms and legs on the same side move together, you have found something worth addressing — before you look at a single blood result.
Start with a discovery call
The TDG Five-Test Programme includes movement assessment alongside the five functional tests — because what the body does under load tells you things the chemistry can’t. Book a free call to find out if this approach is right for you.
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