Why Crossing the Midline Helps You Stay Fit

The simple, ancient movements that are great for your brain.

Would you do me a favour? Would you reach your right hand over to touch your left shoulder?
In doing so, you crossed the invisible vertical line that runs down the centre of your body. This is crossing the midline: reaching, stepping or looking across the midline.

Children have to learn this when reading (eyes movement), when tying their shoes (hands movement), but it is not just a childhood milestone. It is an indication of how well our two brain hemispheres communicate, throughout our life.

What It Does to Your Brain

The brain is divided into two hemispheres, and they don’t automatically share information. That job belongs to the corpus callosum, which is a thick bundle of roughly 200 to 250 million nerve fibres that acts as the brain’s internal broadband connection.

Every time you reach your right hand across to touch your left arm, every time you step your left foot diagonally to the right (you might do that occasionally!), you are sending signals through that cable, keeping it efficient.

Neuroscientists call this ‘bilateral integration’, in other word the coordinated recruitment of both sides of the brain for a single task.

Like most structures in our body, if you don’t use the corpus callosum, you lose it! Research shows that adults who regularly practice movement where they cross the midline, show that the fibres that carry signals between the different brain regions work better!

This translate into better processing speed, clearer thinking (aka less brain fog) and stronger executive function compared to those who don’t.

There is also a compelling connection to neuroplasticity more broadly. Midline-crossing movements require the brain to do something it finds genuinely challenging: override its natural tendency to keep left-side tasks on the left and right-side tasks on the right. That override requires effort. And new movements that require effort are precisely the kind of stimulus that drives the production of BDNF, sometimes described as fertiliser for neurons. BDNF helps keep you neurons healthy and also encourage the growth of new ones. The decline in BDNF is one of the mechanisms underlying cognitive deterioration.

In short: crossing the midline is not a party trick for children. It is a form of cognitive exercise disguised as physical movement.

Modern Life & Midline Crossing

Unfortunately, we don’t really do much midline crossing during a normal day.

Think of a typical day. You wake up, move in a straight line to the bathroom, sit at a desk with the legs uncrossed, type with both hands hovering in front of their respective sides of the keyboard, drive a car (hands fixed at nine and three), sit through meetings, walk in straight corridors, and spend evenings on a sofa staring at a screen directly in front of you.

You might have reacted when reading the above paragraph: ‘But I was told not to cross my legs when sitting!’ First when we talk about midline crossing, we’re talking about dynamic, active movements when the brain has to adjust and coordinate the movement. When you sit and cross your legs, it is passive. Secondly, this is not good for your spine, it might lead to ‘dead leg’ feeling and restrict circulation. So please don’t cross your legs while sitting!

Going back to your typical day, at no point has your nervous system been asked to do anything genuinely cross-lateral. You have spent twelve or more waking hours in a movement environment almost perfectly engineered to keep your two hemispheres in comfortable isolation.

This is new. For most of human history, daily survival required reaching, twisting, climbing, carrying loads across the body, foraging, farming, dancing, and navigating uneven terrain, all of which demanded constant midline crossing and bilateral coordination. Our brains evolved in that movement-rich environment. The corpus callosum developed its extraordinary connectivity not as a bonus feature but as a biological response to a physical world that constantly demanded it.

When that demand disappears, the connectivity gradually weakens. We know that one of the leading causes of injury and loss of independence in older adults comes from falls. They are closely related to poor bilateral coordination and slowed cross-body reaction times.

How to Bring It Back

The good news is that this is entirely reversible, and the interventions are neither expensive nor time-consuming. The research points to a handful of movement practices that reliably stimulate midline crossing and bilateral integration in adults.

Crossing the Midline In Yoga Poses

For those who want something more accessible, even simple daily practices make a meaningful difference. Brushing your teeth with your non-dominant hand. Reaching across the body to retrieve objects rather than turning to face them. Walking with deliberate arm swing - the right arm swings forward as you step the left foot forward- marching with high knees and touching opposite elbow to opposite knee. These are easy ways of prompting the nervous system to re-engage pathways it might not have used for a while.

The key principle in all of them is the same: the movement must cross the body’s midline, and it must require some degree of conscious coordination. Automatic, habitual movement have far less of the neurological benefit. The brain benefits most when it is required to think about what the body is doing.

A brain that is regularly asked to coordinate both its halves is a brain that stays more connected, more responsive, and more resilient. And that, it turns out, is a matter of how you move through every decade of your life.

If this resonated, consider sharing it with someone in your life who thinks brain health is only about crossword puzzles and omega-3s. The body is the brain’s oldest tool for staying sharp.

Much love
Veronique

PS: This kind of movement is woven into everything I teach, including my new book Taming the Walrus.

PS: Images by yanalya on Magnific