Do Your Legs Control Your Brain?

What your body knows and you don't.

Posted Jul 12, 2018

Nadine Wiesner/Pexels
Source: Nadine Wiesner/Pexels

Your legs are not just talking to your brain, they’re telling it what to do. That’s a very good thing. Otherwise your brain might not develop properly and keep adapting through your life.

That’s the conclusion reached reading a study penned by Raffaella Adami and others from the Universities of Milano and Pavia. It helps explain why walking is literally learning.

Pinioned Mice

Doing the experiment in humans was impossible for ethical and practical reasons.  Adami and company pinioned the rear legs of mice while allowing them free use of their front legs. They moved, ate, and socialized as usual.  But their big leg muscles remained inactive.

The consequences were many.  They included:

1. A 70 percent reduction in stem cell proliferation in the subventricular zone of their brains.

2. Immature cell differentiation in brain cells.

3. Lower oxygen and decreased metabolism.

Interestingly, some of the changes also appeared epigenetic in nature, occurring over 10 reproductive cycles in cells in vitro.

Why should brain metabolism slow if you can’t move your legs, but everything else?  Why would brain stem cells stop proliferating and brain cells improperly mature?

Because they’re not getting the right kind of information.

There is plenty of evidence that the use of leg muscles in humans leads to new brain cell growth.  Some of this relates to the production of proteins by muscle cells. Moving really moves us.

Walking As Learning

We tend to see learning in cognitive, linguistic forms. I learn Spanish. You learn calculus. We both learn how to fill in tax forms.

Information in the body is much vaster than our cognitive corpus. The immune system "learns" to find and kill tumors. Muscles "learn" to ride bikes and play soccer. Bones "learn" to survive rocks, stones, and potholes.

This learning is not conscious, for most learning is not conscious. It’s all part of biological intelligence—how your body creates and uses information.

The study of Adami fits what is seen in neurological illness. If you improperly innervate the legs, they atrophy. What’s more interesting and important is the other side of the equation: What the legs are doing to the brain.

The Quick and the Dead

A recent study from 11 population centers in England and Scotland, analyzed by a team from Australia, the UK, and Ireland, found that walking was not just an aid to health; its speed was associated with rates of survival.

It was not the kind of result one might expect. The 50,000 people surveyed gave their own estimate of how fast they walked. How fast was not precisely defined, and self definitions vary a lot, which usually makes it much harder to show statistical significance—there’s a lot of noise in the data.

Nevertheless, walking moderately or fast was associated with about a 20-24 percent decrease in cardiovascular mortality. The numbers were more impressive for older folk. For those over 60, cardiovascular mortality went down 46 percent for moderate walkers and 53 percent for fast walkers.

Especially among the “elderly,” walking fast cut down on the risk of cardiovascular death.  The authors were emboldened to suggest that speed recommendations be included in public health announcements.

Health Is Learned

For those who consider the normal silos of academic research and education, the idea that leg muscles materially change the brain every moment of life was seem strange, or even absurd. For those who think in terms of biological intelligence, it’s obvious.

Moving through an environment means you see more of it. You experience more. You learn more.

What has been missing is a sense of the process.

Much of how we learn is still considered only in cognitive terms. Evolution sees a different picture.

A body in motion engages numerous ecosystems, all of which represent advantage and threat. To survive, it must adapt.

So the legs change. More exercise generally means different kinds of muscle fibrils, in different concatenations and different sizes. That’s implicitly evident to most of us.

But different muscles also give their signals to the brain.  The brain must also adapt.  Now it’s getting clearer that it does more than change synapses and interconnections. If the Adami study proves applicable in people, it also provides them new and more active brain stem cells. It increases overall brain metabolism. It changes how cells look, act, and communicate.

Because information is always flowing. Learning must continue. That’s how we survive, for health itself, our ability to ward off infection and cancer, to navigate the world, depends on growing and adapting.

And the flow of that information is through endless streams of intercommunication working at  levels of intensity and complexity we have not yet glimpsed.

Do the right stuff, and your body gets smarter. All the time.