In a new take on the exercise truism 'use it, or lose it,' researchers show neurological health is an interactive relationship with our muscles and our world

"Our study supports the notion that people who are unable to do load-bearing exercises -- such as patients who are bed-ridden, or even astronauts on extended travel -- not only lose muscle mass, but their body chemistry is altered at the cellular level and even their nervous system is adversely impacted," says Dr. Raffaella Adami from the Università degli Studi di Milano, Italy.


Limiting physical activity decreased the number of neural stem cells by 70 percent compared to a control group of mice, which were allowed to roam. Furthermore, both neurons and oligodendrocytes -- specialized cells that support and insulate nerve cells -- didn't fully mature when exercise was severely reduced.

The research shows that using the legs, particularly in weight-bearing exercise, sends signals to the brain that are vital for the production of healthy neural cells, essential for the brain and nervous system. Cutting back on exercise makes it difficult for the body to produce new nerve cells -- some of the very building blocks that allow us to handle stress and adapt to challenge in our lives.


The researchers gained more insight by analyzing individual cells. They found that restricting exercise lowers the amount of oxygen in the body, which creates an anaerobic environment and alters metabolism. Reducing exercise also seems to impact two genes, one of which, CDK5Rap1, is very important for the health of mitochondria -- the cellular powerhouse that releases energy the body can then use. This represents another feedback loop.


"I have been interested in neurological diseases since 2004," says co-author Dr. Daniele Bottai, also from the Università degli Studi di Milano. "The question I asked myself was: is the outcome of these diseases due exclusively to the lesions that form on the spinal cord in the case of spinal cord injury and genetic mutation in the case of SMA, or is the lower capacity for movement the critical factor that exacerbates the disease?"


"One could say our health is grounded on Earth in ways we are just beginning to understand," concludes Bottai.