The University Network

Leg Exercise Deemed Pivotal For Brain Health

It’s common knowledge that a healthy body is reliant on a healthy brain, but a new study shows that the ability to walk, run, crouch and use leg muscles to lift things also benefits the brain and nervous system.

Researchers from two universities in Italy — the University of Milan and the University of Pavia — have determined that neurological health is equally dependent on signals sent from large leg muscles as it is on signals sent from the brain to the muscles.

The research can be used to help doctors understand why brain function in patients with spinal muscular atrophy, motor neuron disease, multiple sclerosis and other neurological diseases quickly declines when motion is limited or lost.

“We initiated the research because we wanted to know if the effect of severe reduction of movement could exacerbate the outcome of some neurological diseases,” said Daniele Bottai, an assistant professor in the Department of Health Sciences at the University of Milan and co-author of the study.

The study, which was conducted on mice, shows that lack of movement had detrimental effects on some areas of the brains of the mice, he continued.

The results support the concept that people who can’t do load-bearing exercises, such as those who are bedridden or even astronauts who have been in space for a long time, experience an alteration of their body chemistry at the cellular level and damage to their nervous system.

The study

The researchers separated 4-month-old mice into two groups.

The first group of mice had their tails tied by a string to the top of the cage, allowing them to move on their forelimbs but restricting any use of the back legs, said Bottai.

The mice remained this way for 14 days, and researchers gave them food and water and checked their weight, daily.

The control group of mice was left free to roam in a similar cage, said Bottai.

At the end of the study, the researchers examined the region of the brain called the subventricular zone, most commonly associated with maintaining nerve cell health and where neural stem cells produce new neurons.

The full study is published on Frontiers in Neuroscience.

The findings

The researchers determined that the mice with limited ability to move experienced a 70 percent drop in neural stem cells, compared to the control group.

Additionally, the researchers noticed that neurons and oligodendrocytes — cells that insulate and support nerve cells — were unable to fully mature when the mice were restrained and exercise was reduced.

“We determined that neural stem cells derived from the subventricular zone of (restrained) mice show a lower proliferation capability compared to unrestrained mice,” said Bottai. The research proves that use of leg muscles sends signals to the brain that are essential to the development and health of our nervous systems.

The results suggest that cutting back on exercise could make it more difficult for the body to generate new, healthy nerve cells.

“It is no accident that we are meant to be active: to walk, run, crouch to sit, and use our leg muscles to lift things,” Raffaella Adami, a professor in the Department of Health Sciences at the University of Milan and lead-author of the study, said in a statement. “Neurological health is not a one-way street with the brain telling the muscles ‘lift,’ ‘walk,’ and so on.”

The researchers gained additional information by analyzing individual cells.

They found that the bodies of the restricted mice had less oxygen in them, leading the team to conclude that reducing exercise can alter oxygen supply and metabolism in humans.

Bottai claims that it is still premature to extend the results to humans, for testing has only been done on mice.

“But this is a first step in order to think of strategies directed to the treatment of people that are not able to move against gravity,” he said.The findings provide potential solutions to many health concerns, such as cardiovascular impacts from sedentary lifestyles, and give insight into many devastating diseases.

Conclusion

“I have been interested in neurological diseases since 2004,” Bottai said in a statement.

“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 (spinal muscular atrophy), or is the lower capacity for movement the critical factor that exacerbates the disease?”

This research can begin to answer these questions.

It identifies just how important movement and exercise is for the health of our brains and nervous system, and can help doctors, astronauts and everyday people make informed decisions.