Small movements found to have a ‘cleaning effect’ on the brain 

Scientists have found that every time you tighten your abdominal muscles, your brain gently sways inside your skull causing the circulation of cerebrospinal fluids. This simplistic mechanism ‘cleans’ the brain by flushing out harmful waste. 

Cerebrospinal fluids have essential functions providing a cushion for the brain and spinal cord, as well transporting nutrients and clearing waste.  Studies using mice show that when the abdominal muscles tighten, even slightly, they press on a network of blood vessels connecting the spinal cord and brain. 

This pressure causes gentle movement of the brain within the skull, helping the cerebrospinal fluid to move across the brain and carry away waste that could interfere with normal brain function. Patrick Drew, a co-author of the paper and Professor at Penn State University, describes the process as “just like in a hydraulic system, applying pressure to the brain and making it move.” 

“It is thought the movement of fluid in the brain is important for removing waste and preventing neurodegenerative disorders… and it could be another reason why exercise is good for our brain health,” concludes Drew. 

The mechanism was observed in moving mice using advanced imaging techniques. Researchers noticed that the brain shifted before the mice moved, occurring immediately after the abdominal muscles tightened to initiate motion. To confirm that abdominal pressure was responsible for the brain shift, the team lightly applied pressure to the abdomens of anesthetised mice. This caused the brain to move, even though no other movement was involved.  

“Importantly, the brain began moving back to its baseline position immediately upon relief of the abdominal pressure,” Drew said. “This suggests that abdominal pressure can rapidly and significantly alter the position of the brain within the skull.” 

Since there are currently no imaging methods that can capture the movement of cerebrospinal fluid, scientists used computer simulations to show model fluid flow in and around the brain. This interdisciplinary approach shows how scientists can gain a deeper understanding of complicated biological system by combining expertise. 

“In our simulations, we were able to get a sense of the how the brain moving from an abdominal contraction can help induce fluid flow over the brain to help clear waste products,” said Francesco Costanzo, who led the modelling work. 

Drew points out that more research is needed to determine how these findings may apply to humans. However, scientists are hopeful that understanding the mechanical link between movement and brain health may provide strategies to lower the risk of neurodegenerative diseases associated with waste build up.  

By Marina Milsum, May 14, 2026

Edited by Kazuma Oura.