The brain moves inside the skull when the abdominal muscles are working - and that can be important

The study was conducted by scientists at Penn State. They studied mice and used high-precision imaging techniques, including two-photon microscopy and microcomputed tomography. This allowed them to see how the brain shifts slightly at times associated with body movement.

Details

The authors found that contractions of the abdominal muscles constrict blood vessels associated with the spine and brain. According to the researchers, this works similar to a hydraulic system: pressure is transmitted upwards and the brain moves gently inside the skull.

To test whether it's really about the stomach, the scientists separately applied gentle controlled pressure to the abdomen of slightly immobilised mice. Even without normal body movement, the animals' brains shifted, and returned to their original position after the pressure was removed.

The researchers then used computer models to understand how such micro-movements might affect cerebrospinal fluid. This fluid surrounds the brain and spinal cord, protects them and is involved in the excretion of metabolic waste products. Modelling has shown that small movements of the brain can increase the flow of fluid around it.

Why it matters

The work offers another possible explanation for why movement is good for the brain. Usually, the benefits of physical activity are attributed to blood flow, metabolism, hormones and nervous system function. A new study adds a mechanical factor to this: the very movement of the body may help move fluid in and around the brain.

The authors compare the brain to a sponge: if you move or "squeeze" such a system slightly, fluid starts to flow through it better. In theory, this could help remove substances that should not accumulate in the brain.

That said, it's important not to exaggerate the findings. The study was conducted on mice and with the help of models, so we can not yet say that the reduction of the press directly "cleans" the human brain or protects against neurodegenerative diseases. Scientists are talking about a possible mechanism that still needs to be studied.

Background

Cerebrospinal fluid has long been considered important for brain function: it protects nerve tissue, participates in metabolism and helps remove waste products. Previously, much attention has focused on how this process relates to sleep. New work shows that body movement during wakefulness may also play an important role.

This doesn't mean you need to specifically tense your abdominal muscles for the sake of "brain detox." Rather, the study shows that normal movements - walking, standing up, turning the body - may be part of a complex system that keeps fluid circulating around the brain.

Source

The study is published in Nature Neuroscience in 2026 under the title Brain motion is driven by mechanical coupling with the abdomen. The authors used experiments in mice, microcomputed tomography, two-photon microscopy and computer modelling of fluid movement.