Abdominal muscle contractions physically squeeze the veins inside your skull to regulate how blood flows through your brain.

Abdominal pressure creates a mechanical coupling that causes ultrafast constrictions in the brain's venous drainage system. Scientists previously thought that blood flow in the skull was managed almost entirely by local neural signals and the heart. These experiments show that the gut and the central nervous system are physically linked through a high-speed pressure circuit. A simple muscle contraction in the torso can immediately change how blood exits the head. This discovery suggests that simple physical movements might be a way to manage brain pressure during trauma or stroke. It reveals a surprising mechanical link between the middle of the body and the top of the head.