Engaging core muscles through routine physical movements, exercise, or coughing triggers ultrafast constrictions in major brain veins by increasing pressure in blood vessels connected through the spinal column, according to a physiological study published in the Proceedings of the National Academy of Sciences.
Mechanical Forces Link Body Movement to Intracranial Circulation
We often think of the brain as a fortress, sealed inside the skull and protected from the chaos of the body’s movements. But new research demonstrates that intracranial circulation is far more connected to physical motion than scientists previously realized. A collaborative study led by researchers at Michigan State University and Penn State reveals that engaging the abdominal core muscles causes immediate pressure shifts inside the vascular network linked to the brain via the spinal column.
When these core muscles contract, major veins within the brain constrict rapidly, momentarily boosting blood flow. This discovery challenges long-held assumptions about how cerebral circulation works.
“The brain may be protected inside the skull, but it is not isolated from the mechanical forces generated by the rest of the body,” said Qingguang Zhang, assistant professor of physiology at Michigan State University and first author of the paper.
“We were surprised by how rapidly and consistently the veins responded to movement. The brain is often studied as though its circulation is regulated independently of the rest of the body. Our findings show that mechanical signals generated by the body can have immediate consequences for the circulation inside the skull.”
Rethinking the Role of Veins in Cerebral Blood Flow
Historically, cardiovascular research focused primarily on arteries and capillaries when examining how blood moves through tissues. Arteries carry oxygenated blood outward, while capillaries manage nutrient exchange and waste removal. Meanwhile, venous pathways were widely regarded as passive return pipes with little to no active control over local hemodynamics.
The research team observed something entirely unexpected during their investigations: extraordinarily fast constrictions occurring within a tenth of a second in the superior sagittal sinus and bridging veins—the large vessels responsible for draining blood out of the brain. These rapid venous reactions outpaced standard arterial adjustments.
“Arteries and capillaries are surrounded by muscles that can contract to control how much blood passes through them and because of this, they are generally thought of as the main regulators of blood flow,” noted Patrick Drew, professor of biology, engineering science and mechanics, neurosurgery, and biomedical engineering at Penn State, who led the research team alongside associate director duties at the Huck Institutes of the Life Sciences.
“If a region of the brain needs more blood, it can send a chemical signal to arteries and capillaries that tells them to relax and increase flow. Veins have fewer muscles, so we were surprised to see extraordinarily fast constrictions of the superior sagittal sinus and bridging veins.”
As Zhang summarized, “Veins are not simply passive pipes. Our results highlight the other side of circulation. What happens to blood as it leaves the brain can be just as dynamic and physiologically important.”
Everyday Behaviors and Clinical Implications
Conducted primarily in mice, the study tracked how ordinary physical actions—such as walking, running, breathing, and coughing—alter pressures throughout the mammalian body and directly influence cerebral blood flow. Because mammalian physiological structures share deep similarities, the research team suspects identical mechanical pathways govern human neurovascular interaction.
To conceptualize the complexity of this physiological plumbing, Patrick Drew compared the vascular network to municipal infrastructure:
“A city’s water system has to be able to accommodate different use needs of an apartment building or a single-family home, or even a full stadium on gameday. Blood flow in the body must be precisely controlled because different organs need different amounts of blood at different times.”
Uncovering this mechanical coupling between core muscle activity and intracranial veins provides a fresh framework for understanding broader physiological questions. For instance, the findings may help explain why physical exercise yields long-term benefits for brain health, as movement itself directly assists in regulating circulation. The discovery also sheds light on why migraines and headaches tend to intensify with physical motion, given that pain receptors reside within the dura—the membrane surrounding the brain where these dynamic veins are located.
“We are interested in understanding the fundamental mechanisms that control the flow of blood in our brains,” Drew stated. “Like a good mechanic must understand how a car works to diagnose and fix a problem with its engine, we want to understand blood flow in the brain so in the future it will be easier to recognize issues and potentially develop treatments and cures.”
