Abdominal Muscle Tightening Linked to Brain Sway and Potential Health Risks in Study

Researchers at the University of Copenhagen published a study in Nature Neuroscience in 2026 showing that abdominal muscle contractions cause brain sway, based on MRI imaging and high-speed microscopy of awake mice. According to lead author Dr. Drew, this sway results from abdominal pressure compressing blood vessels and pushing blood into the spinal cord, which moves the brain within the skull and enhances cerebrospinal fluid flow through the glymphatic system.

The study found that abdominal muscle contractions compress blood vessels, pushing blood into the spinal cord and causing the brain to sway within the skull, according to lead author Dr. Drew of the University of Copenhagen. This motion enhances the flow of cerebrospinal fluid (CSF) through the glymphatic system, which is responsible for clearing metabolic waste from the brain.

Researchers observed that this gentle brain movement can increase waste clearance by up to 30%, based on computational simulations and imaging data.

Using high-speed multiplane two-photon microscopy on awake, head-fixed mice, the team visualized brain motion primarily directed rostrally and laterally. The brain sway was tightly correlated with locomotion but showed no association with respiration or cardiac cycles, officials said. The motion began before limb movement, consistent with abdominal muscle activation initiating the hydraulic effect. Dr. Drew explained that the vertebral venous plexus transmits pressure from the abdomen to the spinal cavity, effectively pushing blood into the spinal cord and moving the brain inside the skull.

In preclinical experiments, applying direct abdominal pressure on lightly anesthetized mice induced brain motion without other body movements, at force levels lower than those used in blood pressure testing. Simulations confirmed that this brain movement drives interstitial fluid flow into the subarachnoid space, opposing fluid flow patterns observed during sleep. This suggests that the mechanism may support neural waste clearance during waking hours, according to the study published in Nature Neuroscience in 2026 (DOI:10.1038/s41593-026-02279-z).

The researchers extended their findings to humans, conducting MRI imaging on volunteers at the University of Copenhagen. They confirmed slight forward-and-backward brain sway with each abdominal muscle contraction, providing evidence that the mechanism is conserved across species. Dr. Drew noted that the brain returns rapidly to its baseline position immediately after abdominal pressure is relieved, indicating a dynamic and reversible process.

Health implications discussed in the study highlight the potential role of simple physical activities in promoting brain health. Dr. Torres, a co-author, said minimal core engagement, such as core bracing or sitting up straight, may support the glymphatic system’s waste clearance without the need for intense exercise. Dr. Park, another collaborator, emphasized that even gentle tightening of abdominal muscles could provide profound neurological benefits, especially for older adults with limited mobility.

The research team cautioned against forceful or excessive abdominal contractions, which could pose injury risks. They stressed that minimal pressure, lower than standard blood pressure test levels, was sufficient to induce beneficial brain sway in mice. While no harm was observed from slight movements, the researchers plan larger population studies to investigate the relationship between abdominal strength and cognitive decline in humans. They also noted that the current findings are preclinical and that human applications require further validation, particularly for vulnerable groups such as the elderly.

Future research directions include exploring the clinical applications of this mechanism for brain-health routines, especially in older adults or individuals with limited mobility. The team intends to confirm fluid movement and neural waste transport induced by brain sway in larger human cohorts. Comparative studies with other deep abdominal training methods, which have shown benefits for respiration and stability, are also planned. Additionally, the researchers aim to investigate broader connections within the brain-gut-muscle axis, which has implications for energy homeostasis, obesity, and metabolic diseases, as outlined in a 2022 review.

The study was conducted by researchers at the University of Copenhagen and led by Dr. Drew, with contributions from Drs. Torres and Park. It combines advanced imaging techniques, computational modeling, and human MRI to provide new insights into the physiological mechanisms linking abdominal muscle activity to brain health.