Swimming and brain health sit at the center of this piece: what water immersion may change in blood flow, stress, and clear thinking, and where popular claims run ahead of the research.
Key Takeaways
The short version
- Swimming can support brain health through the same big pathway as other aerobic exercise: better circulation, better mood, and chemical signals linked to learning.
- Water immersion adds a real body effect: pressure from water shifts blood in the body and can change measures linked to brain blood flow.
- A well-cited study from two thousand fourteen reports modest rises in cerebral artery blood-flow speed during immersion, not a dramatic “huge surge” claim.
- Brain-Derived Neurotrophic Factor (BDNF) matters in the exercise story, but it should be described with care, not as a magic repair switch.
- The strongest message is simple: swimming can be a good reset for many people, but the details should stay honest and measured.
Story & Details
The claim that keeps spreading
In December two thousand twenty-five, a popular idea keeps resurfacing: swimming is not only cardio for the body, but also a kind of medicine for the brain. The pitch is easy to like. Water feels different. The mind often feels quieter. The body moves in a steady rhythm. The story adds one bold engine behind it all: hydrostatic pressure, the gentle squeeze water puts on the body during immersion.
What immersion really does
Hydrostatic pressure is not a metaphor. It is physics. When a body is submerged, pressure rises with depth and can push blood from the limbs toward the chest. That shift can change heart and vessel signals that also influence brain circulation.
A key paper often linked to this topic, published in two thousand fourteen by Carter and colleagues, measured cerebral blood flow velocity with transcranial Doppler during water immersion. The study reported increases in middle cerebral artery velocity from about fifty-nine to sixty-four centimeters per second, and in posterior cerebral artery velocity from about forty-one to forty-four centimeters per second. It also reported changes in mean arterial pressure and end-tidal carbon dioxide. Those numbers support a modest rise in measured blood-flow speed during immersion, not a sweeping claim that a fixed percentage more blood is forced into the brain in every swimmer, in every pool, in every moment.
Calm, rhythm, and the brain’s “fertilizer”
The most believable part of the swimming story may be the simplest: steady movement plus steady breathing often feels calming. A repeated stroke and a controlled breath can look a bit like moving meditation. That does not require mystical language to be real in daily life.
The biology story often adds Brain-Derived Neurotrophic Factor (BDNF). BDNF is sometimes called “brain fertilizer” because it supports synapses and plasticity, and exercise is linked to higher BDNF activity in many lines of research. Harvard Medical School and Harvard Health Publishing, based in the United States (North America), describe exercise as a driver of brain-friendly changes, including pathways involving BDNF. The careful way to say it is this: exercise supports conditions that help the brain adapt, learn, and stay resilient. The careless way is to promise that BDNF “repairs damaged neurons from stress” as a direct, guaranteed fix.
Mood promises that need softer words
Some versions of the claim go further and say swimming releases serotonin and endorphins faster than land exercise. Mood can improve with exercise, including swimming, but “faster than” is a comparison claim that needs a direct comparison study to carry that weight. Without that, the safer point is still useful: many people feel better after a swim, and mood is a known part of why exercise can help thinking.
A tiny Dutch mini-lesson, pool-ready
Dutch is used in the Netherlands (Europe), and a few short lines can be handy at a pool or sports center.
Ik ga zwemmen.
Word-by-word: Ik = I; ga = go; zwemmen = swim.
Use: simple, everyday, neutral.
Zullen we rustig aan doen?
Word-by-word: Zullen = shall; we = we; rustig = calm; aan = on; doen = do.
Use: friendly, soft suggestion to take it easy.
Even ademhalen.
Word-by-word: Even = just; ademhalen = breathe.
Use: short, practical, often said to pause and reset.
Conclusions
The clean takeaway
Swimming is a strong, human-friendly form of aerobic exercise, and the brain often benefits when the body moves. Water immersion adds real pressure effects that can shift circulation and, in lab measures, can be linked to modest increases in cerebral blood-flow velocity. The best version of the message is not flashy. It is steady, like a good stroke: swim, breathe, repeat, and let the brain enjoy the quiet.
Selected References
Public sources for the key claims
[1] https://pubmed.ncbi.nlm.nih.gov/24553298/
[2] https://www.health.harvard.edu/exercise-and-fitness/working-out-your-brain
[3] https://hms.harvard.edu/news/exercising-mind
[4] https://pubmed.ncbi.nlm.nih.gov/24977699/
[5] https://www.youtube.com/watch?v=ZER-tofPbFg
Appendix
A–Z quick definitions
Brain-Derived Neurotrophic Factor (BDNF). A protein involved in brain plasticity and synapse support; exercise is linked to higher BDNF activity, which is one reason researchers connect movement with learning and memory.
Cerebral blood flow velocity. A Doppler-based measure of how fast blood is moving through certain brain arteries; it can shift with changes in pressure, carbon dioxide, and other body signals.
End-tidal carbon dioxide. A measure of carbon dioxide at the end of exhalation; it reflects breathing and gas exchange and can influence brain blood vessel tone.
Hydrostatic pressure. Pressure created by water that increases with depth; during immersion it can shift blood toward the chest and change cardiovascular signals.
Mean arterial pressure. An average pressure in the arteries across a heartbeat cycle; it helps describe how strongly blood is being driven through organs.
Serotonin. A brain and body messenger linked with mood and many other functions; exercise can influence systems connected to serotonin, but timing and size of effects vary.
Transcranial Doppler. A noninvasive ultrasound method that estimates blood flow velocity in major brain arteries through the skull.
My Diary - Leonardo Cardillo 