Not long ago, my daughter and her friends wanted to go to a playground at a nearby park on a Saturday.
I try not to say her exact age in this newsletter, but let’s just say they’re all are at a stage where they’re old enough to be at the playground by themselves, but maybe not quite old enough to get themselves there unaccompanied.
So, I was on duty. They did their thing on the swings and slides and whatever while I walked a half-mile path around the park six or seven times, working two things:
My ongoing obsession—taking Life Story Magic from the “cool thing I was doing on the side” stage to the “hey this is an actual business delighting lots of customers” stage. (More to come on all of this soon, probably tomorrow.)
And, scanning scientific journals and other sources to find interesting things to write about — like, for example, this newsletter.
Lo and behold, I drank two milkshakes with one straw (nicer metaphor than killing birds, I think), and came across a study of Penn State suggests I was also doing something clever for my brain in the bargain, without even realizing it.
Writing in Nature Neuroscience, a team led by Patrick Drew, a professor of engineering science, mechanics, neurosurgery, and biomedical engineering (quick aside: I suddenly feel like I have a thin resume), say they’ve discovered how the brain is linked to the abdomen through a network of veins called the vertebral venous plexus.
When abdominal muscles contract—even mildly, as they do when you sit up, take a step, or walk around a park track—they compress those veins. That compression sends a small wave of pressure upward into the spinal canal, which causes the brain to shift gently within the skull.
Why should we care about this? Because, the theory goes, this is how the brain cleans itself of toxins.
“Our research explains how just moving around might serve as an important physiological mechanism promoting brain health.
When the abdominal muscles contract, they push blood from the abdomen into the spinal cord, just like in a hydraulic system, applying pressure to the brain and making it move…. It is thought the movement of fluid in the brain is important for removing waste and preventing neurodegenerative disorders. […]
[A] little bit of motion is good, and it could be another reason why exercise is good for our brain health.”
Francesco Costanzo, a similarly credentialed professor of engineering science and mechanics who led the computational modeling in the study, offered an analogy—the brain as a sponge:
“How do you clean a dirty sponge?” Costanzo said. “You run it under a tap and squeeze it out. In our simulations, we were able to get a sense of how the brain moving from an abdominal contraction can help induce fluid flow over the brain to help clear waste products.”
One thing to know about me is that I’m all about brain cleaning—at least since I learned that it was a thing.
It’s a niche interest, but fascinating to me, and it first developed after I came across a study (not while walking in a park) that suggests sleeping on your side, rather than on your back or stomach, appears to make glymphatic clearance more efficient.
Mind blown, at the risk of making a terrible pun. I found it fascinating that brain-cleaning could work in such a literal, physical way.
Then earlier this year, I covered another Nature Neuroscience study from MIT and Boston University showing that when sleep-deprived people lose focus momentarily, what’s happening is that their brains are forcing those same cleaning cycles during waking hours.
“If you don’t sleep, the CSF waves start to intrude into wakefulness where normally you wouldn’t see them,” said study co-author Laura Lewis. “However, they come with an attentional tradeoff, where attention fails during the moments that you have this wave of fluid flow.”
In other words, the brain gets so desperate for maintenance that it hijacks your attention to perform it.
Quick caveats:
The researchers in the walking study were working with mice, not humans. They used two-photon microscopy and Micro-CT imaging to watch living mouse brains shift in real time.
It’s hard to imagine replicating that with human beings walking park trails, building businesses, and looking for writing inspiration on their phones.
The team also built computer simulations to model how that movement drives fluid flow, and the physics are well-supported. However, whether the same mechanism operates at the same scale in humans hasn’t been confirmed yet.
So, don’t treat this as definitive proof that a 20-minute walk prevents neurodegeneration. It doesn’t establish that.
Still, it adds to a growing body of evidence that the brain’s maintenance systems are more physical, more mechanical, and more responsive to ordinary daily behavior than most people realize.
So, my daughter and her friend had a great afternoon. My business got a bit more efficient. And apparently, so did my brain.
All in all, a pretty nice Saturday.
Other things worth knowing …
WaPo: The U.S. military launched retaliatory strikes against Iran on Tuesday evening after an Iranian drone downed a U.S. Army Apache helicopter near the Strait of Hormuz — the most serious military exchange since the ceasefire.
CNBC: The Trump family received about $500 million from their crypto venture World Liberty Financial — but the investors who bought in saw steep losses.
Fortune: OpenAI filed confidential IPO paperwork with the SEC on Monday, joining rival Anthropic — which filed last week — in a race to the public markets. “We expect it to leak so we’re just announcing it,” the company said. OpenAI was last valued at $852 billion; Anthropic at $965 billion.
AP: Apple's WWDC keynote Monday introduced Siri AI — a rebuilt conversational assistant powered by Apple Intelligence in partnership with Google — rolling out to iPhone 11 and newer devices with iOS 27. New features include natural back-and-forth dialogue, on-screen contextual awareness, and a dedicated Siri AI app with conversation history.
Al Jazeera: Sudan's civil war, now entering its fourth year, has created what the UN is calling the world's largest hunger crisis — with 25 million people facing acute food insecurity and aid organizations warning that famine has taken hold in at least five regions.
US News: U.S. power consumption hit its second straight record high in 2025 and will rise further in 2026 and 2027, the Energy Information Administration said. Demand is surging in part due to data centers dedicated to artificial intelligence and cryptocurrency, and as homes and businesses increasingly use electricity instead of fossil fuels for heat and transportation.
NPR: With only days remaining before the U.S. men’s national team opens its World Cup campaign against Paraguay, tickets for the match are not sold out. FIFA dramatically jacked up prices — the most expensive regular seats for the U.S. opener are priced at $2,735, more than the final cost for the 2022 World Cup final, while the cheapest are $1,120.
AFP via Yahoo: Killing the mood: smartphones are reducing birth rates, multiple studies say.
Thanks for reading. I wrote about some of this at Inc.com. See you in the comments.