Exercise Boosts Brain Power—Neuroscientists Don’t Know How

Exercise Boosts Brain Power—Neuroscientists Don't Know How

Key points

Moderate-intensity aerobic exercise (cardio) increases prefrontal cortex oxygenation and boosts brain power.

Even with an insufficient oxygen supply or acute hypoxia, doing cardio can improve cognitive performance.

Increased cerebral blood flow alone may not explain why aerobic exercise improves executive function.

Vitalii Petrenko/Shutterstock My neuroscientist father was always quick to admit that despite decades of brain research, he still didn’t really know how certain lifestyle choices and daily habits improved or diminished cognitive performance.

As a collegiate athlete, Dad learned anecdotally that exercise and a good night’s sleep helped him think better and facilitated peak performance on exams. But later, after graduating medical school, when he performed animal experiments designed to pinpoint how things like exercise and sleep influenced specific brain functions, his research often raised more new questions than it answered.

New human research ( Williams et al., 2023 ) on how moderate-intensity aerobic exercise and sleep deprivation affect cognitive performance answers a few questions but also casts doubt on a widely-held belief that increased oxygen levels in the prefrontal cortex during cardio is the prime driving force of exercise-induced improvements in executive function. This in-press Physiology & Behavior paper was made available online on November 17. 20 Minutes of Cardio Is Enough to Boost Cognitive Performance

This two-pronged study had participants perform cognitive tests that assessed various executive functions under different conditions, including not getting enough sleep and doing cardio in a hypoxic chamber with very little oxygen that mimicked high-altitude conditions.

As expected, exercise improved cognition in almost every situation. Interestingly, small doses (20 mins at moderate intensity) of aerobic exercise could compensate for lower scores on cognitive tasks due to lack of sleep.

Although increased oxygen in the prefrontal cortex was associated with better cognitive performance for most, even when people were experiencing acute hypoxia and their brain was starved of oxygen while doing moderate-intensity aerobic activity, many still did better on cognitive tasks than if they’d been sitting still. “Regardless of sleep or hypoxic status, executive functions are improved during an acute bout of moderate-intensity exercise,” the authors explain. Cerebral Oxygenation From Cardio Isn’t Needed to Boost Executive Functions

Much like a new discovery in my father’s lab often unearthed fresh unknowns, the latest (2023) study by Williams et al. shows that just 20 minutes of exercise can increase cognitive performance even after a poor night’s sleep but the research findings also suggest that increased cerebral oxygenation during cardio isn’t the only way exercise boosts brain power.

This hypoxia study adds to growing evidence suggesting that, contrary to popular belief, exercise-induced cortical oxygenation alone doesn’t explain why moderate-intensity aerobic activity enhances executive function.

“One potential hypothesis for why exercise improves cognitive performance is related to the increase in cerebral blood flow and oxygenation; however, our findings suggest that even when exercise is performed in an environment with low levels of oxygen, participants were still able to perform cognitive tasks better than when at rest in the same conditions,” Thomas Williams explained in a November 2023 news release .

In their recent paper, Williams and co-authors emphasize that although the prefrontal cortex (PFC) is often considered the primary brain region associated with executive function, solid cognitive performance isn’t solely dependent upon the PFC. Rather, they state that optimizing executive functions is “the product of a series of coordinated processes widely distributed across cortical and subcortical brain regions, interconnected through a series of complex neural networks.”

Even though hypoxia reduces prefrontal cortex oxygenation during aerobic activity, the researchers speculate that other brain regions may compensate when the frontal lobes aren’t getting enough oxygen. That said, neuroscientists aren’t exactly sure how different brain regions compensate for cortical deoxygenation when someone doing cardio experiences acute hypoxia.

Williams et al.’s latest findings dovetail with another recent human study ( Moriarity et al., 2019 ), which found that although moderate-intensity aerobic exercise increased prefrontal oxygenation, having more oxygen in cortical brain areas wasn’t necessarily associated with improved cognitive performance.

In fact, the researchers found that higher-intensity exercise (which delivered more oxygen to the brain’s frontal lobes) was associated with slower processing speeds and a reduction in fluid intelligence test scores. Cardio Strengthens Cerebro-Cerebellar Circuitry

The prefrontal cortex is located in the cerebrum’s frontal lobes. The cerebellum is tucked underneath the cerebrum. Cerebral means “relating to the cerebrum.” Cerebellar means “relating to the cerebellum.” Source: BlueRingMedia/Shutterstock

Other research on how exercise boosts brain power suggests moderate-to-vigorous physical activity (MVPA) improves functional connectivity between the frontal lobes and the cerebellum. Making neural circuitry between cortical and subcortical areas more robust may help the entire brain work in concert to coordinate thinking processes better.

Beyond cortical oxygenation, improved functional connectivity between the cerebellum and cerebrum may help explain how rhythmic aerobic exercise improves executive functions regardless of hypoxic status. (See ” Cerebro-Cerebellar Circuits Remind Us: To Know Is Not Enough “)

A few years ago, researchers ( Li et al., 2019 ) found that 30 minutes of aerobic exercise altered the role of the cerebellum’s right hemisphere when processing simple executive tasks. As Lin Li and co-authors explain, “It is plausible that acute exercise might alter the pattern of functional connectivity between cerebellar loops and cognition-related areas of the prefrontal cortex, and thereby further improve the performance of executive function after exercise.” Take-Home Message: More Research Needed

Until recently, it was widely believed that increased prefrontal cortex oxygenation was the primary way moderate-intensity aerobic activity improved cognitive performance. Mountains of evidence suggest that increasing oxygen to the frontal lobes via cardio boosts brain power. However, the latest (2023) findings also imply that cerebral oxygenation alone doesn’t explain why exercise improves executive functions.

More neuroscientific research is needed to identify all the exercise-related neural mechanisms—from prefrontal cortex oxygenation to improved cerebro-cerebellar functional connectivity—that may boost brain power. Hopefully, future studies will elucidate the role cortical and subcortical regions, such as the cerebellum, play in exercise-related upticks in cognitive performance.


Thomas B. Williams, Juan I. Badariotti, Jo Corbett, Matt Miller-Dicks, Emma Neupert, Terry McMorris, Soichi Ando, Matthew O. Parker, Richard C. Thelwell, Adam O. Causer, John S. Young, […]

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