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The Fascinating Phenomenon That Is Your Brain on Exercise
Caitlin Carlson
April 15, 2026
Common knowledge: Exercise is good for you.
A little less common, but still pretty common: Exercise is good for your brain.
Not very common knowledge but should be: The cascade of beneficial effects in the brain when we exercise is remarkable — and understanding that might make people want those benefits.
That last bit is the important part, considering how difficult it is to ignite and maintain motivation in people (maybe even you) to exercise regularly.
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Article Key Points
Exercise significantly enhances brain health, improving cognitive function, mental health, and brain volume. It outperforms medications for depression and anxiety, with aerobic and resistance exercises boosting brain networks and chemicals linked to cognitive decline.
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We’ve come to understand the phenomenon as literal medicine. “The drugs that are out now for dementia, it’s not a magic cure, it’s not as good as exercise,” said Maria Fiatarone Singh, MD, a geriatrician and professor at The University of Sydney, Sydney, Australia. “Exercise trials that are robust tend to change those scores by at least twice as much as what you see from those anti-amyloid plaque drugs.”
Meanwhile, “nature’s antidepressant” continues to build its case. A 2023 review covering nearly 130,000 people published in the British Journal of Sports Medicine found that exercise was 1.5 times more effective than counselling and medications for treating certain mental health conditions. “Exercise is probably more powerful than drugs for the treatment of clinical depression and anxiety,” Singh said.
Those are specific maladies, but when it comes to the broader subject, exercise, cognitive health, and mental health appear to be inextricably linked: Brain volume, cognitive ability, neuroplasticity, neurogenesis, and more all seem to benefit from regular physical activity.
Helping patients understand just how vital exercise may be to their short- and long-term brain health could be the thing that gets them moving.
Exercise and Brain Volume
One of the first studies that looked at this connection landed in 2006. In the six-month randomized clinical trial of 59 older adults, researchers found that aerobic fitness led to significant increases in the volume of different regions of the brain, including white and grey matter. Importantly, these increases were not seen in the control group who did a stretching and toning routine (exercise intensity, as you’ll see, is a theme).
“We and others have found that exercise leads to increases in gray matter—meaning growth in neuronal cell bodies and supporting cells — as well as improvements in white matter integrity, the brain’s wiring system,” said Art Kramer, PhD, a psychology professor and former director of the Center for Cognitive and Brain Health at Northeastern University College of Science, Boston, who conducted the study. Since then, other studies have shown similar results.
Exercise and the Hippocampus
Other studies have looked specifically at the hippocampus, Singh said. The region that lies deep within the brain is responsible for supporting the formation of new memories, and it tends to shrink as we age. But it’s been shown to increase in volume with exercise, and there’s evidence that people who are very active have bigger brains relative to their head size than people who are physically inactive, Singh said.
Exercise also increases the connection between the hippocampus and other regions of the brain, including the prefrontal cortex and the posterior cingulate cortex which support numerous processes such as emotional control, attention, goal setting, and planning, said Kirk Erickson, PhD, a psychology professor in the Center for Neuroscience at the University of Pittsburgh, Pittsburgh.
Exercise Helps Different Brain Networks Communicate Better
In addition to brain structures, multiple neurologic networks, including the central executive network, the default mode network (DMN), and the salience network, show improved integrity and connectivity (how well they communicate with one another) when you exercise.
“Some of these circuits have to do with integrating information from the front of the brain to the back of the brain,” said Kramer. “They support executive control, multitasking, the ability to make rapid decisions, aspects of working memory as well as declarative memory, which helps you remember names, for example.”
Singh concurred, “Some studies, including ours, have shown that the improvements in cognitive function or performance are related to the improvements in these networks or these connections.”
In fact, a June 2025 study published in Brain Structure & Function found that people with higher cardiorespiratory fitness had stronger connections in these three key brain networks. That link between fitness and DMN connectivity was even stronger in people with more depressive symptoms, suggesting this brain network may play a role in how fitness relates to mental health in addition to brain health. This echoes earlier research from 2023 showing the DMN may be one way fitness supports mental health in midlife.
Exercise Regulates Brain Chemicals Linked to Cognitive Decline
Brain chemicals like brain derived neurotrophic factor (BDNF) and insulin-like growth factor (IGF) may also play a role, Kramer said. He’s currently working on a study looking at how exercise decreases beta-amyloid and tau, proteins that are predictors of Alzheimer’s disease risk. “This is pretty neat because drugs do that to a very limited extent, but with very serious side effects like bleeding in your brain,” he said.
Exercise intensity may count with BDNF. A small 2023 study in the Journal of Physiology found that short bursts of high-intensity exercise (six 40-second intervals at 100% VO2 max in the study) increased plasma and serum BDNF, as well as BDNF per-platelet ratio, four to five times more than light exercise.
“The problem is that BDNF is measured in the blood and where you’re looking for its activities is in the brain,” said Singh. “And if you’re not a rat, it’s pretty hard to sacrifice and see what’s happening in the brain.” Singh agreed BDNF and IGF appear to be important growth factors for neurons. But again, we measure them in the periphery. How well they relate to what’s going on in the brain is “not so clear,” she said. “Some studies that have shown that exercise improves peripherally derived or measured IGF one and after exercise. Therefore, it might be a pathway.”
Big Muscles = Big Brains?
“Most of the studies are on aerobic exercise because that’s what people have always thought is important traditionally,” Singh said. But there is growing interest and awareness for the effects of resistance exercise: Muscle matters.
“There seem to be some similarities between aerobic and resistance exercise on the brain and some differences in likely mechanisms,” Erickson said. “There’s a lot of work going on in this space so we’ll likely have more answers in the next few years.”
Initial research suggests that there’s a link between what exercise does to our muscles and what it does to our brains. Singh said there is now evidence of greater hippocampal volume in people with more muscle mass.
There’s more: In a study Singh coauthored in 2017, older adults with mild cognitive impairment who lifted weights for 6 months gained muscle strength which explained a large portion (64%) of the changes in cognition. In other words, those who saw the most muscle strength gains also saw the most cognitive gains. “It doesn’t mean that getting stronger makes you smarter, it just means that whatever it is that allows people to have a more robust anabolic adaptation in their muscles after weightlifting at a higher level, those are the people who get a better response in the function of the brain,” Singh said.
There’s also evidence, from Singh’s earlier research, that the posterior cingulate cortex gets larger after resistance training, which was associated with cognitive benefits (participants who did computerized cognitive training instead of exercise saw no benefits). Gray matter expanded and white matter hyperintensities reversed progression, signaling decreased cerebral vascular disease risk. What’s more, these effects persisted for at least 12 months after the study subjects stopped training, she said.
There’s more: While the hippocampus did not increase in size initially in this study, at 12 months the people who strength trained significantly attenuated and even reversed the hippocampal atrophy seen in those who did either gentle exercise or cognitive training. “So there was a delayed preservation or protection of the hippocampus, which was preceded by this initial change in a different area of the cortex,” she said.
How to Optimize the Brain-Exercise Connection
When it comes to exercise, the “optimal” dose depends on a few factors, including age and whether or not you have preexisting conditions. “In addition, the amount to move the needle for depressive symptoms might be different than the amount needed to enhance memory function,” Erickson said.
That said, the current physical activity recommendations to get a minimum of 150 min/wk of moderate intensity aerobic exercise is probably a good starting point. “Most of us researchers in this area believe that this is likely close to the target that most people should be aiming for in order to achieve some impact on both cognitive and mood outcomes,” Erickson said.
The guidelines also recommend at least 2 days of muscle strengthening activity per week, and Kramer said everyone should strive for that, including older adults so long as they’re cleared by their doctor. There’s also some evidence that other practices, like Tai Chi, could improve cognition. “But, honestly, more rigorous research is really needed to better understand this,” Erickson said of the “best” type and dose of exercise for brain and mental health. “We are getting closer to answering some of these key questions over the next few years.”
Singh reiterates that intensity appears to play a role, with higher intensities and doses likely leading to more benefits. Many of the studies, she said, use a control group that does “sham” or gentle exercise and is compared with a group that does more intense aerobic or resistance exercise — and it’s the latter groups that see the results.
This doesn’t necessarily mean embracing HIIT or lifting incredibly heavy weights, but it does suggest that very low-intensity efforts like stretching don’t affect your brain because they don’t change your aerobic capacity or your muscle strength, Singh said. “I think it’s pretty clear that the kind of exercise that gives you the best fitness outcomes is going to be the kind of exercise that gives you the best brain outcomes.”
