What Running Does to Your Brain (The Science Is Wild)

You’ve probably noticed it. You head out for a run feeling stressed, anxious, or just mentally foggy. Thirty minutes later, you’re calmer. Clearer. Maybe even a little euphoric.

That’s not just “blowing off steam.” Your brain is literally changing while you run. And the science behind it is fascinating.

The Runner’s High Is Real (But Not What You Think)

For decades, scientists credited the runner’s high to endorphins. It made a nice story. You run, your body releases these feel-good chemicals, you feel amazing. Simple.

Except it’s probably wrong.

Here’s the thing: endorphins can’t cross the blood-brain barrier. They’re too large and water-soluble to get from your bloodstream into your brain. So while endorphins might help with pain in your muscles and joints, they’re not what’s creating that blissful mental state.

The real culprits? Endocannabinoids. Your body’s own version of cannabis compounds.

When you run, your body produces molecules called anandamide and 2-AG. These are small, fat-soluble molecules that easily slip through the blood-brain barrier. Once there, they bind to the same receptors that THC targets. The result: reduced anxiety, elevated mood, and that floaty, everything-is-okay feeling runners chase.

A 2024 study measured endocannabinoid levels in runners before and after a 60-minute outdoor run. Both anandamide and 2-AG increased significantly. Mood improved across the board. And interestingly, women showed even higher increases in anandamide than men.

Not everyone experiences runner’s high, though. Research suggests only 69% to 77% of runners have felt it at least once. If you’ve never had that transcendent feeling mid-run, you’re not doing anything wrong. Brains just vary.

Running Might Work Better Than Antidepressants

This one surprised researchers too.

A 2023 study from Amsterdam compared running therapy to antidepressant medication for patients with depression and anxiety disorders. For 16 weeks, one group took SSRIs while the other did group running sessions at least twice a week.

The results? About 44% of both groups improved. Running worked just as well as medication for mental health symptoms.

But here’s where it gets interesting. The running group also saw improvements in weight, waist circumference, blood pressure, and heart health. The medication group? Their physical health markers actually got slightly worse.

And running isn’t just equal to medication in some studies. A systematic review examining 218 randomized trials found that exercise was 1.5 times more effective than psychotherapy or medication at reducing depression, anxiety, and psychological distress.

Walking and jogging specifically came out on top compared to other exercise types. Something about the rhythmic, repetitive nature of putting one foot in front of the other seems to be uniquely therapeutic.

Why does running help so much with anxiety? According to Harvard Health, just five minutes of aerobic exercise can start producing anti-anxiety effects. Running reduces tension, stabilizes mood, improves sleep, and boosts self-esteem. And unlike medication, the effects can be long-lasting even after you stop.

This doesn’t mean you should ditch your antidepressants for running shoes. If medication is working for you, keep taking it. But it does suggest that running has legitimate therapeutic value for mental health, not just as a supplement but as a primary intervention.

Running Literally Grows Your Brain

Your brain can grow new neurons. It’s called neurogenesis, and for a long time scientists thought it stopped in childhood. Turns out they were wrong.

The hippocampus (the part of your brain responsible for memory and learning) continues producing new brain cells throughout your life. And exercise, particularly running, dramatically increases this process.

When mice are given access to running wheels, they develop significantly more new neurons in the hippocampus than sedentary mice. We’re talking two to three times as many hippocampal neurons in rats that exercised for eight weeks.

But do these new neurons actually do anything? Yes. The same studies found that running improved learning capacity, enhanced memory, and strengthened synaptic plasticity (your brain’s ability to form new connections).

The mechanism involves a protein called BDNF (brain-derived neurotrophic factor). Think of BDNF as fertilizer for your brain. It helps neurons grow, survive, and form connections. Running significantly increases BDNF production, which then triggers the cascade of neurogenesis.

In humans, the evidence is just as compelling. A landmark 2011 study found that aerobic exercise increased hippocampal volume by 2% in older adults, effectively reversing age-related shrinkage by one to two years. Your brain’s memory center gets physically larger when you run regularly.

The scientific debate continues about exactly how many new neurons adult humans produce (estimates range from 700 to 1,500 per day in the hippocampus). But the evidence that running stimulates this process is consistent across dozens of studies.

How Much Running Do You Need?

You don’t need to run marathons to get brain benefits.

The anxiety-reducing effects kick in fast. Changes start happening within five minutes of aerobic exercise. A 30-minute run delivers substantial mood improvements that can last for hours.

The runner’s high requires a bit more effort. The 2024 study mentioned earlier used 60-minute runs, but other research suggests the endocannabinoid boost can happen with shorter sessions at moderate intensity. The key seems to be sustained aerobic effort rather than duration.

Long-term brain changes require consistency. The studies showing significant increases in brain cell growth used exercise programs lasting weeks to months. Regular runners showed stronger effects than occasional ones.

The good news? Regular runners also experience greater mood boosts from each run. Your brain essentially becomes more responsive to running’s benefits over time.

The Bottom Line

Running changes your brain in measurable, meaningful ways. It floods your system with endocannabinoids that reduce anxiety and boost mood. It works as well as (and possibly better than) medication for depression and anxiety. And it literally stimulates the growth of new brain cells.

The next time you finish a run feeling mentally sharper and emotionally lighter, know that it’s not your imagination. Your brain just did something remarkable.

And maybe that’s the best reason to lace up and get moving, even when you don’t feel like it. Especially when you don’t feel like it.