Running and Mental Health: Beyond the Endorphin Rush

“I run for my head, not for my legs.” You've probably heard that in your running group, right? And honestly, it's so true. Science increasingly confirms it: running is one of the best tools we have for mental well-being. But—and here's where it gets complicated—like any powerful tool, it can also become a trap. Behind the image of the zen and fulfilled runner, there can sometimes be addiction, avoidance, or unhealthy coping mechanisms. It's worth discussing.

The Runner's High: It's More Than Endorphins

For years, we all believed the “runner's high”—that feeling of euphoria after a good run—was solely due to endorphins. It's a nice thought, but from what I've read, recent research has largely challenged that notion.

In fact, endorphins are large molecules that struggle to cross the blood-brain barrier. While they certainly help reduce muscle pain, the euphoric sensation itself is more complex. Researchers (notably Johannes Fuss's team in Hamburg, around 2015) have identified another key player: the endocannabinoid system.

Anandamide is an endocannabinoid your body produces during sustained effort. It's a small molecule that easily crosses into the brain and binds to the same receptors (CB1) as THC from cannabis. The result: feelings of well-being, reduced anxiety, and altered perception of time. And guess what? Anandamide levels skyrocket after 30 to 45 minutes of moderate-pace running—exactly when you might start feeling that blissful float.

Now, this doesn't mean endorphins are useless; it's likely a mix of dopamine, serotonin, and BDNF (Brain-Derived Neurotrophic Factor) at play. But the famous “endorphin rush,” personally, I think it's too simplistic a shortcut compared to what's truly happening in your brain when you run.

A Natural Anxiety Reliever

Beyond the runner's high, the most proven effect of running on your mind is anxiety reduction. And this happens through several mechanisms:

• Cortisol Regulation: when you run regularly, your resting cortisol levels (the stress hormone) decrease, and your body becomes better at handling stressful situations.
• Controlled Stress: running is a stressor you voluntarily choose. Over time, your body learns to better manage stress in general—a bit like desensitization.
• Moving Meditation: the repetitive stride, the rhythmic breathing, focusing on your sensations… this creates a state of spontaneous mindfulness. Personally, it's when I disconnect best.
• Goodbye Rumination: it's hard to dwell on your worries when your body demands your full attention. Running forces you to disengage, and even if temporary, it breaks the cycle of anxious thoughts.

A major meta-analysis in the British Journal of Sports Medicine in 2023 showed that aerobic exercise—including running—is at least as effective as conventional antidepressants (SSRIs) for moderate anxiety. Caveat: this doesn't mean you should toss your meds for running shoes, but it highlights just how powerful a tool running can be.

Running and Depression: What the Studies Say

The link between running and depression is one of the most studied topics. And the results are quite encouraging: regular running reduces depressive symptoms, boosts self-esteem, and strengthens the feeling of “I am capable of doing difficult things.”

One of the key mechanisms is the production of BDNF—a protein that stimulates the creation of new neurons in the hippocampus, a brain area linked to mood (and often shrunk in people with depression). Essentially, running helps to “rebuild” this area. Pretty wild when you think about it.

But let's be honest. Severe depression is a serious illness, and it's not solved just by going for a run. Anhedonia—that loss of pleasure accompanying depression—makes starting physical activity incredibly difficult. Telling someone in the midst of a depressive episode “go for a run, you'll feel better” is both simplistic and can induce guilt. My take: running is a great complement, but not a standalone treatment.

The Darker Side: Addiction and Bigorexia

While running can be beneficial, it can also become a prison. Running addiction is a real thing: you can't slow down despite injuries, your relationships suffer, you're constantly exhausted… but you keep going.

Warning signs, according to my readings:

• You run despite an injury, telling yourself, “Oh well, it's not that bad.”
• You become anxious or irritable if you miss a session (due to rain, family dinner, fatigue).
• You constantly increase your mileage/volume to achieve the same mental effect—just like with an addictive substance.
• You organize your entire social and family life around your training.

Bigorexia is a more specific form: you never feel trained enough, light enough, or fast enough. You run more and more, eat less and less, and your pursuit of performance becomes an obsession that consumes you instead of enriching you.

The trap is that society applauds athletic discipline. A runner who trains twice a day is admired, not questioned. The line between healthy passion and compulsive behavior is often invisible—even to yourself.

Running as Therapy: Framework and Limits

Some mental health professionals are now integrating running into their protocols, under the name of exercise therapy. And that's great, but the framework matters: we don't just say “run 5 times a week.” We guide the patient through a progressive and adapted practice.

The benefits extend beyond brain chemistry: running provides structure to your week (sessions give it rhythm), a sense of accomplishment (each outing is a small victory), and social connection (running in a group, signing up for a race). For people experiencing isolation or a loss of purpose, these “side” aspects can sometimes be as important as the biological effects.

The limitation is access: when you're dealing with deep depression, financial struggles, or physical limitations, running isn't always possible. And that's okay—walking, yoga, swimming, or simply getting out of the house can provide comparable benefits at a lower intensity.