Why Exercise Works Like Therapy (And What Your Muscles Have to Do With It)

Along with a bit of social pressure, most people start to exercise to be healthier and look sexier. Of course, those exercise journeys usually begin with some dread and reluctance, but if you've embarked on this trip before, you know it gets to the point where it's not so bad.

After a few weeks, the benefits of this purposeful movement, which may start with shedding a few pounds, begin showing up in ways that most people don’t even realize.

One of the most important and underappreciated benefits is its impact on mental health.

Studies show that exercise may be just as effective in treating depression as medication, can help reduce anxiety symptoms, and may reduce reliance on alcohol or drugs in soldiers struggling with PTSD.

Many of these benefits are tied to inputs that influence our psychology. For example, boosting self-efficacy, instilling motivation, and the success of task completion all help flip certain switches in the brain that improve life satisfaction.

But exercise acts as more than just a therapist. Beyond the psychological effects, meaningful physiological changes occur when we move our bodies—changes that help us feel happier and less stressed.

Muscle Hormones

I got on this mental health investigation after listening to a podcast conversation between Rich Roll and health psychologist Kelly McGonigal.

In it, they referenced “hope molecules,” which I initially assumed was a marketing move because “happy molecules” wasn’t catchy enough. But when I looked at the research, I found that “hope” was actually the outcome measured in this specific exercise trial.

The original 2014 study aimed to examine peroxisome proliferator-activated receptor gamma coactivator 1-alpha, better known as PGC-1α.

Despite little mainstream discussion, PGC-1α plays a significant role in the body.

Wikipedia even notes that it “may have played a key role in differentiating humans from apes.” More relevant here, PGC-1α is found in muscle tissue and helps drive adaptations to aerobic exercise, while also influencing inflammation, energy metabolism, and cellular function.

Researchers found that mice genetically designed to produce more PGC-1α in their muscles were less affected by a forced swim test, which is commonly used to model depressive-like behavior. In contrast, mice with lower levels of skeletal PGC-1α gave up more quickly. Because of this, later interpretations of the research labeled PGC-1α as a “hope molecule.”

And this is only one mechanism in the complex interaction between muscles and the rest of the body. Other signaling proteins, known as myokines, further highlight how skeletal muscle communicates systemically.

The fascinating takeaway is that what we often think of as “just muscles”—tissue meant only for movement—also functions like an endocrine organ. In a sense, it sends signals to the brain that say, “Don’t worry, you’ve got this,” especially during times of stress.

Of course, mental health is complex, and a fitness plan alone won’t solve everything. In fact, depression and low motivation are often some of the biggest barriers to getting started.

But there’s a bit of optimism here: once you begin, the body is designed to adapt in ways that make it easier to keep going.