Your Muscles Make Antidepressant-Like Chemicals When You Move

Your muscles are not just for moving your bones. According to Stanford psychologist Kelly McGonigal, they work like an internal pharmacy that manufactures helpful chemicals and releases them when you contract them.

Scientists once described muscle mainly as a way to move bones around and stabilize the skeleton, she says. Now researchers have learned that muscle makes chemicals that fight cancer cells, boost the immune system, support the heart, regulate blood sugar, and help build strength. Some of those chemicals also travel to the brain.

The process is simple. When you use your muscles, the contraction pushes these chemicals, which McGonigal calls hope molecules, into your bloodstream. They ride the circulation through the body to the brain, where they help with stress recovery, resilience, and motivation. McGonigal describes them as working like antidepressant molecules. That phrasing is her way of describing the research, not a tested finding that movement works the same way in people as prescribed antidepressants.

You do not need a strenuous workout to start the flow, and that is the point McGonigal wants people to hear. A walk around the block, lifting heavy things around the house, or a dance party in the living room all count. Your body does not grade on intensity, it reads any engagement as a sign that you are engaged with life and sends support to help you thrive. Less activity means less of the resource. As McGonigal puts it, "going from nothing to anything is the biggest step you can take."

The larger shift is seeing the body as an ally you can draw on. McGonigal says "every time you use your body to engage with life," you are tapping that pharmacy for what she calls "a little more courage, a little more resilience, a little more hope."