A study by researchers at Emory University in the US has shown how exercise can strengthen the brain's resilience to stress through a protein called galanin.

The research team studied two groups – one which regularly exercised and another which didn't. They then measured anxious behavior in the test subjects 24 hours after an artificially created stressful event.

Those who exercised showed less anxious behavior after the stressful event compared to those that didn't exercise.

The exercise group also had elevated galanin levels in the locus coeruleus (LC), a cluster of neurons in the brainstem involved in the stress response.

Crucially, the amount of time spent exercising correlated with the amount of galanin in the LC, which in turn correlated with the degree of stress resilience.

"The neuropeptide galanin has been implicated in stress-related neuropsychiatric disorders in humans," the study reads.

"While pharmacological treatments for these disorders are ineffective for many individuals, physical activity is beneficial for stress-related symptoms.

"Galanin is highly expressed in the noradrenergic system, particularly the locus coeruleus (LC), which is dysregulated in stress-related disorders and activated by exercise.

"Galanin expression is elevated in the LC by chronic exercise, and blockade of galanin transmission attenuates exercise-induced stress resilience."

According to the study authors, the findings could help understand the link between working out and relieving stress – which, apart from a plethora of anecdotal evidence, isn't well understood by scientists.

"Increased physical activity is associated with stress resilience in humans, but the neurobiological mechanisms underlying this effect are not clear," the study authors say.

"This study shows that genetic overexpression of galanin in noradrenergic neurons causes resilience to a stressor and the anxiogenic effects of optogenetic LC activation.

"These findings support a role for chronically increased noradrenergic galanin in mediating resilience to stress."

• The study, titled Chronic environmental or genetic elevation of galanin in noradrenergic neurons confers stress resilience, was published in the Journal of Neuroscience. To read more, click here for the full paper.