In a growingly inactive society, where the average American takes less than 5,000 steps a day, the likely answer would be to blame technology. But a less largely talked about reason is stress. Just like drugs or mental illness, chronic stress can actually alter your brain's dopaminergic systems, making things that were once enjoyable and would release dopamine like exercise, overall less enjoyable to do. Less physical activity has been mentioned to contribute to higher stress levels, in turn creating an endless cycle of stress.
I recently attended a seminar done by Dr. Buhr at Loyola University of Chicago. He investigates the neurobiology of stress exposure and exercise. Dr. Buhr mentioned that there is a link between experiencing high levels of psychological trauma and stress, and lack of exercise. Exercise is important not only for our physical health but also for our mental and emotional health, so if repeated trauma and stress leads to less physical activity, this can be a massive problem. Dr. Buhr’s study worked with mice; he had two groups, an experimental group and a control group. The experimental group received either 50 shocks or 100 shocks, and after 48 hours a wheel was given to the mice. The control group received no shock and had the same access to a running wheel. He found that the mice that received no shocks ran up to 4x more kilometers when compared to the mice that received any type of shock, with the mice that got 100 shocks running less than the 50 shock mice. This part of his study highlights how even acute stress like tail shocks can lead to lessened motivation to exercise. This is especially shocking for mice because it is mentioned that mice genuinely enjoy running and do it for pure enjoyment. So, if these shocks lead to voluntarily choosing to not do something they used to enjoy, it illustrates that this stress may have affected their brain and how it interprets enjoyable things.
Dr. Buhr had a second part to his study where he found out that this amount of stress also affects different brain regions and amounts of neurochemicals released, specifically dopamine. It was found that stress can have inhibitory effects on the dopaminergic system, affecting both the release of dopamine as well as the dopamine response. This could explain why the mice who received the shock no longer enjoyed running, because it didn’t elicit the same neurochemical response in their brain. Dr. Buhr’s study on mice and learning about their inherent love for running made me think about the term “runners high.” Which is defined as “a short-lasting euphoric state following intense exercise.” This positive feeling of euphoria is highly connected to better mood and well-being as well as helps with anxiety, stress, and depression. The finding from Buhr’s study connects to an article I found from Hopkins Medicine called “The Truth Behind ‘Runner’s High’ and Other Mental Health Benefits of Running” because both mention the neurochemicals involved in running and its correlation to stress relief. It mentioned in the article that endocannabinoids are highly associated with this runners high, and these endocannabinoids are what signal for dopamine to be released because they are able to get past the blood-brain barrier and directly affect brain chemistry. If our dopaminergic system has been negatively impacted by stress, like the mice’s were in Dr. Buhr’s study, then this euphoric feeling from running and intense exercise is no longer reachable, and leads to overall less motivation to exercise.
To tie this article back into the study done by Dr. Buhr, there is a high correlation between physical activity and well-being and motivation, so when there is something that causes that disconnect, like prolonged chronic stress, it can be detrimental to the person's (or mice’s) mental health, leading to an endless cycle of stress and depression. With stress comes less exercise and then with less exercise comes feeling worse mentally and physically. It is a never ending cycle that many people have fallen into. While Buhr focuses on acute stress and its relation to physical activity and dopamine systems, the article by Hopkins Medicine highlights the importance of exercise in relation to mental health and happiness. Overall, I believe that this study and news article by Hopkins Medicine provide critical information about how important physical activity is for us, and when there is something impacting our motivation for activity, like the altering of the dopaminergic systems due to stress, it needs to be fixed.
References
Buhr, T. J., Reed, C. H., Wee, O. M., Lee, J. H., Yuan, L.-L., Fleshner, M., Valentine, R. J., & Clark, P. J. (2023). The persistence of stress-induced physical inactivity in rats: An investigation of central monoamine neurotransmitters and skeletal muscle oxidative stress. Frontiers in Behavioral Neuroscience, 17. https://doi.org/10.3389/fnbeh.2023.1169151
Mice really do like to run in wheels | science news. (2019, August 9). Science News. https://www.sciencenews.org/blog/wild-things/mice-really-do-run-wheels
The truth behind ‘runner’s high’ and other mental benefits of running. (2026, July 13). HopkinsMedicine. https://www.hopkinsmedicine.org/health/expert-qa/the-truth-behind-runners-high-and-other-mental-benefits-of-running
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