Excessive physical exertion may affect not only muscles but also chemical processes in the brain. Brazilian researchers found that intense training without sufficient recovery can disrupt dopamine regulation. This neurotransmitter plays an important role in motivation and wakefulness. The findings were published in the journal Neuroscience.
The researchers studied mice divided into two groups. One group ran on a treadmill until complete exhaustion, while the other followed an intensive eight-week program designed to mimic the training routines of professional athletes with overtraining syndrome. By the end of the experiment, the mice were training twice a day, with only four hours of rest between sessions.
The researchers found that animals in the second group continued to have elevated dopamine levels in the hippocampus—a brain region involved in memory formation and emotional regulation—even 48 hours after physical exertion. The level of an enzyme responsible for producing this neurotransmitter also increased. However, no significant changes in serotonin levels were observed.
According to the authors, similar disruptions in humans could be associated with anxiety, insomnia and chronic fatigue, which often accompany overtraining. However, this remains a hypothesis: the study was conducted in mice, and the researchers did not directly examine how changes in dopamine affect sleep or emotional well-being in humans.
The authors emphasize that physical activity is beneficial to the body, but inadequate recovery between intense sessions may have the opposite effect, leading to poorer well-being and reduced athletic performance.
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