Excessive physical exertion may affect not only muscles but also chemical processes in the brain. This is the conclusion of Brazilian researchers, who found that intense exercise without sufficient rest can disrupt the regulation of dopamine, a neurotransmitter associated with 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 training program designed to mimic the routines of professional athletes with overtraining syndrome. By the end of the experiment, the mice were exercising 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 excessive training. 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 without adequate recovery, intense exercise can have the opposite effect, leading to poorer well-being and reduced athletic performance.
Follow NEWS.am Medicine on Facebook and Twitter