Too much physical exertion appears to make the brain tired. That's the conclusion of a study of triathletes published Thursday in the journal Current Biology.
Researchers found that after several weeks of overtraining, athletes became more likely to choose immediate gratification over long-term rewards. At the same time, brain scans showed the athletes had decreased activity in an area of the brain involved in decision-making.
The finding could explain why some elite athletes see their performance decline when they work out too much — a phenomenon known as overtraining syndrome.