Too much exercise could be a bad thing, especially for your brain, according to a new study.
Researchers compared brain MRIs from athletes who trained moderately, to athletes who over-trained.
The small study showed the athletes who over-trained displayed more fatigue in the cognitive control part of the brain system.
Health experts say too much exercise can tire out the brain to the point that where you may have trouble making decisions.
Too much exercise can dull the brain, study says