Too Much Exercise Can Tire Our Brains Out, Too (Discover Magazine D‑brief):
“For years, the National Institute of Sports, Exercise and Performance (INSEP) in France had been studying an unusual phenomenon. If an athlete’s workout regiments were ramped up, it didn’t always lead to a better performance — even if that athlete felt like they were working harder than before.
The organization called this phenomenon overreaching, and knew what the physical symptoms were. But the organization wanted to know if any symptoms of fatigue were appearing in the brain, too. New research says yes. Too-intense workouts can make athletes more impulsive, according to a study published today in Current Biology … This insight is relevant even for people who don’t work out for a living, he says. Not only does the research indicate it’s best to avoid difficult decisions after particularly strenuous workouts, but “if you’re working out hard and start feeling exhausted, annoyed, or are more impulsive, you could be on the path to overtraining,” he says.
- Summary: Overtraining syndrome is a form of burnout, defined in endurance athletes by unexplained performance drop associated with intense fatigue sensation. Our working hypothesis is that the form of fatigue resulting from physical training overload might share some neural underpinnings with the form of fatigue observed after prolonged intellectual work, which was previously shown to affect the cognitive control brain system. Indeed, cognitive control may be required to prevent any impulsive behavior, including stopping physical effort when it hurts, despite the long-term goal of improving performance through intense training. To test this hypothesis, we induced a mild form of overtraining in a group of endurance athletes, which we compared to a group of normally trained athletes on behavioral tasks performed during fMRI scanning. At the behavioral level, training overload enhanced impulsivity in economic choice, which was captured by a bias favoring immediate over delayed rewards in our computational model. At the neural level, training overload resulted in diminished activation of the lateral prefrontal cortex, a key region of the cognitive control system, during economic choice. Our results therefore provide causal evidence for a functional link between enduring physical exercise and exerting cognitive control. Besides, the concept of cognitive control fatigue bridges the functional consequences of excessive physical training and intellectual work into a single neuro-computational mechanism, which might contribute to other clinical forms of burnout syndromes.