Over-Exercising Has An Unexpected Effect On Your Brain

It's no secret that exercise boosts brain power. According to the U.S. Centers for Disease Control and Prevention (CDC), putting in 2.5 hours of moderate-intensity exercise or 75 minutes of high-intensity exercise each week can enhance memory, protect against cognitive decline, and make us more effective learners and problem-solvers. Bring on the workouts!

However, there's a fine line between regular exercise and too much exercise. In fact, continuously pushing our body too hard can put one at risk for what's known as overtraining syndrome, according to researchers from a 2019 study published in the scientific journal Current Biology. Often seen in professional athletes at the top of their game, the condition is characterized by excessive fatigue that results in reduced performance. While it's easy to assume that the more, the merrier, overdoing it on physical activity not only makes us more susceptible to injury, but it may potentially backfire when it comes to our brain health, too.

Over-exercising may diminish cognitive control

In the 2019 study, researchers set out to see if over-exercising could exhaust our brain as well as our body (via Science Daily). The study involved more than 30 professional male endurance athletes. Over the course of three weeks, one group of men maintained their current level of training, while another group boosted their training activity by 40%.

Using exercise tests, questionnaire data, behavioral exams, and brain-imaging technology, the study findings revealed a link between overtraining and mental fatigue. This was evidenced by reduced brain activity seen in the lateral prefrontal cortex, an area of the brain that plays a role in decision-making and cognitive control. Further reinforcing this notion were the results of standardized tests, which showed that participants who had increased their physical activity levels throughout the study were more likely to select tasks with a more immediate payoff than those that would require more time and effort.

Overtraining may slow cognitive reaction time

Similar results were found in a 2023 systematic review published in Sports Medicine – Open, in which researchers looked at findings from seven different studies related to athlete overtraining and cognitive function. While many different means of data collection were used across the studies, one method, the Stroop color word test, showed that athletes who were diagnosed with functional overreaching (FOR), a short-term dip in athletic performance stemming from increased training intensity, took longer to complete the cognitive tasks. This included reading the name of a color that had been written out in front of them or naming the color in which that word was written, such as the word "green" written in red ink.

In light of these findings, the research team emphasized that overtraining can pose health risks to athletes if they are not afforded proper recovery time. In more severe cases, this may lead to the previously mentioned overtraining syndrome, which may take as long as years to recover from. Therefore, it's important for sports staff to keep an eye out for early signs of overtraining to prevent the condition from worsening.