A team of researchers from the Hospital de la Pitié-Salpêtrière in Paris (France) state in their study published in the journal Current Biology, that overtraining syndrome (or burnout ), which is a form of exhaustion in athletes who perform exercise exercises resistance and overloading your body with intensive physical training, can affect the brain and the rest of the body.
The authors believe that some of the neural circuits associated with intensive intellectual work may be involved in this form of fatigue.
Previous studies have already put on the table that fatigue after excessive mental exertion can affect cognitive control. Cognitive control, sometimes called executive control, refers to a person’s ability to change their behavior and thought processes to achieve their goals.
Exercise overload
A physical training overload leads to a significant drop in physical performance as athletes experience an overwhelming sense of fatigue. The researchers wanted to test whether overtraining syndrome arose as part of neural fatigue in the brain, as well as muscle fatigue. They were also interested in whether overtraining affected the same portion of the brain as overwork.
The scientists counted 37 competitive male endurance athletes with an average age of 35 years. Participants continued their regular exercise regimen or increased their training by 40% per session for 3 weeks. The athletes participated in cycling exercises on their rest days so the researchers could monitor their physical performance. They also completed questionnaires about their subjective experience of fatigue. Finally, the researchers used behavioral tests and MRIs to assess the participants’ cognitive ability.
Evaluating the effect
The study showed that over 3 weeks, physical training overload made athletes feel more tired and behave differently.
In tests that evaluated economic options, fatigued athletes were more likely to act impulsively.
Magnetic resonance imaging showed that the physical overload of the athletes led to impaired activation of the lateral prefrontal cortex (area of the brain responsible for higher-order cognitive control (influencing decision-making, planning, inhibition of behavior or motivation, among other things).
Motivational ability is particularly interesting because it defines how the brain processes reward information. The findings of this study show that athletes who experienced physical overload were more likely to act impulsively than those who did not overtrain. Specifically, they opted for immediate rewards rather than rewards that were more meaningful but would take longer to achieve.
The authors explain that although resistance training is generally good for your health, in some cases it could have an unexpected effect on the brain. This study is the first to show that physical training can also induce cognitive fatigue.
Same place in the brain
The authors were particularly impressed by the fact that both physical overload and excessive intellectual work affect the same area of the brain.
“This brain region, therefore, appeared as the weak point of the brain network responsible for cognitive control. It is necessary to control the automatic process that makes you stop when muscles or joints hurt”, comments Mathias Pessiglione, leader of the work .
Limitations
The study had a fairly small sample, only 37 participants, so experts will need to conduct more experiments using larger cohorts to assess whether this is a genuine effect. Furthermore, because the scientists only recruited people who were physically fit, it is unclear whether people at other fitness levels might also experience this effect on decision-making.
Referencia: Neuro-computational Impact of Physical Training Overload on Economic Decision-Making. 2019 Current Biology. Bastien Blain, Cyril Schmit, Anaël Aubry, Christophe Hausswirth, Yann Le Meur,, Mathias Pessiglione. DOI :https://doi.org/10.1016/j.cub.2019.08.054
