TOO MUCH EXERCISE MAY AFFECT OUR ABILITY TO MAKE DECISIONS

A new study finds that exercise not only

causes muscle fatigue but could also

affect the brain. The authors conclude

that overexercising might reduce our

capacity to make decisions.

A recent study concludes that intensive exercise

may affect cognitive abilities.

Researchers at Hôpital de la Pitié-Salpêtrière in

Paris, France, have found that overtraining syndrome

may affect the brain, as well as the rest of the

body.

Overtraining syndrome is a form of burnout in

endurance athletes. It occurs as a result of intensive

physical training overload.

The authors believe that this form of fatigue may

involve some of the same neural circuitry as the

fatigue that follows intensive intellectual work.

Scientists have already found that fatigue following

excessive mental effort 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.

Inducing 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 arises

in part from neural fatigue in the brain, as well as

from muscle tiredness.

They were also interested in whether the overtraining

affected the same portion of the brain as excessive

intellectual work.

The group recruited 37 competitive male endurance

athletes with an average age of 35 years. The

participants either continued with their regular

exercise regimen or increased their training by 40%

per session over 3 weeks.

The athletes participated in cycling exercises on

their rest days so that the researchers could

monitor their physical performance.

 They also

completed questionnaires that asked them about

their subjective experience of fatigue.

Finally, the researchers used behavioral tests and

MRI scans to assess the participants' cognitive

ability.

Assessing the effect

The study, which features in Current Biology , showed

that over 3 weeks, physical training overload led to

the athletes feeling more fatigued and also

behaving differently.

In tests that evaluated economic choices, the

fatigued athletes were more likely to act

impulsively.

MRI scans showed that physically overloading the

athletes resulted in impaired activation of the lateral

prefrontal cortex. This area of the brain is

responsible for higher order cognitive control;

 it

influences decision-making, planning, behavioral

inhibition, and motivational operations, among other

behaviors.