A mental fatiguing computer task of 90 minutes has a negative impact on the running performance. Researchers show that the times at 3000 meters deteriorate by 13 seconds after performing a computer task.


Mental or cognitive fatigue is defined as a subjective state in which cognitive performance is reduced with also changes in mood and feelings of sleepiness.


Cognitive skills or abilities are related to the extent in which you are able to absorb knowledge and information and process it. When processing information all kinds of mental processes play a role. You need your memory but also language, orientation, attention, alertness and ability to solve problems, to form concepts and can visualize things. Furthermore, reasoning, mathematics, reading and writing, making plans and taking initiatives are cognitive functions. So you use your cognitive abilities constantly.

Cognitive functions are related to what we call “intelligence.” You develop your cognitive functions as a child. Parents, family, surroundings and especially the school also play an important role. Cognitive functions are genetically determined. How well you develop these functions has to do with the environment in which you grew up.

Physical and mental activation take place through the same neural networks. That could explain why mental fatigue affects sporting performance. To examine the influence of mental fatigue on the sport performance of runners  runners were examined that were made mentally fatigued  with the aid of a computer program.


Twenty recreational runners have alternately made a mental fatigue task or, as a control, watched a documentary prior to a 3000 m running test. Both of these conditions lasted 90 minutes. The 3000 m running testing was done on a 200 meter indoor track.

In the control situation the average of this run is faster than after the mental task: 11:59 against 12:12. The heart rate, rate of exhaustion and lactic acid did not differ between the two situations.


This examination has shown that a fatiguing mental, cognitive task in this case, has a negative impact on performance. It is therefore recommended not  to do strenuous  brainwork prior to a race, like homework.