Effect Of Strenuous Exercise On Cognitive Control Efficiency

Abstract

During exercise, optimal performance depends on the subject’s ability to simultaneously deal with cognitive and physical demands. Cognitive efficiency is best measured by complex decision making-tasks, such as Simon task. Subjects are requested to press either a left- or right-hand button according to the color of a visual stimulus presented either to the left or to the right of a fixation point. Performance is measured in term of mean reaction time (RT) and error rate (ER). It was classically observed that RT for ipsilateral stimulus-response associations (i.e. congruent trial, CO) was shorter than RT for contralateral stimulus-responses associations (i.e. incongruent trial, IN). This result is explained by the dual-route model of information processing. In this model, the side of the stimulus triggers an automatic and rapid response impulse whereas the color of the stimulus triggers a slower and deliberately controlled response. In IN associations, both responses are in conflict. PURPOSE: to assess the effects of strenuous exercise on cognitive control efficiency and error monitoring. METHODS: 16 healthy subjects (30.6±8.6y, 11 males, mean VO2max 47.3±7.8 ml/kg/min) performed a Simon task while cycling 25 min at rest (15W) or above the first ventilator threshold +5%. Partial errors (PE), which are suppressed incorrect action impulses before they result in an overt error, were recorded by EMG of the response effectors. Correction rate (CR) was calculated by dividing the number of PE by the number of incorrect activations (IA, partial errors plus errors). RESULTS: exercise was associated with shorter RT, higher ER and lower CR in IN and CO associations. Lower IA was observed in CO associations only. For the shortest trials, ER was higher for IN associations whatever the condition (i.e. exercise versus control). CONCLUSION: this study demonstrated that the ability to detect and correct IA was impaired by strenuous exercise for CO situations. Strenuous exercise reduced the occurrence of fast-guesses, the net behavioral result being reflected in an increase in error commission for IN associations.