Prolonged cognitive activity increases perception of fatigue but does not influence perception of effort, affective valence, or performance during subsequent isometric endurance exercise.

Performance of a cognitively demanding task has previously been reported to impair subsequent physical endurance performance, an effect attributed to sensory processes influencing the perceived effort required to maintain performance. However, there is uncertainty regarding the robustness of these performance effects and their putative mechanisms. The present study examined two hypotheses: (1) that prior cognitive activity impairs subsequent physical endurance performance and (2) that the perception of fatigue arising from sustained cognitive performance is associated with the level of effort and affective valence reported during a subsequent physical endurance task. Eighteen participants completed a high (HIGH; a modified version of the Stroop task) and low (LOW; watching a documentary) cognitively demanding task before performing an exhaustive, submaximal (20% maximal voluntary contraction, MVC) isometric contraction of the right knee extensor muscles. The perception of fatigue was elevated and cognitive task accuracy reduced in the HIGH condition. However, physical endurance performance, perception of effort and affective valence reported during the physical endurance task were not affected. In the HIGH condition, the perception of effort and affect were related to endurance time, while significant correlations were found between perceptions of fatigue and both perceived effort and affective valence when assessed across both conditions. The findings indicate that performing a demanding cognitive task does not impair subsequent physical endurance performance nor influence perceived effort and affective valence during a submaximal isometric contraction performed to task failure. The observed relationships offer some support to the idea that fatigue perception may influence affective valence and effort perception.