Prior self-control exertion and perceptions of pain and motivation during a physically effortful task.

Performing a task requiring self-control may impair performance on a subsequent physical task also requiring self-control. The mechanisms explaining why self-control is reduced following prior use currently remain unclear. This study, therefore, explored whether exerting self-control (a) reduces performance, (b) increases perceptions of pain, and (c) reduces motivation during a subsequent, unrelated physical task that requires self-control. In a within-subject design, 55 individuals completed an easy (congruent) Stroop task (no self-control) or a difficult (incongruent) Stroop task (self-control). Participants were then required to perform a lower limb endurance task (i.e., a "wall-sit") until volitional exhaustion and their perception of pain and motivation were recorded during the task. When participants completed the difficult Stroop task, wall-sit time to volitional exhaustion was reduced (133.33±70.28s) compared to when they completed the easy Stroop task (150.49±69.97s, P=0.04). Motivation during the early stages of the wall-sit task explained the reductions in performance (P<0.001). The results suggest that motivation to perform task goals may be an important explanatory mechanism behind performance decrements on physical tasks following the exertion of self-control.