Perceived fatigue does not alter effort-based decision making but does undermine confidence in the ability to perform physical actions

Abstract

Introduction: Protracted physical exertion leads to the development of fatigue. The development of fatigue has previously been associated with increased effort costs, influencing decisions to engage in further physical activity. However, whether fatigue-associated changes to effort-based decisions are reflective of a global aversion to effort in response to fatiguing physical exertion, affecting the decision to engage in physical action performed in other parts of the body, is unclear. Methods: To investigate this, we tested whether effort-based choice behaviour was altered by fatigue, pre-induced through physical exertion of a different body part. Twenty-two healthy male participants made a series of choices between two rewarded actions, which varied in both the level of effort required (relative duration of a submaximal contraction of the dominant knee extensors) and reward obtained (monetary incentives). Participants made their choice under two conditions: 1) a pre-induced state of fatigue and 2) a rested (control) state. Results: Across conditions, participants’ choice behaviour demonstrated the anticipated aversion to effort that interacted with the level of reward on offer. However, though prior physical exertion increased the perception of fatigue, prolonged choice selection-time and reduced self-reported confidence in ability to perform chosen effort-demanding actions, participants choice behaviour did not significantly differ between the two conditions. Conclusions:. The findings suggest that a subjective state of fatigue does not increase the general cost of exerting effort across the body but does increase uncertainty within decision-making processes which may alter evaluative processes that precede changes in cost/benefit computations.