Effects of attentional focus and mental fatigue on performance and perceived exertion during exercise

Abstract

Mental fatigue impairs performance of physically-demanding tasks and increases rating of perceived exertion (RPE) while performing. However, there may be ways of overcoming such performance decrements. One possible method includes the use of attentionally focused instructions. Motor learning research has shown that externally focused instructions can lead to improved performance in comparison to internally focused instructions. The purpose of the present study was to investigate the moderating effect of attentional focus on the mental fatigue – endurance performance relationship as well as the mental fatigue – perceived exertion relationship. Undergraduate students (N = 78) completed two wall sit tasks to volitional failure, one before and one after the completion of a cognitive task. Half the participants were randomly assigned to complete a high cognitive demand task to induce mental fatigue (incongruent Stroop; HMF), while the other half performed a low cognitive demand task (documentary viewing; LMF) before the second wall sit. Immediately prior to the second wall sit, half the participants in each cognitive task group also received instructions to focus their attention either internally (INT) or externally (EXT) during the second wall sit. The main effect of mental fatigue (p < .001, d = .873) during the cognitive task and the main effect of attentional focus (p < .001, d = .883) during the wall sit task were significant, indicating effective manipulations. Results found no moderating effect of attentional focus on wall sit performance (p >.500) or RPE (p = .724). However, between-group analyses were conducted to probe the differences in performance between each group. Results indicated the HMF/INT group performed significantly worse than the LMF/EXT (p = .032) and trended towards performing worse than the HMF/EXT and LMF/INT groups (ps < .090). Significant differences in RPE were also seen between trials for the HMF/INT group (p = .009, d = .592) alone, suggesting detrimental effects of both mental fatigue and internal focus combined. Overall, the data indicate a potential moderating effect of internal attentional focus that may exacerbate the detrimental effects of mental fatigue on performance and RPE.