Mental Fatigue Impairs Physical Performance in Young Swimmers

Purpose: This study aimed to investigate the impact of mental fatigue on heart rate variability, subjective measures of fatigue, and swimming performance in young athletes. Methods: Sixteen swimmers [15.45 (0.51) y old, 7.35 (2.20) y of swimming experience] performed a 1500-m time trial on 2 occasions separated by an interval of at least 72 hours. The 1500-m swimming was preceded by a 30-minute treatment that consisted of performing the Stroop Color and Word test to induce mental fatigue (experimental trial) or watching an emotionally neutral video (control trial). Results: Participants reported higher ratings of mental fatigue and mental effort following the Stroop test when compared with the control trial, but no differences in motivation were observed. The induction of mental fatigue impaired swimming performance, as evidenced by a slower time (1.2%) to complete the 1500-m trial. No intertrial differences were identified for rating of perceived exertion during the swimming test or in heart rate variability after the Stroop and swimming tests. Conclusion: The results indicate that induction of mental fatigue impairs 1500-m swimming performance without changing heart rate variability.