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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.
Penna, Wanner, Campos, Quinan, Mendes, and Prado are with the Exercise Physiology Laboratory, School of Physical Education, Physiotherapy and Occupational Therapy, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil. Penna is also with the Universidade Federal do Pará-Campus Universitário de Castanhal, Castanhal, Brazil. Filho is with Social Interaction and Performance Science Laboratory, School of Psychology, University of Central Lancashire, Preston, United Kingdom. Mendes is also with the Universidade Federal do Maranhão, São Luiz, Brazil. Smith is with The University of Newcastle, Newcastle, Australia.