The influence of time of day on the performance of adolescent swimmers

ABSTRACT

The study aimed to investigate the effects of time-of-day, chronotype, and sex differences on the relationships between anxiety, depression, sleep quality, and swimming performance of normally diurnally active adolescent athletes. Thirty-three competitive swimmers, 20 boys (14.8 ± 1.60 y) and 13 girls (14.4 ± 1.51 y) from two different swimming centers participate in the study. They performed 50 m and 400 m front crawl trials twice, at 08:00 h and 18:00 h, with an interval of 48 h in a 50 m swimming pool. Chronotype, depression, anxiety levels, and sleep quality were accessed by questionnaires. No effect of time-of-day was observed in girls for the 50 and 400 m trials. The swimming performance of boys was similar in the 50 m trials independent of time-of-day, but in the 400 m trial the performance time was better in the evening compared to morning. The best evening performance was observed among N-types. Linear regression analysis of the data of all participants revealed a positive correlation between sleep quality and anxiety level (p = .016; R² = 0.1769) and sleep quality and depression level (p = .006; R² = 0.2192). There was no correlation between chronotype and sleep quality in either sex (p = .4044; R² = 0.0232). We conclude that time-of-day can influence the performance of adolescent swimmers that differs with the distance of the trial and by sex. We also demonstrated the importance of sleep quality among adolescents swimmers as a factor that can influence anxiety and depression and thus consequently affect their performance.

KEYWORDS:

• Swimming
• chronotype
• time-of-day
• exercise
• sex difference
• sleep
• anxiety and depression

Acknowledgements

We would like to thank all the coaches of the swimming teams that allow us to develop this research. We thank CAPES (Coordenação de Aperfeiçoamento de Pessoal de Nível Superior) for the Master scholarship of the first author and Catholic University of Brasília (UCB).

Disclosure statement

No potential conflicts of interest were reported by the author(s).

Additional information

Funding

This work was partially funded from CAPES (Coordenação de Aperfeiçoamento de Pessoal de Nível Superior) with a Master scholarship. All other financial expenses were supported by the authors.