Effect of diurnal variations on cognitive and physical performance among female athletes

Objective: humans' circadian rhythm is an important parameter in understanding current biological, physiological, and psychological status, which broadly affects physical fitness. The physiological mechanisms underlying circadian rhythms remain underexplored despite their potential impact on physical and mental health. The study aims to examine the effect of diurnal variations on cognitive and physical performance in female athletes. Methodology: a counterbalanced within-subjects repeated measures design was employed, involving 15 healthy female university students aged 18 to 25. Each participant underwent cognitive and physical performance tests at three distinct times—6 AM, 12 PM, and 6 PM—on separate days. Results: the study demonstrated a significant effect of diurnal variations on cognitive and physical performance indices. Discussion: cognitive performance showed varied patterns across time points. Perceptual reasoning, measured by the Müller-Lyer test, peaked in the morning and was lowest in the evening. Working memory, assessed via the span digit test, showed moderate values at noon and evening. Strength, measured by the vertical jump, was highest in the evening and lowest in the morning. As assessed by the Illinois Agility Test, agility peaked at noon, with the lowest values recorded in the morning. Conclusions: time of day significantly affects both cognitive and physical performance in female athletes. Strength peaks in the evening, agility at noon, and perceptual reasoning in the morning, while working memory shows moderate performance at noon and evening. These results suggest that athletes and coaches can optimize training and competition schedules based on diurnal cognitive and physical performance variations.