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Circadian Rhythms and External Load Measures in Professional Soccer Players

Year: 2026

Type: article

Abstract: The aim of the present study was to examine the potential effects of circadian rhythmicity on specific external load metrics in professional male soccer players. Twenty players, members of a Greek Super League team, participated in the study. Data were collected from twenty match-day-minus-one (MD-1) training sessions, performed either in the morning (10:30 h, n = 10) or afternoon (15:00 h, n = 10). All sessions followed identical structure, volume, and intensity, ensuring internal validity. The external load metrics examined were total distance (TD), high-speed running (HSR; >19.8 km/h), high-intensity-acceleration count (HIACC; >3 m/s2), high-intensity-deceleration count (HIDEC; <−3 m/s2), and sprint distance (SD; >25.2 km/h). Statistical analysis was conducted using paired t-tests with Bonferroni correction for multiple comparisons (α = 0.01). Our results revealed significantly higher TD, HSR, HIACC, and HIDEC values (p < 0.01) during morning sessions compared to afternoon, suggesting a diurnal pattern favoring morning performance. No significant difference was found for SD (p > 0.01) despite the observed tendency for higher morning-values. These findings support the notion that time of day influences training output and that habitual morning training may lead to improved physical performance due to training-induced adaptations. Since in elite soccer even minor changes in performance could be decisive for the outcome of a competition, accounting for circadian factors in training planning could be crucial for competition performance.

Source: Applied Sciences

DOI: 10.3390/app16062742

Authors: Nikolaos E. Koundourakis, Minas-Panagiotis Ispirlidis, Adam L. Owen, Nikolaos Androulakis, Giorgos Pafis, Michalis Mitrotasios