Diurnal variations in physical performances related to football in young soccer players

This study investigated the effects of time-of-day on aerobic and anaerobic performances during the Yo-Yo, repeated sprint ability [RSA] and the Wingate tests in young soccer players. In a counterbalanced and a random order, twenty junior male soccer players completed the Yo-Yo, the RSA, and the Wingate tests at two different times-of-day: 07:00 and 17:00 h. During the Yo-Yo test, the total distance [TD] covered and the estimated maximal aerobic velocity [MAV] were determined. The peak power [PP] during each sprint, the percentage of decrement of PP [PD] and total work [Wtotal] during the RSA test were, also, measured. In addition, during the Wingate test, the peak [P[peak]] and mean [P[mean]] powers were recorded. During the Wingate test, P[peak] and P[mean] were significantly higher at 17:00 than 07:00 h [P<0.05] with diurnal gains of 3.1 +/- 3.6 and 2.9 +/- 3.5% respectively. During the RSA test, PP during the first two sprints, Pdec and Wtotal were, also, higher in the evening [P<0.05] with amplitudes of 4.8 +/- 4.6, 3.1 +/- 3.0, 13.1 +/- 32.1, and 4.1 +/- 2.5% respectively. Likewise, TD and MAV during the Yo-Yo test were higher at 17:00 than 07:00 h with diurnal gains of 13.1 +/- 10.7 and 4.2 +/- 3.3 respectively. The present study confirms the daily variations of both aerobic and anaerobic performances during the Yo-Yo, the RSA, and the Wingate tests in trained young Tunisian soccer players