Abstract
The present study was designed to evaluate the effect of time-of-day and racial variation on muscle power and fatigue during a 30-s Wingate test. In a randomized order, 36 footballers - 12 black Tunisians (BT), 12 white Tunisians (WT), and 12 South Africans (SA) were asked to perform a 30-s Wingate test during two experimental sessions, which were either at 08:00 or 17:00 h. At the beginning of each test session, resting core temperature was recorded. Peak (PP) and mean (MP) power as well as the fatigue index (FI) were calculated during the Wingate test. In all groups, core temperature, PP and MP were significantly higher (p < 0.001) in the afternoon than in the morning and considerably more so in SA than in WT and BT (p < 0.05). However, no major difference was observed between WT and BT in regards to all parameters. Also, FI was unaffected by either time-of-day or racial variation. Our results show that the diurnal variation of muscle power during the Wingate test can differ between races.