High Intensity Exercise Affects Diurnal Variation of Some Biological Markers in Trained Subjects

The study investigated if markers of muscle injury and antioxidant status were affected by a Wingate test performed at 2 different times of day. 15 young male footballers performed 2 tests (randomized) at 07:00-h and 17:00-h. Fasting blood samples were collected before and 3 min after each test for assessment of markers of muscle injury and antioxidant status. Resting oral temperature was recorded during each session. Peak power (10.76±1.05 vs. 11.15±0.83 W.kg − 1) and fatigue index (0.41±0.04 vs. 0.49±0.13%) during the Wingate test, and core temperature, were significantly higher (all p − 1, respectively, for creatine kinase; both p − 1 for total antioxidant status; p<0.05). The results indicate that muscle injury and antioxidant activity after the Wingate test were higher in the evening, suggesting a possible link between the biochemical measures and the diurnal fluctuation of anaerobic performance. However, repetition of this study after prescribed rather than self-selected exercise intensity is recommended.