Biochemical Response Comparisons of a Competitive Microcycle Vs. Congested Fixture Periods in Elite Level European Champions League Soccer Players

The aim of this investigation was to analyses differences between post-game biochemical responses in congested (CP, when two consecutive games were played within 4 days or less) vs. non-congested (NCP, when two consecutive games were played within 5 days or more) periods. Assessment of creatine kinase (CK) and salivary cortisol (sCort) and immunoglobulin-A (sIgA) were performed across 12 separate training macrocycles of 14 competitive professional matches. The NCP analysis revealed significantly higher CK values from one day after match day (MD+1) than values found in MD and MD+2 (Effect size (ES): 0.82-1.13, p<0.0033). The CP analysis revealed no significant changes in CK values between MD, MD+1 and MD+2. Higher values on MD+2 in CP vs. NCP were also revealed (ES:0.27, p<0.05). No significant changes in sCort and sIgA were observed. Congested competitive periods induce significant biochemical changes revealed amongst elite soccer players that should influence their preparation and management