Creatine Kinase concentration is not related to indicators of physical match performance in English Premier League soccer players

The aim of the present investigation was to determine the relationship between blood creatine kinase (CK) and physical match performance in elite male soccer players. Fifteen elite outfield soccer players (mean ± S.D.; age, 26 ± 4 years; height, 1.8 ± 0.6 m; body mass, 84 ± 6 kg) who played for a professional soccer team competing in the English Premier League were examined. Blood samples were collected 48 hrs following a competitive match. Analysis for CK concentration was performed immediately after collection via spectrophotometry using a commercially available reagent kit (Reflotron® Systems, Roche, Mannheim, Germany). Physical match performance data was collected using a computerised tracking system (Prozone®) from > 6 matches for each player. The physical performance variables selected to examine the relationship between CK and physical match performance included total distance, total high-intensity running distance, total high-intensity running number of efforts, total sprint distance, total sprint number of efforts, average speed and recovery time. Mean ± S.D CK concentration 48 hrs post match was 520 ± 224 µ.mol.l-1 though large individual variation in the CK response at this time point was observed (184 µ.mol.l-1 to 1573 µ.mol.l-1). No significant correlation coefficients were obtained between any of the chosen indicators of physical match performance and CK concentration 48 hrs post match. This data would suggest that CK concentrations are elevated as a consequence of playing a soccer match. Creatine kinase may be of limited value in tracking subtle changes in the performance of players during the competitive season