CHANGES IN PLASMA CREATINE KINASE AND FREE RADICALS IN PROFESSIONAL SOCCER PLAYERS THROUGHOUT A HALF-SEASON

Abstract

Plasma creatine kinase (CK) activity and free radical (FR) levels may indicate some changes following acute and prolonged physical exercise. These parameters have certain activity and concentration characteristics, the changes in which may mean adaptation or non adequate adaptation of the reserves. The aim of this study was to evaluate the changes in plasma CK activity and FR levels in professional soccer players during a competition half-season. A total of 30 professional soccer players from a first league soccer club were the subjects in this study. They were evaluated on three occasions: before the pre-seasonal training period, before the competition season, and at the end of the half-season. Venous blood samples were taken before and following a maximal incremental treadmill test, and serum plasma levels of CK and FR were determined using spectrophotometric and “D-ROMs” methods, respectively. Descriptive statistics and ANOVA were used to analyze the results. Taking into account the three training periods, plasma CK activities decreased and FR levels increased both significantly (p<0.05) at the end of the half-season. The reason for the significantly decreased exercise induced plasma CK responses at the end of the season might be caused by muscular adaptation. With supportive data about soccer performance, mood and aerobic/anaerobic capacity alterations, these changes could help in assessing risks of inadequate adaptation, overtraining or stagnation in the training processes.