Purpose: To report creatine kinase ([CK]) responses during a soccer World Cup preparatory and first-leg period and to determine the influence of aerobic fitness on postmatch [CK] responses. Methods: Eleven national-team players were analyzed in this study. A lactate threshold test was performed during the first 3 d, whereas fingertip blood was drawn most mornings (21 out of 30 d) for [CK] measurements. One-way repeated-measures analysis of variance was used for determining the effect of time on [CK] measurements, whereas Pearson correlation coefficient was used for assessing associations between the changes in [CK] and velocities associated with blood lactate concentrations of 2 (v2) and 4 mmol·L−1 (v4). Results: Peak [CK] concentrations were consistently reached on the first day after the match with values of 474 (261), 520 (419), and 460 (126) U·L−1 but with no significant differences between them. [CK] concentrations returned to prematch values (331  U·L−1) on the second day after the match. The change in [CK] concentration between prematch and postmatch day was largely correlated (r = .614, P = .044) with v2. Conclusions: Top-level soccer players display low levels of muscle damage during official tournaments, and they recover before the next match. Postmatch muscle damage is greater in players with higher aerobic endurance because this fitness quality enables them to execute high-intensity activities known to be a major contributor to muscle damage.
Daniel Bok and Igor Jukić
Javier Raya-González, Fabio Yuzo Nakamura, Daniel Castillo, Javier Yanci and Maurizio Fanchini
ratio and injury occurrence with European top-level players. The results obtained in the current study did not follow the trend of previous soccer studies. This could be explained by the different sample (size and typology) examined in the present study 28 and the number of injuries that occurred
Thorben Hülsdünker, Clara Rentz, Diemo Ruhnow, Hannes Käsbauer, Heiko K. Strüder and Andreas Mierau
Double 10 23 I4 f 22 Double 15 22 I5 f 20 Single 10 26 Mean 22 12 22 C1 m 18 Single 10 20 C2 f 26 Double 17 8 C3 f 25 Single 20 30 C4 f 25 Double 15 22 C5 f 23 Double 10 20 Mean 23 14 20 Abbreviations: f, female; m, male. As this study focused on top-level players, only a small sample of 10