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AIM: The primary purpose of this study was to investigate the relationship between the pre-game to post-game changes in creatine kinase concentration (DeltaCK) and impact-related game statistics in elite rugby union players. METHODS: Twenty-three elite male rugby union players each provided interstitial fluid samples obtained via electrosonophoresis (ESoP) 210 min before and within a maximum time of 30 min after up to five rugby union games. Specific game statistics that were deemed to be important in determining the relationship between impact and CK were obtained from AnalyRugby software for each individual player. Regression equations to predict DeltaCK from game statistics were created using a backwards random-effects maximum likelihood regression. RESULTS: The DeltaCK (mean (SD)) from pre-game to post-game was 926.8 (204.2) IU. Game time and time defending were significantly correlated to DeltaCK in both the forwards and backs. The predicted DeltaCK (mean (95% confidence limit)) was 1439.8 (204.9) IU for the forwards and 545.3 (78.0) IU for the backs and was significantly correlated with the actual DeltaCK (r = 0.69 and r = 0.74). CONCLUSIONS: CK increased from pre-game to post-game in a position-specific manner. A large proportion of the DeltaCK can be explained by physical impact and thus can be predicted using a prescribed number of game statistics. As the DeltaCK is an indicator of muscle damage, the prediction of DeltaCK provides a theoretical basis for recovery strategies and adjustment of subsequent training sessions after rugby union games.
Smart et al. (Thu,) studied this question.