The relationship between changes in interstitial creatine kinase and game-related impacts in rugby union.
OBJECTIVE
The primary purpose of this study was to investigate the relationship between the pre-game to post-game changes in creatine kinase concentration (Delta[CK]) 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 Delta[CK] from game statistics were created using a backwards random-effects maximum likelihood regression.


RESULTS
The Delta[CK] (mean (SD)) from pre-game to post-game was 926.8 (204.2) IU. Game time and time defending were significantly correlated to Delta[CK] in both the forwards and backs. The predicted Delta[CK] (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 Delta[CK] (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 Delta[CK] can be explained by physical impact and thus can be predicted using a prescribed number of game statistics. As the Delta[CK] is an indicator of muscle damage, the prediction of Delta[CK] provides a theoretical basis for recovery strategies and adjustment of subsequent training sessions after rugby union games.
School of Sport and Exercise Science, Waikato Institute of Technology, Private Bag 3036, Hamilton, New Zealand. daniel.smart@wintec.ac.nz
D J
DJ
Smart
N D
ND
Gill
C M
CM
Beaven
C J
CJ
Cook
A J
AJ
Blazevich
D000328:Adult; D015415:Biomarkers / Q000378:metabolism; D003402:Creatine Kinase / Q000378:metabolism*; D004586:Electrophoresis; D005538:Football / Q000502:physiology*; D006801:Humans; D008297:Male; D018763:Muscle Fatigue / Q000502:physiology*; D010806:Physical Education and Training / Q000379:methods; D012044:Regression Analysis
D015415:Biomarkers; D003402:Creatine Kinase