Blood-borne fatigue markers during major international football tournaments - a retrospective analysis of data from the FIFA World Championships and UEFA European Championships 2006 - 2016

• Published in: Science and medicine in football 2020-04, Vol.4 (2), p.135-141
• Main Authors: Hecksteden, Anne, Meyer, Tim
• Format: Article
• Language: English
• Subjects: individualization; Interindividual variation; monitoring; reference range
• ISSN: 2473-3938; 2473-4446
• DOI: 10.1080/24733938.2019.1692144

Purpose:Monitoring of recovery needs is considered essential during international football tournaments, with blood-borne markers being an objective, well understood and conveniently measurable option. However, reference values from this level of play are largely lacking. Methods:We therefore report a retrospective analysis of the blood-borne fatigue markers creatine kinase (CK) and urea (U) from the German national football team during the FIFA World Championships and UEFA European Championships from 2006-2016. Values from 68 players could be analysed resulting in 1019 values for CK and 943 values for U. For 2014 and 2016, additional player tracking data were available. Results:Mean values (90% CI) for CK and U were 343.4 (333.3-353.6) U/l and 39.5 (39.0-39.9) mg/dl, respectively. Considerable between-subject variation was present accounting for 44% of random variability for logCK and 45% for logU. A significant decrease over time (p < 0.001) could be observed for both indicators. Total running distance and high-speed running were significantly correlated with CK levels 2 days after the match with a disproportionate CK response for overtime matches. Conclusion:Taken together, monitoring of recovery needs in elite football is likely to benefit from individualized reference values. When group-based reference ranges are used, they should be current and football-specific.