Blood-borne fatigue markers during major international football tournaments
Blood-borne fatigue markers during major international football tournaments – A retrospective analysis of data from the FIFA World Championships an UEFA European Championship 2006 – 2016
Hecksteden A, & Meyer T. 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. Sci & Med Football, 2019.
- DOI: 10.1080/24733938.2019.1692144
Introduction: The importance of detailed and specific information about fatigue markers during major international football tournaments is salient. During recent years, considerable advances have been made in the assessment of exercise-induced fatigue and recovery needs. This includes the establishment of new parameters and biomarkers as well as improvements in diagnostic accuracy by algorithms for the individualized interpretation of measured values.
Purpose: Considering the scarcity of published data from this level of competition the authors report a retrospective analysis of fatigue markers from the German national football team during the FIFA World Championships and UEFA European Championships from 2006- 2016.
Method: Values from 68 players could be analyzed resulting in 1019 values for creatine kinase (CK) and 943 values for urea (U). For 2014 and 2016, additional player tracking data were available.
- Variation of CK and U: Subject ID accounted for 44% of variance in logCK and for 45% of variance in logU, indicating substantial interindividiual variation in both parameters (fig. 1).
- Time trend: A significant decrease over time (p<0.001) could be observed for both indicators.
- External match load and fatigue markers: A highly significant association could be detected between total running distance and high-speed running, respectively, and CK levels the second day after the match. Surprisingly, the number of sprints was not significantly related to CK. No associations could be detected between any of the selected indicators of external match load and urea concentrations. Overtime matches seem to be associated with disproportionate CK responses in those players who play most or all the game time.
TAKE HOME MESSAGES
– The striking differences in habitual CK and U levels between players illustrated in figure 1 emphasize the need for individualized reference ranges when aiming to assess the recovery needs of individual players with optimal accuracy.
– The chosen markers will likely have to be interpreted on the background of individualized reference ranges when aiming at a precise and reliable assessment of recovery needs for specific players.
– When group-based reference values have to be used (e. g. as a starting point for new players) they should be current and football-specific.
– The statements of the FSI team confirm that the assessment and treatment of the recovery process must have a specific and individualized character.