Game demands and fatigue profiles in elite football – an individual approach -Implications for training and recovery strategies

The physical activities performed during a football game are of intermittent prolonged character, including explosive actions and running at different speeds. The prolonged intermittent activities are conjoined with periods where physical intensity is markedly increased. The intense periods and prolonged activities affect the physiological and metabolic systems which provoke fatigue both temporarily throughout the game as well as towards the end of a game. Therefore, physical training in football should aim to reach physiological and metabolic adaptations to be able to resist fatigue in order to perform optimally throughout the game. Furthermore, post-game recovery and restoration of performance seems to be a slow process. Physical game demands, training responses and recovery can vary largely between players and needs to be studied with individual emphasis. The aim of the thesis is to improve the understanding of physical game demands, fatigue profiles in male elite football players with an emphasis on individual differences and implications for fitness training strategies. Running distance and in-game fatigue profiles were investigated through an analysis of game activity data from top-class football players (n = 473). Post-game fatigue and recovery profiles were examined using maximum voluntary contraction in various muscle groups after a simulated football model in competitive players (n = 12). Inter-individual relations between physical game demands and physical response in different small-sided game formats were investigated with global positioning system techniques on professional players (n = 45). Finally, muscular adaptations and physical performance responses of two different training protocols (four weeks of small-sided games or speed endurance training) were examined by means of pre- and post-intervention muscle biopsies and performance tests on 39 competitive football players. The results demonstrated that all playing positions indicate temporary fatigue after intense periods during a football game. However, after shorter intense periods central defenders were the only position that did not show a decline in running performance. A large inter-player variation in running performance between and within playing positions was found. Post-game fatigue showed large inter-player differences between various muscle groups and between players. Muscle performance in all investigated groups had recovered within 24 hours post-game except trunk-muscles, which was back to baseline values within 48 hours post-game. The physical response in small-sided game formats differed from game demands on an individual level. High intensity training was more potent in up-regulating muscle oxidative capacity and physical performance compared to small-sided games. In conclusion, individual differences in game demands and fatigue profiles are large and need to be considered when planning training. Small-sided games seem not to be the most appropriate training method to meet the individual game demands of all individual players. Thus, in order to increase exercise performance and associated physiological adaptations, additional high-intensity training should be considered for some individual football players