GAME-INDUCED FATIGUE PATTERNS IN ELITE FEMALE SOCCER PETER KRUSTRUP, 1 METTE ZEBIS, 2 JACK M. JENSEN, 1 AND MAGNI MOHR 1 1 Department of Exercise and Sport Sciences, University of Copenhagen, Copenhagen, Denmark; and 2 Sports Medicine Research Unit, Copenhagen University Hospital, Copenhagen, Denmark ABSTRACT Krustrup, P, Zebis, M, Jensen, JM, and Mohr, M. Game-induced fatigue patterns in elite female soccer. J Strength Cond Res 24(2): 437–441, 2010—The purpose was to examine the fatigue pattern of elite female soccer players after competitive games. Soccer players (n = 23) from the Danish women Premier League performed a countermovement vertical jump test, a repeated 30-m sprint test, and the Yo-Yo intermittent endurance level 2 (Yo-Yo IE2) test at rested state and after a competitive game. Average heart rate during the game was 86 6 1% of maximal heart rate with no differences between halves. Blood lactate was 5.1 6 0.5 mmolÁL 21 after the first half, which was higher (p , 0.05) than after the second half (2.7 6 0.4 mmolÁL 21 ). Yo-Yo IE2 performance was 484 6 50 m after the game, which was 62% lower (p , 0.05) than at rested state (1,265 6 133 m). Average sprinting time of three 30-m sprints was 5.06 6 0.06 seconds after the game, which was 4% slower (p , 0.05) than at rest (4.86 6 0.06 seconds). No game-induced effect was observed on vertical jump perfor- mance. Significant inverse correlations were observed between Yo-Yo IE2 test performance and fatigue index during the repeated sprint test both at rest (r = 20.76, p , 0.05) and after the game (r = 20.66, p , 0.05). The study demonstrates that the type of fatigue that occurs after a female soccer game does cause marked impairment in intense intermittent exercise and repeated sprint performance but does not affect vertical jump performance. These findings support the notion that decre- ments in distance covered by sprinting and high-speed running toward the end of elite female games are caused by fatigue. KEY WORDS intermittent exercise performance, sprint, jump, blood lactate, football INTRODUCTION T he distances covered by high-intensity running have been proposed to be of great importance for performance in elite soccer because this parameter clearly distinguishes between top class and high- level elite players (19,20). Significant reductions in sprinting and high-speed running have been observed toward the end of elite games for men (1,20) and women (17,19). It has been discussed whether this phenomenon is a result of physio- logical fatigue or due to tactical and psychological factors. The findings that the amount of high-intensity running in the last 15-minute period is correlated with training status (17) and that replacement players perform 25% more high- intensity running and 63% more sprinting in the last quarter of the game than players playing the entire game (20) support the notion that the lowered match intensity is caused by fatigue. However, to provide direct evidence of development of fatigue during elite soccer games, it is necessary to combine motion analyses with performance tests performed before and after games. Sprint tests performed before and after elite male games have demonstrated that peak running speed and repeated sprint performance deteriorate considerably during games (18,22,26). However, it is unknown to what extent elite female soccer players are affected by a competitive game. The etiology of fatigue is complex and is highly dependent on exercise mode (8). Thus, performance may be attenuated during a repeated sprint test after a game as stated above, but the degree of game-induced fatigue may develop differently in other exercise tasks. For example, Bangsbo and Mohr (4) showed that peak sprinting speed was hampered in the final 15-minute interval of a game, indicating that the ability to develop peak power is also impaired toward the end of a game. On the other hand, discrepancy seems to exist regarding the game-induced effect on activities demanding a high rate of force development in men (10,12,23,24). For example, studies show significant impairment in jump performance after a simulated soccer game (23), whereas others observe no change immediately after a soccer game compared with rested state (12). Thus, fatigue resistance during intense intermittent exercise, repeated sprints, and countermovement jumps may be differently challenged by a competitive female soccer game. Address correspondence to Magni Mohr, mmohr@ifi.ku.dk. 24(2)/437–441 Journal of Strength and Conditioning Research Ó 2010 National Strength and Conditioning Association VOLUME 24 | NUMBER 2 | FEBRUARY 2010 | 437