Fatigue induced changes in eggbeater kick kinematics affect performance and risk of injury

Purpose: To investigate the physical and physiological response to different formats of various-sided games. Methods:Eighteen elite female soccer players wore 15Hz global positioning system (GPS) devices and heart-rate monitors during various-sided games (small: 4v4 and 5v5, medium: 6v6 and 7v7, large: 8v8 and 9v9). Results:Players covered more relative sprinting distance during large-sided games when compared with small- (p < 0.001, d = 0.69) and medium- (p < 0.001, d = 0.54) sided games. In addition, a greater proportion of total acceleration efforts that had a commencement velocity < 1 m/s were observed in small-sided games (44.7% ± 5.5) when compared to large-sided games (36.7% ± 10.6) (p = 0.018, d = 0.94). This was accompanied by a greater proportion of acceleration efforts with a final velocity equivalent to the sprint threshold in large-sided games (15.4% ± 7.7), than small-sided games (5.2% ± 2.5) (p < 0.001, d = 1.78). The proportion of time spent in heart rate zone 4 (> 85% HRmax) was greatest during small-sided games (69.8% ± 2.5) compared with medium- (62.1% ± 2.8, d = 2.90) and large- sided games (54.9% ± 3.1) (p < 0.001, d = 5.29). Conclusion: The results from this study demonstrate that coaches can use small-sided games as an aerobic conditioning stimulus and to develop players’ explosiveness and repeat sprint ability over short durations. Large-sided games can be used to maintain aerobic capacity and develop maximum speed over longer distances.