Effects of Two Competitive Soccer Matches on Landing Biomechanics in Female Division I Soccer Players

Fatigue has been proposed to increase the risk of knee injury. This study tracked countermovement jump, knee isometric strength, and kinetics and kinematics in 8 female soccer players (experimental group) during an anticipated sidestep maneuver before and after two matches played over a 43-h period. Time points were: Before and after match 1 (T0 and T1), 12 h after the first match (T2), and immediately after the second match (T3). A control group participated only in practice sessions. Isometric knee extension strength decreased by 14.8% at T2 (p = 0.003), but knee flexion was not affected until T3, declining by 12.6% (p = 0.018). During the sidestep maneuver, knee joint degrees of flexion at initial contact was increased by 17.1% at T3, but maximum knee and hip angle at initial contact were unchanged. Peak resultant ground reaction force (GRF) increased by 12.6% (p = 0.047) at T3 (3.03 xBW) from 2.69 xBW at T0, while posterior GRF was significantly higher than T0 at all three subsequent time points (T1 = 0.82 +/- 0.23 xBW, T2 = 0.87 +/- 0.22 xBW, T3 = 0.89 +/- 0.22 xBW). Anterior tibial shear force increased significantly (p = 0.020) at T3 (1.24 +/- 0.12 xBW) compared to T1 (1.15 +/- 0.13 xBW), an 8.8% increase. Lateral tibial shear force was significantly higher at both T1 (0.95 +/- 0.20 xBW) and T3 (1.15 +/- 0.38 xBW) compared to T0 (0.67 +/- 0.25 xBW). These findings suggest that participation in a soccer match has significant effects on both physical performance parameters and kinetics/kinematics during a sidestep cut, but these can be more pronounced after a second match with short rest.