Comparison of knee joint kinematics during a countermovement jump among different sports surfaces in male soccer players

Background: The present study aimed to compare the knee joint kinematics during a countermovement jump (CMJ) among different sports surfaces in male soccer players.Methods: The study included 20 male soccer players (age, 21.8 ± 2.0 years). Kinematic data were collected using a motion-capture system that included 6 infrared cameras at a sampling rate of 200 Hz. The participants performed CMJ with the hands placed on the waist. The surfaces included natural grass, artificial grass, sand, and a rubber indoor surface prepared in the laboratory.Results: There was no difference in knee joint angle flexion during the countermovement of the jump phase and eccentric phase after the jump (EPAJ) (landing) among the 4 surfaces (P = 0.115 and P = 0.073, respectively). There was a significant difference in the knee joint angle velocity during the countermovement phase and concentric phase of the jump (CPJ) among the 4 surfaces (P = 0.006 and P = 0.001, respectively). However, there was no difference in the knee joint angle velocity during the landing phase among the 4 surfaces (P = 0.134). There was a significant difference in jump height among the 4 surfaces (P = 0.001).Conclusion: Sports surfaces can influence the knee joint angular velocity and jump height, but might not affect the knee joint angular displacement.