Biomechanics of the Lower Extremity in Youth Football League: FIFA 11+ One Leg Squat Analysis

Background: Football carries substantial injury risks, especially for youth players. Providing biofeedback of lower limb motion during functional tasks is a crucial part of injury prevention programs such as FIFA 11+. While the FIFA 11+ warm-up program providing individualised feedback remains challenging, wireless sensor systems such as the DAid® Pressure Sock system, NOTCH® Inertial Sensor System, and PLUX Wireless Biosignals (muscleBAN kit) System offer potential solutions. Aim: This study aims to explore the correlation of lower limb biomechanical variables during the FIFA 11+ Part 2 exercise "One Leg Squat" in youth football players using wireless sensor systems and video recordings. Methods: Using wireless sensor systems and video recordings, we analysed lower limb biomechanics during the "One Leg Squat" exercise in youth football players. Results: Our findings showed significant associations: hip adduction correlated positively with foot plantar pressure centre (COP1y), intern al hip rotation correlated strongly with COP1y and COP2x, and gluteus medius activity. Conversely, COP1y showed a negative correlation with gluteus maximus activity. Conclusions: The results support the potential of wireless sensor systems in monitoring the biomechanical changes of the lower extremity movements and lay the groundwork for future biofeedback methods based on the DAid® smart socks system technology for evaluating lower limb motion, especially the changes in the centre of pressure of the plantar surface of the foot, during functional tasks in Football Youth League players.