Investigation research on the mechanism of knee joint injury in table tennis players landing before and after fatigue during stroke play

This study investigated the relationship between lower extremity biomechanics and anterior cruciate ligament (ACL) injury in table tennis players before and after fatigue. We compared the biomechanical changes in the lower limbs of table tennis players during landing after completing a chasse-step while stroking, both before and after fatigue. A further aim was to examine ACL injury and provide a reference for training table tennis players. Ten national Level I table tennis players underwent lower extremity neuromuscular fatigue by running at a constant speed. Biomechanical data of the athletes were collected before and after fatigue. The effects of movement and characteristic time before and after fatigue on biomechanics were determined using a paired sample t-test. After fatigue, the angle of the ankle joint and the range of motion of the knee joint were significantly reduced (p < 0.001), while the angle of motion of the hip joint did not change considerably (p = 0.747). The angular velocity of the ankle and knee joints increased significantly after fatigue (p < 0.001), but the angular velocity of the hip joint decreased significantly (p = 0.013). Additionally, the ankle plantar flexion moment (p = 0.003), knee flexion moment (p < 0.001), and hip flexion moment (p < 0.001) increased significantly after fatigue. The ankle power (p = 0.023), knee power (p = 0.009), and hip power (p < 0.001) were significantly reduced throughout the landing cycle after fatigue. Fatigue in table tennis athletes reduces the sagittal plane buckling angle of the knee and ankle joints during landing. This change increases ground reaction and knee joint forces, significantly elevating the risk of knee injuries, including ACL tears. The reduced flexion angle exposes the knee to greater torque and diminishes its shock absorption capacity, heightening the risk of lower limb injuries. These findings underscore the need to address the impact of fatigue on landing mechanics in sports training and rehabilitation, emphasizing preventive measures.