Previous Knee Injury Alters Bilateral Supraspinal Excitability During Torque Control: An Exploratory Study

Background: Knee ligament and meniscal injuries may cause persistent neuromuscular alterations despite successful return to sport (RTS). However, whether previous knee injury affects supraspinal excitability during torque control remains unclear. This observational study investigated the association between previous knee ligament or meniscal injury and supraspinal excitability in female university basketball players using long-latency reflexes (LLRs). Methods: Nineteen athletes participated, including five with a history of knee injury who had completed rehabilitation and returned to sport. During a sustained knee extension task at 25% of maximal voluntary isometric contraction, LLR characteristics (appearance rate, latency, duration, LLR/Mmax ratio, and phase count) were recorded from the ipsilateral opponens pollicis muscle. Comparisons were made between injured and non-injured limbs, between dominant and non-dominant limbs, and between the injured limbs of previously injured athletes and the dominant limbs of healthy athletes. Results: Healthy athletes demonstrated significantly shorter latency and greater LLR duration, LLR/Mmax ratio, and phase count in the dominant limb than in the non-dominant limb (p < .05). In contrast, no significant interlimb or dominance-related differences were observed in athletes with previous knee injury. Compared with the dominant limbs of healthy athletes, the injured limbs of previously injured athletes exhibited significantly prolonged LLR latency. Conclusion: These findings suggest that previous knee ligament or meniscal injury is associated with bilateral alterations in supraspinal neuromuscular control and delayed supraspinal processing during torque control. LLR assessment may complement conventional RTS evaluations by providing objective neurophysiological information relevant to safer RTS decision-making. Keywords: Long-latency reflex, neuromuscular control, knee injury, sports