ABSTRACT

　 There is no previous study which have examined how neural control abnormalities due to anterior cruciate ligament （ACL） injury affect muscle feed-forward （FF）control when an unpredictable event occurs in the landing. By using the prolonged vibration stimulation to the infrapatellar tendon, in the present study, the similar neural abnormalities occurred after ACL injury could be induced in healthy subjects. The study design using the neural abnormalities induced by prolonged vibration stimulation in healthy individuals enable to compare the effect before and after the occurrence of neurological abnormalities. It is difficult to extract direct effects of the neural abnormalities in experiments with actual patients with ACL injury since it is impossible to predict when and who would get injured. In the present study, furthermore, all subjects were imposed unpredictable event which is called Surprised Landing task. The task was designed to impose unexpected landing task under the same conditions to subjects. The EMGs before and after the induction of neural control abnormalities were compared to identify changes in pre-landing muscle activity. The results of present study demonstrated that activation of vastus medialis and rectus femoris were significant increased in muscle activity of the first half part after passage of the false plate by the induction of neural control abnormalities （p=0.014，0.04） . There was no significant difference in all muscles in the latter half. Those results might suggest that the enhanced corticospinal pathways excitability induced by the ACL injury complement the declined activity in the spinal reflex pathway of some muscle in FF control of unpredictable events.

DECENTE SPORTS SCIENCE Vol.43/The DESCENTE AND ISHIMOTO MEMORIAL FOUNDATION FOR THE PROMOTION SPORTS SCIENCE