TY - JOUR T1 - 132 Neuromuscular responses of the hamstring and trunk muscles during unanticipated trunk perturbations JF - British Journal of Sports Medicine JO - Br J Sports Med SP - A53 LP - A53 DO - 10.1136/bjsports-2021-IOC.123 VL - 55 IS - Suppl 1 AU - Ayako Higashihara AU - Jurdan Mendiguchia AU - Takashi Ono AU - Yasuharu Nagano AU - Shogo Sasaki AU - Shinshiro Mineta AU - Norikazu Hirose Y1 - 2021/11/01 UR - http://bjsm.bmj.com/content/55/Suppl_1/A53.1.abstract N2 - Background Trunk movement is considered to be involved in lower extremity injuries. Hamstring strain injuries often occur when movements are unanticipatedly perturbed by the opponents.Objective To examine the neuromuscular responses of the hamstring and trunk muscles during unanticipated trunk perturbations in the athletes with and without a history of hamstring strain injury.Design Descriptive laboratory study.Setting College athletes.Participants Male college athletes were recruited, 11 with a history of unilateral hamstring strain injury and 10 without prior injury.Assessment In the kneeling position, the participants wore a chest harness attached to a cable that was pulled backward as a resisting force. They were instructed to resist the force isometrically and keep their initial position as possible as they could when the perturbations were applied. The force was released with a cue (CUE) and without cue (NoCUE). Trunk acceleration, three-dimensional kinematic data, and surface electromyography (EMG) signals of the erector spinae, internal oblique, gluteus maximus, biceps femoris, and semitendinosus muscles were measured.Main Outcome Measurements (1) Maximum trunk acceleration; (2) angular displacement of the trunk, pelvis, hip, and knee; (3) onset latency; (4) EMG activation in the 50-ms window before the perturbation; and (5) EMG activation in the 100ms after the perturbation.Results The maximum trunk acceleration and displacement were significantly greater during the NoCUE than during the CUE in both groups (p<0.05). The injured group demonstrated significantly delayed onset of the gluteus maximus and erector spinae muscles during the NoCUE compared with the CUE (p<0.05), while no difference was observed in the uninjured group. There was no difference in the phasic EMG activities between groups.Conclusions Athletes with a history of hamstring strain injury displayed reduction in the neuromuscular coordination of pelvis and trunk muscles when they controlled the unanticipated trunk movement. ER -