Anticipatory effects on knee joint loading during running and cutting maneuvers

Purpose: To determine how unanticipated performance of cutting maneuvers in sport affects the external loads applied to the knee joint and the potenti al risk for ligament injury. Methods: A 50-Hz VICON motion analysis system was used to determine the lower limb kinematics of 11 healthy male subjects during running and cutting tasks performed under preplanned (PP) and unant icipated (UN) conditions. Subjects performed the UN tasks in response to a light stimulus on a target board. A kinematic model was then used in conjun ction with force place data to calculate the three-dimensional loads at the knee joint. Results: External flexion/extension moments at the knee joint were similar between PP and UN conditions: however, the varus/valgus and in ternal/external rotation moments during the UN cutting tasks were up to twi ce the magnitude of the moments measured during the PP condition. Conclusio n: Cutting maneuvers performed without adequate planning may increase the r isk of noncontact knee ligament injury due to the increased external varus/ valgus and internal/external rotation moments applied to the knee. These re sults are probably due to the small amount of time to make: appropriate pos tural adjustments before performance of the task, such as the position of t he foot on the ground relative to the body center of mass. Subsequently. tr aining for the game situation should involve drills that familiarize player s with making unanticipated changes of direction. Practise sessions should also incorporate plyometrics and should focus on better interpretation of v isual cues to increase the time available to preplan a movement.