CONTEXT: Instruction can be used to alter the biomechanical movement patterns associated with anterior cruciate ligament (ACL) injuries. OBJECTIVE: To determine the effects of instruction through combination (self and expert) feedback or self-feedback on lower extremity kinematics during the box-drop-jump task, running-stop-jump task, and sidestep-cutting maneuver over time in college-aged female athletes. DESIGN: Randomized controlled clinical trial. SETTING: Laboratory. PATIENTS OR OTHER PARTICIPANTS: Forty-three physically active women (age 21.47 +/- 1.55 years, height 1.65 +/- 0.08 m, mass 63.78 +/- 12.00 kg) with no history of ACL or lower extremity injuries or surgery in the 2 months before the study were assigned randomly to 3 groups: self-feedback (SE), combination feedback (CB), or control (CT). INTERVENTION(S): Participants performed a box-drop-jump task for the pretest and then received feedback about their landing mechanics. After the intervention, they performed an immediate posttest of the box-drop-jump task and a running- stop-jump transfer test. Participants returned 1 month later for a retention test of each task and a sidestep-cutting maneuver. Kinematic data were collected with an 8-camera system sampled at 500 Hz. MAIN OUTCOME MEASURE(S): The independent variables were feedback group (3), test time (3), and task (3). The dependent variables were knee- and hip-flexion, knee-valgus, and hip- abduction kinematics at initial contact and at peak knee flexion. RESULTS: For the box-drop-jump task, knee- and hip-flexion angles at initial contact were greater at the posttest than at the retention test (p < 0.001). At peak knee flexion, hip flexion was greater at the posttest than at the pretest (p = 0.003) and was greater at the retention test than at the pretest (p = 0.04); knee valgus was greater at the retention test than at the pretest (p = 0.03) and posttest (p = 0.02). Peak knee flexion was greater for the CB than the SE group (p = 0.03) during the box-drop-jump task at posttest. For the running-stop-jump task at the posttest, the CB group had greater peak knee flexion than the SE and CT (p <= 0.05). CONCLUSIONS: Our results suggest that feedback involving a combination of self-feedback and expert video feedback with oral instruction effectively improved lower extremity kinematics during jump-landing tasks.

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