The spectrum of cognitive-motor impairments following anterior cruciate ligament reconstruction (ACLR) is poorly defined. This knowledge gap is an important problem because recent evidence indicates that the current dependence on isolated motor tests for ACLR clinical decision making is insufficient to ensure restored function in complex sports environments or prevent a second injury. Under existing tests, the interaction between cognition and motor control is routinely missed and deficits are allowed to remain despite passing discharge criteria. Mounting evidence demonstrates that the interaction of cognitive and motor function is impaired after musculoskeletal injury, including ACL tears. There is a critical need for studies that establish the scope and severity of cognitive-motor impairments in ACLR patients to provide novel therapeutic targets. The long-term goal of this research is to improve ACLR rehabilitation outcomes. The objective of this R03 is to demonstrate the spectrum of cognitive-motor impairments with rigorous lab-based metrics following ACLR. Clinical translation will be achieved by validating cost-effective and simple tests for cognitive-motor performance against lab-based measures. The central hypotheses are that 1) simultaneous cognitive tasks will reveal neuromuscular impairments following ACLR, 2) clinical surrogate tests will be related to lab-based metrics, and 3) worse cognitive-motor impairments will predict poorer patient-reported outcomes of knee function and psychological factors. The study objective will be achieved through two specific aims: 1) elucidate the spectrum of dual-task impairments that persist following ACLR, and 2) demonstrate the clinical relevance of dual-task impairments following ACLR. For the first aim, 3D biomechanical analyses will be done for jumping tasks with an innovative approach of systematically adding simultaneous cognitive tasks (i.e., dual tasks) that target specific cognitive processes (e.g., decision making). Clinical cognitive-motor dual-task tests will also be validated. Greater increases in frontal plane knee motion (ACL injury risk factor) when visually- demanding cognitive tasks are added will support the primary hypothesis for the first aim. Strong correlations between dual-task impairments in clinic-based tests and dual-task impairments in frontal plane knee motion from lab-based tests will support the second hypothesis. Greater dual-task impairments on lab-based tests associating with worse patient-reported outcomes of knee function and psychological factors will support the hypothesis of the second aim. The approach is innovative because it will systematically introduce different types of cognitive challenges designed around the neurophysiological changes associated with ACL injury that go unquantified in current treatment. The research is significant because it will identify novel therapeutic targets for ACLR rehabilitation by determining the most salient cognitive-motor imp...