Context Emerging evidence suggests that lower quadriceps rate of torque development (RTD) following anterior cruciate ligament reconstruction (ACLR) may be associated with altered landing mechanics. However, the influence of quadriceps RTD magnitude and RTD limb symmetry on landing mechanics limb symmetry remains unknown. Objective To assess the influence of quadriceps RTD magnitude and RTD limb symmetry on sagittal plane landing mechanics limb symmetry in females with and without ACLR during functional landing tasks. Design Cross-Sectional Study Setting Laboratory Patients or Other Participants Thirty-eight females (ACLR=19, 19.2±1.8 years-old, 164.1±7.0 cm, 63.8±7.6 kg, Time after surgery: 20.1±9.5 months; Control=19, 21.1±3.3 years-old, 167.3±7.3 cm, 67.3±9.3 kg). Main Outcome Measure(s) Landing mechanics were assessed during double-leg and single-leg jump-landing tasks (DL and SL), and a side-cut task (SC). Quadriceps RTD was collected during isometric muscle contractions. Separate stepwise multiple linear regression models determined the amount of variance in limb symmetry in sagittal plane knee moment at initial contact (IC), peak vertical ground reaction force (vGRF), and loading rate that could be explained by quadriceps RTD magnitude or RTD limb symmetry, group (ACLR or Control), and their interaction. Results In ACLR females, greater quadriceps RTD limb symmetry was associated with greater symmetry in sagittal plane knee moment at IC during DL (P=.004). Peak vGRF and loading rate could not be predicted by quadriceps RTD magnitude or RTD limb symmetry, group, or their interaction during all tasks. Conclusions Developing greater quadriceps RTD symmetry, but not RTD magnitude, likely enables more symmetrical sagittal plane knee landing mechanics during double-leg task in ACLR females, and thus may reduce the risk of a second ACL injury. Such protective effect was not found during single-leg tasks that may not allow for a compensatory landing mechanism of shifting load to the uninvolved limb as is possible during a double-leg task.

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Background: Early sport specialization has been associated with an increased risk of musculoskeletal injuries and unfavorable psychological outcomes; however, it is unknown whether sport specialization is associated with worse cognitive, postural, and psychological functions in first-year collegiate student-athletes. Methods: First-year collegiate multisport (MA) and single-sport (SA) student-athletes were identified using a pre-collegiate sport experience questionnaire. The cognitive, postural, and psychological functions were assessed by the Immediate Post-Concussion Assessment and Cognitive Testing (ImPACT), Standardized Assessment of Concussion (SAC), Balance Error Scoring System (BESS), and Brief Symptom Inventory 18 (BSI-18). Results: MA student-athletes performed higher in cognitive outcomes (e.g., higher ImPACT visual memory composite scores [ß = 0.056, p < 0.001]), but had higher psychological distress (e.g., higher BSI-18 global severity index [ß = 0.057, p < 0.001]) and no difference in postural stability (p > 0.05) than SA student-athletes. Conclusions: This study indicated first-year collegiate athletes with a history of sport specialization demonstrate lower cognitive performance but decreased psychological distress and no differences in static postural stability as compared to their MA counterparts. Future studies should consider involving different health measures to better understand the influence of sport specialization on overall physical and mental health.

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