Differential influence of quadriceps rate of torque development on single- and double-leg landing mechanics in anterior cruciate ligament reconstructed and control females
This paper provides valuable insights into how the dynamic function of the quadriceps affects knee stability during landing in females, especially those recovering from ACL reconstruction. This has broad implications for improving clinical outcomes in ACL rehabilitation and for developing targeted injury prevention programs.
College of Health researcher(s)
Highlights
Quadriceps RTD and Landing Mechanics
The study found that the rate of torque development in the quadriceps significantly influences landing mechanics. This is crucial because improper landing mechanics are a known risk factor for ACL injuries and re-injuries. The faster and more effectively the quadriceps can develop torque, the more stable the knee joint during high-impact activities like landing, which potentially reduces the risk of injury.
Comparison Between Single and Double-Leg Landings
The research highlights differences in the influence of quadriceps RTD on single-leg versus double-leg landings. This distinction is important because single-leg landings typically present a higher risk for ACL injuries due to increased instability and unilateral loading.
Implications for ACL Reconstruction Recovery
For females who have undergone ACL reconstruction, the study underscores the importance of focusing on improving quadriceps RTD during rehabilitation. Enhanced quadriceps RTD could lead to better control and stability of the knee, which might decrease the likelihood of re-injury upon return to sport.
Abstract
Purpose
The capacity to explosively contract quadriceps within the critical timeframe associated with anterior cruciate ligament (ACL) injury, quantified by the rate of torque development, is potentially essential for safe landing mechanics. This study aimed to investigate the influence of explosive quadriceps strength on ACL-related sagittal-plane landing mechanics in females with and without ACL reconstruction (ACLR).
Methods
Quadriceps explosive strength and landing mechanics were assessed in 19 ACLR and 19 control females during isometric contractions and double- and single-leg jump landings. A stepwise multiple linear regression model determined the variance in each of the landing biomechanics variables for the ACLR limb and nondominant limb of controls that could be explained by the group, rate of torque development and/or their interaction. If peak kinetic variables could be predicted by the rate of torque development or interaction, additional analyses were conducted, accounting for knee flexion as a covariate in the regression model.
Results
During single-leg landings, ACLR females exhibited greater knee flexion at initial contact than controls (p = 0.04). Greater quadriceps rate of torque development predicted higher peak posterior ground reaction force and anterior tibial shear force in both groups (p = 0.04). However, after controlling for knee flexion angle at those peak forces, quadriceps rate of torque development was not predictive. In double-leg landings, greater explosive quadriceps strength was associated with quicker attainment of peak knee extension moment and posterior ground reaction force in the ACLR limb (p = 0.03).
Conclusion
Regardless of ACL injury status, females with greater explosive quadriceps strength adopted safer single-leg landings through increased knee flexion, potentially mitigating ACL loading despite encountering higher peak forces. During double-leg landings, a greater explosive quadriceps strength of the ACLR limb is associated with faster achievement of peak force upon landing. Incorporating explosive quadriceps strengthening into post-ACLR rehabilitation and injury prevention programmes may enhance landing mechanics for reducing primary and subsequent ACL injury risks.
Level of Evidence
Level II.