Association Between Rate of Torque Development, Strength, Landing Biomechanics, And Dynamic Postural Stability In Physically Active Males

Abstract

During exercise and sport, physically active individuals often perform movements that require dynamic postural stabilization. Postural stability has been linked to ankle and knee injuries and examining factors associated with stabilization may provide insight as to how poor stability influences joint loading. PURPOSE: To examine mechanisms associated with postural stability during a Forward Jump Single-Leg Landing task (FJSL). METHODS: Dynamic postural stability index (DPSI), a composite of the anterior-posterior, medial-lateral, and vertical ground reaction forces, kinematics, knee extension strength (KES), and knee extension rate of torque development (RTD) were collected on 23 males (Age: 23.9 ± 1.3 years, Height: 178.4 ± 7.1 cm, Mass: 84.4 ± 8.6 kg). KES and RTD were collected using an isokinetic dynamometer. DPSI, sagittal plane joint angles at initial contact ([email protected], [email protected], [email protected]) and peak flexion angles (KneePkFlex, ANKPkFlex) were collected during a FJSL for the dominant (DOM) and non-dominant (NON) limb using a 3D motion capture system. Paired samples t-tests examined lower extremity asymmetries in DPSI, kinematics, KES, and RTD. Pearson correlation coefficients examined the relationships between KES, RTD, DPSI, and landing kinematics. Significance was set at p≤0.05. RESULTS: Subjects demonstrated asymmetrical DPSI (p=0.003) and asymmetrical ANKPkFlex (p=0.033) but not asymmetrical KES or RTD (p>0.05). Increased KneePkFlex and ANKPkFlex correlated with an improved DPSI (r=-0.519, p=0.016 and r=-0.466, p=0.033) on the DOM limb while KneePkFlex and [email protected] correlated with an improved DPSI on the NON limb (r=-0.472, p=0.031 and r=-0.520, p=0.016). Neither KES nor RTD correlated with DSPI or any of the kinematic measures for their respective sides. (p>0.05). CONCLUSIONS: Biomechanical stabilization strategies utilized the knee but the DOM, which had better stabilization, incorporated more ANKPkFlex, likely distributing weight over the forefoot. Neither strategy related to KES or RTD. Incorporating movement and balance components focused on symmetrical coordination of corrective movement strategies, including ankle stability, into current training programs may be necessary for improved dynamic postural stabilization.