Strength affects sagittal plane knee biomechanics that may protect the ACL during various cutting manoeuvres
Year: 2016
Type: dissertation
Abstract: Strength has been associated with reduced ACL incidence in sport but the specific mechanisms are less clear.The purpose of the investigation was to examine how strength may alter biomechanics to reduce injury risk during these manoeuvres, as well as explore how knee angle varies in response to different cutting conditions.Fourteen trained subjects were split into a stronger and weaker group (28.6 vs 17.5 N/kg -1 ), determined by relative peak isometric strength in a unilateral squat.Each participant was fitted with reflective markers, and lower limb, sagittal plane, kinetics and kinematics were evaluated using a tri axial force plate, and a 16 camera motion analysis system.Subjects performed 18 trials divided into six different cutting conditions, comprising of 2 cutting angles (45° and 90°), at 2, 4 and 6 m.s -1 .A mixed design ANOVA (2x2x3) determined that between strength groups (n=7), significant increases in hip extensor moments (p ˂ 0.05), and reductions in knee extensor moment (p ˂ 0.05) during weight acceptance in the strong group were observed.In addition, knee angle at initial contact was more flexed in the strong group (p = 0.05).When group data was collapsed, significant peak knee flexion differences existed for cut angle (p ˂ 0.001), but not for velocity.Results suggest increasing lower extremity strength may reduce ACL loading by redistributing impact forces to the hip and alleviating stress at the knee, as well as reducing ACL strain directly by a more flexed knee position at ground contact.In addition, peak flexion posture is dependent on cut angle, not velocity, perhaps as a way to increase excursion to reduce ground reaction forces, and knee extensor moments, during movements with greater multi planar stresses.
Author: Davies, William
Language: English
Subfield: Surgery
Field: Medicine
Domain: Health Sciences
Open Access status: green
Funder: St Mary's University
OpenAlex ID: W2602600365