The effect of in-flight perturbations on landing biomechanics
Arnett, Scott W.
MetadataShow full item record
The exact mechanisms occurring at the time of an ACL injury are still not known. The focus of recent ACL injury research has been extended to include the interaction of biomechanical and environmental factors. One such interaction is an in-flight perturbation. Although these events have been implicated in ACL injuries, the effects of these events on drop landing biomechanics were previously not known. Therefore, the purpose of the study was to determine the effect of a linear and rotational in-flight perturbation on landing biomechanics. Twenty five college-aged female soccer and basketball athletes performed drop landings with and without in-flight perturbations. Three dimensional ground reaction forces and lower extremity joint kinematics and kinetics were analyzed. Paired t-tests were used for statistical analyses ( . = 0.05). Compared to the non-perturbed condition (CON), peak vertical ground reaction force (VGRF) was decreased during the perturbed condition (PERT). There were no significant lower extremity joint kinematic magnitude differences between conditions for the linear or rotational perturbations. Peak hip and knee extensor moments and peak plantarflexor moments were significantly greater during the PERT compared to the CON condition for the linear perturbation but not the rotational perturbation. The difference in peak VGRF was in the opposite direction of the original prediction, which could be interpreted as anticipation by the performer leading to an altered landing strategy. During the PERT compared to the CON condition, increased force could be placed on the ACL due to the shear force created by the peak knee extensor moment. In addition, landing strategies used by individual participants varied, specifically at the knee, which may predispose certain individuals to an ACL injury. Of particular interest were the individual participant variations in joint kinematic and kinetics during the PERT compared to CON landings. The findings of this project support that individual landing strategies exist, and these strategies could predispose certain individuals to an ACL injury. While both perturbations did not lead to similar alterations in landing strategies, it remains that an in-flight perturbation does appear to influence landing biomechanics.