Hip-Abductor Fatigue, Frontal-Plane Landing Angle, and Excursion during a Drop Jump

Abstract

Context:The influence of hip-muscle function on knee-joint kinematics during landing has been inadequately investigated.Objective:To determine the effect of bilateral hip-abductor fatigue on frontal-plane tibiofemoral landing characteristics and vertical ground-reaction force (vGRF) during the landing phase of a drop jump.Design:Experimental, pretest–posttest.Setting:Research laboratory.Participants:20 recreationally active college-age students.Intervention:Isometric bilateral hip-abductor-fatigue protocol.Main Outcome Measures:Frontal-plane tibiofemoral landing angle, excursion, and vGRF during landing from a drop jump under prefatigue, postfatigue, and recovery conditions.Results:After the fatigue protocol, participants landed in a greater valgus orientation than in the prefatigued state. No differences in frontal-plane excursion or vGRF were noted.Conclusions:Isolated bilateral hip-abductor fatigue alters frontal-plane lower extremity orientation during a double-leg landing. Because an increase in valgus orientation has been observed at or near the time of noncontact anterior cruciate ligament injuries, we recommend improving hip-abductor muscle performance to lessen the risk of such injuries.