Co-contraction of hip musculature and its effect on knee valgus during a jump-landing task (2008)
Undergraduates: David C. Oates II, Lindsay DiStefano, Michelle Boling, David Bell
Faculty Advisor: Darin Padua
Department: Exercise & Sport Science
The Anterior Cruciate Ligament (ACL) is a frequently injured ligament in sports-related tasks, and one of the most time-consuming and costly to recover from. ACL injury not only affects the sports community, but any active community. Many factors and structures have been found to play a role in ACL injury, including knee valgus angle (knocked knee appearance). Certain muscle groups have an effect on the degree of knee valgus angle, including hip abductors (gluteus maximus and medius) and adductors. Our research focus was on studying the contraction of hip abductors and adductors during a jump-landing task and determining if there was any correlation between the contraction of the muscles and knee valgus angles during the jump.
Our study consisted of 32 active female subjects who displayed visible knee valgus during a squat. The data for each subject’s jump landing task, which consisted of the subjects jumping from a box and upon impact with the ground immediately jumping up as high as they could, was then collected using a motion analysis system. The data from the subjects’ jumps were then organized in Excel and analyzed using SPS software. Upon analysis, there were no strong correlations between the contraction values for the individual muscles and any knee valgus measurements throughout the jump-landing task. The next set of analysis focused on the co-contraction ratios of hip abductors versus hip adductors (using average values of the gluteus medius and gluteus maximus divided by the adductors’ values) and any correlation with knee valgus angles. This second analysis yielded a strong, negative correlation between the co-contraction ratios of hip abductors/adductors and knee valgus moment at initial contact of the subject during their jump-landing task from the box. Despite this negative correlation finding, more research needs to be done to determine other factors in knee valgus angles.