Assessment of Football Player Knee Joint Motion During Vertical Step Down Movement

Neal, E., McGinley, S., Carruth, D. W., Knight, A., & Hale, B. (2011). Assessment of Football Player Knee Joint Motion During Vertical Step Down Movement. Proceedings of 2011 Annual Meeting of the Southeast Chapter of the American College of Sports Medicine. Greenville, SC.

Abstract

Lower extremity kinematics have been examined during different motions, including jumping, landing, squatting, and cutting exercises, primarily among healthy participants. Very little research has examined these variables among elite athletes. A difference in motion between the dominant and non-dominant leg could affect athletic performance and increase the potential for injury. The purpose of this study was to examine the motion of the knee joint during a vertical step down exercise and compare the dominant and non-dominant leg among elite level athletes. Eight healthy NCAA Division I football players (height = 1.87 + .06 m; mass = 99.22 + 18.84 kg) completed the testing. The participants performed three repetitions of a vertical step down exercise off a 25.4 cm for both the dominant and non-dominant leg. The testing leg was placed on the side of the box, with the non-testing leg in slight hip flexion and full knee extension. The participants were instructed to squat down until the heel of the non-testing leg tapped the floor, and then return to the starting position. Three repetitions were performed. The participants’ knee joint motion in the sagittal plane was recorded during the exercise using a motion analysis motion capture system. The data was analyzed with a 2 (range) by 2 (leg) ANOVA with repeated measures on the last factor. The results revealed no significant differences in knee motion between the dominant and non-dominant legs. Despite differences in hip motion in the sagittal plane between the dominant and non-dominant leg, this did not occur at the knee. Future research should examine the motion of the knee in the frontal plane, specifically the amount of knee abduction (valgus) at peak knee flexion. This study is an initial collaboration between the Center for Advanced Vehicular Systems, the Department of Kinesiology, the Department of Industrial and Systems Engineering, and the athletic department to develop a sport performance program to assist in the prescription of exercises and to improve exercise technique in order to improve athletic performance and reduce the potential for injury.