A Hamstring Fatiguing Protocol Has No Effect On Knee Joint Moments During Landing

Abstract

Hamstring activation has been shown to decrease anterior tibial translation, and thus, might decrease stress to the anterior cruciate ligament (ACL). If this muscle activation is diminished from fatigue, the ACL could be predisposed to injury. The effects of fatiguing the hamstrings on knee joint moments during a functional task could provide insight into the prevention and treatment of ACL injuries. PURPOSE To compare flexion, valgus, and internal rotation moments of the knee during single-leg landing from a height of 60 cm before and after a hamstring fatiguing protocol. METHODS Eight males (25±4.1 yrs.) and eight females (25±2.2 yrs.) performed 5 trials of single-leg landing on the dominant limb from a height of 60 cm and then participated in a hamstring fatiguing protocol of the same limb. Immediately following the fatiguing protocol, subjects were asked to repeat the 5 trials of single-leg landing. Knee joint moments (flexion, valgus, and internal rotation) were calculated from the raw ground reaction forces and the kinematic values from a 10 camera motion analysis system (VICON, V624, Oxford Metrics Ltd., Oxford, UK). The effects of gender and hamstring fatigue on knee joint moments were analyzed using three two-way ANOVAs with repeated measures on hamstring fatigue state. RESULTS A significant interaction for hamstring state by gender on knee internal rotation moments (F1,14 = 5.08, P = .041) was seen during landing. However, no individual differences existed (P >0.05). There were no differences in knee flexion or valgus moments between genders or hamstring states (P >0.05). CONCLUSIONS Gender and hamstring fatigue state had no significant effect on knee flexion, valgus, or internal rotation moments during a single-leg landing.