Repeated side-cutting knee and hip biomechanics for a macro-cycle of a professional rugby league season

Abstract

The aim of this study was to determine the variability of lower-limb side-cutting biomechanics in professional rugby league players during a season. Thirteen male professional players were included with a mean age of 22 ±3.4 years. The study used a one-way repeated measures experimental design. Subjects were tested at three time points, separated by four weeks, over the last three months of a season. Peak knee valgus and internal rotation moments (Nm/kg- 1), and flexion angle (°), and hip abduction moment (Nm/kg-1) during the weight-acceptance of the stance phase were collected for all side-cutting maneuvers. A one way repeated-measures ANOVA was performed on the data with Bonferroni post-hoc analysis identifying differences between testing sessions. Mean hip and knee kinematics and kinetics were similar for all measures. There was a significant difference in peak knee flexion angle (°) (Left = F(1, 17) =4.895, Right = F(2, 24) =6.603) and knee valgus moment (Nm/kg-1) (Left =F(2, 24) =9.535, Right =F(2, 24) =6.060) showing significant variability between testing sessions one and three for right knee flexion and knee valgus in both limbs. Bi-lateral knee valgus moments were also significantly different between sessions two and three. Professional rugby league players have shown to be more efficient during the weight-acceptance phase of a side-cutting manoeuver compared to recreational athletes which may be beneficial to reducing frontal plane knee loading and injury risk at the knee. In addition, this study has reinforced the link between the hip and the knee in providing proximal stability for distal mobility.