Impact of an Elevated Rear Component of the Ski Binding on Joint Angles of the Lower Extremity and the Center of Mass in Recreational Skiers.

Abstract

Recently, an elevated rear component of the ski binding has been associated with a reduced ACL injury risk. However, the underlying mechanism is unknown. This study aimed to evaluate the impact of elevated rear components of the ski binding on lower extremity joint angles and the center of mass (COM) in recreational skiers. To evaluate ankle, knee and hip joint angles and the COM, a cohort of 25 subjects (mean age: 25.4 ± 1.8 years) performed unipedal standing trials within a ski boot at four heel heights (position 0: +0.2 cm; position 1: +0.5 cm; position 2: +1.5 cm and position 3: +3.0 cm) on a force plate using an optical motion capture system. Repeated measures ANOVA revealed that flexion angles at the ankle joint significantly differed (η2 = 0.145) and were lowest at position 3, indicating a more neutral ankle joint (-1°). Flexion angles at the knee joint significantly increased with increasing heel height (η2 = 0.715) and were highest at position 3 (+6.9°), indicating a more flexed knee joint. Hip joint angles were not significantly different between the four different conditions (η2 = 0.082). The anterior-posterior COM position differed significantly between the four testing positions (η2 = 0.668) and was most anterior at position 3 (+3.7 cm), indicating a forward movement of the COM. An elevation of the heel component of the ski binding causes an increase in knee flexion accompanied by a forward movement of the COM, both potentially increasing hamstring co-activation as an advantageous preventive measure for ACL injuries in recreational skiing.