Biomechanical Analysis of Snowboard Jump Landings: A Focus on the Ankle Joint Complex

Abstract

Snowboarding is an extremely popular and steadily growing snow sport. Jumping is an integral part of both recreational and competitive participation, predisposing individuals to an elevated risk of impact related injuries to the lower limbs. Five studies are presented in this dissertation, each of which linked directly to the overall goal of furthering the limited data available on the biomechanical demands placed on snowboarders during jump landings. A qualitative observational analysis of landing and falling events within terrain parks revealed that snowboarders fall once for every five attempts, with landing technique found to influence the risk of falling, and potentially dangerous body motions were identified during falls. These outcomes provided motivation for the quantitative studies (N=4) which aimed to provide a normative database of landing dynamics and investigate the influence of snowboarding equipment modification on the measures taken. Custom-built snowboard force plates were used to measure all components of landing ground reaction forces (GRF), and a snowboarding ankle anatomical model was developed to estimate joint kinematics, lateral ankle ligament strain, and joint reaction moments based on 3D marker data recorded with a video based system. Tests of precision and validity for these unique tools were conducted and presented prior to inclusion in the individual studies. As expected the external load applied at the boot sole is substantial during the landing event with the joints of the ankle complex rotating to positions close to published ROM limits. Binding angle and boot stiffness appear to carry potential for injury risk modification during landings by eliciting changes in external force, joint kinematics and moments acting at the joint level. Jump dimensions were found to influence the impact loads applied to the body with both magnitude and rate of measured GRFs found to increase with jumps of greater size. Asymmetries were identified between the limbs for the kinematic and kinetic measures suggesting there is scope for tailoring snowboard equipment based on position on the snowboard. The data presented throughout this document form a starting point for further in-depth analyses of snowboard specific movements from injury prevention and performance maximisation perspectives.