A biomechanical analysis of how rider behavior and equivalent fall height affect landing stability in World Cup Slopestyle for freeski and snowboard

Purpose: The purpose of this project was to investigate different rider behavioral factors along with Equivalent Fall Height (EFH), to see how they affected landing stability for World Cup Slopestyle athletes on freeski and snowboard. Landing stability was used as a surrogate measure of injury risk. Methods: The data was collected from a Slopestyle competition in Seiser Alm, using a geodetic video method. 3-dimensional models of the athletes’ center of mass trajectories were reconstructed, so physical parameters such as EFH could be calculated. Further, a qualitative assessment of landing stability and rider behavioral factors was done, including average angular velocity (ωavg), axial motions, and rider orientation during landing. Landing stability was classified as “good” or “bad”, and logistic regression with landing stability as the dependent variable were used to calculate probability of bad landing stability with different values of EFH and rider behavioral factors. Results: Snowboarders showed bad landing stability twice as often as skiers, which can be explained by elementary differences in attachment to equipment and range of motion. EFH significantly increased probabilities of bad landing stability for skiers and snowboarders, while ωavg significantly increased probabilities of bad landing stability for snowboarders. Skiers showed an interaction effect between ωavg and axial motions, where monoaxial maneuvers showed higher probabilities of bad landing stability compared to multiaxial maneuvers on high ωavg. This can be caused by a higher proportion of the ωavg around one axis, and not distributed around several axes. Switch landings significantly increased the probability of bad landing stability for snowboarders, but not for skiers. Conclusion: For skiers, increased EFH values, along with high ωavg in monoaxial maneuvers showed the highest probabilities of bad landing stability. For snowboarders, increased EFH values, together with increased ωavg and switch landings gave the highest probabilities of bad landing stability. This means that rider behavior impacts landing stability, which emphasizes that keeping EFH values low is important