INTRODUCTION: Several snowboarding disciplines are established competitions at Olympic Winter Games. The halfpipe may be considered as one of the most spectacular and attention-gaining events as a series of jumps with ever increasing complexity are executed consecutively within each run. As performance is evaluated by a team of judges there are important factors such as air time and amplitude which strongly affect ratings. Only very limited research exists yet, such that a full understanding of factors contributing to performance is missing. The goal of this study was to establish the potential of using two multidimensional force sensors during take-off and landing within training runs in a halfpipe in competitive freestyle snowboarders. It was aimed at providing preliminary descriptive data on take-offs and landings from basic tricks. METHOD: Six freestyle snowboarders (3m, 3f, 16.1 ± 1.3 y) of the German National Team participated in the study. Two custom-built, snowboard-specific, six degree-of-freedom force plates (diameter: 200 mm, height: 31 mm, mass: 0.9 kg) mounted between board and binding (500 Hz, McAlpine et al. 2011) and a handheld camera were used for collection of board reaction forces and descriptive kinematics while boarders executed straight airs, switch and 360-deg jumps in a competition ready halfpipe (Laax, Switzerland). The collected data were analysed offline and average forces were determined in an interval of 0.5 s before take-off and after landing. The current analysis included only normal forces and assessed rear foot/front foot force ratios. RESULTS: Preliminary analysis revealed that most boarders had an asymmetric force distribution during takeoff in the straight jumps. The ratio was appr. 65/35 rear/front with some variation between individuals. Landing forces were generally more evenly distributed. For the switch take-offs the load ratio was about 55/45 but inter-individually highly variable. DISCUSSION: Rider perceptions varied but generally did agree in that the basic jumps were not affected by the extra weight of the plates. Coaches` expectations were a ratio of 60/40 for optimally executed take-offs indicating a considerable deviation for the athletes tested. The observed inter-individual differences indicate that force characteristics may be a useful measure to assess an athlete`s technical level while representative values need to be established. Future research may include kinematic analyses or generate a feedback tool for training purposes. CONCLUSION: The proposed methodology has great potential to improve our understanding of loading during take-off and landing, as well as movement technique in snowboarding disciplines and may be useful as a training tool once close to real-time feedback can be generated.
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