INTRODUCTION: Ski deflection strongly influences the quality of the carving turn and the performance in para-alpine skiing. In general, it is thought that sit-skiers have more difficulty controlling their center of mass and making skis deflected than standing skiers (Langelier et al., 2013). However, no studies have investigated ski deflection during a run for sit-skiers. Recently, we developed a new method to measure ski deflection using a Fiber Bragg Grating sensor (hereinafter FBG) as an alternative method to the strain gauge that had been the mainstream method proposed by Yoneyama et al. (2008). Thus, this study aimed to reveal the ski deflection for a sit-skier using the FBG while comparing a standing skier. METHODS: A sit-skier classified as LW11 and a standing skier performed a run in an alpine ski course (Sugadaira, Japan, maximum slope angle: 23°) using the same ski for Giant Slalom (Length: 188 cm, R > 30). The ski deflection was measured using the FBG (Lazoc Inc.) and compared between the sit-skier and the standing skier. To determine the phases of the run, inertial measurement units were used. RESULTS: A standing skier evenly deflected the entire ski during a run. On the other hand, a sit skier deflected the afterbody of the ski more than the forebody during a run. The forebody deflection for the sit-skier was smaller than that for the standing skier. DISCUSSION/CONCLUSION: We found that the sit-skier had difficulty deflecting the forebody of the ski. If sit-skiers deflected the forebody of their skis as much as standing skiers, they could expand the range of their carving turn technique. In our future work, we need to develop a ski, binding, and/or sit frame that can deflect the forebody of the ski to improve the sit-skier`s performance.
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