This study aimed to identify technical issues to improve the competitive performance of junior female alpine skiing racers and compile useful information for considering systematic guidance guidelines. A questionnaire on the technical characteristics of junior female racers, targeting alpine skiing coaches with extensive experience in competitions and teaching, was conducted. The questionnaire included questions on “technical characteristics of top-level racers,” “technical issues of junior female racers,” “acquisition technical elements of junior female racers,” and “important teaching elements of the skiing technique.” The obtained responses were subjected to qualitative analysis using SCAT. The questionnaire results indicated that the technical elements of “accurate turn composition for course situations,” “accurate skiing,” “accurate positioning,” “accurate down weight motion,” and “accurate center of gravity shift” were necessary to achieve the highest level of competitive performance. The technical issues that junior female racers faced were “ski manipulation through physical movements dependent on ski performance” and “lack of experience in a variety of situations that lead to improved alpine skiing skills.” To establish the technical elements of top-level racers, the junior period, which is the stage of fine coordination, positioning, and turning movements to create high skiing speeds, was positioned as the instructional aim. The five instructional elements that contributed toward achieving this instructional aim included “skiing operation,” “basic posture,” “leg operation,” “center of gravity movement,” and “improvement of the limit speed.”

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　【Purpose】This study was to compare the lower limb joint angles and center of mass （COM） positions measured by Theia 3D markerless and marker-based motion capture systems.【Methods】Sidebox jumps were performed on 9 healthy adults. Ten video cameras for markerless motion capture and 12 video cameras for optical marker-based motion capture were used for simultaneous recording. We compared the lower limb joint angle and the position of the center of mass （COM） of the body from landing on the right platform to taking off【. Results】The relative reliability of the lower limb joint angle was r = 0.59 to 0.99, and the absolute reliability was less than 3.2°. The relative reliability of COM showed a strong correlation of r = 0.97 to 0.99, and the absolute reliability was less than 1.1 cm.【Conclusion】Very similar measurements were made by the two systems, and the use of Theia 3D markerless motion capture system was used not only for walking but also for sports movements such as jumping and landing and in fields that were previously difficult to perform. It is sugested that measurement is possible.

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　Standard advice for beginner and intermediate snowboarders is to place your weight on the front foot when following the fall line or traversing the slope. This stance is considered best for beginner or intermediate snowboarders who are learning how to shift their center of gravity to the front of the board to turn the nose toward the fall line［ called‘nosedrop’in Japanese］ or to rotate the board when traversing the slope. The purpose of this study is to determine whether this is also the best stance for advanced snowboarders. Our research suggests that when snowboarders make a carving turn, excessive pressure on the forefoot may make it difficult to perform an ideal turn as the tip of the board may cut into the snow surface more than necessary and create more resistance than necessary. In this study, we measured the pressure distribution and center of pressure（ COP） applied to the soles of both feet when the vertical movement was performed while standing straight or leaning forward with respect to the slope. The results showed that the pressure distribution of the forefoot decreased when all subjects moved vertically. In addition, when all subjects moved vertically, the COP moved nearer the center of the stance. The results suggest that it is possible to perform carving turns with less deceleration by standing up vertically, and as a result preventing the tip of the board from digging into the snow surface more than necessary and consequently receiving more resistance from the snow surface than necessary.

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