Quantitative Analysis of Elite Giant Slalom Turn Technique Using Broadcast Video Images and 3D CAD Model Matching

This study aimed to quantitatively analyze giant slalom turn kinematics using a video-based three-dimensional computer-aided design (3D CAD) model-matching method. The analyzed skiers included the top five finishers (WT) and one top-ranked Japanese elite skier (JP). Broadcast competition footage was analyzed to estimate the ski edging angle, center of mass (COM) position, and knee joint and hip joint angle during the turning motion. One turn cycle was divided into five phases: neutral position (NP), edging start (ES), load start (LS), turn maximum (TM), and edging finish (EF). Phase durations and kinematic variables were compared descriptively. JP demonstrated a longer total turn duration than WT, particularly during the LS–TM phase. During the NP–ES phase, WT elevated the COM while simultaneously shifting it inward, whereas JP lowered the COM. JP demonstrated greater hip and knee flexion during the early turn phase compared with WT. This study demonstrates the feasibility of extracting quantitative kinematic information from broadcast competition footage using a 3D CAD model-matching approach. The findings suggest that differences in COM and lower-limb movements may reflect different turning movement strategies. Because only one Japanese elite skier was analyzed, the findings should be interpreted as exploratory observations and cannot be generalized to all Japanese alpine skiers.