Mast pumping techniques, which require large whole-body motions in the sagittal plane, are commonly used in windsurfing to increase board speed in light wind conditions. Previous studies have not addressed the biomechanical characteristics of mast pumping. Therefore, this study examined the profiles of the upper- and lower-limb joint motions during mast pumping and their effects on the boom motion. The three-dimensional motions of the whole body and boom during mast pumping were measured over thirty cycles from eight male collegiate windsurfers, using optical and inertial sensor-based three-dimensional motion capture systems. The intra-individual relationships between boom motion and the joint angle displacement were analyzed using simple linear regression. Time-series data of upper- and lower- limb joint angles showed that flexion-extension motions were synchronized with the motion of the boom. Additionally, intra-individual relationships showed variability in both the slopes and significance levels of the regression lines between participants. These results indicate that the upper- and lower-limb joint motions contributing boom motion would vary among windsurfers during mast pumping. Understanding these variations may help optimize individualized training programs and improve mast pumping techniques in light wind conditions.

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This study aims to develop a myoelectric prosthetic hand socket that adapts to changes in residual limb circumference resulting from variations in physical conditions and user growth. Typically, insufficient contact between the residual limb and the electromyography sensor may reduce the operability of the myoelectric prosthetic hand. Conventional sockets address this issue by deforming to fit the current residual limb circumference; however, such deformation can cause skin pinching, thereby hindering proper socket attachment. To address this issue, this study incorporated a cushioning wire to prevent direct contact between the deformed area and the skin, thus mitigating skin pinching. Evaluation results of the internal pressure measurements, electromyography data acquisition, and user interviews confirmed that the socket effectively adapts to changes in residual limb circumference while reducing the incidence of skin pinching.

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