ORCID Profile
0000-0001-8797-7014
Current Organisation
University of Tsukuba
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Publisher: Informa UK Limited
Date: 23-12-2015
Publisher: Informa UK Limited
Date: 23-08-2021
Publisher: Informa UK Limited
Date: 12-11-2021
Publisher: Elsevier BV
Date: 12-2014
DOI: 10.1016/J.HUMOV.2014.09.003
Abstract: The goal of this research is to clarify the mechanism by which unsteady forces are generated during sculling by a skilled swimmer and thereby to contribute to improving propulsive techniques. We used particle image velocimetry (PIV) to acquire data on the kinematics of the hand during sculling, such as fluid forces and flow field. By investigating the correlations between these data, we expected to find a new propulsion mechanism. The experiment was performed in a flow-controlled water channel. The participant executed sculling motions to remain at a fixed position despite constant water flow. PIV was used to visualize the flow-field cross-section in the plane of hand motion. Moreover, the fluid forces acting on the hand were estimated from pressure distribution measurements performed on the hand and simultaneous three-dimensional motion analysis. By executing the sculling motion, a skilled swimmer produces large unsteady fluid forces when the leading-edge vortex occurs on the dorsal side of the hand and wake capture occurs on the palm side. By using a new approach, we observed interesting unsteady fluid phenomena similar to those of flying insects. The study indicates that it is essential for swimmers to fully exploit vortices. A better understanding of these phenomena might lead to an improvement in sculling techniques.
Publisher: Informa UK Limited
Date: 27-09-2019
DOI: 10.1080/14763141.2019.1654536
Abstract: The purpose of this study was to establish the asymmetry and body wave characteristics related to shoulder, hip, knee, and ankle roll in unilateral arm utee swimmers. Three unilateral arm utee swimmers, including one Paralympic medallist (swimmer A), volunteered in this study. They conducted two 10-15 s front crawl tests with sub-maximum and maximum speeds in a flume. Shoulder, hip, knee, and ankle roll litude and progression of a torsional body wave was quantified using a motion capture system and a Fourier analysis. Swimmer A showed 50% higher stroke frequency than the other swimmers. Swimmers achieved larger shoulder roll litude towards the affected than the unaffected side by 19-89%. Swimmer A showed body wave velocity slowing down when it travelled caudally, while national level swimmers presented increasing wave velocity, suggesting that swimmer A had a less effective kicking than the other swimmers. In conclusion, the technique of the unilateral arm utee swimmers was characterised by a large shoulder roll angle towards the affected side. The Paralympic medallist had larger shoulder roll asymmetry and less effective kicking than the other swimmers and yet achieved higher swimming speed because of his high stroke frequency.
No related grants have been discovered for Hideki Takagi.