Cohen Raymond C Z, Cleary Paul W, Harrison Simon M, Mason Bruce R, Pease David L
Computational Informatics, CSIRO, Clayton, VIC, Australia.
J Appl Biomech. 2014 Oct;30(5):609-18. doi: 10.1123/jab.2013-0260. Epub 2014 Jun 30.
The purpose of this study was to determine the pitching effects of buoyancy during all competitive swimming strokes--freestyle, backstroke, butterfly, and breaststroke. Laser body scans of national-level athletes and synchronized multiangle swimming footage were used in a novel markerless motion capture process to produce three-dimensional biomechanical models of the swimming athletes. The deforming surface meshes were then used to calculate swimmer center-of-mass (CoM) positions, center-of-buoyancy (CoB) positions, pitch buoyancy torques, and sagittal plane moments of inertia (MoI) throughout each stroke cycle. In all cases the mean buoyancy torque tended to raise the legs and lower the head; however, during part of the butterfly stroke the instantaneous buoyancy torque had the opposite effect. The swimming strokes that use opposing arm and leg strokes (freestyle and backstroke) had smaller variations in CoM positions, CoB positions, and buoyancy torques. Strokes with synchronized left-right arm and leg movement (butterfly and breaststroke) had larger variations in buoyancy torques, which impacts the swimmer's ability to maintain a horizontal body pitch for these strokes. The methodology outlined in this paper enables the rotational effects of buoyancy to be better understood by swimmers, allowing better control of streamlined horizontal body positioning during swimming to improve performance.
本研究的目的是确定在所有竞技游泳姿势（自由泳、仰泳、蝶泳和蛙泳）中浮力的俯仰效应。在一个新颖的无标记运动捕捉过程中，使用了国家级运动员的激光身体扫描和同步多角度游泳录像，以生成游泳运动员的三维生物力学模型。然后，使用变形表面网格来计算每个划水周期内游泳者的质心（CoM）位置、浮心（CoB）位置、俯仰浮力扭矩和矢状面转动惯量（MoI）。在所有情况下，平均浮力扭矩倾向于抬高腿部并降低头部；然而，在蝶泳的部分阶段，瞬时浮力扭矩具有相反的效果。使用相对的手臂和腿部划水动作的游泳姿势（自由泳和仰泳）在CoM位置、CoB位置和浮力扭矩方面的变化较小。左右手臂和腿部同步运动的姿势（蝶泳和蛙泳）在浮力扭矩方面的变化较大，这影响了游泳者在这些姿势中保持身体水平俯仰的能力。本文概述的方法使游泳者能够更好地理解浮力的旋转效应，从而在游泳过程中更好地控制流线型水平身体姿势，以提高成绩。
