Gonjo Tomohiro, Fernandes Ricardo J, Vilas-Boas J Paulo, Sanders Ross
Department of Physical Performance, Norwegian School of Sport Sciences, Oslo, Norway.
Institute for Sport, Physical Education & Health Sciences, The University of Edinburgh, Edinburgh, Scotland, UK.
Sports Biomech. 2023 Dec;22(12):1590-1601. doi: 10.1080/14763141.2021.1921835. Epub 2021 May 19.
The purpose of the present study was to investigate differences between front crawl and backstroke swimming in hydrodynamic (produced by swimmers) and buoyant torque around the transverse axis. Ten swimmers performed 50 m front crawl and backstroke at four selected velocities (same velocities for both techniques). All trials were recorded by four underwater and two above-water cameras to collect data for three-dimensional whole-body motion during one stroke cycle (defined as a period between two consecutive wrist entries to the water). The inverse dynamics approach was applied to obtain buoyant and hydrodynamic torque around the transverse axis. The differences between front crawl and backstroke techniques across four levels of velocity were assessed with a two-way repeated-measures ANOVA. There was a main effect of technique on the mean buoyant and hydrodynamic torque, with 30-40 % larger leg-raising buoyant torque and leg sinking hydrodynamic torque in front crawl than in backstroke ( ≤ 0.001). The time-series data revealed that the hydrodynamic leg-sinking torque had its peaks during the first half of the underwater upper-limb motion in front crawl, but that was not observed in backstroke, implying that the strategy of counterbalancing the buoyant torque is different between the techniques.
本研究的目的是调查自由泳和仰泳在流体动力学（由游泳者产生）以及横轴周围浮力扭矩方面的差异。十名游泳者以四种选定的速度（两种泳姿速度相同）进行50米自由泳和仰泳。所有试验均由四台水下摄像机和两台水上摄像机记录，以收集一个划水周期（定义为两个连续手腕入水之间的时间段）内三维全身运动的数据。采用逆动力学方法获取横轴周围的浮力和流体动力学扭矩。通过双向重复测量方差分析评估自由泳和仰泳技术在四个速度水平上的差异。技术对平均浮力和流体动力学扭矩有主要影响，自由泳中抬腿浮力扭矩和腿部下沉流体动力学扭矩比仰泳大30 - 40%（≤0.001）。时间序列数据显示，自由泳中腿部下沉流体动力学扭矩在水下上肢运动的前半段达到峰值，但仰泳中未观察到，这意味着两种技术平衡浮力扭矩的策略不同。
