Kuhn Jessica, Legerlotz Kirsten
Institute of Sport Sciences, Humboldt-Universität zu Berlin, Berlin, Germany.
Front Sports Act Living. 2022 Aug 10;4:948034. doi: 10.3389/fspor.2022.948034. eCollection 2022.
The movement of undulatory underwater swimming (UUS), a swimming technique adapted from whales, is mainly limited by human anatomy. A greater ankle joint flexibility could improve the imitation of the whale's flap of the fin and therefore enhance USS performance. The aim of this study was to investigate the impact of ankle joint flexibility on swimming velocity and kick efficiency during UUS by comparing kinematics of swimming trials with reduced, normal, and enhanced maximum angles of plantar flexion. Ten well trained swimmers (5m and 5f; 22 ± 4years; 177 ± 7cm; 74 ± 15kg), performed multiple trials of UUS with normal, restricted, and increased ankle joint flexibility on two separate days in randomized order. Kick frequency was controlled by a metronome. Plantar flexion (PF) was restricted by tape application on both feet and increased by passive-dynamic stretching. All trials were filmed. Kinematics were obtained with two-dimensional motion analysis. Tape application restricted maximum PF by 10.42% while stretching increased PF by 6.87% compared to normal PF. Swimming velocity and kick efficiency significantly decreased during swimming with restricted PF (1.13 ± 0.13ms; 0.69 ± 0.09m) compared to normal (1.20 ± 0.14 ms; 0.72 ± 0.10m) and increased (1.22 ± 0.15ms; 0.73 ± 0.10m) PF. Swimming velocity and kick efficiency did not differ between normal and increased PF. Body height normalized swimming velocity correlated significantly with PF angle ( = 0.538). The results suggest that UUS velocity is affected by impaired PF. Particularly swimmers with low or average maximum PF angles may benefit from a long-term ankle joint flexibility program to improve their UUS performance.
波动式水下游泳（UUS）是一种借鉴鲸鱼的游泳技术，其动作主要受人体解剖结构的限制。更大的踝关节灵活性可以改善对鲸鱼鳍部摆动的模仿，从而提高波动式水下游泳的表现。本研究的目的是通过比较跖屈最大角度减小、正常和增大时的游泳试验运动学，来探究踝关节灵活性对波动式水下游泳时游泳速度和踢水效率的影响。十名训练有素的游泳者（5名男性和5名女性；年龄22±4岁；身高177±7厘米；体重74±15千克），在两天内以随机顺序对踝关节灵活性正常、受限和增加的情况进行了多次波动式水下游泳试验。踢水频率由节拍器控制。通过在双脚上粘贴胶带限制跖屈，并通过被动动态拉伸增加跖屈。所有试验均进行了拍摄。通过二维运动分析获得运动学数据。与正常跖屈相比，粘贴胶带使最大跖屈受限10.42%，而拉伸使跖屈增加了6.87%。与正常（1.20±0.14米/秒；0.72±0.10米）和增大（1.22±0.15米/秒；0.73±0.10米）跖屈相比，受限跖屈游泳时游泳速度和踢水效率显著降低。正常和增大跖屈之间的游泳速度和踢水效率没有差异。身高标准化的游泳速度与跖屈角度显著相关（r = 0.538）。结果表明，波动式水下游泳速度受跖屈受损的影响。特别是最大跖屈角度较低或中等的游泳者，可能会从长期的踝关节灵活性训练计划中受益，以提高他们的波动式水下游泳表现。
