Faculty of Sport Science, Burapha University, Chonburi 20131, Thailand.
Centre of Research, Education, Innovation and Intervention in Sport (CIFI2D) and Porto Biomechanics Laboratory (LABIOMEP-UP), Faculty of Sport, University of Porto, 4099-002 Porto, Portugal.
Int J Environ Res Public Health. 2021 Feb 14;18(4):1858. doi: 10.3390/ijerph18041858.
We compared the hydrodynamic characteristics and pull-out strategies of four backstroke-to-breaststroke turning techniques in young swimmers. Eighteen 11 and 12-year-old swimmers participated in a 4 week intervention program including 16 contextual interference sessions. The hydrodynamic variables were assessed through inverse dynamics, and the pull-out strategy kinematics were assessed with tracking markers followed by 12 land cameras and 11 underwater cameras. Swimmers randomly completed sixteen 30 m maximal backstroke-to breaststroke-open, somersault, bucket and crossover turns (four in each technique) with a 3 min rest. The data showed higher drag force, cross-sectional area and drag coefficient values for the first (compared with the second) gliding position. The crossover turn revealed the highest push-off velocity (2.17 ± 0.05 m·s), and the somersault turn demonstrated the lowest foot plant index (0.68 ± 0.03; 68%), which could have affected the first gliding, transition and second gliding depths (0.73 ± 0.13, 0.86 ± 0.17 and 0.76 ± 0.17 m). The data revealed the consistency of the time spent (4.86 ± 0.98 s) and breakout distance (6.04 ± 0.94 m) among the four turning techniques, and no differences were observed between them regarding time and average velocity up to 7.5 m. The hydrodynamic characteristics and pull-out strategy of the backstroke-to-breaststroke turns performed by the age group swimmers were independent of the selected technique.
我们比较了四种仰泳转蛙泳转身技术在年轻游泳运动员中的流体力学特征和出水策略。18 名 11 岁和 12 岁的游泳运动员参加了一个为期 4 周的干预计划，包括 16 个情境干扰课程。通过反向动力学评估流体动力学变量，通过跟踪标记评估出水策略运动学，然后使用 12 个陆地摄像机和 11 个水下摄像机。游泳运动员随机完成了 16 次 30 米最大仰泳-蛙泳-开放式、翻滚、桶式和交叉式转身（每种技术各 4 次），每次休息 3 分钟。数据显示，第一次（与第二次相比）滑行位置的阻力、截面积和阻力系数较高。交叉式转身显示出最高的蹬离速度（2.17 ± 0.05 m·s），而翻滚式转身显示出最低的脚植指数（0.68 ± 0.03；68%），这可能影响了第一次滑行、过渡和第二次滑行的深度（0.73 ± 0.13、0.86 ± 0.17 和 0.76 ± 0.17 m）。数据显示，四种转身技术的出水时间（4.86 ± 0.98 s）和出水距离（6.04 ± 0.94 m）保持一致，在出水时间和平均速度达到 7.5 m 之前，四种转身技术之间没有差异。年龄组游泳运动员进行的仰泳转蛙泳转身的流体力学特征和出水策略与所选技术无关。
