Yamakawa Keisuke Kobayashi, Shimojo Hirofumi, Takagi Hideki, Sengoku Yasuo
Department of Sport Wellness Sciences, Japan Women's College of Physical Education, Tokyo, Japan.
Department of Health and Sports, Niigata University of Health and Welfare, Niigata, Japan.
Front Sports Act Living. 2022 Apr 15;4:829618. doi: 10.3389/fspor.2022.829618. eCollection 2022.
This study aimed to investigate the changes in kinematics and muscle activity with increasing swimming velocity during underwater undulatory swimming (UUS). In a water flume, 8 male national-level swimmers performed three UUS trials at 70, 80, and 90% of their maximum swimming velocity (70, 80, and 90%V, respectively). A motion capture system was used for three-dimensional kinematic analysis, and surface electromyography (EMG) data were collected from eight muscles in the gluteal region and lower limbs. The results indicated that kick frequency, vertical toe velocity, and angular velocity increased with increasing UUS velocity, whereas kick length and kick amplitude decreased. Furthermore, the symmetry of the peak toe velocity improved at 90%V. The integrated EMG values of the rectus femoris, biceps femoris, gluteus maximus, gluteus medius, tibialis anterior, and gastrocnemius were higher at 90%V than at the lower flow speeds, and the sum of integrated EMGs increased with increasing UUS velocity. These results suggest that an increase in the intensity of muscle activity in the lower limbs contributed to an increase in kick frequency. Furthermore, muscle activity of the biceps femoris and gastrocnemius commenced slightly earlier with increasing UUS velocity, which may be related to improving kick symmetry. In conclusion, this study suggests the following main findings: 1) changes in not only kick frequency but also in kicking velocity are important for increasing UUS velocity, 2) the intensity of specific muscle activity increases with increasing UUS velocity, and 3) kick symmetry is related to changes in UUS velocity, and improvements in kick symmetry may be caused by changes in the muscle activity patterns.
本研究旨在调查在水下波动式游泳（UUS）过程中，随着游泳速度增加，运动学和肌肉活动的变化情况。在水槽中，8名男性国家级游泳运动员分别以其最大游泳速度的70%、80%和90%进行了三次UUS试验（分别为70%V、80%V和90%V）。使用运动捕捉系统进行三维运动学分析，并从臀区和下肢的八块肌肉收集表面肌电图（EMG）数据。结果表明，踢腿频率、垂直脚趾速度和角速度随着UUS速度的增加而增加，而踢腿长度和踢腿幅度则减小。此外，在90%V时，峰值脚趾速度的对称性得到改善。股直肌、股二头肌、臀大肌、臀中肌、胫骨前肌和腓肠肌的肌电图积分值在90%V时高于较低流速时，且肌电图积分总和随着UUS速度的增加而增加。这些结果表明，下肢肌肉活动强度的增加有助于踢腿频率的提高。此外，随着UUS速度的增加，股二头肌和腓肠肌的肌肉活动开始时间略有提前，这可能与改善踢腿对称性有关。总之，本研究得出以下主要结论：1）不仅踢腿频率的变化，而且踢腿速度的变化对于提高UUS速度都很重要；2）特定肌肉活动的强度随着UUS速度的增加而增加；3）踢腿对称性与UUS速度的变化有关，踢腿对称性的改善可能是由肌肉活动模式的变化引起的。
