Kinugasa Ryuta, Kubo Shimpei, Endo Keiko
Faculty of Human Sciences, Kanagawa University, Yokohama, Japan.
Front Sports Act Living. 2021 Jul 27;3:694989. doi: 10.3389/fspor.2021.694989. eCollection 2021.
From a biomechanical viewpoint, no longitudinal quantitative studies have been conducted on inexperienced paddlers. The present study aimed to investigate changes in three-dimensional paddling kinetics and kinematics, whole-body kinematics, and muscle activity with four-week on-water kayak training in a novice paddler. The participant practiced kayak paddling on river for four weeks. Before and after training, paddling kinetics and kinematics, body kinematics, and electromyography (EMG) activity were measured using a kayak ergometer. After the four-week training, the time required for on-water paddling for 270 m was reduced by 7.3% from pre to post training, while the average impulse in the x-direction significantly ( < 0.001, partial eta squared [η] = 0.82) increased from 71.9 ± 1.9 to 91.1 ± 5.4 N kg s. Furthermore, with training, the stroke rate and stroke length in the x-direction significantly ( < 0.001, partial η = 0.80 and 0.79, respectively) increased from 62.8 ± 1.2 to 81.0 ± 2.9 spm and from 1.53 ± 0.04 to 1.71 ± 0.02 m, respectively. After training, the transition time significantly ( < 0.001, partial η = 0.32) decreased (from 0.04 ± 0.01 to 0.01 ± 0.01 s), and there was an increase in paddle catch position (from -0.88 ± 0.01 to -1.04 ± 0.03 m). The pull time was not significantly changed ( = 0.077, partial η = 0.08) because of the increasing stroke length after training, meaning that substantial pull time, which defined as pull time relative to the stroke displacement, was shorter in post-training than in pre-training. The relative change in average impulse in the x-direction with training was significantly ( = 0.857, = 0.014) correlated with that of vastus lateralis EMG. These results indicated that after four-week kayak training of the novice paddler, the key mechanism underlying time reduction to perform on-water paddling for 270 m was associated with (1) increased average impulse along the propulsive direction caused by an increase in vastus lateralis EMG and (2) a higher stroke rate, which was attributed to a reduction in the pull and transition times.
从生物力学的角度来看，尚未对缺乏经验的划桨者进行纵向定量研究。本研究旨在调查一名新手划桨者经过四周水上皮划艇训练后，三维划桨动力学和运动学、全身运动学以及肌肉活动的变化。参与者在河流上进行了四周的皮划艇划桨练习。在训练前后，使用皮划艇测力计测量划桨动力学和运动学、身体运动学以及肌电图（EMG）活动。经过四周的训练，水上划桨270米所需的时间从训练前到训练后减少了7.3%，而x方向的平均冲量显著增加（<0.001，偏η² = 0.82），从71.9±1.9增加到91.1±5.4 N·kg·s。此外，通过训练，x方向的划桨频率和划桨长度显著增加（<0.001，偏η分别为0.80和0.79），分别从62.8±1.2增加到81.0±2.9次/分钟和从1.53±0.04增加到1.71±0.02米。训练后，转换时间显著减少（<0.001，偏η = 0.32）（从0.04±0.01减少到0.01±0.01秒），并且划桨抓水位置增加（从-0.88±0.01增加到-1.04±0.03米）。由于训练后划桨长度增加，拉桨时间没有显著变化（= 0.077，偏η = 0.08），这意味着相对于划桨位移定义的有效拉桨时间在训练后比训练前更短。x方向平均冲量随训练的相对变化与股外侧肌EMG的相对变化显著相关（= 0.857，= 0.014）。这些结果表明，新手划桨者经过四周的皮划艇训练后，水上划桨270米时间减少的关键机制与以下因素有关：（1）股外侧肌EMG增加导致推进方向上的平均冲量增加；（2）划桨频率提高，这归因于拉桨和转换时间的减少。
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