The Study of Utilizing Ratio of Countermovement Jump and Dynamics of Lower Extremity During Swimming Grab Start

• Main Authors: Ching-Wen Lee, 李靜雯
• Other Authors: Chenfu Huang
• Format: Others
• Language: zh-TW
• Published: 2004
• Online Access: http://ndltd.ncl.edu.tw/handle/06142378749765368748

博士 === 國立臺灣師範大學 === 體育學系 === 92 === The start is one of the important factors in swimming competitions. Especially, the swimmers in sprints have to pay more attention to the training of the start to gain more benefits. There was twofold in the purpose of this study. First, to investigate the utilizing ratio of countermovement jump applying in grab start in order to estimate its performance. Second, to understand the specific muscular strength in swimming grab start to schedule the training program. Ten male elite competitive swimmers were asked to participate in this study. The subjects data showed that: Ages 19 ± 2.6 yr, body weights 67.6 ± 5.1 kg, body heights 1.76 ± 0.04 m and 50m freestyle 25.15 ± 1.25s (mean ± S.D.). Redlake high speed cameras (250Hz), force plate (500Hz) and JVC camera (120Hz) were used simultaneously to record the process of entire movement. The analyzed system used in this study were Peak Motus 7.0 and Bio Ware softwares. Utilizing ratio, net muscle joint moment, and power were calculated through utilizing ratio function and inverse dynamics method. The results showed that the ranges of average force utilizing ratio (URFa), average power utilizing ratio (URPa), and impulse utilizing ratio (URIa) were 50%~75%, 15%~35%, and 18%~42%, respectively. Knee and hip joints were the main contributing factors to grab start. The pattern of contraction of hip joint in block late phase of grab start were different from the other jumping movements. Due to against to the ground reaction moment, the hip flexors were eccentrically contracted during the block late phase of grab start. The conclusions of this study were: 1. The average force utilizing ratio (URFa) was a reliable parameter for estimating the swimming start performance. Through the method of calculating the average force utilizing ratio, it was easy to understand the level of exerting countermovement jump ability during grab start. 2. Through increasing average forces in extension phase of grab start will improve start performance. 3. It was suggested that athletes should not only practice ankle and knee extensors with concentric contraction, but also should focus on hip flexors eccentric contraction training.