以熵探討籃球跳投協調型態之變異
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2007
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跳投為籃球運動重要的技能之一,在越高技能水準的比賽,越顯外線投籃對籃球比賽勝負的重要,因此過去有許多文獻探討投籃動作的變異性,以建構有效的控制或學習投籃技巧的策略,而隨運動行為領域與動力系統的發展,由多肢段產生的協調形態,肢段間相互的複雜關係與其變異性更引發研究者們的興趣。
本研究的跳投動作定義為從膝關節角度最小值至腕關節最大角速度為止的動作過程,共招募七位超級籃球聯賽(SBL)現役球員(年齡 (y):22.8 ± 1.2,身高 (cm):185 ± 10.1,體重 (kg):86.1 ± 10.8,球齡 (y):8.8 ± 1.7),使用Phasespace動態光點擷取系統 (480Hz) 與兩部數位攝影機 (JVC, 30Hz),共蒐集單手跳投500次、其中一實驗參與者1500次跳投的動作進行相對相位、訊息熵及相互訊息的比較。
用於分析之資料總命中率為78.6%,結果顯示籃球跳投動作時,關節最大角速度出現順序為髖→膝→踝→肩-肘→腕關節,且準備起跳到身體騰空之前,膝-踝關節有最穩定的相對相位,同時相互訊息達到最高值,顯示此時膝-踝關節產生緊密的連結,相同的情形出現在肩-肘關節最大角速度時,所以在上肢開始要產生投籃動作,肩-肘關節也為一組連結,雖然其餘關節在各實驗參與者之間皆不一致,顯示在高水準的選手中跳投動作有不同的協調型態的變異現象,因此,跳投動作除了肩-肘、膝-踝之間的穩定之外,並無特定的動作形式,要能將個體產生的協調練習至穩定,可能是提高命中率的要點之一。
Basketball is a popular game in Taiwan and it is also an essential activity in physical education courses from elementary to senior high school. The basic skills of basketball include dribbling, passing, lay-ups and shooting. Allsen pointed out that approximately 67% of the shots during the games were jump shots, suggesting that jump shots are important in basketball games. However, jump shot is a multi-segment movement, control of this multi-segment movement is important for shooting accuracy. The movement degeneracy plays an important role in performing multi-segmental coordination. There were 7 participants who are playing in SBL recruited for this study (age (y):22.8 ± 1.2,height (cm):185 ± 10.1,weight (kg):86.1 ± 10.8,training year (y):8.8 ± 1.7). Apparatuses for the experiment included the Phasespace system (480 Hz) and two digital cameras (JVC, 30 Hz). The single hand jump shot was used as the experimental task, all participants completed 500 shots a day and one of them performed extra 1000 shots on the other day. Mean of shooting average of analyzed data was 78.6 %, for basketball jump shot, the segmental peak velocities occurred in the order of hip, knee, ankle, shoulder-elbow to the wrist. In terms of relative phase, the most stable performance of the knee-ankle and shoulder-elbow pairs coincide with the peak velocity of one or both of the involved segments which may signify the basis of a successful jump shot performance. There were no other consistent movement pattern observed in the study further provide the evidence of movement degeneracy among highly practiced performers.
Basketball is a popular game in Taiwan and it is also an essential activity in physical education courses from elementary to senior high school. The basic skills of basketball include dribbling, passing, lay-ups and shooting. Allsen pointed out that approximately 67% of the shots during the games were jump shots, suggesting that jump shots are important in basketball games. However, jump shot is a multi-segment movement, control of this multi-segment movement is important for shooting accuracy. The movement degeneracy plays an important role in performing multi-segmental coordination. There were 7 participants who are playing in SBL recruited for this study (age (y):22.8 ± 1.2,height (cm):185 ± 10.1,weight (kg):86.1 ± 10.8,training year (y):8.8 ± 1.7). Apparatuses for the experiment included the Phasespace system (480 Hz) and two digital cameras (JVC, 30 Hz). The single hand jump shot was used as the experimental task, all participants completed 500 shots a day and one of them performed extra 1000 shots on the other day. Mean of shooting average of analyzed data was 78.6 %, for basketball jump shot, the segmental peak velocities occurred in the order of hip, knee, ankle, shoulder-elbow to the wrist. In terms of relative phase, the most stable performance of the knee-ankle and shoulder-elbow pairs coincide with the peak velocity of one or both of the involved segments which may signify the basis of a successful jump shot performance. There were no other consistent movement pattern observed in the study further provide the evidence of movement degeneracy among highly practiced performers.
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Keywords
跳投, 相對相位, 訊息熵, 相互訊息, jump shooting, relative phase, information entropy, mutual information