Publication:

以決策樹分析世界級網球選手正拍擊球得分技術

目的：網球屬於開放型的運動，想要贏得一場比賽除了將自身的能力發揮出來，還必須因應對手的打法而作出調整。本文以Roger Federer與Rafael Nadal兩位職業網球選手2007～2019年之對戰影片進行分析，共計10場。方法：採用標記分析，將正拍所有技術的擊球站位與擊球落點兩個變項進行標記，然後使用決策樹分析（classification and regression tree, CART），將所得資料進行分析，並製作網球選手在比賽時正拍技術之模型，以利瞭解Roger Federer與Rafael Nadal兩位網球選手正拍擊球習慣及優缺點。結果：在後場時Roger Federer以站位1打向落點3的次數最高，Rafael Nadal則是以站位2打向落點1；進入中場後Roger Federer以站位4打向落點1的次數最高，Rafael Nadal則是以站位3打向落點3。在後場得分Rafael Nadal比Roger Federer多一個落點，為落點6。雙方選手失分前三名為後場正拍站位、後場閃正拍站位、站位4。Roger Federer的贏球數前三組站位與落點為站位1落點3、站位4落點1、站位4落點3；Rafael Nadal為站位2落點1、站位2落點3、站位1落點1跟落點3。雙方選手的正拍最高得分站位與最高失分站位皆相同，Roger Federer為站位1，Rafael Nadal為站位2，雙方選手的正拍總球數得分皆大於失分。結論：兩位選手的最高得失分皆為正拍站位，在後場時雙方正拍得分皆打向對方的正拍為主，進入中場以打向對手反拍為主要得分策略。Roger Federer的贏球站位包括中場與後場，而Rafael Nadal的贏球站位以後場為主，並利用大角度的抽球來增加得分。

Purpose: Tennis is an open skills sport. To win a game, one must not only exert one's abilities but also make adjustments to the opponent's hits accordingly. This study is focused on the analysis of the playing habits of two professional tennis players, Roger Federer and Rafael Nadal. Video recordings of ten matches, from 2007 to 2019, were used for analysis. Methods: Notational analysis is used to mark two identified variables for analysis: all the technical striking positions of forehand shot and landing point of the ball. Classification and regression tree was used to analyze the collected data, and to develop a model for tennis players forehand technique in competition to understand Roger Federer's and Rafael Nadal's batting habits, strengths, and weaknesses. Results: From the back court, Roger Federer uses his forehand shot at striking position 1 and aims to landing point 3 with the highest frequency. In contrast, Rafael Nadal toward landing point 1 by using forehand shot at striking position 2. When both players at the mid court, Roger Federer mostly aims to hit the shot to landing point 1 at striking position 4. On the other hand Rafael Nadal tries to hit the shot to landing point 3 at striking position 3. In terms of the winning shots at back court, Rafael Nadal has one more drop points than Roger Federer namely drop 6. In terms of losing points of forehand shot, both players lost most point by forehand shot at the back court, they ran around the backhands to whip forehand shot, and is batting position 4. In Roger Federer's winning points, first is at striking position 1 towards position 3 at the back court. Second is striking position 4 towards landing 1, and third is at striking position 4 toward landing point 3 at the mid court. As for Rafael Nadal's winning points, first is at striking position 2 towards landing point 1 at the back court. Second is at striking position 1 towards landing point 1. And third is towards landing 3 at the back court. The highest winning points and losing points of both players are at the same striking position. Roger Federer is at striking position 1 and Rafael Nadal is at striking position 2. Both players have the same striking position with highest points by using their forehand shot. Conclusion: Both players tend to strike towards opponents' forehand when they are at the back court, and tend to aim to each other's backhand as main strategy at the mid court. Roger Federer's winning positions include mid court and back court. On the other hand, Rafael Nadals main winning position is at the back court, and he increased the angle of forehand swing to win more points. Both players have the same batting position of highest points by using forehand swing.