Youlian Hong and Yuenzhen Lu
Youlian Hong, Paul D. Robinson and Wan Ka Chan
The purpose of this paper was to profile game strategy used by world’s top female squash players in international competitions using postevent notational analysis methods. A total of 10 matches from the Ladies Hong Kong Open 1993 and 1994 were selected for analysis. A total of 15 right-handed competitors, who were ranked in the top 15 in the world at that time, were involved in the matches. Matches were played under the International scoring system. A 3-CDD video camera, positioned behind the court, was used to record the player’s performance throughout the matches. Frame-by-frame video notation was used to record the player, the kind of stroke, the position where the stroke was made, and the success or failure of that stroke. Shots were classified as “effective”, “ineffective”, “winning” and “losing” shots. Statistics show that the mean number of games per match was 4, rallies per game was 13.57 and shots per rally was 12.44. Of all the shots, 57.13% were “effective”, 31.36% were “ineffective”, 6.24% were “winning” and 5.27% were “losing” shots. Over half (62.01%) of all shots played were the drive, followed by drop (18.20%), volley (11.23%), boast (5.06%) and lob (3.50%). Of all shots played, 43.81% were in the back left court, 32.66% in the back right court, 13.04% in the front left court, and 10.49% in the front right court, showing that these right-handed players preferred to attack the backhand of the opponent. The drive (45.9%) was found to provide the greatest contribution shots to winning scores, with the next greatest being the drop (27.9%), then the volley (20.2), the boast (5.6%) and, finally, the lob (0.5%). Almost an equal number of cross-court shots and straight shots were played. In an average game, the winner played 50% more winning shots than the losing player, showing that in high level competition of female squash, the attacking shots, which produce the most winning scores, are required for success.
Shiu Hong Wong, Tianjian Ji, Youlian Hong, Siu Lun Fok and Lin Wang
The low impact forces of Tai Chi push-hand exercises may be particularly suited for older people and for those with arthritis; however, the biomechanics of push-hand exercises have not previously been reported. This paper examines the ground reaction forces (GRFs) and plantar force distributions during Tai Chi push-hand exercises in a stationary stance with and without an opponent. Ten male Tai Chi practitioners participated in the study. The GRFs of each foot were measured in three perpendicular directions using two force plates (Kistler). The plantar force distribution of each foot was measured concurrently using an insole sensor system (Novel). The results showed that the average maximum vertical GRF of each foot was not more than 88% ± 6.1% of the body weight and the sum of the vertical forces (103% ± 1.4%) generated by the two feet approximately equals the body weight at any one time. The horizontal GRFs generated by the two feet were in the opposite directions and the measured mean peak values were not more than 12% ± 2.8% and 17% ± 4.3% of the body weight in the medio-lateral and antero-posterior directions respectively. Among the nine plantar areas, the toes sustained the greatest plantar force. This study indicates that push-hand exercises generate lower vertical forces than those induced by walking, bouncing, jumping and Tai Chi gait, and that the greatest plantar force is located in the toe area, which may have an important application in balance training particularly for older adults.
Youlian Hong, Shao Jun Wang, Wing Kai Lam and Jason Tak-Man Cheung
The lunge is the most fundamental skill in badminton competitions. Fifteen university-level male badminton players performed lunge maneuvers in four directions, namely, right-forward, left-forward, right-backward, and left-backward, while wearing two different brands of badminton shoes. The test compared the kinetics of badminton shoes in performing typical lunge maneuvers. A force plate and an insole measurement system measured the ground reaction forces and plantar pressures. These measurements were compared across all lunge maneuvers. The left-forward lunge generated significantly higher first vertical impact force (2.34 ± 0.52 BW) than that of the right-backward (2.06 ± 0.60 BW) and left-backward lunges (1.78 ± 0.44 BW); higher second vertical impact force (2.44 ± 0.51 BW) than that of the left-backward lunge (2.07 ± 0.38 BW); and higher maximum anterior-posterior shear force (1.48 ± 0.36 BW) than that of the left-backward lunge (1.18 ± 0.38 BW). Compared with other lunge directions, the left-forward lunge showed higher mean maximum vertical impact anterior-posterior shear forces and their respective maximum loading rates, and the plantar pressure at the total foot and heel regions. Therefore, the left-forward lunge is a critical maneuver for badminton biomechanics and related footwear research because of the high loading magnitude generated during heel impact.