The purpose of this study was to compare the difference in spatial control of tennis footwork in relation to the difference of players’ skill level. Intermediate (N=5) and novice (N=4) male tennis players volunteered to take part in this study. Subjects hit a ball ejected from a ball machine with a forehand groundstroke toward straight as fast as possible. At impact, some subjects used open stance, the others used closed stance. Intermediates hit a ball closer to the net and at a higher position than novices. The ball speeds for intermediates were higher than those of novices and intermediates made fewer mistakes than novices. Intermediates using closed stance showed lower standard deviations of the last two foot placements than novices. The significant correlations between an impact position and the last two or three foot placements were observed in intermediates. On the other hand, the significant correlation was found only between an impact position and the last foot placement in novices. These results indicated that intermediates were able to anticipate an impact position earlier and more accurately than novices, and intermediates adjusted their footwork based on their spatiotemporal anticipation.

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The purpose of this study is to analyze the relations between changes in sweating, fluid intake and those in environmental temperature and pool water temperature (PWT) while one is swimming. The subjects were 10 male and 12 female high school students who practiced swimming long distances after school (15:30～18:30) in summer. Their sweating rate (SR), fluid intake (FI), and dehydration (SR－FI, DEH) were measured. The PWT ambient temperature (dry bulb temperature, DBT), and wet bulb globe temperature (WBGT) during swimming were 26.1～31.3℃, 20.8～34.0℃, and 20.3～29.7℃ respectively, which shows that PWT correlated with DBT or WBGT significantly (p＜ 0.001). The mean values of SR during swimming were about the same with males (0.340kg/h) and females (0.347kg/h). However, the mean value of FI in females (0.176kg/h) was lower than that in males (0.243kg/h). The SR, FI, and DEH measured when PWT was higher than 30.0℃ were two times greater than those measured when PWT was lower than 29.9℃. The SR, FI, and DEH significantly (p＜ 0.05 ～ 0.001) correlated with PWT or WBGT, while the correlation coefficients (r) of SR,FI, and DEH with PWT were greater than those with WBIGT. These results suggest that environmental temperatures (WBGT, DBT) are related to the elevation in PWT, and that SR remarkably increases when PWT is higher than 30.0℃. Thus, fluid supply in swimming, is as important as in land exercise, when PWT is over 30.0℃ in summer.

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The purpose of this study was to evaluate the feature of the acting composition seen in present synchronized swimming for challenge person by extracting the actions. We set five elements included in action to record acts of challenge person’s synchronized swimming ― how to supporting body, presence of rotation and the axial direction of rotation, motion of arms and legs, and movement of entire body. And we named a movement that is composed of five elements “action”. We classified actions to three groups to examine whether these actions are similar to original actions in synchronized swimming ― motions that seen in original synchronized swimming (SY), original motion of challenge person’s (CH) and swimming form motion (SW). We find 290 actions in 7 solo acts and named 45 actions. All of action could be recorded by these 45 codes in this study. We recorded acts by using these codes like making dance scores. There were a lot of SY and SY actions were more intentionally more than CH in six of seven solo acts. SY was more than CH and SW in two. CH tends to adopt alternative way in supporting body. This study can be said that the dance score is profitable to record and evaluate act of synchronized swimming for challenge person.

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This study was conducted to analyze situations of the occurrence and causes of injuries in 89 college American football players during the season 2006 at D University. The site, time, and severity (time until recovery) of injuries were investigated, and their relations with the position, grade, and muscle strength were evaluated. About half (46.0%) of the injuries occurred in the lower extremities. Most of the injuries occurred in the middle or late period of the football season. The percentage of football players who sustained injuries (injury rate) varied among grades. The injury rate was higher in backs than in linemen. The mean time until recovery to a playable level after injury was approximately a month (32.4days) for all injuries. Muscle strength was significantly lower in freshmen than in players of other grades. The players who were injured only once during the season showed significantly higher muscle strength than those who were not injured or injured 2 or more times. The injury rate is considered to be directly related to the number of physical contacts but to be also affected in a complex manner by other factors such as cumulative fatigue with an associated decrease in muscle strength, proprioceptive deficit, and psychological pressure. Continuation of weight training throughout the season, restriction of the number of physical contacts, modification of practice methods to avoid cumulative fatigue, and support for players recovering from injuries are considered to be important for the prevention of injuries.

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