We evaluate the performance of J-league players using data envelopment analysis (DEA) in order to try to identify player characteristics from the standpoint of efficiency. We use time played as the input and the numbers of ten basic plays or actions such as goals, assists, crosses, passes, dribbles, tackles, interceptions, clears, blocks and fouls as output. We then analyse the performance of J-league field players using data from the 2008 season based on the CCR (Charnes-Cooper-Rhodes) model. In this analysis, we evaluate field players by position, i.e. forwards, midfielders and defenders, and discuss their characteristics in reference to their efficiency scores, virtual input and output values, reference sets, and their targets for improvement.

The activity profiles of field-based team sports players (e.g. soccer, handball, and basketball) fluctuate randomly depending on game situation, from brief periods of maximal or near maximal intensity to longer periods of low-intensity activity. On the other hand, the activity patterns of track athletes are nearly constant. The purpose of this study was to compare the characteristics of physical fitness for field-based team sports players, endurance runners and sprinters from the viewpoint of energy supply during intermittent sprint exercise. Twenty-four university-trained males (field-based team sports players: F; n = 8, endurance runners: E; n = 8 and sprinters: S; n = 8) completed an intermittent sprint exercise test. The test consisted of three 5 × 30m (every 40s) repeated-sprints, with sprints separated by a 4-min rest period. Sprint times were recorded during intermittent sprint exercise test from 0-15m, 15-30m, and 0-30m by electronic photo cells. Oxygen uptake (VO₂), minute ventilation (VE), heart rate (HR), and blood lactate concentration (La) were also measured during the test. An incremental treadmill test and a 40s anaerobic power test were also performed to determine maximal aerobic and anaerobic capacities. The F group had a significantly faster 0-15m sprint time than E (P < 0.05), but not when compared with the S group; while, the F group had a signifi cantly slower 15-30m sprint time than the S group (P < 0.05). The F group also had a significantly lower La during intermittent sprint exercise test than the S group (P < 0.05), but not when compared with the E group. In contrast, VO₂ during intermittent sprint exercise test in the interval phase showed no significant differences among the groups. Although no significant differences were observed, lower La indicated a sufficient phosphocreatine resynthesis in the interval phase in the F and E groups. These fi ndings showed that the F group performed the repeated-sprint as fast as the S group from 0-15m with lower anaerobic energy supply. Furthermore, the results suggested the need for regular implementation of repeated-sprints in the F group. In conclusion, field-based team sports players have superior repeated-sprint ability than sprinters, especially over short distances

The purpose of this study was to analyze the world top-level matches after 2009 and to clarify the characteristic of game aspects of sevens rugby through the comparison with 15-a-side rugby game. The main results showing the feature of sevens rugby game were as follows. 1) Try scoring rate per play was higher, and all scores were occupied by the try and conversion afterwards. 2) The average out-of-play time was about 15 seconds shorter though the average in-play time was about 10 seconds shorter, so the time for recovery during the game was limited. 3) The rate of tries in the attacking area of 22m to GL was lower, while a higher value of almost one third was indicated in the own area back from 10m. 4) The rate of tries from lineout possession was lower and 10%, while a higher value of 25% was marked respectively from PK and turnover possession. 5) Frequency of occurrence of kick-off and 50m restart kick was highest in all set plays and the rate of tries from the possession was higher. These results suggested sevens rugby to be a different game from 15-a-side rugby clearly, and to have to develop the original strategy, skill, and training method of sevens.

The purpose of this study was to clarify the influence of the short-term intensive dribbling training (DRI-TR) on ball skill. Subjects were 43 eighth-grade soccer players; 20 in a training (TR) group, and 23 in a control (CONT) group. The ball skill test, which consisted of a dribbling test, trapping test and passing test, was carried out before and after each group’s training. The items measured in the dribbling test and trapping test were time, number of ball touches, and missed touches. The item measured in the passing test was the number of successful passes. The TR group performed DRI-TR for 14 weeks. Training took place three times per week for approximately 30 min after the usual two-hour team training started. After DRI-TR, the TR group followed their usual training program, which had individual, group, or team focus. The CONT group also followed their usual training with individual, group, or team emphases for two-hour per session approximately four times per week over 14 weeks. The results showed that after 14 weeks of training the time needed in the dribbling test and trapping test decreased significantly for the TR group (p<0. 05), but did not decrease for the CONT group. The number of ball touches and missed touches in the dribbling test and the trapping test for the TR group also decreased (p<0. 05) , while the number of successful passes in the passing test for both groups did not increase in spite of the 14 weeks of training. Consequently, this study clarified that DRI-TR intended for soccer players in the eighth grade caused improvement of dribbling and trapping skills, but hardly affect passing skill.

Since the 1990’s, there have been many research studies that focus on career transitions for professional athletes in Japan. The main reason for this is that during that period, amateur sports teams, such as soccer and basketball, were spun off from divisions of companies to become separate professional teams. Consequently, this changed forced how athletes view the transition to a second career because they can no longer count on being employed by the companies that had previously run teams as part of their corporate operations. Research studies primarily covered top athletes but did not distinguish between the amateur and professional athletes. In reviewing the assumptions and results of such previous research with respect to professional status, this study will present the basic themes of such research. For example, early research investigated the actual reasons why and how athletes decide to change career; whereas later research seek to study how athletes specifically deal with career changes. Finally, in order to determine the effectiveness of actual support programs, the authors of this study proposes that more thorough investigation is needed to scrutinize how the career transitions of ex-professional football players have changed over time by using a “longitudinal” analysis.

The purpose of this study was to determine the effect of two different dosages of BCAA supplementation on muscle damage in conjunction with a lower-body resistance exercise bout in soccer players. 30 male soccer players participated in a double blinded designed study conducted during exercise protocol. All subjects in a randomized and double-blind design were divided into three groups. All subjects were participated in lower- body resistance exercise bout (6 sets, 10 repetitions, 70% 1RM). The BCAA was given at doses of 200, 450 mg.kg^-1 BW for supplemental groups 1 and 2, respectively, 30 minutes before and after to exercise tests and carbohydrate (dextrin) was given at dose of 200 mg.kg^-1 BW for placebo group. To identify enzymes activity (IU/L), venous blood samples were obtained 30 minutes prior to exercise and at 24 and 48 hours post exercise. Data were statistically analyzed using 2-way repeated measure ANOVA and Bonfferoni test. Baseline CK and LDH were determined 30 minutes before the exercise test. Baseline serum values for CK, LDH were not different between groups. However there were significant increases (p< 0.05) between the pre exercise and post exercise values for CK, LDH from 24 hours to 48 hours posttest, but there were no significant differences between two groups (p< 0.05).

These results suggested that two different dosages BCAA supplementation did not affect muscle damage during lower- body resistance exercise bout 48 hours later in soccer players.

American football is an intense contact sport, and a lot of injuries occur in both games and practices. A constructive injury report system has been established within the National Collegiate Athletic Association (NCAA) and many changes and modifi cations to the NCAA rules on football have been made as a result of these longitudinal data. However, there are few longitudinal studies that include detailed data on American football injuries in Japan. The purpose of this study is to ascertain the characteristics of collegiate American football injuries in both games and practices in Japan based on longitudinal data. The subjects were 523 students who played American football at T University from 1999 to 2008. 790 collegiate American football-related injuries were reported. The game injury rate (GIR: 43.4/1,000 athlete-exposures (A-Es)) was more than 6 times higher than the practice injury rate (PIR: 6.6/1,000A-Es) (χ² =25.9, P<0.05), although the PIR was much higher than that for the NCAA. Injuries to the lower extremities such as sprained knees and ankles as well as muscle-tendon strains in both games and practices are very common. In conclusion, we should consider the intensity and quantity of running programs and the change in the guidelines with respect to the contact in scrimmages to reduce the PIR.