Koichi Iwai

Difference in contributions to the team’s score in female wheelchair basketball at the 2016 Rio Paralympics by physical capability classification

[Purpose] This study clarified differences in players’ contributions to the team’s score in female wheelchair basketball at the 2016 Rio Paralympics by physical capacity classification, and examined the roles required in the team. [Subjects and Methods] This study used stats (record of play contents) for players who played for more than 20 minutes from the official box scores of all 31 games at the 2016 Paralympics. Players were divided into three groups by physical capacity classification: low, middle, and high. The average stats for each group were compared and the covariance structure was analyzed to determine the role of each group during the game. [Results] Comparisons showed that the higher the class, the higher the value of many stats items. Important elements were defensive rebound, steal, and turnover in the low group; and score, offensive rebound, and turnover in the high group. [Conclusion] Players in the high group have more plays related to the ball. Those in the low group should increase the numbers of steals and defensive rebounds and reduce turnover. High group players are required to have scoring ability, acquire offensive rebound, and reduce turnover.

Contributions to the team score by male wheelchair basketball players with different physical capacities at the Rio 2016 Paralympics

[Purpose] The contributions of male wheelchair basketball players with different capability classifications to the team score at the Rio 2016 Paralympics were evaluated. The roles required for team members belonging to each such classification were determined. [Participants and Methods] Statistics obtained from the official box scores of all 42 games included at the Rio 2016 Paralympics were used in this study. Players who participated for >20 minutes in each game were included in the analysis. Players were divided into 3 groups (low, middle, and high) based on their capability classification. The mean statistical data related to each group were compared, and the covariance structure was analyzed to determine the role of each player group. [Results] Many statistical values were higher in players belonging to the high group. In the high group, the relevant variables were field goals scored, field goals attempted, assists, and turnovers. In the low group, the relevant variables were field goals scored, steals, and turnovers. [Conclusion] Many plays related to the ball depended on the high group. High-group players are required to demonstrate strong scoring ability and to reduce turnovers. Conversely, low-group players should increase the numbers of field goals made, increase steals, and reduce turnovers.

Changes of deleted mtDNA after endurance exercise: response to Dr. Short's letter

1. First, we would like to respond to Dr. Short’s comment that our study was not well controlled. Dr. Short suggested that blood samples should have been collected from the subjects for several days before the start of exercise to ascertain whether or not the level of mtDNA deletion was stable. We agree that this is a very good idea, and we would like to adopt this idea in our next experiment. Dr. Short also stated that it is important to present data to establish the natural variability of this deletion. We would like to present more data regarding this point from our soon-to-be published papers (Iwai et al. 2003b and unpublished data). When physical activity was restricted for a short period of time (3 days) by forced bed rest, the mtDNA deletion was not seen. Furthermore, the mtDNA deletion was seen with 80 W of exercise loading, but not with 40 W of exercise loading (measured by bicycle ergometers). In other words, the threshold value for induction of the mtDNA deletion seems to be between 40 W and 80 W. Due to individual differences in physical fitness, this value of 40 W may not be an accurate expression, but it is nonetheless clear that there is a threshold value for inducing mtDNA deletion. It is also important to point out here that the threshold level of exercise loading for mtDNA deletion is not very high, and it is very likely that physically active people may easily exceed it. Therefore, it will be important to closely monitor the level of activity during the rest periods before and after exercise. However, this will be difficult to do in actual experiments, as study subjects will need to be monitored for a very long period of time. Therefore, as suggested by Dr. Short, it may be more practical to ascertain changes during a rested state. Moreover, Dr. Short stated that the effects of uncontrolled factors (such as infection, diet, menstrual cycle, stress, sleep patterns) on changes in leucocytes were not ruled out. We had also stated in the original paper that the effects of these factors were not investigated in detail, but we would like to mention that none of the participants were smokers or had contracted an infectious disease during the study. 2. Dr. Short commented that there was a lack of actual and quantitative data in the paper, and, in fact, our paper does not contain any quantitative data. This, however, was attributable to the analytic method employed in this study. In the quoted studies (Corral-Debrinski et al. 1992; Cortopassi et al. 1992; Hayakawa et al. 1992), the mtDNA deletion mutation was detected from heart or muscle tissues from elderly subjects or patients with certain diseases. In these individuals, the amount of mtDNA deletion mutation was high, and as a result, it was much easier to quantify. However, in our experiment, only a small amount of mtDNA mutation was detected. Consequently, nested PCR, which is a highly sensitive test, was used to amplify the minute amount of mtDNA mutation and then to detect the mtDNA deletion. It is very difficult to quantify the amount of mtDNA mutation using the nested PCR assay, so please do not interpret the lack of quantitative data in the paper as alack of data. 3. Dr. Short stated that the number of subjects was too small. As stated in item 2, we did not measure Eur J Appl Physiol (2003) 90: 224–225 DOI 10.1007/s00421-003-0898-z