Purpose: Multiple regression equations that estimate the maturity offset for peak height velocity (PHV) have been used in studies regarding adolescents. However, to estimate the maturity of a Japanese population with characteristic proportions, a multiple regression equation developed using a sample of Japanese adolescents is necessary. This study aimed to develop a multiple regression equation that estimates the maturity offset for PHV that can be used for Japanese youth. Methods: Morphometry data of individuals (207 males and 209 females) aged 6 to 18 years were collected. Age at PHV was calculated from the change in the height of each individual, and a multiple regression equation was developed using morphometric data at each age (height, sitting height, lower limb length, and weight) and chronological age. The newly-developed multiple regression equation was compared with a previously-reported equation to determine if it is suitable for Japanese youth. Results: The coefficient of determination (R²) of the multiple regression equation was 0.948 for boys and 0.930 for girls. The differences between the estimated and measured maturity offsets obtained from the multiple regression equation in this study were −0.09 ± 0.81 years for boys and −0.28 ± 0.95 years for girls. In contrast, the differences between the estimated and measured maturity offsets obtained in previous studies were −1.25 ± 1.17 years for boys and −3.40 ± 1.59 years for girls. Conclusion: The newly-developed multiple regression equation is more accurate than previously-reported equations and accurately estimates the maturity offset of Japanese youth in a reliably and practically.

This study investigated the association between nutritional intake and indices of muscle mass or strength in 104 female Japanese university students who participated in sports activities during their junior and senior high school periods and had a high current physical activity level (PAL). Body composition was measured by the bioelectrical impedance method, and appendicular muscle mass (AMM) and skeletal muscle mass index (SMI) were evaluated as muscle mass. PAL was estimated using a factorial method and nutritional intake status was investigated using a food frequency questionnaire based on food groups (FFQg). Grip strength was measured as an index of muscle strength. According to the criteria for diagnosis of sarcopenia, four of the participants had low muscle mass and one also had low grip strength. Although there were no significant differences in body size or grip strength between participants with a high versus low SMI, participants with a low SMI had a significantly higher percentage of body fat (27.7 ± 4.7% vs. 23.3 ± 4.1%), and significantly lower AMM (16.0 ± 1.4 kg vs. 20.6 ± 1.5 kg), total energy intake (1770.4 ± 386.5 kcal/d vs. 2017.1 ± 389.9 kcal/d), and protein intake (57.3 ± 15.0 g/d vs. 67.0 ± 14.2 g/d), as well as a tendency to have a significantly lower carbohydrate intake (239.6 ± 49.3 g/d vs. 268.1 ± 54.4 g/d), than those with a high SMI. These results indicate that even some female university students with a high PAL have a lower muscle mass and might have a low dietary intake, mainly protein and carbohydrate. The results of multiple regression analysis of AMM, SMI, or grip strength with PAL and nutrient intake revealed that PAL and total energy intake or protein intake were significantly and positively associated with muscle mass and strength. These results suggest that a high PAL as well as total energy intake and protein intake among the macronutrients contribute to high muscle mass and muscle strength in young women.

Objective: This study aimed to clarify the factors related to the narrowing of life space by cross-sectionally examining the relationship among life space, motor function, and the Japanese Knee Osteoarthritis Measure (JKOM) score in community-dwelling older adults. The second purpose was to extract the JKOM items related to life space as we considered that subjective knee pain and function could affect the life space even when limitation was not clear in daily life. Method: Life space was evaluated in 36 older adults. Motor functions were measured using a 10-m walk time, timed up and go test, Mini-BESTest, and 30-second chair-stand test. Subjective knee pain and function were assessed using the JKOM. We investigated the correlation among life space, motor function, and JKOM score. Multiple regression analysis was used to examine the JKOM items related to life space. Results: The items that showed significant correlation with life space were “total score,” “pain and stiffness,” “participation in social activities,” and “general health conditions” in the JKOM. The item “participation in social activities” in the JKOM was extracted as a knee function that affected life space. Conclusion: This study showed a significant correlation between life space and subjective knee pain and function in community-dwelling older adults. Furthermore, functional impairment around the knee was more relevant to the life space. Therefore, identifying knee problems at an early stage and taking a preventive approach are necessary before such problems occur in response to the narrowing of life space in community-dwelling older adults.

Athletes who spend more time planning and executing plays can anticipate the outcome of their reactions more quickly and accurately, thus increasing the likelihood of effective plays. Video stimuli that replicate real sports have been used to study players’ reactions toward stimuli in various sports. However, the low frame rates of the video stimuli used in previous studies have resulted in errors when measuring reaction time. Further, a video display delay occurs in experiments where computers are used. The purpose of this study was to develop a novel and accurate reaction time measurement system to solve these problems. A video taken with a high-speed camera was used as the stimulus video to enable measurement of the time from the keyframe to the response. A marker was displayed on the computer screen during the keyframe in the stimulus video and was detected by a photosensor attached to the computer to compensate for video display delay. Using the new measurement system, the time required for a block maneuver reaction by volleyball players, known as the block reaction time (BRT), was measured in 15 male collegiate volleyball players. The BRTs were 0.214 ± 0.051, 0.616 ± 0.150, and 0.233 ± 0.065 s against the left, center, and right attacks, respectively. The measured BRTs were shorter than those measured using light stimuli in previous studies, probably because participants in this study were able to predict the direction of the ball toss using cues gleaned from the setter’s preliminary movements.

The study examined the relative energy contributions during 60-s supramaximal exercise with different exercise intensities. Nine male track and field sprinters performed a 60-s Wingate anaerobic test and a 60-s cycling tests at five intensities of 55%, 65%, 75%, 85%, and 95% mean power of the Wingate anaerobic test. The relative contributions of aerobic and anaerobic energy during the 60-s cycling tests were estimated by the ratio of O₂ uptake and O₂ deficit, the latter being calculated as the difference between O₂ demand and O₂ uptake. %VO₂max of the 60-s cycling tests ranged from 100 ± 7 to 163 ± 11%VO₂max. As exercise intensity increased, O₂ uptake, O₂ deficit, and anaerobic energy contributions during the 60-s cycling tests increased (p < 0.05). In contrast, in the first ~40 s during the 60-s cycling, the anaerobic energy contributions were not significant differences between each intensity. O₂ uptake per 10 s increased with time course till 40 or 50 s in each intensity (p < 0.05). The different results of these at the first ～40 and 60 s during the 60-s cycling tests could be attributed to the insufficient increase in O₂ uptake during the last 20 s of the test. These results suggest that, as exercise intensity increases, the anaerobic energy contribution becomes more prominent in the latter half of the 60-s exercise (i.e., 50 and 60 s) compared to the first 30 and 40 s.

This study investigates the relationship between the individual characteristics of athletes and the perceived impact of COVID-19 on their daily lives and athletic activities. Participants were 476 Japanese athletes (250 males and 226 females; mean age=28.39 ± 6.53 years) registered as respondents at an Internet research company and who met the athletic-related inclusion criteria. The investigation took place from the 6^th–13^th April 2020, just before the Japanese government declared a state of emergency due to the COVID-19 pandemic. Participants answered questions related to socio-demographic variables, the impact of COVID-19 on daily life and athletic activities and completed the Kessler Psychological Distress Scale. The results showed that the emergency declaration area, marital status, and gender were directly related to annual income, and that they indirectly influenced the impact of COVID-19 on athletes’ daily lives and athletic activities through annual income. Additionally, although a state of emergency being declared in the region impacted the daily lives of all participants and their athletic activities, unmarried and female athletes with low incomes were among the most affected by COVID-19-related measures.

Previous studies have shown that self-consciousness traits are closely related to choking under pressure (Baumeister, 1984; Wang et al., 2004). However, it has not be distinguished between private and public self-consciousness. This study investigated the influence of private and public self-consciousness of athletes on the factors of choking under pressure. 281 subjects were asked to respond to a questionnaire on choking factors (Murayama and Sekiya, 2012) and a self-consciousness scale (Tsuji, 1993), and data from 253 subjects were analyzed. The results showed that higher private and public self-consciousness had more choking experience. Furthermore, we examined the influence of private and public self-consciousness on the factors of choking and found that private self-consciousness showed significant positive effects to be associated with changes in motor control, vicious circles, abnormal physical sensations, and conscious processing (attention to movement). In contrast, public self-consciousness showed significant positive effects on changes in motor control and vicious circles, perceptual and cognitive confusion, feelings of physical heaviness and weakness, passivity, and safety-oriented strategies. The results indicate that private and public self-consciousness affect different factors of choking under pressure.

One form of assisted training is a downhill sprint, which uses a portion of gravity. This study aimed to compare sprinting on multiple downhill and level ground to clarify the parameters related to sprint velocity and differences in movement. The subjects were 17 male university athletics students, made to sprint 50 m on level ground and five downhill slopes (slope=1, 2, 3, 4, and 5°), respectively. The results showed that the sprint velocity were higher than on level ground for downhill sprint at all slopes (1°, 2°, 3°, 4°, and 5°), and even higher than on other slopes at 4° and 5°. In addition, minor changes in sprint kinematics were observed at 1°, 2°, and 3°, while major changes were observed at 4° and 5°. In particular, many joint angle differences were observed between 4° and 5°, suggesting that they were due to gravity-assisted velocity increases on downhill slopes and structural features of the slopes. Therefore, it is clear that downhill has different effects on sprinting depending on the degree of slope.

In inclusive physical education classes, teachers focus on building relationships between children in the regular classroom and children with disabilities. However, the type of knowledge teachers have or apply to their classes has remained unclear. Also, in relation to the process of creating teaching materials, the type of knowledge applied when planning classes, or the degree to which the content or procedures need to be modified or adjusted for each physical activity depending on teachers' aims, has not been adequately investigated. The purpose of this study was to clarify the knowledge of teachers needed for conducting inclusive physical education classes. For the interview, teachers conducting inclusive physical education classes were asked to share their thoughts about lesson plans and actual instruction while watching a video of their own lesson practice. To examine their knowledge, SCAT, a qualitative data analysis method, was applied to the contents of the interviews. Then, the themes and constructs extracted by SCAT were classified into the seven knowledge domains of Shulman's knowledge base. As a result, the following points were clarified: (1) In this case study, “pedagogical context knowledge” (PCK), which is knowledge specific to teachers, was applied when the teacher gave guidance for building relationships between children in regular classes and children with disabilities. This knowledge allowed teachers to play a bridging role with the aim of making the two parties mutually responsive in order to build consensus. (2) When teachers created teaching materials for the inclusive physical education classes, they employed a two-stage reconstruction approach, using different knowledge at each stage. In the first stage, teachers developed materials based on sports and other sources using “knowledge of content” and “knowledge of general teaching methods”. In the second stage, the teachers modified the physical education materials to take into account the participation of children with learning disabilities in the inclusive physical education classes using PCK such as changing the equipment to make ball handling easier and changing the rules to facilitate competition. These findings indicate that teachers apply their own knowledge of inclusive physical education to actual lessons.

The purpose of the present study was to investigate the relationship between emotion regulation strategies (reappraisal and expressive suppression) and psychological competitive ability during sports games. A total of 492 athletes completed the Japanese version of the Emotion Regulation Questionnaire (EQR-J) and the Diagnostic Inventory of Psychological-Competitive Ability for Athletes (DIPCA.3). The DIPCA.3 was used to assess psychological competitive ability as the dependent variable, and multiple regression analysis was conducted to analyze the effects of reappraisal and expressive suppression on psychological competitive ability. The results indicated that reappraisal had a positive effect on all 5 factors of the DIPCA.3. The participants were also classified into 3 clusters: the first cluster comprised players who had a strong tendency to use reappraisal, the second cluster comprised players who had a strong tendency to use expressive suppression, and the third cluster comprised players who did not use either of the emotion regulation strategies. Subsequently, one-way analysis of variance was conducted with each cluster as an independent variable and the DIPCA.3 as the dependent variable. The players who had a weak tendency to use both reappraisal and suppression had the lowest scores for 4 of the 5 factors. These findings indicate that athletes who use reappraisal or suppression as an emotion regulation strategy have better psychological competitive ability during competitive games.

This study aims to investigate the kinetic mechanisms of controlling the whole-body linear momentum (WBLM) and whole-body angular momentum around the whole-body center of mass (WBAM) in the single-support phase after tripping during gait. Twelve young participants were made to trip during gait, and the kinematics and kinetics of their recovery responses were recorded using a 17-camera motion capture system and force platform. We found that the knee-flexion torque of the support leg dominantly contributed to the decrease in the forward WBAM increased owing to tripping, whereas this torque caused a significant forward WBLM at foot landing. The ankle-plantarflexion torque of the support leg contributed to the prevention of the body descent in the first half of this phase, although this effect decreased in the later phase, resulting in the increase in the downward WBLM at foot landing. The ankle-plantarflexion torque also contributed to the increase in the forward WBLM at foot landing. These results indicate that the ankle- and knee-joint torque exertions of the support leg are the main contributors to the change in WBLM and WBAM in the single-support phase after tripping during gait. This study also suggests that there is a trade-off relationship between the control of WBLM and WBAM, and younger adults prioritize the WBAM adjustment during this phase.

The aim of this study is to describe the history of the Junior High School Sports Federation (JHSSF) based on reexamination of the relationship between education and competition in school sports. Previous studies have maintained that there was a conflict between education and competition in school sports, and that the potential educational effects of sports were impeded by its competitive focus. However, it is assumed that the JHSSF held competitions like athletic meets under the guise of educational activity. To fully understand the historical development of school sports we should instead reexamine whether the educational aspect of school sports is actually combined with its competitive one. This reorientation of perspective would then allow for new research questions, such as how the JHSSF was formed and developed, and how and why it combined education and competition in school sports. The present study attempts to answer these questions, which previous studies have not, by analyzing documents gathered from official annual reports of the JHSSF. The study produced a number of findings. Beginning in 1947 with the establishment of the postwar junior high school system, the JHSSF first developed at the prefectural level. Initially the association was formed by physical education teachers under the influence of the Ministry of Education, while also accepting the assistance of the junior high school principals’ association, boards of education and sports federations. In 1955, the national level of the JHSSF was initially formed in order to control the junior high school sports and as a counter organization to sports federations. Crucially, the JHSSF differed from sports federations in that it was specifically driven by educational ideals. Yet, even with such an organization principle, it encouraged sports and even athletic meets under the name of educational activities. At that time, some prefectures did not have local JHSSF branches; however, by 1967 all prefectures had designated branches and the association finally became a national organization. In conclusion, this study has clarified that the JHSSF had to compete against sports federations and thus included a system of competitions within the ethos of school sports. By continuing to combine education and competition in school sports, it was possible to utilize athletic meets for the realization educational ideals. The present findings suggest that there is the possibility of modifying the prior consensus that education is opposite to competition in school sports in Japan.