To evaluate the association of serum BDNF concentration with high-intensity interval training, 12 healthy male volunteers, aged 28-48 years, completed 16-week high-intensity interval training (HIIT) using ergometer. Training program consisted of >90% VO₂ peak for 60 sec separated by 60 sec active rest period for 8-12 sets twice weekly for 16-week. Maximal exercise tolerance tests were performed before (0-week), 4-week, and 16-week after the intervention program. VO₂ peak as well as peak watt was linearly increased after 4-week (9% for both VO₂ peak and peak watt) and 16-week HIIT training (15% for VO₂ peak and 18% for peak watt, p<0.01). However, there was no change in serum BDNF concentration by HIIT. On the other hand, there was a positive association of serum BDNF concentration at baseline with % increase in peak watt after the intervention (ρ=0.60, p<0.05). The association between BDNF and exercise training is still unclear, and more studies are needed to clarify the above positive association.

To date, there has been no comprehensive study on the relationship of stress response, coping and lifestyle (e.g., diet, exercise habits, and sleeping habits) with premenstrual syndrome (PMS) for female athletes. This study aimed to examine this relationship. We used a web questionnaire to acquire the required data from Japanese female university athletes. Based on structural equation modeling, we used the PMS score as an outcome and examined its relationship to stress response, emotion-focused coping, dietary intake, amount of exercise in club activities surveyed by club unit, and sleeping time. Our study included 257 subjects (average age, 20 years). The results showed that the stress response was a direct factor in the PMS score (standardized coefficient: .63). Emotion-focused coping and dietary intake were associated with PMS scores through stress response (-.26 and -.27, respectively). Emotion-focused coping was also associated with the dietary intake (.19). Factors associated with emotion-focused coping were amount of exercise (.22) and sleeping time (.27). The amount of exercise was associated with sleeping time (-.26). These results suggest that avoiding stressors, enhancing emotion-focused coping, reducing the stress response by maintaining a balanced and sufficient diet, performing an appropriate amount of exercise, and improving sleep habits may be effective in managing PMS.

The purpose of this study was to compare the characteristics of starters and non-starters with respect to the anthropometric and physical fitness in a Japanese university rugby team. Our sample pool consisted of 54 players of the K University rugby team, who were registered for the official games (all 7 games/year) in 2018 and 2019. The starter group (26 players) comprised of players with more than 3 games/year while the non-starter group (28 players) comprised of players that registered for official games but played less than 3 games. Anthropometric parameters, such as height, body mass, skinfold (8 items), girth (5 items), body composition, muscular strength, intermittent endurance, and sprint time, were assessed. We found that the starter group for forwards had lower skinfold (Biceps, Iliac crest, Supraspinale, Abdominal, Front thigh, and Medial calf) and percentage body fat than in the non-starter group. The starter group for backs had muscle strength of narrow chinning is higher than in the non-starter group. Finally, our study helped to clarify the physical factors that influence the difference in athletic performance between starters and non-starters in university rugby team. The forward starters had lower percentage body fat and better body composition and backs starters had better narrow chinning. The findings provide information to university rugby players who want to become starters, as well as help the coaching staff understand the factors that need to be strengthened in the players.

We aimed to evaluate the associations of individual-level social capital (SC) and physical activity (PA) among Japanese elderly men and women. Individuals aged 65 or above were selected via population-based random sampling of 3000 adults, aged 20 years or above and living in Fujisawa city, who were asked to complete self-administered questionnaires. The sample consisted of 260 men [median (25-75% tile) age 73 (68-78) yrs] and 274 women [73 (68-78) yrs]. The daily duration of PA, SC [e.g., norms of reciprocity (mutual support in the community), social networks (relationship with community people, exchange with other generations), social participation (participation in community organization activities)], socio-economic status [educational attainment, work with income, perceived household economic status], and demographic characteristics [sex, age, living arrangements, BMI, physical limitations] were assessed. Multivariate logistic regression analyses were used to calculate odds ratios (OR) for associations of SC with PA, stratified by sex. High level of mutual support in the community, relationship with community people, and exchange with other generations were associated with longer PA time in men after adjusting for potential confounders in the final model (OR = 2.40 (95% CI: 1.24-4.67), 5.28 (1.42-19.66), and 4.24 (1.15-15.67), respectively). In women, relationship with community people and participation in community organization activities were associated with longer PA time (3.10 (1.32-7.26) and 2.50 (1.27-4.91), respectively). The association of individual-level SC and PA differed between men and women. Future studies can investigate whether similar results can be obtained in other areas or attempt to conduct a large-scale survey.