The relationship between participation in extracurricular school club activities in adolescence and subsequent depressive state experiences in adulthood, after joining the workforce, is unclear. The present study aimed to explore this relationship in new recruits of the Japan Ground Self-Defense Force (JGSDF). In April 2013, 925 recruits of the JGSDF, all of whom were male and aged 18–27 years, were enrolled. Club activity status during high school was categorized as follows: participated in sports club, participated in nonsport club, or no club participation. Depressive symptoms were assessed with the 20-item version of the Center for Epidemiologic Studies Depression Scale (CES-D), at the baseline survey and a second survey conducted 2 months later, in June 2013. Analysis of covariance was used for association between club activity status and changes in CES-D scores. After a 2-month period, results showed a significantly higher average of CES-D score changes for participants in nonsport club activities (β = 3.90, 95% confidence interval = 2.22–6.71) or those with no club activities (β = 2.24, 95% confidence interval = 0.20–2.94), compared to those who participated in a sports club. These findings were adjusted for age, baseline CES-D score, regular exercise, smoking status, alcohol consumption, sleep duration, and breakfast habits. Recruits without a history of sports club participation may be at higher risk of developing depressive symptoms than those who participated in a sports club. Our results may be useful for the early detection of people who are susceptible to depression engaged in occupations such as the JDSF.

In this study, the characteristics of the athletic careers of Japanese college baseball players were identified, and relationships between their athletic careers and levels of performance and injury were analyzed. A questionnaire survey was conducted for 589 players in teams affiliated with the All-Japan University Baseball Federation; the relationship between their background in competitive activity and levels of performance in competitive experience was analyzed with a chi-square (χ²) test. In total, 541 players participated in the survey. Survey results showed that the average age at which they started playing baseball was 7.8 ± 1.8 years, and the average age at which they specialized in baseball was 10.0 ± 3.2 years. In terms of athletic experience and college performance level, the χ² test showed a significant association (χ² = 8.83, Cramer’s V = 0.133, p < 0.05). Moreover, significantly more players specialized before 12 years of age, with experience in other sports, and significantly fewer players specialized after 13 years of age, with experience in other sports (p < 0.05). Therefore, childhood sports experience may influence performance levels of college players, and Japanese baseball players tend to specialize early.

Although physical activities have many health benefits, adverse events and near misses, such as injuries and falls, can occur during these activities. This study aimed to assess the occurrence of adverse events and near misses during sports activities conducted independently by community residents. A survey questionnaire was sent via the internet to the leaders or directors of sports organizations at six public sports centers or associations. In total, 108 individuals answered the survey, with 60% male and 40% female respondents. Individuals aged 50–69 years accounted for 60% of the total number of respondents. All respondents were asked about their experiences of adverse events and near misses within the past three years: the reports of these incidents were obtained using the recall method. Duplicate adverse events and near misses were identified based on the sports discipline, time of occurrence, and sex and age of person involved to determine if there were duplicate reports. Most of the respondents’ activities as staff were performed once a month, with each activity lasting 1–2 h. Forty-five adverse events were reported, including 26 injuries, 13 falls, and 6 others (such as heat stroke, vertigo, and presyncope). Twenty-four near misses were reported, including 12 near collisions with people or objects, five near falls, and seven other incidents. We found that approximately 30% of the respondents experienced adverse events, suggesting the need for documentation of adverse events, implementation of safety measures, and proper safety education for operating staff.