The level of secretory immunoglobulin A (SIgA) in saliva is associated with the risk of upper respiratory infection and has been identified as a condition indicator for athletes and an indicator of mucosal immune function in the elderly. In addition, it has been suggested that non-specific polyreactive SIgA is present in human saliva and colostrum. The purpose of this study was to establish a new detection method of polyreactive salivary SIgA. Using saliva samples from eight healthy individuals, indirect ELISA was used to detect anti-LPS antibodies (LPS ELISA), and competitive ELISA was used to detect LPS antibodies after competition with DNA (LPS-DNA ELISA). The difference in SIgA concentration between LPS ELISA and LPS-DNA ELISA is thought to be the concentration of the polyreactive SIgA, which responds to both DNA and LPS. First, we determined the concentration for coating LPS and DNA as 10 μg/ml, and the saliva sample dilution was determined as 1/2. The concentration of anti-LPS antibody contained in the saliva sample, which is strongly reactive to LPS, was defined as the standard. Compared to the SIgA concentration determined by LPS ELISA, SIgA concentration of LPS-DNA ELISA did not decrease in two samples, but was reduced in 6 samples. The decrease in SIgA concentration is thought to be the concentration of polyreactive SIgA that reacts with both DNA and LPS. Notably, we found sample-to-sample differences in the concentration of polyreactive SIgA.

This study aimed to observe the conditions of Japanese college athletes during the COVID-19 pandemic for the prevention of psychiatric and sleep disorders. A survey was conducted with 100 players before and after they refrained from sports activities due to the emergency measures (April 7–May 14, 2020) against COVID-19. The survey items used were the Hospital Anxiety and Depression Scale (HADS) for psychiatric symptoms (anxiety and depression) and the Pittsburgh Sleep Quality Index (PSQI) for sleep. A survey on the living conditions was based on a web-based questionnaire. Sleep dysfunction (PSQI ≥ 6), anxiety (HADS-A ≥ 8), and depression (HADS-D ≥ 8) were found in 20 (20%), 19 (19%), and 18 (18%) players before the emergency measures, and 32 (32%), 20 (20%), and 31 (31%) players after emergency measures, respectively. Of the 100 participants, 36 (36%) developed sleep dysfunction or depression as they lived alone, were anxious about school life (e.g., friendships), and were financially unstable regarding living expenses (e.g., not able to work part-time). Due to these findings, it is necessary to actively intervene in the mental health of university students.

High-intensity interval training improves the vascular endothelial function better than moderate-intensity continuous training. However, few studies have examined the effects of repetition training consisting of high-intensity exercise, followed by complete rest, on arterial function. We performed this study to investigate the effects of repetition training of high-intensity exercise on the vascular endothelial function determined by flow-mediated vasodilation. Twenty healthy male participants were randomized and stratified into two training groups, one group performed moderate-intensity continuous training (n = 10) while another performed repetition training of high-intensity exercise (n = 10). Both groups exercised 3 times a week for 6 weeks. Before and after each training protocol, the vascular endothelial function of the right brachial artery was assessed by flow-mediated vasodilation. In the moderate-intensity continuous training group, flow-mediated vasodilation changed 9.92 ± 2.45% to 10.58 ± 2.93% (ns). In the repetition training of high-intensity exercise group, flow-mediated vasodilation changed 7.26 ± 1.46% to 8.58 ± 1.22% (p < 0.05). A greater increase in vascular endothelial function was observed in high-intensity repetition training compared to moderate-intensity continuous training. These results suggest the possible effect of repetition training on the prevention of cardiovascular disease.

In female athletes, iron deficiency and anaemia have marked effects on performance and could also impair health. Female athletes often limit their diet to control their weight, and thus may not obtain sufficient iron. Iron is difficult to absorb, so it is necessary to devise an efficient intake method. Absorption of non-haem iron seems to increase when taken with ʟ-ascorbic acid (vitamin C [VC]). ʟ-Ascorbic acid 2-glucoside (VCG), a food additive that binds glucose and thus improves its stability, is often added to beverages. Therefore, the effects of simultaneous intake of iron and VCG on iron nutrition were examined in female athletes. The subjects were 41 female college student athletes, and a placebo test was conducted in which a drink containing 200 mg VCG and 6 mg iron was consumed twice daily for 2 months. The placebo group consumed only the iron without VCG. Iron nutrition status was evaluated by blood tests, dietary surveys and subjective symptoms before and after the 2 months. Blood tests were also performed to determine the effects of iron intake on liver function and hepcidin levels. After 2 months, the VCG/iron drink had increased serum iron and blood VC levels in the VCG group compared to the placebo group. By contrast, aspartate aminotransferases (AST) tended to decrease in the VCG group, and no increase in hepcidin was observed in either group. This suggests that long-term iron intake through beverages can improve iron nutritional status in female athletes, and that VCG may enhance this status by suppressing the oxidative damage to the liver associated with iron intake.

Despite extensive studies on the incidence and characteristics of football (soccer) injuries using a time-loss definition, the exact magnitude of injuries and illnesses in football players remains unclear. This study aimed to examine the prevalence and burden of health problems among university football players based on all physical complaints. Ninety-four male university football players were prospectively followed up during the 2020 competitive season in Japan. The study period was divided into the self-training period (SP) and the football period (FP). All participants were asked to complete the Japanese version of the Oslo Sports Trauma Research Center Questionnaire on Health Problems (OSTRC-H2.JP) every Sunday. The main outcome measures were the prevalence of all health problems and substantial health problems and their burdens. The average response rate to the OSTRC-H2.JP was 88.8% [95% CI, confidence interval: 87.7%–89.9%]. Overall, the average weekly prevalence of all health problems was 19.7% [95% CI: 18.3%–21.1%]. During the FP, the average weekly prevalence of all health problems and substantial health problems were 22.9% [95% CI: 21.0%–24.7%] and 15.3% [95% CI: 13.7%–16.9%], respectively. Injuries were the main problem, with traumatic injuries in the ankle, thigh, and foot representing the greatest burden. This study indicated that approximately 20% of university football players experienced injuries or illnesses. Traumatic injuries in the ankle, thigh, and foot represented the greatest burden on self-reported reliance using broad definitions of injury and illness. Therefore, injury prevention should focus on preventing these complaints.

Several studies have demonstrated that athletes show superior performance in general cognitive functions compared to non-athletes. However, the effects on cognitive function might vary depending on the athlete’s sport type. In athletes, the visuospatial working memory is a crucial function for immediate response to each situation and experience. However, no studies have yet examined the association between visuospatial working memory and sport types. This study aimed to investigate whether sport type influences the differences in visuospatial working memory in athletes using a cross-sectional study. A total of 67 young individuals, including 59 athletes (long-distance running, tennis, kendo, and soccer players) and eight non-athletes (controls), participated in the study. Athletes were classified into static, interceptive, or strategic depending on their sport type. The reaction time, accuracy, and balanced integration score (BIS) of the spatial working memory task (SWMT) were examined in all participants. Strategic athletes showed a shorter reaction time and higher BIS value of SWMT than static athletes and non-athletes. We concluded that the visuospatial working memory of strategic athletes was better than that of non-athletes and static athletes. This finding suggests that visuospatial working memory might play an important role in determining athletic performance in strategic sport types, making improved visuospatial working memory a key advantage for strategic athletes.

Mixed martial arts (MMA) is a combat sport with a high incidence of concussions, including knockouts (KO) due to direct attacks to the head. Once a concussion occurs in a fighter, the rate of concussion recurrence increases. Therefore, participation in matches may be weakened to head impacts as fighters experience repeated concussions. In this study, we investigated the relationship between the occurrence of concussions in male mixed martial arts athletes during the most recent match and their past match records. The analysis included 104 male fighters who competed in elite-level professional MMA competitions. In the most current match, 44 fighters experienced a concussion and 60 fighters did not. Previous KO losses (mean, 2.9) were significantly higher in the fighters who had experienced a concussion compared to fighters who had not (p < 0.0001). Concussion rates (65.0%) were significantly higher in fighters with three or more previous KO losses compared with the rates for fighters with less than 3 previous KO losses (p = 0.03). The odds ratio for the occurrence of concussions in fighters with a history of KO losses was 2.3 times that of fighters without a history of KO losses (p = 0.004). Fighters who had competed in more than 30 matches had a significantly higher incidence of concussions (60.8%) than fighters who had competed in less than 30 matches (37.0%) (p = 0.04). The occurrence of concussions in male MMA fighters is related to the number of previous KO losses and the number of matches.

There was a mistake in this paper, and it will be corrected.