The purpose of this study was to investigate the injury patterns and risk factors of injuries among high school handball players in Japan. A total of 1299 (709 male and 590 female) subjects who played in the 2018 Japanese National High School Handball Championship participated in this study. The questionnaire on injury experience was distributed two weeks before the championship and was collected at the representation meeting the day before the championship. The main results were as follows: 1) The subjects (n=625, 48.1%) reported experiences of injuries in the previous year. Female had significantly more suffer injuries than male. 2) The main body parts of injuries were the ankle, knee, and finger in traumatic injuries and the lower leg, lumber spine/lower back, and knee in overuse injuries. The main types of injuries were sprain, ligamentous rupture, and fracture in traumatic injuries and stress fracture, other bone injuries, and lesion of meniscus or cartilage in overuse injuries. The main cause of injuries was “contact with another athlete”. 3) Age, female players, and back players were associated with increased the occurrences of injuries. Goalkeepers were associated with decreased the occurrences of injuries. These results indicated that a high prevalence of injuries in high school handball players, and it is important to take preventive measures based on age, gender, and player position.

The yips represent a disorder that makes it challenging for an individual to perform automatic and coordinated movements in sports activities. The cause of the yips is not sufficiently clarified, and limited information is available regarding throwing yips in baseball. Therefore, this study was designed to clarify the incidence and characteristics of the throwing yips among college baseball players. Total 107 players of the college baseball team participated in the study and completed the questionnaire by answering questions about their experience of the yips (loss of control to throw the ball accurately for more than 1 month), the symptom intensity, and changes observed in the symptoms in different situations. The 47.1% of players met the definition of throwing yips. The symptoms of the yips were more pronounced with short-distances and low intensity of throwing. Moreover, there were various subjective symptoms, such as the issue about co-contraction of the upper limb, sensory function, body ownership, and movement planning. Various physical symptoms associated with throwing yips suggest that the yips are not only a disorder of motor skills, but result from movement disorders. The present results show that the occurrence of the yips depends on the throwing condition; this finding provides useful insights into the mechanism and the treatment of the yips. Interdisciplinary studies that aim to elucidate the cause of the yips and develop effective intervention are necessary.

Premenstrual syndrome (PMS) that occur during late luteal phase is a problem for many female athletes. Many studies reported that subjective condition is affected by PMS in female athletes. Moreover, female athletes with PMS have higher stress and/or anxiety levels during luteal phase compared with non-PMS athletes. However, the relationship between PMS and physical performance in female athletes are not clarified yet. The purpose of this study was to investigate the relationship between premenstrual syndrome (PMS) and jump performance in female track and field athletes. Sixteen participants who has natural basal body temperature pattern with the menstrual cycle (observed low-temperature and high-temperature phase), were participated in this study. PMS was assessed by ACOG’s premenstrual syndrome questionnaire. As physical performance, counter movement jump (CMJ) and rebound jump (RJ) were evaluated in low-temperature phase and high-temperature phase. The result of this study, no significant differences were observed in body composition and physical performance between low-temperature phase and high-temperature phase. However, compared with participants who had non-symptom, participants who had a breast tenderness of PMS showed larger decreases in jump height of CMJ (p = 0.038) and RJ index (p = 0.015) in high-temperature phase. Therefore, PMS may have a negative effect on physical performance during high-temperature phase in female athletes.

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 aim of the present study was to examine the factors associated with exercise participation in mothers with primary school children. A cross-sectional study of 315 mothers of primary school children was completed. Participants were recruited from fourteen elementary schools in which their children were enrolled. Exercise participation and associated factors including demographic, psychological, behavioral, and environment factors were assessed by questionnaire. After controlling for age, body mass index and sociodemographic variables, results of logistic regression indicated that holding a full-time job (OR=0.15 (0.05-0.44), p < 0.01) and high frequency of cleaning (OR=0.30 (0.14-0.65), p < 0.01) were significantly negatively correlated with exercise participation. Moreover, high self-efficacy of exercise (OR=3.11 (1.66-5.84), p < 0.01) and car driving (OR=2.68 (1.57-4.56), p < 0.01) were significantly positively associated with exercise participation. The findings of this study suggest that employment status, psychological and behavioral factors were related with exercise participation in mothers with primary school children.

In the present study, we examined the sex-related differences and cross-sectional age-related changes in the cross-sectional area of the psoas major muscle. The cross-sectional area was corrected for fat-free mass (FFM-corrected), which was calculated as the 2/3rd power of the total fat-free mass. A total of 240 adults (114 men, 126 women, age: 20-81 years) were included in the study. The cross-sectional area of the psoas major muscle was measured by 0.2T magnetic resonance imaging (MRI), and the total fat-free mass was measured by air displacement plethysmography. We demonstrated that the FFM-corrected cross-sectional area of the psoas major muscle was greater in males than females across all age groups. Furthermore, we examined the mean FFM-corrected cross-sectional area of the psoas major muscle across different age groups and demonstrated that it decreased with age. Our findings, when combined with previous results, show a peak in the 20s, which declined with age. Our study revealed sex-related differences and cross-sectional age-related changes in the FFM-corrected cross-sectional area of the psoas major muscle. Our findings also suggest that it is important to define reference values and ranges that take into account age- and sex-related differences when assessing the psoas major muscle by FFM-corrected cross-sectional area.