In order to characterize the neural control of the circulation in an organism undergoing a rapid somatic growth, we compared the arterial baroreceptor reflex in two groups of male Wistar rats anesthetized with urethane. The first group consisted of 36 rats of 6-7 weeks old, known to exhibit the greatest rate of increase of the body weight during the life span, whereas the second group consisted of 30 full-grown rats of 20-22 weeks old. When arterial pressure was controlled by phenylephrine or nitroglycerin, the reflex change in renal nerve activity was elicited over the arterial pressure range 15-30 mmHg lower than that of full-grown rats. The difference was attributable partly, but not exclusively, to the lower operating range of arterial baroreceptors in the former groups. Although no difference was observed between the two groups with respect to the reflex fall in arterial pressure in response to graded electrical stimulation of the aortic nerve, the accompanying bradycardia was significantly smaller in 6-7 weeks old rats primarily due to the difference in the vagally mediated component of the reflex response. In conclusion, the arterial baroreceptor reflex of growing rats, as compared to full-grown counterparts, is characterized by deviation of the operating range of arterial baroreceptors as well as the arterial baroreceptor reflex itself to lower arterial pressure range and poor development of the vagally mediated reflex bradycardia.

The purpose of this study was to clarify physical characteristics related to low back pain (LBP) in collegiate track and field athletes. We particularly focused on the nature of the track and field. The subjects were 21 male collegiate track and field athletes including only sprinters, hurdlers, long jumpers and triple jumpers. The examined parameters were physical characteristics, isokinetic flexor and extensor strength in the knee and trunk regions. The evaluation of LBP was estimated by a questionnaire test and orthopedic surgeons' diagnosis. According to these evaluations, we divided all track and field athletes into two groups ; LBP group (n＝11, 52.4%) and no LBP group (n＝10, 47.6%). As a result, a take-off leg of knee flexor/extensor strength ratio in the LBP group was significantly lower than that in the no LBP group (P＜0.05). The LBP group showed a significant difference between a take-off leg and a lead leg in knee flexor strength compared with the no LBP group (P＜0.05). The LBP group has been short engaged in the track and field than the no LBP group (P＜0.05). In the trunk flexor and extensor strength, there was no significant difference between the LBP and the no LBP group in this study. These results suggest that the imbalanced knee muscle strength may be one of some factors related to chronic low back pain in collegiate track and field 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.

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.