The purpose of this study was to investigate the effect of changes in post-absorptive resting metabolism (PARM) on plasma triiodothyronine (T3) levels under a prescribed diet. The subjects were 31 sedentary female college students (19.9±0.9 yrs). Subjects stayed in a metabolic ward at the National Institute of Health and Nutrition for 18 days. PARM was measured 4 times during the experimental period. Additionally, blood was collected 4 times during the experimental period, and general health care including the measurement of thyroxin by blood biochemical examination was carried out. Subjects were divided into three groups (n=26, n=4, n=1), two of which were analyzed for this study. The two groups were divided according to thyroid function: Group N (n=26) included subjects in which T3 was judged to be within the normal range during the experimental period; Group L (n=4) included subjects for whom T3 was not normal during the study period, and was judged to be under the normal range at least once. The remaining 1 subject had a T3 judged to be over the normal range. For Group N, several parameters decreased significantly during the course of the experiment: weight was 51.5±4.97 vs. 50.8±4.3 kg (p<0.01); T3 was 1.16±0.19 vs. 1.01±0.12 ng/ml (p<0.01); and PARM was 3.1±0.2 vs. 2.9±0.2 ml/min/kg (p<0.05). For Group L, several parameters also decreased significantly during the course of the experiment: weight was 53.6±4.9 vs. 52.6±4.5 kg (p<0.01); T3 was 0.94±0.15 vs. 0.75±0.07 ng/ml (p<0.01); and PARM was 2.9±0.2 vs. 2.7±0.1 ml/min/kg (p<0.05). The average PARM of Group N was significantly higher than that of Group L (7.0%). PARM during the luteal phase of the menstrual cycle was significantly higher than during the menstrual phase (3.5 %), in subjects for whom the phases of the menstrual cycle were distinguishable (n=13). According to the 2005 Dietary Reference Intakes (DRIs) for Japanese, the basal metabolic rate (BMR) is calculated at 23.6 kcal/kg body weight/day, or 3.27 ml/min/kg translated for VO2 for women within the 18~29 year age group. However, the values calculated from the measurements of this research study were approximately 9.5% lower for Group N and 15.8% lower for Group L than that of the DRIs. Future investigation is required to explain the reasons for the difference in PARM between this study and that of previous ones.
We investigated the effects of long-term administration of bisoprolol (β-blocker), exercise and their combination on blood pressure, heart rate, and baroreflex function in spontaneously hypertensive rats (SHR). SHR aged 5 week were randomly assigned to control group (C), bisoprolol-treated group (Biso), exercise group (Exer), and combination group (Biso+Exer)(n=8/each group). In Biso and Biso+Exer, bisoprolol (20 mg/kg/day) was administered. In Exer and Biso+Exer, exercise training was performed on treadmill 5 days/week for 12 weeks. Systolic blood pressure (SBP) and heart rate (HR) were measured using the tail-cuff method under restraint from 5 to 16 weeks of age. After 12-week intervention period, sigmoidal mean artery pressure (MAP) and HR reflex curve were obtained by intravenous injections of various doses of phenylephrine and nitroprusside under non-restraint condition. To determine vagal component of baroreflex function, baroreflex MAP-HR relation were also examined after intravenous injections of atenolol (β-blocker). After measurements of all baroreflex function, atropine was additionally injected to determine intrinsic HR. At 15 and 16 weeks of age, SBP and HR in Biso and Exer were significantly lower than those in C. SBP and HR in Biso+Exer were further reduced compared with Biso. Before atenolol, resting MAP, HR and upper and lower HR plateaus in the sigmoid curve were lower in Biso, Exer, and Biso+Exer compared with C. There were no significant differences in these parameters between Biso and Biso+Exer. There were no significant differences in baroreflex gain before atenolol among the four groups except for between Biso and Biso+Exer. After atenolol, baroreflex gain and HR range in Biso, Exer, and Biso+Exer were significantly higher than those in C. HR range of sympathetic component (upper HR plateau before atenolol-itrinsic HR) was significantly reduced in Biso, Exer, and Biso+Exer compared with C. There were no significant differences in baroreflex gain of vagal component or HR range of vagal and sympathetic component between Biso and Biso+Exer. These findings suggest that both chronic treatment with β-blocker and exercise decrease resting blood pressure and HR in SHR, associated with reduced sympathetic component and increased vagal component of baroreflex function. The additive effects of β-blocker and exercise are not evident under non-stressful conditions, but could be obtained in the presence of stress such as restraint.
In the present study, we examined cardiovascular response to static and dynamic hand-grip exercise at equivalent work load (peak tension) and tension-time index (TTI, integrated tension for time) in healthy young (n=8) and elderly (n=8) males. Static and dynamic exercises were conducted for 75 s and 150 s at 30% of maximal voluntary contraction (MVC) and for 45 s and 90 s at 50%MVC, respectively. Arterial pressure was continuously measured on a beat basis. Blood pressure at the end of exercise and the magnitude of pressor response induced by exercise did not differ significantly between static and dynamic exercises at the two work loads. The magnitude of pressor response tended to depend on work load. These findings were the same in both age groups. Consequently, it was indicated that blood pressure responses to static and dynamic hand-grip exercise at equivalent work load and TTI did not differ both in young and elderly people. Furthermore, it was suggested that central command and muscle metabolite induced stimulation of the exercise pressor reflex during static and dynamic exercise were similar based on the results of relative perceived exertion and blood pressure response during post-exercise arterial occlusion.
The college years are an opportune timepoint of intervention in the primary prevention of osteoporosis. However, the effects of anthropometrical measures and lifestyle-related factors on the changes in bone mass during college years are unclear. The purpose of this study was thus to identify the determinants of the changes in calcaneal quantitative ultrasound (QUS) bone parameters (stiffness index: SI, speed of sound: SOS, broadband ultrasound attenuation: BUA) over 2 years in healthy Japanese college women (n=128). Correlation analysis revealed several significant relationships between the change rates in QUS parameters and anthropometry. Particularly, the changes in SI and BUA are highly correlated with the 2-year change in lean body mass (LBM). The subsequent multiple liner regression analysis also supported that the change in LBM was the significant predictor for the incremental rate of SI and BUA. All subjects then categorized into some grades, concerning about following lifestyle-related and physical variables during the last 2 years, living condition, sleeping time, alcohol consumption, smoking, meal skipping, dairy foods intake, instant foods intake, regular physical activity, regularity of menstruation, history of fracture, and history of dieting to reduce body weight. The incremental rates of all QUS parameters (i. e., SI, SOS, BUA) were positively associated with participation in regular physical activity. In addition, women who have continuously participated in regular physical activity from high school to college showed significant increases in SI and SOS compared with those who are not physically active or whose level of physical activity decline during college years. In conclusion, our study indicates that changes in QUS parameters in college-aged women were influenced by changes in anthropometric measures, especially LBM. It might suggest the importance of participation in regular physical activity to increase skeletal muscle mass. Our results also support the view that college women should maintain or increase regular physical activity before and after entering the college to maximize peak bone mass or lessen the age-related loss in bone mass in adulthood.
Divers' heart rates were measured under real ocean diving conditions with the purpose of evaluating the workload during SCUBA diving. For the subjects, all-out tests were conducted and evaluated in each of the following conditions: 1. ergometer cycling, 2. ergometer cycling using diving regulator, 3. fin-swimming in a swimming pool with diving equipment. No significant heart rate difference was found between the pre-dive and post dive of each subject; although, in novice divers, high heart rates such as 140/min or more were observed especially during the dive gear wearing phase on the topside and/or floating on the surface phase, suggesting there should be some high heart rate inducing factors, other than the exercise, like stress. Whereas, in the results of the all-out tests, the heart rate for fin-swimming was 16~18 beats/min lower, as well as 5.7~14.2 ml/kg/min lower for VO2max, as compared to the ergometer cycling. This may suggest that fin-swimming like scuba diving could give a diver some degree of physical load without on increased heart rate.