Journal of Physiological Anthropology最新文献

This study attempts to clarify whether intensity of exercise influences functional sympatholysis during mild rhythmic handgrip exercise (RHG). We measured muscle oxygenation in both exercising and non-exercising muscle in the same arm in 11 subjects using near infrared spectroscopy (NIRS), heart rate, and blood pressure. We used the total labile signal to assess the relative muscle oxygenation by occlusion for 6 min. Subjects performed RHG (20 times/min) for 6 min at 10%, 20%, and 30% of maximal voluntary contraction (MVC) at random. We used a non-hypotensive lower body negative pressure (LBNP) of 220 mmHg for 2 min to elicit reproducible enhancement in muscle sympathetic nerve activity (MSNA) at rest and during RHG. LBNP caused decreases of 16.4% and 17.7% of the level of muscle oxygenation at rest (pre) in exercising (forearm) and non-exercising (upper arm) muscle respectively. Muscle oxygenation in non-exercising muscle with the application of LBNP during RHG did not change significantly at each intensity. In contrast, the decrease in muscle oxygenation in exercising muscle attenuated progressively as exercise intensity increased (10% MVC 8.8+/-2.8%, 20% MVC 7.1+/-2.0%, 30% MVC 4.6+/-3.0%), when LBNP was applied during RHG. The attenuation of the decrease in muscle oxygenation due to LBNP during RHG at 10%, 20%, and 30% was significantly different from that at rest (p<0.01). These findings indicate that functional sympatholysis during mild RHG might be attributed to exercise intensity.

This study aimed to determine the accuracy of segmental body composition variables estimated by single-frequency BIA with 8-point contact electrodes (SF-BIA8), compared with dual-energy X-ray absorptiometry (DXA). Subjects were 72 obese Japanese adults (43 males and 29 females) aged 30 to 66 years. Segmental body composition variables (fat free mass: FFM, fat mass: FM, and percent fat mass: %FAT) were measured by these techniques. The correlations between impedance values and FFM measured by DXA were calculated. To examine the consistency in predicted values (SF-BIA8) with the reference (DXA), significant mean differences were tested by t-test and the degree of the difference was assessed by effect size. Correlations between the reference and predicted values were calculated. Additionally, the standard error of estimation (SEE) when estimating the reference from the predictor and the relative value of the SEE to the mean value of the DXA measurement (%SEE) were calculated. Systematic error was examined by Bland-Altman plots. High correlations were found between impedance and FFM measured by SF-BIA8. FFM in the extremities showed high correlations with the reference values, but systematic error was found. SF-BIA8 tended to overestimate FFM in the trunk. The consistencies in %FAT and FM with the reference value are inferior to those for FFM, and SEE values in %FAT and FM were greater than those for FFM. The accuracy of the estimated values in the trunk (FFM, %FAT, and FM) are inferior to those of the total body and extremities.

The origin of the slow component (SC) of oxygen uptake kinetics, presenting during exercise above the ventilatory threshold (VT), remains unclear. Possible physiologic mechanisms include a progressive recruitment of type II muscle fibers. The purpose of this study was to examine alterations in muscle activity through electromyography (EMG) and mean power frequency (MPF) analysis during heavy cycling exercise. Eight trained cyclists (mean +/- S.E.; age = 30 +/- 3 years, height = 1771 +/- 4 cm, weight = 73.8 +/- 6.5 kg, VO2max = 4.33 +/- 0.28 l min(-1)) completed transitions from 20W to a workload equaling 50% of the difference between V(T) and VO2max. VO2 was monitored using a breath-by-breath measurement system, and EMG data were gathered from surface electrodes placed on the gastrocnemius lateralis and vastus lateralis oblique. Breath-by-breath data were time aligned, averaged, interpolated to 1-s intervals, and modeled with non-linear regression. Mean power frequency (MPF) and RMS EMG values were calculated for each minute during the exercise bout. Additionally, MPF was determined using both isolated EMG bursts and complete pedal revolutions. All subjects exhibited a VO2 SC (mean amplitude = 0.98 +/- 0.16 l min(-1)), yet no significant differences were observed during the exercise bout in MPF or RMS EMG data (p > 0.05) using either analysis technique. While it is possible that the sensitivity of EMG may be insufficient to identify changes in muscle activity theorized to affect the VO2 SC, the data indicated no relationship between MPF/EMG and the SC during heavy cycling.

It is important that task performance is physiologically evaluated in consideration of arousal level. But there are relatively few preceding studies. In this study, the relationship between task performance and physiological indices was studied with regard to attentiveness concentration. The subjects were eight healthy college students. They performed calculations and a visual display terminal (VDT) task. Electroencephalogram (EEG) frequency component, alpha attenuation coefficient (AAC), skin potential level (SPL), blood flow of the finger tip skin (BF), and visual analog scale (VAS), were measured. In order to quantify task performance, correlations between the task performance and physiological indices during the mental task were analyzed. The results suggest that AAC correlates with the error rate in calculation. BF also correlates with the error rate in calculation, while the calculation speed correlates with SPL. It can be inferred that the task speed and error rate are supposed to be related to the different physiological background.

This study aimed to examine how the muscularity of the abdomen at the umbilicus level differs between sedentary middle-aged and young men. Magnetic resonance imaging was applied to determine the cross-sectional areas of skeletal muscle, subcutaneous fat, and interperitoneal tissue in 43 middle-aged (40 58yrs) and 38 young (21-29 yrs) men. The cross-sectional area of the skeletal muscle was analyzed as the sum of those of the rectus abdominis, abdominal oblique, lower back, and iliopsoas skeletal muscle groups. The middle-aged men showed greater waist circumference and whole abdominal cross-sectional area than the young men. In addition, the cross-sectional areas of subcutaneous fat and interperitoneal tissue were greater in the middle-aged men than in the young men. However, the total cross-sectional area of the skeletal muscle was similar between the two groups, although its percentage to the whole abdominal cross-sectional area was higher in the young men compared to the middle-aged men. Among the four skeletal muscle groups analyzed, the percentage of the cross-sectional areas in abdominal oblique muscles to that of total skeletal muscle was higher in the middle-aged men than in the young men and that of the lower back muscles was the reverse. These results were similar even when cross-sectional area data were analyzed using a subsample (33 middle-aged and 23 young men) matched for body height and mass. Thus, the present study indicated that the total muscularity of the abdomen at the umbilicus level was similar between the middle-aged and young men, but the relative distributions of lower back and abdominal oblique muscles varied between the two generations.

BCG immunization, utilizing whole-body coordination, is a highly cost-effective means of health intervention for preventing miliary tuberculosis (TB) and TB meningitis. In this study, we investigated the appropriate age by which a child should have completed his or her BCG immunization and discuss the current BCG immunization rate in Akita Prefecture, Japan. BCG immunization rates in urban and rural areas were 90.1% and 80.7%, respectively. Our immunization data were lower than the World Health Organization's (WHO) recommended rate. Immunization coverage rates in urban settings were higher than those in rural areas among infants four months to fifteen months of age, except for those six months old. We recommend: (1) completing BCG immunization by the age of twelve months, (2) preparing and educating parents for BCG immunization by means of a health policy, and (3) changing BCG immunization methods from group to individual inoculation. Immunization coverage rates may be increased or maintained to prevent miliary TB and TB meningitis.

This study investigated the effects of worn-out shoes on lower leg stability, shock absorption and energy cost during prolonged walking. Seven male subjects (23.4 +/- 0.5 yr) walked at 4.8 km/h for 60 minutes wearing three different pairs of shoes: two of these pairs had severely and moderately worn soles (EASC: Excessive Attrite Shoe Condition and MASC: Moderate Attrite Shoe Condition, respectively) and the other pair had no wear (NASC: No Attrite Shoe Condition). Impact acceleration at the subtalar at heel strike, rearfoot angles (the subtalar joint and the lower leg) during stance phase, and oxygen uptake (VO2) were measured throughout the 60-minute walk. At the 10th minute of walking, worn-out shoes increased the supination of the subtalar joint and extortion of the lower leg. In addition, VO2 was significant larger in EASC (808.3 ml x min(-1)) than in NASC (749.5 ml x min(-1)). During the 60-minute walk, however, there were no time effects of shoe condition on the rearfoot angles and on VO2. In contrast, impact acceleration at the subtalar joint in EASC remained almost constant until the 30th minute of walking, and then began to elevate. In conclusion, worn-out shoes increased the energy cost and reduced lower leg stability during walking, although these changes were not influenced by walking duration within 60 minutes. However, prolonged walking showed the potential negative effect of worn-out shoe on shock absorption.