Meeting new challenges toward the 21st century--the "Journal of Physiological Anthropology and Applied Human Science".
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Anthropology, Physical↗
Biomedical subjects
A Yasukouchi
Publications and source records attributed to A Yasukouchi.
Effects of color temperature of fluorescent lamps on body temperature regulation in a moderately cold environment.
A study on the effects of different color temperatures of fluorescent lamps on skin and rectal temperatures in a moderately cold environment involving (i) changes in skin temperature of 7 male subjects exposed to an ambient temperature ranging from 28 degrees C to 18 degrees C (experiment I) and (ii) changes in skin and rectal temperatures and metabolic heat production of 11 male subjects exposed to ambient temperature of 15 degrees C for 90 min (Experiment II) was conducted. In Experiment I, the reduction of mean skin temperature from the control value was significantly greater under 3000 K than under 5000 K or 7500 K lighting. In Experiment II, the reductions in mean skin temperature and rectal temperature were respectively greater and smaller under 3000 K than those under 5000 K or 7500 K lighting. However, metabolic heat production was not affected by color temperature conditions. The relationships between morphological and physiological parameters revealed that no significant relation of rectal temperature to body surface area per unit body weight was found only under 3000 K. Furthermore, while the mean skin temperature was independent on the mean skinfold thickness under 3000 K, a significant negative correlation between the rectal and mean skin temperatures was observed. Therefore, body heat loss might be suppressed effectively by increasing the vasoconstrictor tone under a color temperature of 3000 K, and the body shell was dependent only on morphological factors under 5000 K and 7500 K lighting.
Adult↗
Analysis of heart rate variability during mental task with reference to ambient temperature.
The purpose of this study was to evaluate the cardiac autonomic control over mental task under various ambient temperatures (21 degrees C, 28 degrees C and 35 degrees C). Seven healthy male subjects engaged in the mental tasks, which consisted of distinctive reaction-time tasks. Respiratory coefficient of variation of instantaneous heart rate (CVRESP), derived from the cross-correlation function between heart rate and respiratory curve, was used as a parameter to assess parasympathetic nervous functions. The difference between total coefficient of variation (CVIHR) and CVRESP was used as a parameter to assess sympathetic nervous functions. The mean heart rate increased at high ambient temperature (35 degrees C) and also during mental task. Both the effects of ambient temperature and task conditions were significant on heart rate, and also on CVIHR. Moreover, the effects of ambient temperature and task conditions in CVIHR were divided into the effect of ambient temperature on CVRESP and the effect of task conditions on the difference between CVIHR and CVRESP. These results implied that respiratory modulated parasympathetic activity might control basal the effect of ambient temperature, and the other components including sympathetic activity contribute to the increase in heart rate due to mental task.
Adult↗
Effects of mental task on heart rate variability during graded head-up tilt.
In this study, we used spectral analysis of heart rate variability (HRV) to estimate the changes in autonomic control in response to disparate stimuli produced by mental task and graded head-up tilting. The low frequency (LF) component of HRV provided a quantitative index of the sympathetic and parasympathetic (vagal) activities controlling the heart rate (HR), while the high frequency (HF) component of HRV provided an index of the vagal tone. We studied 17 healthy male subjects (21-25 yr of age) who were placed on a tilt-table and the graded tilt-protocol involved tilted sine angles 0.0, 0.2, 0.4, 0.6, 0.8, and 1.0. These tilt-protocols were repeated with or without the mental task, which consisted of auditory distinctive reaction-time tasks. The basal autonomic mode against the graded head-up tilt was characterized by reciprocal changes in sympathetic and vagal tones. There were significant increases of HR corresponding to the mental task with lower tilt-angle, albeit the changes with higher tilt angles were not significant. Furthermore, there were increases and decreases of the LF component induced by the mental task at lower and higher tilt-angles, respectively. These results revealed that the different responses of HR and LF component against the same tasks could be derived from the alterations of autonomic mode during gradual changes in autonomic control.
Adult↗
Blood lactate disappearance during breathing hyperoxic gas after exercise in two different physical fitness groups--on the workload fixed at 130% AT.
This study aimed to investigate the effects of hyperoxic gas breathing on the disappearance of blood lactate after exercise in two groups having different physical fitness and to determine the most effective O2 concentration in consideration of workload. Our previous study has demonstrated that hyperoxic gas breathing brought out different effects among subjects. In respect of these effects, it was thought necessary to pay attention to exercise intensity. Therefore, the exercise intensity of this study was set by using relative workload of anaerobic threshold (AT) from the aspect of blood lactate. Ten healthy male students participated as subjects and were divided into 2 groups; a group consisting of 5 active students whose mean AT was 60.4% VO2max (Higher AT group) and the other group consisting of 5 inactive students having the mean AT of 48.8% VO2max (Lower AT group). All subjects underwent three cycles of ergometer exercise on a bicycle (workload; 130% AT) for 5 min and recovery session for 6 min. The hyperoxic gas breathing was given only for the recovery session. The conditions of breathing were air, 30, 40, 60 or 80% O2. Blood for determination of the blood lactate level was taken only in the recovery session. When compared with air-breathing, the blood lactate level was significantly reduced in the condition of more than about 60% O2 breathing in Higher AT group, but not in Lower AT one. Together with the previous findings, it was found that the blood lactate level was markedly reduced by more than 60% O2 breathing in Higher AT group without relation to the workload in the range of about 70 to 80% VO2max. In Lower AT group, however, the effects of hyperoxic gas breathing were dependent on the exercise intensity; 30% and 40% O2 breathings were effective for the subjects with more than about 65% VO2max, but not in a lower intensity than it. These results indicate that the effects of hyperoxic gas breathing on the disappearance of blood lactate are dependent on the exercise intensity and the physical capacity.
Adult↗
Blood lactate disappearance during breathing hyperoxic gas after exercise in two different physical fitness groups--on the work load fixed at 70% VO2max.
The purpose of this study is to evaluate effects of breathing hyperoxic gas on blood lactate disappearance after submaximal exercise in two different physical fitness groups and to clarify the most effective oxygen concentration in each group. Fourteen healthy male students participated as subjects in this study. They were divided in two groups by difference in their anaerobic threshold (AT). Seven males were treated as Higher AT group and the others as Lower AT group. Subjects wore a T-shirt, short pants and sports shoes and performed three sessions; each consisting of five minutes of exercise and six minutes of rest, at a workload of 70%VO2max on a bicycle ergometer. Hyperoxic gas was breathed only during recovery periods. Oxygen rates of 21, 30, 40, 60, 80 and 100% in inspired gas were employed. According to the results of blood lactate (BLA), the most effective oxygen condition on BLA disappearance was obtained over 60% in Higher AT group and at 30% oxygen in Lower AT group. Thus, it was especially noteworthy that the effects of hyperoxic gas in Higher AT group were different from those of Lower AT group. It is thought that the effects of breathing hyperoxic gas were dependent on physical fitness, which have caused many reports to be in conflict hitherto.
Adult↗
Effects of reduction in arousal level caused by long-lasting task on CNV.
The present study aimed at investigating an inverted-U relationship between contingent negative variation (CNV) and arousal level by examining the effects on CNV of gradually reduced arousal level by long-lasting task. The subjects conducted a simple reaction time task consisting of warning stimuli (S1) and imperative stimuli (S2). This task consisted of 200 trials and lasted about 40 minutes. During this task, spontaneous EEG before S1 and SPL (skin potential level) were measured as indicators for arousal level. The 200 CNV, EEG and SPL data were classified into 5 blocks each of which included 40 trials of data. Analysis was made in seven subjects in whom reduction in the arousal level in long-lasting task was shown by increase in the relative power values of alpha waves before S1 and decrease in the SPL. As a result, the amplitude of early CNV at Fz was observed to increase from the earlier half phase (block 1) to the middle phase (block 3) and to decrease from the middle phase (block 3) to the latter half (block 5). In the middle phase, the amplitude was the greatest. The low amplitude of early CNV in the early half of the task (block 1) was inferred to have been induced by excessive arousal state because of the low relative power values of alpha waves and the high SPL at this time. On the other hand, the low amplitude in the later phase (block 5) was inferred to have been induced by reduction in arousal level because of the high relative power values of alpha waves and the low SPL. These results suggested that CNV amplitude and arousal level was in an inverted-U relationship.
Adult↗
Effects of changes in arousal level by continuous light stimulus on contingent negative variation (CNV).
The purpose of the present study was to investigate an inverted-U relationship between contingent negative variation (CNV) and arousal level which was influenced by extraneous environment. As an extraneous stimulant, stimulation by light was adopted, and five levels of luminance conditions, 10 cd/m2, 100 cd/m2, 320 cd/ m2, 1,000 cd/m2, and 1,800 cd/m2 were provided randomly. Under five luminance conditions, seven subjects who had been accustomed a measurement of CNV executed simple reaction time tasks to evoke CNV. Outside CNV, spontaneous EEG prior to S1 was measured as an indicator for arousal level. As a result, a negative correlation existed between the logarithm of luminance and the relative power value of alpha waves at Fz. Otherwise, an increase in luminance caused an increase in CNV amplitude until the luminance level reached 320 cd/m2, beyond which however CNV amplitude was found to decrease. These tendencies were most remarkable in the phase of early CNV at Fz. The low amplitude of early CNV seen in the high luminance conditions was inferred to have been induced by excessive arousal state because of the low relative power value of alpha waves, while the low amplitude in the low luminance conditions was inferred to have been induced by low arousal state because of the high relative power value of alpha waves. However, changes in arousal level by light stimulus caused no effect on reaction time. From these findings, it was suggested that a definite "inverted-U" relationship existed between the change in arousal level by light stimulation and resultant CNV, and that it could be discriminated as to whether reduction in CNV is caused by excessive arousal effect of environment by analyzing spontaneous EEG preceding S1.
Adult↗
The relationships between lumbar curves, pelvic tilt and joint mobilities in different sitting postures in young adult males.
The lumbar lordosis and pelvic tilt of twenty male subjects were measured in standing and in three different sitting postures with the trunk-thigh angles of 120 (sitting A), 90 (sitting B), and 60 (sitting C) degs and the knee angle was constant at 90 deg. Ten more male subjects participated in the supplemental study, in which additional condition of the knee angle was employed in postures of the trunk-thigh angles of 90 and 60 degs. Some joint mobilities were also measured to investigate the relations of the mobilities to lumbar lordosis and pelvic tilt. The lumbar curve decreased and the pelvis rotated rearward significantly as the trunk-thigh angle and the knee flexion decreased. The great alteration of the lumbar curve was observed between standing and sitting A, which was much different from the results of Keegan (1953) studied in the subjects of lateral recumbent position. There was a high correlation coefficient between the lumbar curve and the pelvic tilt (r = 0.909), so that the relations of the pelvic tilt to the joint mobilities were investigated. When the knee angle was constant, the pelvic tilt is related significantly to the hamstrings between standing and sitting A and to the gluteus maximus between sitting A and sitting C. However, at different sitting postures with the trunk-thigh angles of 90 and 60 degs involving different knee flexions, hamstrings added to gluteal muscles affected significantly lumbar curve and pelvic tilting.(ABSTRACT TRUNCATED AT 250 WORDS)
Hip Joint↗
Effects of the direction and distance of horizontal arm movements on local muscular strain--a fundamental study on the teller workplace in bank.
This study was conducted to examine the relative differences in the muscular strain of the hand-arm-shoulder system in the repetitive arm movements which would directly depend on the layout of devices at teller counter. The subjects were five young male adults. The manual handling task was standardized and the repetition frequency was in self-pace. The arm movements were characterized by the different direction measured from the frontal plane of the subject between 0 degrees to 150 degrees combined with the distance measured from the acromion to the fixed points of 300, 500 and 700mm. The movements to all of the fourteen points tested were evaluated on both sides of the arms and shoulders by the integration of the EMG signals (IEMG) as to m. deltoid pars media and clavicularis, m. trapezius pars descendens, m. pectoralis major pars clavicularis and m. extensor carpi radialis brevis. It was found that IEMG of the deltoid muscles were sensitive to the direction and distance of the arm movements while the trapezius muscle showed the relative lower dependence on the direction. There were significant combined effects of the direction and distance in all muscles; i.e. effect of reach distance was greater with decreasing the arm angle, which was obvious at distance longer than 500mm in the arm abduction. When IEMG was divided by the task time in self-pace which increased in the arm abduction, the peak value was observed at the angle of 30 degrees. It was suggested that if the repetitive movement was required at the same frequency as at the angle of 30 degrees the position near the arm abduction (the angle of 0 degrees) would become the most expensive working direction.
Adult↗
Breathing pattern and subjective responses to small inspiratory resistance during submaximal exercise.
Breathing patterns and subjective responses to small resistances were investigated in seven subjects during moderate exercise. Inspiratory resistances of 0.15 (R1), 0.25 (R2) and 0.30 (R3) kPa.l-1.s were tested against control of 0.06 kPa.l-1.s with no added resistance. Subjective responses to small inspiratory resistances were evaluated through whole experiments including periods before and after exercise, herein called SNS. Average SNS significantly increased above the R2 condition. Above the R2 condition, significant changes in the breathing components of volume, flow and timing were also observed during exercise. SNS grew as a power function of peak inspiratory pressure (P(imax)) measured during exercise within such small range of stimulation less than the R3 condition and individual differences in the relationship between SNS and P(imax) were observed. All subjects felt at least some discomfort below the resistance of R3 and two subjects felt it below around R1 condition. It was suggested that breathing pattern was selected to limit peak pressure at the R3 condition by further increasing inspiratory work for a breath and this tendency was reinforced in load-sensitive subjects with longer inspiratory time and lower peak flow rate. We concluded that breathing patterns depend mainly on peak work, especially in load-sensitive individuals, which is likely to be one of the primary determinants of a worker's tolerance to respirators.
Adult↗
Changes in breathing pattern at loads near perceptual threshold at different work levels.
Five subjects were tested to determine the threshold for detection of an added resistance to inspiration in three tests, one at rest and two with exercise (mild = 50 W; moderate = 100 W) on a cycle ergometer. Changes in the breathing pattern were examined at added resistances near the perceptual threshold. Added inspiratory resistances with a 50% probability of detection were very variable at rest; they decreased significantly from rest (250 Pa.l-1.s-1) to moderate exercise (98 Pa.l-1.s-1) in four subjects. It is suggested that physical exercise may cause discomfort even when workers wearing a respirator do not have any abnormal sensation during sedentary work. Breathing patterns were compared between resistance loaded and unloaded breathing during each test. Decreases in inspiratory peak flow and acceleration of flow early in inspiration were found in resistance loaded breathing in almost all tests and a tendency for tidal volume to decrease was found during moderate exercise only. The ratios of resistance loaded to unloaded breathing for inspiratory time (ti) and total time (tt) tended to be greater in the detected than in the undetected responses at rest and during mild exercise but not during moderate exercise. This would imply that further prolongation of ti and tt in the detected responses was attributable to conscious or subconscious aspects of the resistance leading responses: however, these adjustments in breathing, which reduce frequency, would be less likely to occur as the work rate increases.
Adult↗
Characteristics of pulmonary diffusing capacity for CO at rest and during exercise.
Characteristic patterns of changes in pulmonary diffusing capacity (DL) at rest and during exercise were investigated and characteristics of normal DL values concerned on sex, age, and ethnic groups were examined by viewing our studies and other reports. The relation of DL and pulmonary capillary blood volume (Vc) was represented as a logarithmic regression at rest and as a linear regression during exercise. The curve relation at rest is considered to show that the increase in Vc mainly reflects the process of transport from pulmonary capillary recruitment to pulmonary capillary dilation. The increasing rate of DL was not decreased during exercise, which seemed to be due to an increase in pulmonary blood flow accompanying exercise. The linear regression was also found between DL and oxygen intake during exercise and the slope was always constant among individuals and among subject groups. The general results concerned with sex difference in Japanese or ethnic difference between Japanese and Caucasians in both sexes could show that DL per stature was greater in males or Caucasians than in females or Japanese in young adults, however, the sex or ethnic difference disappeared in middle or old aged group. DL per alveolar volume which showed no sex or ethnic difference in young adults, was greater in middle or old aged group of females or Japanese than in that of males or Caucasians.
Adolescent↗
Effect of precooling on heat tolerance of resting men in a hot environment: comparison with seasonal effect on it.
Four healthy Japanese males volunteered as subjects. They were exposed to hot environment of 50 degrees C with 50% relative humidity for 61 minutes immediately after the precooling where they rested in a 10 degrees C for 30 minutes. Their physiological data were compared with that of a previous report (Iwanaga et al., 1983), in which we studied the physiological responses of the same subjects at rest in a 50 degrees C without precooling in summer and winter. After precooling (PC), all the four subjects completed heat exposure for 61 minutes. But without precooling in summer (NC), two of the subjects stopped heat exposure before 61 minutes because of hyperthermia. Rectal temperature (TR) was lower in PC than in NC before and during heat exposure. During heat exposure, TR in PC had risen at the 30th minute, but TR in NC at 20th minute. Whereas there was no difference in heart rate (HR) during heat exposure between summer and winter, in PC HR remained lower than in NC because rising time of HR was prolonged during heat exposure.
Acclimatization↗
Effects of added resistive loads to inspiration on submaximal work performance.
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Adult↗
Sex differences in human thermoregulatory response to cold.
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Adolescent↗
Characteristics of pulmonary diffusing capacity in Japanese--aging effect on the sex and ethnic differences.
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Adolescent↗
Thermal effect on uniform increase in pulmonary diffusing capacity during exercise.
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Adult↗