To investigate how illuminance and color temperature in illumination affect the autonomic nervous system and central nervous system in conditions tending to lower physiological activity, and with an ordinary residential setting in mind, we performed an experiment on 8 healthy male subjects. The experimental conditions consisted of 4 conditions provided by a combination of 2 levels of color temperature (3000 K, 5000 K) and 2 levels of illuminance (30 lx, 150 lx). Physiological measurement was carried out during a process of 22 minutes of light exposure followed by 20 minutes of sleep in darkness. Heart rate variability (HRV) was used as an index of the autonomic nervous system, and alpha attenuation coefficient (AAC) and mean frequency of EEG were used as indices of the central nervous system. Subjective evaluation of drowsiness during the experiment was also carried out immediately following the 20 minutes sleep. No effect on HRV from illumination was noted, but significantly (p < 0.05) lower values for AAC were obtained under 3000 K conditions than 5000 K conditions in measurements during the first half of light exposure (Session 1). During alpha attenuation testing, significantly (p < 0.05) lower values for mean frequency in the theta-beta EEG bandwidth were also obtained under 3000 K conditions than 5000 K conditions, but that pattern persisted in measurement during the second half of light exposure (Session 2). Subjective drowsiness was also higher under 3000 K conditions than 5000 K conditions. These results suggest that low color temperature light creates a smooth lowering of central nervous system activity, and that low color temperature illumination can be used effectively in a bedroom or other such environment where it is desirable to facilitate lowered physiological activity.
To derive an optimal illuminance of nighttime illumination, we conducted an experiment with 7 healthy young individuals and 7 healthy elderly individuals as subjects. After 20 minutes of adaptation to darkness, subjects were exposed to illumination under 5 conditions comprising 0.5 lx, 1 lx, 3 lx, 10 lx, or 30 lx vertical illuminance of the facial region, and heart rate variability (HRV) and electroencephalogram (EEG) were measured, and discomfort was evaluated by subjective report. Results of LF/(LF + HF) (LF = low frequency, HF = high frequency) demonstrated a V-shaped trend for the young groups beginning during exposure and ending post exposure, with 3 lx conditions representing the minimum value, a value markedly lower than that for 30 lx conditions. From these results we inferred that approximately 3 lx illuminance could best suppress physiological stress. Evaluation of discomfort by subjective report also demonstrated an increase in discomfort evaluation scores under high illuminance conditions. The alpha-wave proportion of EEG during exposure fell markedly on 3 lx or higher illuminance conditions, and we inferred that visual sensory information and cortical activity level were adequately attained in 3 lx or higher illuminance conditions. These results suggest that the optimal illuminance of nighttime illumination is approximately 3 lx.
The effects on cognitive performance of breathing air, oxygen and nitrox gas mixtures at surface ambient pressures were investigated during an expedition to the Everest region of Nepal. A slight improvement in grammatical reasoning at altitude was found under nitrox (p < 0.05) and mathematical reasoning showed improvement at altitude on air (p < 0.05), oxygen (p < 0.01) and nitrox (p < 0.01). There were non-significant trends towards decreasing mathematical ability, coupled with an increase in variance on both grammatical and mathematical test performance, with increasing pO2 (all p > 0.05). The results suggest that there is a subtle interaction on cognition as indicated by a significant three-way interaction between subject x altitude x gas (p < 0.05).
Heart rate variability (HRV), a non-invasive index of autonomic controls of the heart, has extensively been employed in various fields of study. The application range of this index persists to expand over the research horizon, and the need continues to demand technical complements for hitherto known deficiencies. Concurrent technical advances in recent years have yielded methodological techniques capable of performing quantitative analysis of HRV. However, as various approaches designed for HRV analysis exist, quantitative comparisons of the investigations have become difficult. Current physiological interpretations of the components of HRV are also inconsistent. Moreover, the issue of respiratory control has been much disputed when determining the HRV. In an attempt to clarify the current controversial state in HRV measurement, the present paper, based on the physiological background of HRV, pursued various procedures of HRV measurement and furnished global explanations for special features characterizing the various analytical approaches adopted thereof.
The purpose of this study was to evaluate the relationship between onset of blood lactate accumulation (OBLA) and long-distance running performance in order to examine whether OBLA can be a good predictor of long-distance running performance even in elite male runners with similar performance levels. Eleven highly-trained male long-distance runners participated in this study. The average running velocities of the individuals' running performance were 5.918 +/- 0.084 m.s-1 and 5.672 +/- 0.095 m.s-1 for 5000 m (V5000) and 10,000 m (V10000), respectively. The blood lactate concentrations and heart rate responses were measured immediately after field running, and the average value of running velocity corresponding to OBLA (VOBLA) was 5.447 +/- 0.132 m.s-1. Variations of these three velocities expressed as a coefficient of variance (CV) ranged from 1.4 to 2.4%. A strong inverse relationship between heart rate corresponding to OBLA (HROBLA) and performance was observed (r = -0.709, p < 0.02 for V5000 and r = -0.830, p < 0.01 for V10000), while there was a lack of significant relationship between VOBLA and performance (r = 0.293, NS for V5000 and r = 0.130, NS for V10000). Furthermore, the average value of HROBLA obtained in this study (174.5 +/- 8.2 b.min-1) was quite similar to that of the heart rate threshold reported by some previous researchers. In conclusion, VOBLA alone could not explain the small variation of long-distance running performance, and HROBLA should be used in place of VOBLA for evaluating long-distance running performance in elite runners with quite similar performance levels.
The ergometer can be a versatile means of measurement if attachments are developed for special purposes or if attachment is developed for multi-uses. In this study, an ergometer attachment for the measurement of power was designed and the measurement of power and the maximum anaerobic power in swimming was tested. A rotation drum was attached to one pedal of an ergometer. The rotation of this drum was synchronized with the rotation of the pedal. One end of a wire for a traction by a swimmer was connected to the drum. The other end of the wire was attached to a belt around the waist of a swimmer. The swimmer swam at full strength, thus causing the drum to rotate. The rotational velocity of the drum was detected as voltage by a magnetic permanent motor and transformed to wire tractional velocity; this velocity was equal to swimming velocity. The wire tension (= load) was controlled by a load adjusting lever of the ergometer. This wire tension was equal to the load which was added to the swimmer. The power calculation was based on a curved regression equation approximated from the load and the velocity. This equation was shown as follows; (P + a) (v + b) = (P0 + a)b or its development (P + a)v = b(P0 - P) and provided that P: force or load, v: swimming velocity, P0: maximum tractional force, a and b: constants. This ergometer attachment made it possible to measure and evaluate the power and the maximum anaerobic power in swimming with ease and at low cost. Measurement and evaluation are easily performed using the system, which is just one example of the possible applications of the ergometer.
In this study we investigated the effects of age factors on physiological responses to deep water running (DWR) compared with those of treadmill running (TMR) while the water and ambient temperatures were kept in thermoneutral conditions. Fourteen young healthy non-smoker males (Age = 20.4 +/- 3.3 years, Height = 170.7 +/- 6.2 cm, Weight = 65.1 +/- 11.4 kg) and fourteen middle aged healthy non-smoker males (Age = 38.6 +/- 4.4 years, Height = 171.8 +/- 4.7 cm, Weight = 75.4 +/- 9.6 kg) were selected for the study. Two maximal tests, one on the treadmill and the other running in deep water using the Wet Vest (Lincoln life jacket) were completed by each subject. The order of trial was counterbalanced with half of the subjects in each group completing TMR first and the rest of those completing DWR first. Although the young males had significantly (P < 0.05) higher relative VO2max, HRmax than the middle aged males, there were no significant differences in absolute VO2max, respiratory exchange ratio (RER), maximal ventilation (VEmax), ratings of perceived exhaustion (RPE), and peak blood lactate values between the two groups. In conclusion, the VO2max, HRmax, VEmax, and peak blood lactate value in response to DWR were significantly lower than those to TMR in both the young and the middle aged males in the thermoneutral conditions. However, there was no significant interaction between age and exercise modes other than RPE of legs at maximal efforts in the present study. We found that the decrease in the maximal physiological responses to DWR compared to TMR is not different between the young and middle aged males.
Moisture inside the footwear can considerably affect the thermal insulation. In this study with a thermal foot model there was simulated three sweat rates (3, 5 and 10 g/h). Five types of footwear with various insulation levels (dry insulation from 0.19 to 0.50 m2. K/W) were tested. The footwear insulation reduction was calculated for 1.5 hour period. The reduction in insulation was related to sweating rate and initial insulation. The footwear with high insulation lost even in percentile more insulation than thin boots under the same conditions (9-19% at 3 g/h, 13-27% at 5 g/h and 19-36% at 10 g/h). A relationship between insulation decrease and sweating rate was established. An 8-hour sweating test (5 g/h) and a test for determining evaporative heat, losses were carried out in addition. The insulation reduction during the first 1.5 hours of the 8-hour test answered for more than half of the total reduction.
The objective of the present study was to test a hypothesis that a high dietary salt intake potentiates a cold induced increase in blood pressure in normotensive men. Male subjects (n = 12) were given 7 g day-1 sodium chloride during the cold months of the year, divided in 3-4 doses per day and dissolved in water, for 14 days additional to their normal diet which contained on the average 9.7 g sodium chloride per day. The same subjects, having their normal diet, served as controls. The resting blood pressure was measured on the fourteenth day seven times at the intervals of five minutes in a climatic chamber in thermoneutral conditions. Then the subjects, wearing a three-layer winter clothing, moved into a wind tunnel (-15 degrees C, air velocity 3.5 ms-1) in which they stayed for fifteen minutes and the blood pressure was recorded at the intervals of three minutes. After the cold exposure, the subjects moved back into the climatic chamber for 30 min and the blood pressure was measured as before the cold exposure. Blood samples were drawn before and after the experiment for ion and hormone measurements. A 12 h urine sample was collected just prior to the cold exposure. A significant difference both in systolic (7 mmHg) and in diastolic (7 mmHg) blood pressure was found between a salt load group and control group under thermoneutral conditions, repeatedly measured over 30 min (paired Student's t-test; p < 0.05). During the whole body cold exposure, blood pressure significantly increased both with and without the extra salt load (repeated measures ANOVA, Student-Newman-Keuls; p < 0.05). The level to which the mean arterial pressure increased during the exposure was independent of the salt intake and the profile of the mean arterial pressure curve was similar in both groups. The systolic pressure increased by a 25 mmHg in both groups during the cold exposure. The increase in the diastolic pressure was significantly (paired Student's t-test, p < 0.05) higher in the high salt group (18 +/- 4 mmHg) than in the control group (12 +/- 3 mmHg) thus supporting partly our hypothesis. After the two-week high salt intake, serum Na+, K+, Cl-, Hct, and plasma Hb were at the similar level as before the extra salt intake. Plasma renin activity, NT-proANP, ANP, and serum aldosterone were not different between the groups, both before and after the cold exposure. The main findings are: 1) the mean arterial pressure increases to the same level and in the same manner independent of the salt load during a short whole body cold exposure and 2) in cold the diastolic blood pressure increases significantly more in people under a very high salt diet.
This paper documents the physical measurements of the Korean population in order to construct a data base for ergonomic design. The dimension, volume, density, mass, and center of mass of Koreans whose ages range from 7 to 49 were investigated. Sixty-five male subjects and sixty-nine female subjects participated. Eight body segments (head with neck, trunk, thigh, shank, foot, upper arm, forearm and hand) were directly measured with a Martin-type anthropometer, and the immersion method was adopted to measure the volume of body segments. After this, densities were computed by the density equations in Drillis and Contini (1966). The reaction board method was employed for the measurement of the center of mass. Obtained data were compared with the results in the literature. The results in this paper showed different features on body segment parameters comparing with the results in the literature. The constructed data base can be applied to statistical guideline for product design, workspace design, design of clothing and tools, furniture design and construction of biomechanical models for Korean. Also, they can be extended to the application areas for Mongolian.
The objective of this study was to examine changes in sailors' physical characteristics during three different time periods immediately before the 1996 New Zealand Olympic trials, as a result of a newly introduced sport science programme. Twenty five (19 male and 6 female) Olympic development squad members volunteered as subjects and completed fitness tests at different times between April 1995 and March 1996 after being administered with individualised physical training programmes. Statistically significant improvements were observed in body weight, sum of skinfolds, flexibility (assessed using a sit-reach test), aerobic endurance (assessed using a maximal effort 2500 m rowing test) and strength (assessed as the maximum number of push-ups, pull-ups, and sit-ups that could be completed in 2 minutes) over the three time periods. Thus, physical training was effective in improving many aspects of sailors' fitness, especially early in the sailing season as a result of pre-season training. Physical performance correlated poorly with both light and heavy wind racing performance. The results suggest that individually tailored training programmes will increase sailing specific fitness. However, it is impossible to know what proportions of racing performance can be attributed to physical fitness, skill, talent, and technology, therefore the effect of physical training on racing performance is difficult to determine.
The objective of this study was to determine the change in elite dinghy sailor's knowledge and use of sport science, three years after the adoption of a sport science support (SSS) programme by Yachting New Zealand for its elite dinghy sailors. A questionnaire was administered to 28 (22 male, six female) elite sailors in April 1994 and to 33 (24 male and nine female) in March 1997 during a training camp for elite sailors. 15 of the sailors participated in 1994 and 1997. The questionnaire asked whether or not the sailors used a training race diary and inquired about their knowledge and use of sport science in the areas of nutrition, psychology and physical conditioning. In 1997, additional questions enquired about sailor's perception of sport science and its affect on their racing performance. Between April 1994 and March 1997, sailors received sport science support in nutrition, psychology and physical conditioning. Sailors reported a greater amount of fluid drunk on a four-hour sail in 1997 than in 1994 and a greater proportion of sailors ate a high carbohydrate meal after a race in 1997 than in 1994. In 1997, sailors reported feeling less anxiety before a race, and the sailors common to 1994 and 1997 reported feeling less sick before a race in 1997 than in 1994. Increases were observed in volume and intensity of physical training, and improvements were noticed in the chosen type of aerobic training in 1997. Most sailors believed that their knowledge and use of sport science has increased and that their increased use of sport science has led to improvements in racing performance. The results suggest that elite New Zealand sailors' use of sport science improved in the areas of nutrition, sports psychology and physical conditioning between 1994 and 1997. However, when the results were compared with those of Legg and Mackie (1999), it was evident that greater physical conditioning improvements had occurred between 1994 and 1995 than had been sustained since, while the majority of sailor's sport psychology improvements occurred between 1995 and 1997. Sailors reported fluid intake between 1994 and 1997 had steadily improved. The reason for sailor's change in emphasis on different areas of sport science over time may be a result of their adopting ideas with which they were most familiar (physical conditioning and nutrition) first, and then adopting the less widely understood discipline of sport psychology once they felt that they had mastered their use of physical conditioning and nutrition. This study indicates that sailors are beginning to understand the importance of personal preparation using sport science principles.
It is known that lactate, the level of which is increased during exercise, disappears more rapidly during low-intensity exercise than during passive recovery (Belcastro and Bonen, 1975; Stamford et al., 1981). This is because lactate can be used as an energy source during low-intensity exercise. If lactate can be used in such a way, it is supposed that the lactate that is produced during high-intensity exercise would disappear more rapidly during simultaneous low-intensity exercise. Therefore, in this study, we had subjects perform both incremental arm exercise and low-intensity steady-state leg exercise at the same time. This protocol was adopted for the following reason. During incremental exercise, if lactate elimination is affected by simultaneous leg exercise, it is supposed that the lactate threshold (LT), the point at which lactate production exceeds elimination, would also be affected. However, because arm exercise was performed, it was difficult to obtain blood samples from the fingertip. Therefore, we used respiratory gas kinetics to examine the effect of low-intensity leg exercise on ventilatory threshold (VT) during incremental arm exercise.
The present study attempted to design and evaluate a small portable electromyogram (EMG) amplifier that can output enhanced EMG and its root mean square (RMS) value. The production and design were of a laboratory scale without any special or high cost circuit construction. The designed amplifier was actually innovated according to the actual working conditions based on physiological anthropology. The present amplifier was compared with commercially available products and proved to be of practical use. The device was installed with a sufficiently small body depicting 8-channel variable gain AC amplifier and variable time-window RMS-to-DC converter. The prototype was battery-driven and well-shielded to minimize external noise interference.
This research clarified the changes in body shape among Japanese women aged in their 20's, by measuring the subcutaneous fat distribution over the whole body and its circumference at certain points. The subjects, 13 healthy women, were measured twice, once in their early 20's and 5 years later in their late 20's. Subcutaneous fat thickness was measured at 14 points on the body using the B-mode ultrasound method and the body size was measured directly at 8 points on the body using a steel measure. Subcutaneous fat thickness tends to increase with age, except at the cheek, neck, bust and leg. Significant increases were detected especially at lower parts of the trunk such as the waist and infragluteal region. Meanwhile, despite the significant change in subcutaneous fat thickness, the circumferences measured did not change, and also weight tended to decrease with age. Based on this finding, except for fat, body mass, such as muscle and bone, decreases with age due to decreased exercise and changes in calorie intake. Cluster analysis of the accumulation patterns of subcutaneous fat indicated that there were the following 3 patterns of subcutaneous fat accumulation from the early 20's to the late 20's. I. Accumulation on the whole trunk (bust, abdomen, waist and back) and upper arm--trunk/upper arm accumulation pattern. II. Significant accumulation around waist--waist accumulation pattern. III. Even accumulation at abdomen, side abdomen, hip and lower hip--abdomen/hip accumulation pattern.
The present study investigated the validity, reliability, objectivity, and practicability of methods with skinfold caliper (SF), ultrasound (US), bioelectrical impedance (BI), and sulfur hexafluoride (SHD) using identical subjects, and evaluated comprehensive usefulness by comparing selected methods or equations. In examining validity, underwater weighing (UW) was employed to obtain the criterion of validity. The subjects were healthy Japanese, 16 males and 15 females, aged 18 to 32 years. The prediction equation developed by Nakadomo et al. (1990b) was considered to be suitable for BI. With respect to the validity, BI and SHD assessing total body when estimating body composition would be more valid than those assessing partial subcutaneous skinfold thickness. A comprehensive evaluation through an examination with respect to the validity, reliability, objectivity, and practicability suggests that the BI could be the best method to assess human body composition in vivo.
A heated full-scale hand model has been used to determine indirectly hand and finger heat losses of human subjects exposed to four ambient cold conditions (0, 4, 10 and 16 degrees C, air velocity approximately 0.3 m/s). Heat transfer coefficients determined with the hand model, were used to calculate heat flux based on measured skin to ambient temperature gradients. The responses of eight subjects from a previous study were used for the analysis. The measurements were carried out in a small climate chamber which was cooled by evaporating liquid carbon dioxide. The thermal hand was put into the chamber in a vertical position with the thumb up. The surface temperature of the thermal hand was controlled at 21, 25, 28, 31 and 34 degrees C under each of the four ambient cold conditions, in order to investigate possible temperature dependence of the calculated combined convective and radiate heat transfer coefficient (hCR). The value of hCR varied between approximately 9-13 W/m2 degree C for fingers and palm and back of hand, respectively. Calculated heat losses showed significant individual variation, corresponding to the maintained skin to ambient temperature gradient. Individual values from about 50 to more than 300 W/m2 were calculated. Several subjects showed CIVD and heat fluxes associated with this phenomenon were sometimes doubled. The measurement results showed realistic and comparable with literature date. The advantages of the thermal hand model can be counted as easy to use; directly measures the heat loss; highly reproducible and no interruption. It appears that a heated hand model provides a useful methods for analysis and quantification of hand heat loss.
The relative contributions of genetic and environmental components in the variability of anthropometric measurements were studied in 54 twin pairs. Thirty pairs of monozygotic (MZ) and 24 pairs of dizygotic (DZ) twins were investigated to estimate the role of genetic, environmental and hereditary factors determining anthropometric measurements comprising body weight, standing height, sitting height, knee height, arm span, chest circumference and biiliac diameter. Within-pair variance for all the measurements were significantly smaller (p < 0.05-0.01) in MZ twins than in DZ twins of both-sex twin group. Within-pair correlations for those measurements were higher (p < 0.01) in both MZ and DZ twins. Correlation values were, apparently, higher more in MZ than in DZ twins. Besides, all the measurements are highly heritable components and heritability estimates ranged 40%-91%. When both MZ and DZ twin pairs of both-sex population were classified, based on age and sex, into different sub-groups interindividual variabilities were altered to a certain degrees. These data state that anthropometric measurements are influenced by genetic factors than environmental factors and besides, age and sex are possibly associated, to some extent, with the genetic influence upon anthropometric measurements.
This study investigated the metabolic demands of deep water running (DWR) compared with those of treadmill running (TMR) while the water and ambient temperatures were kept under thermoneutral condition. Two maximal tests, one on treadmill and the other running in deep water using the Wet Vest (Lincoln life jacket) were undertaken by twenty healthy non-smoker males (Age = 28.0 +/- 9.2 years). The order of trials was counterbalanced with half of the subjects completing the treadmill first and the rest completing the water running first. Oxygen consumption (VO2), ventilation, heart rate (HR), respiratory exchange ratio (RQ), ratings of perceived exertion (RPE) and blood lactate were measured. VO2max (2.68 vs 3.40 ml/kg/min), HRmax (171.5 vs 190.8 beats/min), maximal minute ventilation (98.5 vs 113.31/min), and peak blood lactate value (10.44 vs 12.47 mmol/l) in response to DWR were significantly lower than those of TMR in the thermoneutral conditions. The lower VO2max and HRmax values of DWR compared to those of TMR are shown to be attributed to the hydrostatic effects caused by water and different muscle recruitment patterns between DWR and TMR.
In this study, we measured the shape of the face, legs, hands and fingers during the course of a day to determine the amount of swelling. We examined the relationship between the perception of swelling and the degree of actual swelling, and considered the influence of seasonal factors. The topology of the face was measured using the 3D curved shape measuring apparatus, VOXELAN, while the circumference of the legs and fingers and the volume of the hands were also recorded. The measurements were used to determine the amount of change in each parameter, which was then used to determine the degree of swelling. The subjects for the experiment were 10 healthy Japanese women aged 24 to 30 years of standard build (BMI: 19.3-25.0). Measurements were carried out twice a day in the mornings and afternoon, first between 8:30 and 10:00 a.m. and then between 4:00 and 5:30 p.m. At each measurement session, subjects were asked if they perceived swelling to have occurred. We investigated the relationship between the degree of actual swelling and the reported perception of swelling. We also investigated the influence of seasonal factors by conducting the same tests on the same subjects in summer (August 1997) and in winter (February-March 1998). The relationship between perceived and actual swelling differs depending on the part of the body. For the face, actual swelling correlates strongly with perceived swelling. This trend is particularly noticeable for the upper eyelids. For the thigh and lower leg, on the other hand, there was no significant difference. The frequency with which subjects reported the perception of swelling varied depending on the area of the body, and was generally extremely low for the thighs, hands and fingers. With respect to seasonal variation, swelling in the face, hands and feet tended to be more pronounced during the summer. In the facial region, the biggest difference was in the lower eyelid, where swelling increased more than five times. This level of variation suggests that the atmospheric temperature is the main factor affecting swelling.
