Increased VDT operations have produced an entirely new working environment and have made the burden too heavy for living bodies, causing health troubles to pose a social problem. To reduce such burden to a possible extent, the environment capable of receiving information effectively was studied from the viewpoint of lighting condition. Two experiments were conducted on problems within the visual field and illuminance in the circumference. The results show that the range where glare gives unpleasantness is smaller than the range where it changes the pupil. They also show that higher luminance in the circumference is desirable if the contrast of display characters is not degraded and that lower display brightness is desirable to the extent that visibility is not affected.

View full abstract

Surface electromyograms (EMG) during dynamic contractions of elbow flexors were studied in reference to muscle contraction speed, the change of muscle length, contraction strength and the change of muscle contraction strength. Subjects flexed their arms at elbow joint angle of 40-150 degrees with loads 1, 3 and 6kg at the flexion-extension period of 2, 4 and 8sec. One flexion was divided into five phases by the elbow joint angle ; shortening contraction with the start of contraction (phase1), shortening contraction without the start of contraction (phase2), the period when shortening contraction changes to lengthening contraction (phase3), Iengthening contraction without the end of contraction (phase4) and lengthening contraction with the end of contraction (phase5). Surface EMG of muscle biceps brachii was integrated and the power spectrum was calculated. The value of integrated EMG increased in parallel with the speed of contraction. The degree of the increment was larger in shortening contractions than in lengthening contractions. This result by integrated EMG was explained by the energy loss caused by muscle shortening. Relative power in low frequency was more at fast contraction, Iengthening contraction, Iight strength contraction and contraction when the muscle is lengthened. These effects were discussed from the viewpoint of the synchronization of motor unit activity.

View full abstract

9 young males and 7 young females were used as subjects. Subjects were exposed to hot environment at 50°C in supine position for 61min after resting at 28°C for 30min. Rectal and mean skin. temperatures were measured during exposure. Increase in rectal temperature tended to be larger in male than in female, though the difference of increase in rectal temperature between both sexes was not significant statistically. In male subjects, increase in rectal temperature was correlated with body weight, body fat content, skinfold thickness, body surface area and body surface area-to-mass ratio. But, such relationships were not shown in female subjects. Oxygen uptake, heart rate and pulmonary ventilation were linearly correlated with rectal temperature for males and females. Relationship between rectal temperature and ventilatory equivalent was found only for 4 males. It was suggested that a part of the males showed increase in ventilatory equivalent as a response to hyperthermia.

View full abstract

Maximum local energy metabolic rates of seven muscle groups have been attempted to predict with somatometric indices, which are easily measured. The predicted muscle groups were the muscles of the anterior abdominal wall (M₁), the erector spinae muscles (M₂), the muscles of the buttock (M₃), the posterior femoral muscle (M₄), the anterior femoral muscle (M₅), the posterior crural muscle (M₆), and the anterior crural muscle group (M₇). The prediction equations were constructed by using multiple regression technique. Dependent variables were energy metabolic rateY₁(kcal/h), Y₁ Per BSA(m₂) and Y₁ Per LBM(kg) (i = 1, ---, 7). Independent variables were length, girth, depth, breadth and volume related to each region over the predicted muscle group. The prediction equations could be obtained. However the accuracy of those for M₁ and M₂ was rather doubted. Adding skinfold thickness to the independent variables, the prediction equations for M_l and M₂ Were obtained as equation (10) and (11) respectively. The most valid prediction equations for M₃-M₇ in the present study were equation (5)-(9).

View full abstract

The ventilatory threshold (VT ; determined by gas exchange parameters) has been applied for many purposes regarding to physical working capacity in many studies. VT, however, contains the subjective variation, because it is determined from some criteria of gas exchange parameters visually. Recently, there are some reports that lactate threshold (LT)and VT do not always occur simultaneously. In this study, we employed the segmented regression analysis to estimate LT and VT objectively, and re-examine the relationships of LT computed, VT computed, and VT deterTnined visually. Thirteen young male subjects performed an incremental-load ergometer work in which the initial work rate was the 4 min unloaded cycling and thereafter the work rate was increased 150 kgm every 2 min until exhaustion. Gas exchange parameters were measured by Douglas bag method continuously, and blood samples for LA analysis were obtained last 30 sec each work rate from warmed ear lobe. It is supposed that LA and V_E changes against V_o2 during progressive work is fitted by three segment model, so we employed the segmented regression analysis to all data and data below 85% V_o2max of LA and V_E vs. V_o2, and estimated LT(all), LT(85%), VT(all), and VT(85%), respectively. VT(visual) was a mean value of four observers who visually inspected the graph of V_E, V_E/V_o2, and V_E/V_co2 vs. V_o2 according to two criteria described below, 1) non-linear increase in V_E, 2) increase in V_E/V_o2 Without corresponding increase in V_E/V_co2. The results of this study were 1) LT(85%) is always consistent with LT(all) and have a standard deviation of about 0.1L/min-V_o2, 2) all variables that computed or inspected by gas exchange informations and LT(85%) do not always occur and these results suggest limitations and invalidity of using gas exchange parameters to estimate LT.

View full abstract

Four relatively fit young men performed duplicate 50-min bouts of experiment including rest and cycle ergometer exercise of 100W and 150W in ambient temperatures of 25°C and 40°C. To study responses of skin blood flow in different ambient temperatures during exercise as compared with those at rest, forearm blood flow (FBF) and rectal temperature (Tr) were measured. In each case, rising Tr throughout the period of experiments was observed. The linear relationship between FBF and Tr shown in all subjects was unaltered by the ambient temperature, and was altered by the intensity of work. We concluded that the higher body temperature results in more skin blood flow at a level of work load and that the higher intensity of work the less skin blood flow at a given body temperature.

View full abstract

Japan marine science and technology center conducted twenty-four saturation dives including the project SEATOPIA (max 100m), the project SEADRAGON (max 300m simulation dive) and et.al. in the period from 1972 to 1984. In those projects, the studies about diver's water balance and body heat loss were carried out. This paper discussed about the urine flow and the insensible water loss on the divers staying under helium rich hyperbaric environment. The results obtained are as follows. 1. Urine flow is increased in proportion to the environmental pressure. This phenomenon is clear with the night urination. 2. Insensible water loss at 31 ATA is decreased to 1/2 of the value at 1 ATA. 3. The decrease of insensible water loss contains 44% within the night urination's increase in the case of 31 ATA, the remains case consists the high moisture inside the blanket and the cold stress by helium gas.

View full abstract

In the first place the principle and properties of a hood method for measurement of metabolism during sleep are described. In the next place the hood system built by authors as a trial is described. This system consists of a hood, an electric blower, a wet gas meter and 300-liter gas bags. The dead space of the hood is about 10 liters. The blow rate was adjusted at 25, 30 and 40 l/min. The VO₂ and VCO₂ values were measured for 3 adult men, the correlation coefficients between the hood method and the Dougles bag method were 0.978 and 0.980, respectively. No relationship appeared between blow rate and accuracy of measurement.

View full abstract

A small chamber was constructed for hyperbaric pharmacological and biochemical studies. This chamber has an internal volume of 30 Iiter and working pressure is up to 11 bar. It is consisted of the following : (1) a system of remote injection ; (2) measuring of the EEG (electroencephalograph), brain temperature, ECG (electrocardiograph) ; (3) a system of direct blood collection. Especially, being collected whole blood, the inside different pressure of syringe was from 0.2 to 0.7 kg/cm². These results of injection of the drug and collection of the whole blood was satisfied.

View full abstract

[in Japanese]

View full abstract

[in Japanese]

View full abstract