The purpose of this study was to investigate the effect of the exposure to bright light on EEG activity and subjective sleepiness at rest and at the mental task during nocturnal sleep deprivation. Eight male subjects lay awake in semi-supine in a reclining seat from 21:00 to 04:30 under the bright (BL; >2500 lux) or the dim (DL; <150 lux) light conditions. During the sleep deprivation, the mental task (Stroop color-word conflict test: CWT) was performed each 15 min in one hour. EEG, subjective sleepiness, rectal and mean skin temperatures and urinary melatonin concentrations were measured. The subjective sleepiness increased with time of sleep deprivation during both rest and CWT under the DL condition. The exposure to bright light delayed for 2 hours the increase in subjective sleepiness at rest and suppressed the increase in that during CWT. The bright light exposure also delayed the increase in the theta and alpha wave activities in EEG at rest. In contrast, the effect of the bright light exposure on the theta and alpha wave activities disappeared by CWT. Additionally, under the BL condition, the entire theta activity during CWT throughout nocturnal sleep deprivation increased significantly from that in a rest condition. Our results suggest that the exposure to bright light throughout nocturnal sleep deprivation influences the subjective sleepiness during the mental task and the EEG activity, as well as the subjective sleepiness at rest. However, the effect of the bright light exposure on the EEG activity at the mental task diminishes throughout nocturnal sleep deprivation.
This study aimed to determine the factor structure of the center of foot pressure (CFP) movement during static upright posture, and to objectively categorize and summarize parameters to evaluate CFP movement. The subjects were 220 healthy young males and females. The measurement of CFP was carried out 3 times with 1 min rest and the mean of trials 2 and 3 was used for the analysis. The measurement device was an Anima's stabilometer G5500. The data sampling frequency was 20 Hz. Thirty-four parameters with high reliability were selected from the following 6 domains except for the center position which is a fundamental attribute: distance, distribution of amplitude, area, velocity, power spectrum, and body sway vector. Factor analysis (principal factor method and promax rotation) was applied to a correlation matrix consisting of 32 parameters. Four factors abstracted were interpreted as follows; unit time sway, front and back sway, left and right sway and high frequency band of power spectrum. The reliability coefficient (ICC=0.89–0.95) and the congruence coefficient (φ=0.80–0.97) between factors abstracted from the original and the cross-validity groups were very high. It was considered that the CFP movement consists of the above 4 factors that evaluate the amount of body sway and can be synthetically evaluated by them.
Effects of sleep deprivation and season on thermoregulation during 60 min. of leg-bathing (water temperature of 42°C, air temperature of 30°C, and relative humidity of 70%) were studied in eight men who completed all 4 experiments for normal sleep and sleep deprivation in summer and winter. Rectal temperature (Tre), skin temperature, total body sweating rate (Msw-t), local sweating rate on the back (Msw-back) and forearm (Msw-forearm), and skin blood flow on the back (SBFback) and forearm (SBFforearm) were measured. The changes in Tre (ΔTre) were smaller (P<0.05) for sleep deprivation than for normal sleep regardless of the season. This decrease in ΔTre was significant only in summer (P<0.05). Mean skin temperature (T(mean of)sk) was higher (P<0.05) for sleep deprivation than for normal sleep regardless of the season. Msw-t was smaller (P<0.05) for sleep deprivation than for normal sleep regardless of season, although Msw-back and Msw-forearm were similar. SBFback and SBFforearm tended to be higher for sleep deprivation than normal sleep. The sensitivity of SBF to Tre was higher (P<0.05) for sleep deprivation than for normal sleep. These data indicate that seasonal differences in thermoregulation were small because of morning time. Sleep deprivation increased dry heat loss and restrained Tre rise, in spite of decreased sweating rate.
The purpose of this study was to clarify the lower extremity function in terms of the shock absorption during unsynchronized-foot landings. The characteristics of the supination and pronation in the ankle joint at landing were investigated, assuming that the measurements of the impact force on the body could be demonstrated by the changes that occurred during 3 different landing motions: —unsynchronized-foot landings, synchronized-foot landings, and one-foot landings. Subjects jumped to the floor from 10-cm footstools 3 times for each type of landing. For the synchronized-foot landing, the rear foot angle was 92.2° at the start of landing and did not change significantly from landing start to 100 msec. For the one-foot landing, rear foot angle was 95.1° at the start of landing and decreased rapidly to 87.1° by 75 msec, and then increased rapidly to 90.8° by 140 msec. For the unsynchronized-foot landing, the rear foot angle was 93.8° at the start of the landing, decreased rapidly to 88.0° by 75 msec, and then increased rapidly to 89.9° by 115 msec. It was clarified that the lower extremity function for the shock attenuation during landing with the unsynchronized-foot was similar to that with one-foot landings, and the lower extremity function for supporting the body after another foot landing was similar to that after the synchronized-foot landings in this study.
More than sensory stimuli, odorous stimuli were employed to facilitate the evocation of emotional responses in the present study. The odor-stimulated emotion was evaluated by investigating specific features of encephalographic (EEG) responses produced thereof. In this study, the concentrations of the same odor were altered; viz., the changes in odor-induced emotional level were compared with the concurrently monitored EEG response features. In addition, we performed the mental task to evoke the arousal state of the brain and investigated the resemblance of response characteristics of the resting state to the post-mental task resting state.
The aims of this study were to determine reference norms for a fat-free mass index (FFMI) and fat mass index (FMI) in a large population of healthy children in Japan, to observe differences in these values in three age groups between ages three and eleven, and to develop percentile distributions for these parameters. Five hundred twenty-two boys and six hundred forty-nine girls with a wide spectrum of stature, body mass, and body composition underwent bioelectrical impedance analysis (BIA) for the determination of fat-free mass (FFM) and fat mass (FM). Both FFM and FM were divided by stature2 to give FFMI and FMI, as described previously. Normal FFMI and FMI were defined within the range of the 25th to 75th percentile of age- and gender-specific data in this study. The reference norms for FFMI (3–11 yrs) were 12.7–13.4 kg/m2 in boys and 12.0–13.0 kg/m2 in girls. A modest increase in boys was observed with an age increase; otherwise, there were no marked age differences in FFMI for the children as a whole. The reference norms for FMI were 2.8–3.6 kg/m2 in boys and 3.2–3.8 kg/m2 in girls. For each 3-year category (i.e., ages 3–5, 6–8 and 9–11 yrs.), FMI progressively increased by an average of 28.6% in boys and 18.8% in girls, compared to an increase in BMI of 11.0 and 11.3% respectively. FFMI and FMI are appropriate for many purposes, and have the advantage of expressing both aspects of body composition in common units. In conclusion, the data presented as percentiles can serve as reference in comparing a child's body composition to that of healthy children of the same age and gender. The reference standards should be appropriate for almost all children in the Japan for whom stature, body mass, and body composition can be measured satisfactorily. However, a more sophisticated approach is ultimately required for evaluating body composition. This article is a preliminary attempt to promote future research in the area of childhood body composition.
Post-exercise related time course of muscle oxygenation during recovery provides valuable information on peripheral vascular disease. The purpose of the present study was to examine post-exercise hyperemia (forearm blood flow; FBF, Doppler ultrasound) assessed by peak FBF, excess FBF and the time constant for FBF (FBFTc) following isometric handgrip exercise (IHE). Post-exercise hyperemia was assessed in an ischemic and non-ischemic state at different exercise intensities and durations. Peak FBF and excess FBF were defined as the maximum FBF during recovery, and the total amount of FBF volume, respectively. FBFTc represents the time to reach approximately 37% of the change in FBF between peak FBF and resting FBF (delta peak FBF). Ten subjects performed IHE at “10% and 30% maximum voluntary contraction (MVC)” for 2 min with or without arterial occlusion (AO), followed by 2 min of AO alone (Study I). In Study II, six subjects performed 30%MVC-IHE with AO for “100%, 66%, 33% and 10% of the exhausted exercise duration” (time to exhaustion). In Study I, although peak FBF and excess FBF were significantly higher in ischemic than non-ischemic IHE for both 10% and 30%MVC (p<0.05), FBFTc was similar in the ischemic and non-ischemic conditions. The peak FBF, excess FBF and FBFTc were all significantly higher at 30% than at 10%MVC (p<0.05). In Study II, the peak FBF and excess FBF increased linearly compared to the absolute and relative exercise durations for ischemic IHE. FBFTc increased exponentially when compared to the absolute and relative exercise durations. These data suggest the ischemic exercise has a larger hyperemic response compared to the non-ischemic exercise. In conclusion, the peak FBF, excess FBF and FBFTc seen during post-exercise hyperemia are closely correlated with exercise intensity and duration, not only in non-ischemic, but also in the ischemic exercise. In combination with the ischemic exercise, these parameters could potentially prove to be valuable indicators of peripheral vascular disease.
This study compared the body water turnover in endurance athletes and age-matched sedentary men. Eight competitive endurance athletes (20.8±1.9 yr) and age-matched eight sedentary men (21.6±2.5 yr) participated in this study. Total body water and body water turnover were measured using the deuterium (D2O) dilution technique. Urine samples were obtained every day for 10 days after oral administration of D2O. The day-by-day concentrations were used to calculate the biological half-life of D2O and body water turnover. Maximal oxygen uptake (VO2max) and oxygen uptake corresponding to ventilatory threshold (VO2VT) as an index of aerobic capacity were determined during a graded exercise test. Both VO2max and VO2VT were higher in the exercise group than in the sedentary group (P<0.05). The biological half-life of D2O was significantly shorter in the exercise group than in the sedentary group (5.89±0.81 days vs. 7.52±0.77 days, P<0.05), and the percentage of the body water turnover was significantly higher in the exercise group than in the sedentary group (11.99±1.96% vs. 9.39±1.21%, P<0.05). The body water turnover was correlated with VO2max and VO2VT, respectively (P<0.05). Based on these findings, this study speculates that a level of physical activity may induce a body water turnover higher in the healthy state, since the better trained subjects have a higher body water turnover.