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.
Wearing behavior and thermoregulatory responses of five young women (YG; 20 ± 1 yr) and five aged women (AG; 65 ± 3 yr) to indoor cold in summer were investigated in this study. The subjects were exposed to 21.0 ± 0.5°C and 55 ± 5%RH while seated during a 90-minute experiment. The subjects were allowed to select and wear for thermal comfort clothing whenever they needed additional clothing during the experiment. Rectal temperature (Tre) and temperatures of 7 sites (head, chest, forearm, hand, thigh, leg, foot) of the skin of the subjects were measured every 10 minutes. Mean skin temperature (Tsk) of the subject was obtained every 10 minutes. First selection time of additional clothing was monitored and weight of selected total clothing was calculated. The results for this study were as follows: Tre and Tsk gradually decreased in YG and AG, however Tre decreased less than Tsk which decreased greater in AG than YG (p<0.01). AG’s first selection of additional clothing and thermal sensation response were slower than YG’s. Furthermore, total clothing weight was less in AG than YG. It was concluded that clothing selection behavior would modify the intrinsic thermoregulatory responses of the aged women to the cold stress in the summer.
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 relationships between individual differences in psychophysiological responses and tendency of Type A behavior pattern (TABP) were investigated during mental arithmetic (MA) at a steady rhythm, challenging calculation (Uchida-Kraepelin serial addition test: UK test), music listening, and exposure to an 80 dB SPL of white noise. Each mental task was sustained for 5 minutes. Sixteen healthy Japanese adults, (10 males and 6 females) with an age from 18 to 36 years old volunteered for this study. The KG’s Daily Life Questionnaire (KG Questionnaire) was used to investigate the tendency toward TABP, which included three sub-factors: aggression-hostility, hard-driving and time urgency, and speed-power items. Recorded physiological variables were respiratory rate (RR), skin resistance response (SRR), eyeblinks, and heart rate (HR) calculated using frequency analysis to render high frequency power (HF) and the ratio of low/high frequencies (L/H ratio). During the MA and UK tests, significant increases in HR, L/H ratio, RR occurred, while significant decreases in HF were observed. Eyeblinks significantly increased during the MA test and significantly decreased during the UK test. During music and white noise, no significant changes occurred except for SRR, which decreased significantly. The coefficient of variances in each response was over 20% for almost all variables, indicating that individual differences in the magnitude of each response were large, even if the direction (increase or decrease) of the change was the same in almost all subjects. The highest correlation coefficients (r) between the mean values of relative magnitude for each variable and TABP scores during the MA and UK tests were obtained for the L/H ratio (MA: r=0.591, UK test: r=0.577) and the RR (MA: r=-0.576, UK test: r=-0.511). These values were statistically significant (p<0.05). Similar results were obtained for TABP sub-factors. Though other investigations have reported relationships between HF and TABP, we found no significant relationship. It was suggested that sympathetic nerve activity became greater for TABP individuals than for Type B individuals under stress conditions.
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 α-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.