The aim of the present study was to evaluate the sweat loss response during short-term heat acclimation in tropical natives. Six healthy young male subjects, inhabitants of a tropical region, were heat acclimated by means of nine days of one-hour heat-exercise treatments (40±0°C and 32±1% relative humidity; 50% VO_2peak on a cycle ergometer). On days 1 to 9 of heat acclimation whole-body sweat loss was calculated by body weight variation corrected for body surface area. On days 1 and 9 rectal temperature (T_re) and heart rate (HR) were measured continuously, and rating of perceived exertion (RPE) every 4 minutes. Heat acclimation was confirmed by reduced HR (day 1 rest: 77±5 b·min⁻¹; day 9 rest: 68±3 b·min⁻¹; day 1 final exercise: 161±15 b·min⁻¹; day 9 final exercise: 145±11 b·min⁻¹, p<0.05), RPE (13 vs. 11, p<0.05) and T_re (day 1 rest: 37.2±0.2°C; day 9 rest: 37.0±0.2°C; day 1 final exercise: 38.2±0.2°C; day 9 final exercise: 37.9±0.1°C, p<0.05). The main finding was that whole-body sweat loss increased in days 5 and 7 (9.49±1.84 and 9.56±1.86 g·m⁻²·min⁻¹, respectively) compared to day 1 (8.31±1.31 g·m⁻²·min⁻¹, p<0.05) and was not different in day 9 (8.48±1.02 g·m⁻²·min⁻¹) compared to day 1 (p>0.05) of the protocol. These findings are consistent with the heat acclimation induced adaptations and suggest a biphasic sweat response (an increase in the sweat rate in the middle of the protocol followed by return to initial values by the end of it) during short-term heat acclimation in tropical natives.

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A total of 978 Japanese students, who visited the health services center of a college in Japan for medical check-ups, were asked to anonymously complete a 55-item questionnaire which assessed their attitudes toward sex and sexual behavior. Seven hundred eighty-five Japanese students (80.3%) responded to the questionnaire. In this survey, 90% of male students and 83% of female students indicated that they expected to have sexual intercourse before marriage, while 8% of male students and 3% of female students indicated that it was not wrong to have extramarital sexual intercourse after marriage. In addition, 75% of sexually experienced students reported that they used a condom during their first sexual intercourse, while 73% reported using a condom during their most recent sexual intercourse. The more sexual partners students had had up to the time of the study, the less condom use they reported for both their first and most recent sexual intercourse. The proportion of Japanese students who used a condom is high in comparison to that of students in other countries. However, as students are prone to have sexual intercourse with non-steady, casual partners, more efforts are needed to promote safe sex practices among college students in Japan.

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In order to compare the physiological and the subjective responses to low relative humidity of elderly and young men, we measured saccharin clearance time (SCT), frequency of blinking, hydration state of the skin, transepidermal water loss (TEWL), sebum level recovery and skin temperatures as physiological responses. We asked subjects to evaluate thermal, dryness and comfort sensations as subjective responses using a rating scale. Eight non-smoking healthy male students (21.7±0.8 yr) and eight non-smoking healthy elderly men (71.1±4.1 yr) were selected. The pre-room conditions were maintained at an air temperature (Ta) of 25°C and a relative humidity (RH) of 50%. The test-room conditions were adjusted to provide 25°C Ta and RH levels of 10%, 30% and 50%.
RH had no effect on the activity of the sebaceous gland or change of mean skin temperature. SCT of the elderly group under 10% RH was significantly longer than that of the young group. In particular, considering the SCT change, the nasal mucous membrane seems to be affected more in the elderly than in the young in low RH. Under 30% RH, the eyes and skin become dry, and under 10% RH the nasal mucous membrane becomes dry as well as the eyes and skin. These findings suggested that to avoid dryness of the eyes and skin, it is necessary to maintain greater than 30% RH, and to avoid dryness of the nasal mucous membrane, it is necessary to maintain greater than 10% RH. On the thermal sensation of the legs, at the lower humidity level, the elderly group felt cooler than the young group. On the dry sensation of the eyes and throat, the young group felt drier than the elderly group at the lower humidity levels. From the above results, the elderly group had difficulty in feeling dryness in the nasal mucous membrane despite being easily affected by low humidity. On the other hand, the young group felt the change of humidity sensitively despite not being severely affected by low humidity. Ocular mucosa and physiology of skin by dryness showed no difference by age. In the effect of longer exposure (180 min.) to low RH, only TEWL showed a slight decrease after 120 minutes in 30% RH, and all the measured results showed no noticeable differences compared with the result at 120 minutes.

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The purpose of this study was to examine the output properties of muscle power by the dominant upper limb using SSC, and the relationships between the power output by SSC and a one-repetition maximum bench press (1 RM BP) used as a strength indicator of the upper body. Sixteen male athletes (21.4±0.9 yr) participated in this study. They pulled a load of 40% of maximum voluntary contraction (MVC) at a stretch by elbow flexion of the dominant upper limb in the following three preliminary conditions: static relaxed muscle state (SR condition), isometric muscle contraction state (ISO condition), and using SSC (SSC condition). The velocity with a wire load via a pulley during elbow flexion was measured accurately using a power instrument with a rotary encoder, and the muscle power curve was drawn from the product of the velocity and load. Significant differences were found among all evaluation parameters of muscle power exerted from the above three conditions and the parameters regarding early power output during concentric contraction were larger in the SSC condition than the SR and ISO conditions. The parameters on initial muscle contraction velocity when only using SSC significantly correlated with 1 RM BP (r=0.60–0.62). The use of SSC before powerful elbow flexion may contribute largely to early explosive power output during concentric contraction. Bench press capacity relates to a development of the above early power output when using SSC.

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The purpose of this study was to evaluate the validity and reliability of coating methods (plaster bandage, inelastic tape, and the alginate method) and an indirect method using a three dimensional (3D) whole body scanner. The surface area of geometric solids was measured five times using the three coating methods, and analyzed through 2D scanning and a planimeter. Second, to examine the accuracy of the alginate method more closely, the surface areas of boards with different surface properties at various inclines were measured and compared. Lastly, the surface area of a human arm was measured using the three coating methods and a 3D scanning method. The results are as follows: 1) The three coating methods were statistically valid and reliable for measuring the surface area of geometric solids. 2) The planimeter was rejected because the mean error was bigger than in 2D scanning. 3) The method showing the least error was the inelastic tape method, but that method was not recommended because it was too tiresome and laborious. 4) The greater the curvature and smaller the size of a geometric solid, the greater the error. 5) In measuring surface area using the alginate method, the objects that were smoother and had steeper angles showed a greater surface area: however, the mean error was less than 1%. 6) In measuring a human arm, the surface area obtained by 3D scanning was less than any other surface area obtained in the three coating methods, because the 3D scanner could not discern the armpit and fingers. In conclusion, the method using alginate was statistically valid and reliable in the measuring of surface area both of geometric solids and real human skin.

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We investigated changes in saccadic reaction time during maintenance of neck flexion in elderly individuals. Subjects comprised 49 volunteers, including 19 young adults and 30 elderly adults. Elderly subjects were separated into 2 groups (trained group: n=18; untrained group: n=12) based on responses to a questionnaire concerning activities of daily living. Saccadic reaction time was measured at angles of neck flexion of 0° (resting position), 10° and 20°, with the chin either resting on a stand (chin-on) or not (chin-off). Reaction time was determined as the latency to the beginning of eye movement toward the lateral target, which was moved at random intervals in jumps of 20° amplitude. In the chin-on posture, the angle of neck flexion had no significant effect on reaction time in any group. In the chin-off posture, the flexion angle significantly affected reaction time in both young and elderly trained groups. Significant shortenings of the reaction time were obtained at 10° and 20° neck flexion in the young group, and at 20° neck flexion in the elderly trained group. No significant shortening of reaction time was noted in the elderly untrained group. These findings suggest that neural function associated with shortening of saccadic reaction time due to neck extensor activity decreases with age, and the decrements become more marked with inactivity in daily life.

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