Hiromi Tokura

Impact of Fabric Moisture Transport Properties on Physiological Responses when Wearing Protective Clothing

This purpose of this study was to investigate the impact of fabric moisture transport properties (MTP) on physiological responses when wearing protective clothing. Ten healthy subjects wore two kinds of personal protective equipment (PPE) ensembles and exercised on a treadmill, worked on a computer, and moved a mannequin in an environment that simulated where health carers work. PPE1 consisted of cotton underwear and 100% polyethylene outerwear. PPE2 consisted of cotton underwear with moisture management function and outerwear made of waterproof breathable fabric. The results showed that there were significantly higher cumulative one-way transport capacity, liquid moisture management capacity, and wetting time in PPE2 than in PPE1 underwear. There was significantly higher water vapor permeability (WVP) in PPE2 than in PPE1 outerwear. Deep ear canal temperature, mean skin temperature, and chest wall skin and clothing microclimates (temperature and humidity) were significantly lower with PPE2 than PPE1. The level of plasma oxygen saturation was significantly higher with PPE 2 than PPE1. In the present study, due to the MTP of the fabrics, liquid sweat transferred from the skin surface to the opposite surface quickly and speeded up the processes of evaporation and heat dissipation. It was concluded that the fabrics MTP, when incorporated into protective clothing, is the main physiological mechanism for reduced heat stress.

Effect of Moisture Management on Functional Performance of Cold Protective Clothing

This paper reports a study on the effect of moisture management in the design of cold protective clothing. In this research, two kinds of clothing systems were tested, a traditional clothing system (clothing A), and a specially designed moisture management clothing system (clothing B). Both clothing systems have the same four-layer structure (underwear, vest, coat, and outer jacket), but with use of different functional fabrics. The experiments were conducted in a climate chamber where the temperature was controlled at —15 °C. Eleven young male subjects took part in wear trial experiments, in which they were dressed in clothing A or B and walked on a treadmill. The humidities and temperatures at the skin surface and at different layers of the clothing system were measured together with measurements of thermal and moisture sensations. The experimental results showed that the moisture management property of fabrics significantly affected the moisture diffusion and temperature distributions in the cold protective clothing systems, and influenced the thermal and moisture sensations.

Effects of Moisture Absorption of Clothing on Pitching Speed of Amateur Baseball Players in Hot Environmental Conditions

The purpose of this study was to investigate the effects of the hygroscopic properties of clothing material on pitching speed and some physiological responses in amateur baseball players. The experiments were performed on four male players of a regular high school baseball team and comprised two clothing types with different moisture absorption properties, namely, cotton (Type C) and polyester and polypropylene (Type P). One test session was conducted with seven innings, with a 5-minute rest time between each inning. During each inning the test subject pitched 20 balls with a 20-second interval between each pitch. From the results, in the hot environments, the trained baseball players tended to pitch balls with higher speed and less deviation of speed when wearing Type C clothing, especially in the second session. Type C clothing with a higher moisture regain compared to Type P clothing may have diminished accumulated thermal induced fatigue in the subjects.

Subjective time runs faster under the influence of bright rather than dim light conditions during the forenoon

The study investigated if 6 h morning bright light exposure, compared with dim light exposure, could influence time sense (range: 5-15 s). Eight women served as participants. The participant entered a bioclimatic chamber at 10:00 h on the day before the test day, where an ambient temperature and relative humidity were controlled at 25 degrees C and 60%RH. She sat quietly in a sofa in 50 lx until 22:00 h, retired at 22:00 h and then slept in total darkness. She rose at 07:00 h the following morning and again sat quietly in a sofa till 13:00 h, either in bright (2500 lx) or dim light (50 lx), the order of light intensities between the two occasions being randomized. The time-estimation test was performed from 13:00 to 13:10 h in 200 lx. The participant estimated the time that had elapsed between two buzzers, ranging over 5-15 s, and inputting the estimate into a computer. The test was carried out separately upon each individual. Results showed that the participants estimated higher durations of the given time intervals after previous exposure to 6 h of bright rather than dim light. The finding is discussed in terms of different load errors (difference between the actual core temperature and its thermoregulatory set-point) following 6-h exposure to bright or dim light in the morning.

Effect of Evening Exposure to Dim or Bright Light on the Digestion of Carbohydrate in the Supper Meal

In a previous study we found that daytime exposure to bright as compared to dim light exerted a beneficial effect on the digestion of the evening meal. This finding prompted us to examine whether the digestion of the evening meal is also affected by evening light intensity. Subjects lived in light of 200 lux during the daytime (08:00–17:00 h) and took their evening meal at 17:00 h under 20 lux (evening dim‐light condition: 17:00–02:00 h) or 2000 lux (evening bright‐light condition: 17:00–02:00 h) until retiring at 02:00 h. Assessment of carbohydrate digestion of the evening meal was accomplished by a breath hydrogen test that is indicative of the malabsorption of dietary carbohydrate. Hydrogen excretion in the breath in the evening under the dim‐light condition was significantly less than under the bright‐light condition (p < 0.05). This finding is the opposite to that obtained in previous experiments in which subjects were exposed to the different intensities of light during the daytime, and indicates that the exposure to dim light in the evening exerts a better effect on carbohydrate digestion in the evening meal than does the exposure to bright light.

Time sense for short intervals during the follicular and luteal phases of the menstrual cycle in humans

The present study investigated if the time sense (using short intervals) was influenced by the phase of the menstrual cycle. Fourteen women (age: 21.8+/-1.3 years, height: 158.1+/-4.6 cm, body weight: 50.9+/-3.2 kg, mean+/-S.D.) were examined. Their menstrual phase was checked by the participants themselves prior to the study, by measuring oral temperatures after waking but while still in bed over the course of 1-2 months. Participants entered a climatic chamber (26 degrees C, 60% RH, 200 lx) at 09:00 h during either the follicular or luteal phase, and sat quietly on a sofa for 4 h before performing the time sense tests. These used intervals ranging from 1 to 60 s, and consisted of time estimation and time production. In the time estimation test, the participant was required to estimate the interval between two signals provided by buzzers; 10 random intervals were given. For the time production test, the participant was required to produce the interval displayed on a screen by pushing the space key of a computer twice; 10 random intervals were given. The order of testing during the follicular and luteal phases, and of performing the time estimation and time production tests, was counterbalanced. The results indicate that the time sense ran significantly faster during the luteal phases. The findings are discussed in terms of a higher load error between the actual core temperature and its thermoregulatory set-point during the luteal phase of the menstrual cycle.

Seasonal Variation in Amount of Unabsorbed Dietary Carbohydrate from the Intestine after Breakfast in Japanese Subjects

We previously showed that daytime dim‐light exposure has a negative effect on the efficiency of dietary carbohydrate absorption in the evening, whereas evening‐time dim‐light exposure has a beneficial effect. These results suggest that seasonal changes in the environmental light may affect gastrointestinal activity, and that there might, therefore, be seasonal variation in the efficiency of dietary carbohydrate absorption from the intestine. In order to prove this hypothesis, we measured the amount of dietary carbohydrate unabsorbed from the intestine after a breakfast in healthy female Japanese subjects during the four seasons of the year. We estimated the amount of unabsorbed dietary carbohydrate by the breath hydrogen test, which measures the amount of hydrogen in exhaled air. A 6 g solution of lactosucrose, an indigestible trisaccharide, was used for comparison. Two groups of subjects, 12 subjects in Osaka and 14 subjects in Nagano, were studied in the winter (January to February), spring (April to May), summer (July to August), and autumn (October to November) of 2004. We found the following results: (1) In no season were there any significant differences between the two subgroups in the orocecal transit time of the breakfast and the lactosucrose solution. Nor were there any significant differences in the amount of unabsorbed dietary carbohydrate from the breakfast. (2) Using the pooled data of the total of 26 subjects, there was no significant seasonal variation in the orocecal transit time of the breakfast or the lactosucrose solution. (3) There was a significant seasonal variation in the amount of unabsorbed dietary carbohydrate from the breakfast. (4) The amount of unabsorbed dietary carbohydrate from the breakfast was largest in winter and smallest in autumn. Results in spring and in summer were similar and intermediate between those in winter and autumn. Post hoc multiple comparison tests showed that the amount of unabsorbed dietary carbohydrate in winter was significantly larger than in autumn. (5) In winter, the average ratio of the amount of unabsorbed dietary carbohydrate to the total amount of carbohydrate in the breakfast was about 12%; in autumn it was about 6%. These results clearly show that there is seasonal variation in the efficiency of intestinal dietary carbohydrate absorption among young female Japanese subjects.

Effects of fabric surface energy on human thermophysiological responses during exercise and recovery

AbstractThe present paper reports a study on influences of fabric surface energy of cotton and polyester garments on clothing microclimates and human thermophysiological responses during intermittent exercise and recovery. Eight healthy males wearing the garments prepared performed exercises and rest according to the following protocol: rest for 30 min, run on treadmill for total 60 min of three sessions with different intensity and duration, and then sit quietly for 30 min for recovery, all at 30 °C and relative humidity of 30 %, while the microclimate humidity (Hmc) and temperature (Tmc), the clothing outside surface humidity (Hco) and temperature (Tco), the skin temperatures and ear canal temperature (Tear_canal) were measured. The garments are made of: (a) hydrophilic and hydrophobic cotton knitted fabrics, and (b) hydrophilic and hydrophobic polyester knitted fabrics. During and after exercise, for cotton, hydrophilic garment resulted in significant lowerΔHmc, ΔHco, ΔTmc during recovery, higher

Physiological significance of bright vs. dim light intensities during the daytime for thermoregulatory responses, digestive functions and evening dressing behavior in the cold⋆

\Delta \overline {\rm T} _{sk}