A study on the effects of different color temperatures of fluorescent lamps on skin and rectal temperatures in a moderately cold environment involving (i) changes in skin temperature of 7 male subjects exposed to an ambient temperature ranging from 28°C to 18°C (experiment I) and (ii) changes in skin and rectal temperatures and metabolic heat production of 11 male subjects exposed to ambient temperature of 15°C for 90 min (Experiment II) was conducted. In Experiment I, the reduction of mean skin temperature from the control value was significantly greater under 3000 K than under 5000 K or 7500 K lighting. In Experiment II, the reductions in mean skin temperature and rectal temperature were respectively greater and smaller under 3000 K than those under 5000 K or 7500 K lighting. However, metabolic heat production was not affected by color temperature conditions. The relationships between morphological and physiological parameters revealed that no significant relation of rectal temperature to body surface area per unit body weight was found only under 3000 K. Furthermore, while the mean skin temperature was independent on the mean skinfold thickness under 3000 K, a significant negative correlation between the rectal and mean skin temperatures was observed. Therefore, body heat loss might be suppressed effectively by increasing the vasoconstrictor tone under a color temperature of 3000 K, and the body shell was dependent only on morphological factors under 5000 K and 7500 K lighting.
Surface electromyogram (EMG), blood pressure (BP), blink rate (BR) and heart rate (HR) were recorded before and during 4 types of mental task. The mental task involved 3 tasks that encompassed the memory (M), visual search (VS) and color-word (CW) tasks besides the control task (CT) of maintaining a similar posture while focusing on a single spot on the computer screen. Except for CW, any voluntary movement for response to visual stimuli given were not demanded. Slightly but significant increases in integrated EMG (iEMG) were shown in terapezius, biceps and gastrocnemius muscles during tasks except for CT. Especially in the trapezius muscle during M, the most remarkable enhancements of iEMG and BP were shown. In VS and CW tasks, significant decreases in BR were observed, although in M and CT tasks there were no significant changes in it. There were no significant changes in HR in any type of tasks. The present study demonstrated the increase in muscle tension due to mental needs of cognitive tasks per se accompanying changes in BP and BR. And, enhancement of these physiological responses by memory loads and eyeball movement was discussed as a possible mechanism.
The purpose of the present study was to determine whether knee extension strength gain in middle-aged and elderly persons is associated with improvement in the limits of stability when leaning his/her body in various directions. The resistance training group (EXT; 4 males, 17 females) completed two bilateral knee extension training sessions, consisting of one set of exercises, per week for 10 weeks. The non-training control group (CONT; 4 males, 3 females) were instructed not to train their legs during the 10-week control period. One set of exercises consisted of 8-12 repetitions of a dynamic resistance exercise until volitional fatigue for knee extension. The initial load for training was set at 70% of the one-repetition maximum (1-RM). The thickness of the rectus femoris (RF) and vastus lateralis (VL) muscles were measured using a B-mode ultrasound apparatus. The postural control measures, obtained using the Balance Master system, included the percentage limits-of-stability (%LOS) and path length (%Path). The 1-RM in EXT was increased significantly by resistance training (p<0.001). In addition, significant differences were observed between the percentage increase of 1-RM in EXT and those in CONT at wk 5 and at wk 10 of resistance training (p<0.001). However, no significant increase in muscle thickness of RF or VL was found in EXT. The %LOS to the rear target in EXT was increased significantly by resistance training (p<0.05-0.01). In addition, the percentage change in %Path was decreased significantly by resistance training (p<0.001). Therefore, strength gain in quadriceps femoris appears to be associated with improvement in the %LOS and %Path for the rear. In conclusion, strength gain in quadriceps femoris is thought to possibly enable accurate movement of the COG farther from the center target towards the rear, suggesting that strength gain has a positive influence on a person’s perception of their ability to avoid falls.
The experiment investigated the effects of skin pressure by clothing on whole gut transit time and amount of feces. Comparisons of transit time and amount of feces were taken between 6 young female adults with and without a girdle. The skin pressure applied by a girdle (mean ± SD) on participant’s waist, abdomen and hip region was 16.6 ± 7.80 mmHg, 17.1 ± 4.5 mmHg and 12.6 ± 5.0 mmHg, respectively. The difference of skin pressure with and without a girdle was about 10 mmHg. During each experimental period of 4 days with and without a girdle, the whole gut transit time and amount of feces were measured. The whole gut transit time of each day was determined as the time between the oral intake of each day’s markers and their first appearance in the stool. The whole gut transit times of the markers taken on the first day were significantly prolonged (p<0.05) and those of the markers taken on the second day tended to be prolonged for participant using a girdle (p<0.1). The whole gut transit time of the markers taken on the third day could not be compared because they were not excreted into the stool. The cumulative increases of feces on the third day and the fourth day were significantly reduced with a girdle (p<0.05). These results indicate that the skin pressure by clothing has an effect on whole gut transit time and the amount of feces.
In order to reveal the influence of clothing skin pressure on digestion of food through the gastrointestinal tract, we examined the absorption of dietary carbohydrate and orocecal transit time of a test meal by means of a breath hydrogen test on 7 healthy young women. In this experiment, we collected breath samples from the participants wearing loose-fitting experimental garment on the second day of the experiment and from the same participants but wearing an additional tight-fitting girdle on the following day for 16 hours and 9 hours, respectively. Skin pressure applied by a girdle on participant’s waist, abdomen and hip region was 15.5 ± 0.4 mmHg (mean ± SE), 11.0 ± 0.2 mmHg, and 13.6 ± 0.6 mmHg, respectively, and the values were 23 times larger than those of the experimental garment. The hydrogen concentration vs. time curve showed that breath hydrogen levels at its peaks (15:00, 15:30, 16:00, 16:30, and 17:00 hr) on the third day of the experiment were significantly higher than those of the corresponding time on the second day (p<0.05 at 17:00 and 15:00, p<0.01 at 15:00, 16:00 and 16:30). Consequently, significantly pronounced breath hydrogen excretion was observed under the “pressure” clothing condition (p<0.01). On the other hand, the transit time of the test meal for the subjects wearing a girdle did not differ significantly from that for the subjects wearing the garment of less pressure (270 ± 18 minutes and 263 ± 21 minutes, respectively). These results indicate that the clothing skin pressure has an inhibitory effect on the absorption of dietary carbohydrate in the small intestine, but no effect on the orocecal transit time of a meal.