To determine the predictability of blood lactate accumulation from excess CO2 output derived from bicarbonate buffering of lactic acid during constant exercise, eight normal active volunteers were studied during three stages of constant exercise on a cycle ergometer. Three work rates consisted of 100% (stage I), 120% (stage II) and 150% (stage III) of each subject's anaerobic threshold (AT), each of which was lasted for 4 min. Excess CO2 output (Ex CO2, ml) at each stage of constant exercise was estimated from the integral of difference between total VCO2.and aerobic VCO2 (from regression line for VCO2 and VO2 at exercise intensities below the AT obtained in incremental exercise test). Ex CO2 Per body mass (Ex CO2·mass-1) was increased progressively with blood lactate (La) accumulation from rest to each stage of constant exercise. Mean values (± SD) in the measured La accumulation (ΔLa, measured) and predicted La accumulation (ΔLa, predicted) at three stages of constant exercise were 1.82 ± 0.83 vs 3.19 ± 1.70 for stage I, 5.58 ± 3.47 vs 7.09 ± 3.28 for stage II and 12.19 ± 2.36 vs 12.74 ± 1.83 mmol·l-1 for stage III, respectively. There was a significant difference between ΔLa, measured and ΔLa, predicted at Stage I (p<0.05), but no significant differences between these two variables at stage II and III. The averaged difference from ΔLa, predicted to ΔLa, measured at stage III (0.55 rrunol·l-1) showed a tendency to be smaller than stage I (1.38 mmol·l-1) and II (1.50 mmol·l-1). On the other hand, ΔLa, predicted was found to correlate very closely with ΔLa, measured (r=0.954, P<0.001, n=20). The results of this study suggest that the changes of La accumulation could be predicted from excess CO2 0utput generated in constant exercises above the AT.
To investigate the development of motor ability according to age and physique, a comparison was made among races and/or living standards of schoolchildren in Republic of Honduras, and between Honduran and Japanese schoolchildren. Based on the results of these comparisons, the extent to which exercise contributes to the development of motor ability was examined. Subjects were schoolchildren of typical three races in Honduras: Negroid, Mongoloid (native Indio), and mixed race (Mongoloid, Caucasoid, and Negroid), who attended public elementary schools. For a further comparison, schoolchildren of mixed race attending private schools, whose living standards are thought to be different from children attending public schools, were also selected. Comparing physique among races from the measurement values in the test battery, Negroid group ranked highest followed by the mixed race group and Mongoloid group. The results for the comparison of motor ability were also in the same order. From the viewpoint of living standards, the physique and motor ability of the private school children, who were from wealthy families, was better than that of the public school children. However, when the degrees of motor development were compared using revised values based on age and physique, the differences among groups became smaller, and there was no significant difference between groups in the 50-meter dash or in the standing long jump. However, a comparison with Japanese schoolchildren showed that, even if there was no difference in physique, Japanese schoolchildren were still superior in motor ability. These results suggest that differences in the degree of motor development are mainly due to differences in exercise experience.
This study was conducted to observe the effects of endurance exercise training on antioxidant enzyme activity in the liver and gastrocnemius muscle of rats being fed dietary casein and soy protein. The respective influences of dietary casein and soy protein on the activity of antioxidant enzymes were also compared. Thirty-nine male Wistar rats, aged 3 weeks, were randomly assigned to six groups: a normal protein control group, a normal protein endurance training group, a casein protein control group, a casein protein endurance training group, a soy protein control group, and a soy protein endurance training group. The endurance exercise training groups were adapted to a treadmill for 2 weeks prior to the date the rats were forced to run for 60 min at 25 m/min, 5 days/week for 12 weeks. We found that antioxidant enzyme activity in the gastrocnemius muscle was neither effected by the dietary proteins (casein and soy protein) nor by the above endurance exercise training load. However, hepatic Cu, Zn-SOD activity increased significantly for the dietary casein and soy protein diet groups as compared with the normal protein diet group (P<0.01). Furthermore, significant increases both in hepatic Cu, Zn-SOD activity in the normal protein group and hepatic GSHpx activity in the casein and soy protein groups were observed when rats were loaded with 25 m/min of endurance exercise training (P<0.01). These results suggest that, under the above experimental conditions, a casein or soy protein diet increase hepatic Cu, Zn-SOD activity, while endurance exercise training is effective in increasing hepatic Cu, Zn-SOD activity on a normal protein diet and in increasing hepatic GSHpx activity for cysteine and methionine deficient diets.
The purpose of this study is to obtain some knowledge related to physiological and psychological effects of head heating by radiation on the vital body under varying conditions of the environmental temperature and physical activity. The study was proceeded with experiments 1 and 2 using 8 women, all in good health as subjects. In experiment 1, firstly the subject at rest was kept at an ambient temperature of 28°C for 40 minutes. Then, moving to a room kept at an ambient temperature of 18°C or 28°C, the state at rest was maintained with head heating at 3 radiant intensities (without radiation, 35°C and 40°C of globe temperature) for a further 40 minutes. In experiment 2, continued from the same procedure of experiment 1, work on the ergometer was performed for 30 minutes with head heating at 2 radiant intensities (without radiation and 35°C of globe temperature). Items measured were tympanic temperature, skin temperatures, heart rate, and subjective sensations. The principal results obtained are as follows: 1) Tympanic temperature, forehead skin temperature and score of thermal sensation of head increased, while the others decreased at 18°C. 2) Decrease of scores was inhibited by head heating in finger skin temperature, toe skin temperature and heart rate. 3) When radiant intensities at 35°C and 40°C were compared, statistical significant difference was noted in forehead skin temperature only, the difference of radiant conditions gives a little effect to the vital body. 4) Effects brought by head heating during rest decreased owing to the addition of work.
To clarify the stage of fibrinolytic activation by hyperbaric oxygen (HBO) exposure, we examined its alterations in human during and after the HBO exposure. Eight healthy female volunteers breathed oxygen at 284 kPa (2.8 atmospheres absolute). Blood samples were collected before compression, shortly after compression to the pressure 284 kPa, shortly before the start of decompression, shortly after decompression, and then again 3 hours after decompression. We estimated the euglobulin fibrinolytic activity (EFA) and, the activities and antigens of both tissue-type plasminogen activator (t-PA) and plasminogen activator inhibitor-1 (PAI-1). The PAI-1 activity and PAI-1 antigen showed significant decrease after compression to a pressure 284 kPa, before the start of decompression, and after decompression. The EFA level and t-PA activity rose significantly shortly after decompression, and 3 hours later returned on baseline. These findings suggest that fibrinolytic activity is elicited after HBO rather than during HBO.
A variety of types of artificial illumination has recently become available, differing in the quality of illumination and range of color temperature. In our previous studies we found that in subjects with normal color vision the nocturnal fall in core temperature and the increase of urinary melatonin excretion were suppressed by bright blue or green light, but not by bright red or dim lights. The aim of our present study was to examine from the view point of chronobiology whether the lights of different color temperature often used in everyday life may affect core temperature and urinary melatonin secretion differently. Experiments were carried out on five subjects with normal color vision. They were exposed for 5 hr (from 21:00 h to 2:00 h) to two kinds of bright (1000 lx) light of different color temperature (6500 K, 3000K) with dim (50 lx) light as a control; after exposure they slept in darkness. Our main results were as follows: The light with a high color temperature of 6500 K more strongly suppressed the nocturnal fall of the core temperature and the nocturnal increase of melatonin secretion than the light with a low color temperature of 3000 K. This difference was particularly evident for core temperature during the sleep period following experimental illumination.
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