ABSTRACT
The guidelines for the prevention of heat disorders during sports activities were established 13 years ago in Japan. Since then, various studies on preventive measures against heat disorders have been done, yielding new knowledge about its prevention. It has been reported that the incidence of heat disorders is high in children and the elderly, and heat acclimatization and clothing are the factors involved in this disorder. We proposed to lower the WBGT (wet-bulb globe temperature) limit for warning (discontinuation of hard exercise) from “28°C or more” to “25°C or more” (corresponding to an ambient temperature of 28°C) for non-acclimatized persons, children, the elderly, and persons wearing clothes covering the entire body. We also indicated that heat disorders can occur due to unpredictable causes, because the mechanism is very complicated.
ABSTRACT
No abstract available.
ABSTRACT
Effects of drinking on body temperature during exercise and recovery in heat were studied in the field. Five healthy baseball players participated in baseball training with and without fluid re-placement on summer days, and rectal temperature, body weight loss, rating of thirst and the amount of water consumption were measured.<BR>The rectal temperature was significantly lower throughout exercise when fluid replacements were allowed. The normalization of rectal temperature during rest periods was also significantly accelerated by fluid replacement. The rating of thirst was significantly correlated with the increase in rectal temperature and sweat loss, and also with the volume of fluid intake. Although full rehydration was not observed, body fluid replacement by drinking is suggested to be advantageous for body temperature regulation during exercise in heat.
ABSTRACT
The relationship between environmental conditions and water balance during training for baseball and American football was analyzed. The environmental conditions were assessed in terms of WBGT (wet-bulb globe temperature) based on NDB (natural dry-bulb temperature), NWB (natural wet-bulb temperature) and GT (globe temperature), as WBGT=0.7NWB+0.2GT+0.1NDB, <BR>During baseball training, a commercially available sports drink was provided <I>ad libitum</I>, whereas during American football training, the effect of free water intake was compared between tap-water and sports drink. The sweat rate and the amount of water consumption were significantly correlated with WBGT under each experimental condition. Body weight loss was 0.2% body wt./h during baseball training, whereas during American football training, body weight loss was 0.5%/h with tap-water and 0.4%/h with sports drink on average, revealing a significantly higher value for tap-water.<BR>These results indicate that both sweat loss and water intake during exercise increase with WBGT, and that body weight loss is maintained at a fairly constant level during exercise with free water intake, although the loss is significantly higher when tap-water is provided.
ABSTRACT
The relationship between environmental conditions and water balance during training for baseball and American football was analyzed. The environmental conditions were assessed in terms of WBGT (wet-bulb globe temperature) based on NDB (natural dry-bulb temperature), NWB (natural wet-bulb temperature) and GT (globe temperature), as WBGT=0.7NWB+0.2GT+0.1NDB, <BR>During baseball training, a commercially available sports drink was provided <I>ad libitum</I>, whereas during American football training, the effect of free water intake was compared between tap-water and sports drink. The sweat rate and the amount of water consumption were significantly correlated with WBGT under each experimental condition. Body weight loss was 0.2% body wt./h during baseball training, whereas during American football training, body weight loss was 0.5%/h with tap-water and 0.4%/h with sports drink on average, revealing a significantly higher value for tap-water.<BR>These results indicate that both sweat loss and water intake during exercise increase with WBGT, and that body weight loss is maintained at a fairly constant level during exercise with free water intake, although the loss is significantly higher when tap-water is provided.
ABSTRACT
Deaths and morbidity due to heat disorders during physical activity were gleaned from newspaper reports between 1970 and 1990. The environmental temperatures (dry-bulb temperature and relative humidity) recorded at the closest meteorological observatory at the time of occurrence were used to calculate the wet-bulb temperature and WBGT (wet-bulb globe temperature), and the relationship between heat disorders and environmental temperature was analyzed.<BR>During the 21-year period, 108 cases of heat disorders (91 deaths and 477 casualties) were reported in newspapers. Of the 91 deaths, 9 were in females and 82 were in males, and mean ages were 23.3 years, females and 19.0 years, males.<BR>It was possible to record the environmental conditions at the time of the heat disorder in 99 cases. The results indicated that almost all disorders occurred at ranges higher than 25.5°C, dry-bulb temperature, and 20.0°C, wet-bulb temperature, 40% relative humidity, and 24.0°C, WBGT. The mean WBGT was 28°C at physiological intensities less than 12-RMR (Relative Metabolic Rate) and 25.8°C at RMR higher than 15.<BR>The seasonal distribution was from April to November. In cases observed in April, May and November, abrupt rises in WBGT in the 1.2-3.4°C range were observed on the day of occurrence in comparison with the previous day, suggesting that the degree of heat acclimatization is olso an important factor in preventing heat disorders.
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Indexes to prevent heat casualties have been reported by many investigators based on different temperature scales including wet bulb temperature, wet bulb globe temperature, dry bulb temperature and so on. In this report, environmental temperature of an athletic field in Tokyo area was monitored in summer of 1981 to 1985, using natural wetbulb temperature (NWB), natural drybulb temperature (NDB), globe temperature (GT) and air velocity (A. V.) and WBGT (Wet Bulb Globe Temperature Index) was calculated, from NWB, GT and NDB on the result.<BR>The highest temperature observed was 33.2°C in WBGT, 28.0°C in NWB and 37.5°C in GT. Highly significant correlations were obtained between WBGT and other parameters, than for A. V.<BR>Based on the regression equation between WBGT and NWB, preventive measures for athletes in hot conditions were compared.
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Physical fitness of 900 volunteers over 60 years of age were analyzed using a 6-item battery test to obtain fundamental data on the fitness status of the aged Japanese. The test battery consisted of stepping, vertical jump, grip strength, breath holding, body flexion and one-leg balancing, and could be performed safely with relatively mild physical stress in the elderly after simple screening by measurement of resting blood pressure and oral check on mobility problems of the knee and the hip. Males showed significantly higher values in vertical jump, grip strength and breath holding, while females showed significantly higher values in body flexion. There were no sex differences in stepping and one-leg balancing. Lowing trend was found in the score with age in all items except breath holding, but the extent of the reduction differed among the measure elements of fitness. Most of measured items showed significant correlations each other. The values obtained with this test are considered to be useful for future analysis of the fitness of aged people and also to determine the exercise appropriate for them.