Five healthy, nonacclimatized male subjects were exposed to a moderate heat stress level of 57.2℃(DBT), 15-20㎜Hg(pH₂O), 0.75M/sec(air current). Rectal temperature, mean skin temperature, heart rate, body weight before and after the experiment were recorded in every 5 minutes and mean body temperature and the rate of body teat storage was computed. Craig index of thermal strain was also determined and the relationship among those parameters were investigated. The summary of the finding was as follows.
1. The average length of voluntary tolerance time was 45 munutes (25 to 70 min) which virtually agreed with results of previous studies.
2. The amount of heat storage voluntarily tolerated(the value at the time of ceasing experiment) was 1.66-1.91 Cal per kilogram. Individual variation was large owing partly to small numver of experiments and wide distribution of subject´s ages.
3. Craig index was 2.63 in average(2.14-3.02) and the considerable degree of relationship was noted between the index and the rate of heat storage and voluntary tolerance time, both.
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