{"title":"Factors affecting an increase in core body temperature and heat tolerance during hot water immersion","authors":"Yuta Masuda, I. Kato, K. Nagashima","doi":"10.7600/jpfsm.10.243","DOIUrl":null,"url":null,"abstract":"The aim of the present study was to clarify the factors affecting an increase in core body temperature during 40°C water immersion to the subclavian level. Fifteen healthy males were immersed in water for 60 min. Rectal temperature (T rec ) and skin temperature (T sk ) at four skin sites were determined. Minute ventilation (V ・ E ) was measured, and metabolic rate was determined by indirect calorimetry. Skin blood flow and sweat rate at the forehead were assessed using laser-Doppler flowmetry (%LDF head ) and dew hygrometry (SR head ), respectively. Hot feeling was assessed with a visual analog scale. When T rec reached 39°C or participants reported an extremely hot feeling, the experiment was ceased. Eleven participants were unable to complete the protocol (ten participants due to T rec > 39°C; and one due to excessive hot feeling). T rec increased with immersion period. Mean T sk was unchanged from 20 min. V ・ E and metabolic rate increased with immersion period. %LDF head and SR head increased after immersion and remained unchanged from 15 and 30 min, respectively. Change in T rec from the baseline at 15, 30, and 45 min was correlated to cumulative change in metabolic rate from the baseline at 0-15, 0-30, and 0-45 min. No correlations were observed between change in T rec and cumulative changes in V ・ E , %LDF head , and SR head from baseline, hot feeling, body weight and body composition. Water immersion at 40°C induced a large difference in the increase of T rec , in which metabolic responses to heat stress may be involved. The relationship between heat tolerance and change in T rec is different among individuals.","PeriodicalId":55847,"journal":{"name":"Journal of Physical Fitness and Sports Medicine","volume":null,"pages":null},"PeriodicalIF":0.0000,"publicationDate":"2021-09-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Journal of Physical Fitness and Sports Medicine","FirstCategoryId":"1085","ListUrlMain":"https://doi.org/10.7600/jpfsm.10.243","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"","JCRName":"","Score":null,"Total":0}
引用次数: 0
Abstract
The aim of the present study was to clarify the factors affecting an increase in core body temperature during 40°C water immersion to the subclavian level. Fifteen healthy males were immersed in water for 60 min. Rectal temperature (T rec ) and skin temperature (T sk ) at four skin sites were determined. Minute ventilation (V ・ E ) was measured, and metabolic rate was determined by indirect calorimetry. Skin blood flow and sweat rate at the forehead were assessed using laser-Doppler flowmetry (%LDF head ) and dew hygrometry (SR head ), respectively. Hot feeling was assessed with a visual analog scale. When T rec reached 39°C or participants reported an extremely hot feeling, the experiment was ceased. Eleven participants were unable to complete the protocol (ten participants due to T rec > 39°C; and one due to excessive hot feeling). T rec increased with immersion period. Mean T sk was unchanged from 20 min. V ・ E and metabolic rate increased with immersion period. %LDF head and SR head increased after immersion and remained unchanged from 15 and 30 min, respectively. Change in T rec from the baseline at 15, 30, and 45 min was correlated to cumulative change in metabolic rate from the baseline at 0-15, 0-30, and 0-45 min. No correlations were observed between change in T rec and cumulative changes in V ・ E , %LDF head , and SR head from baseline, hot feeling, body weight and body composition. Water immersion at 40°C induced a large difference in the increase of T rec , in which metabolic responses to heat stress may be involved. The relationship between heat tolerance and change in T rec is different among individuals.