Abstract:This study investigated the physiological thermal response of people under simulated weightlessness using a 6° head down bed rest (HDBR) model to ensure the human body functions in the weightlessness way. Thermal responses of six male participants were experimentally determined. The relationship between thermal comfort and heart rate variability (HRV) was also scrutinized. Physiological responses of participants under different environmental conditions were observed including core temperature, sweating, and mo… Show more
“…Regarding the risk of bias due to deviations from the intended interventions, three studies (Brenner et al 1997, Yamamoto et al 2007, Zhu et al 2020 with a small sample size (n 8) did not report statistical power data or sample size calculations. Concerning the missing outcome data, no articles were ranked as 'high risk'.…”
Section: Risk Of Bias and Quality Of The Studiesmentioning
Objective: To conduct a systematic review about the possible effects of passive heating protocols on cardiovascular autonomic control in healthy individuals. Approach: The studies were obtained from MEDLINE (PubMed), LILACS (BVS), EUROPE PMC (PMC) and SCOPUS databases, simultaneously. Studies were considered eligible if they employed passive heating protocols and investigated the cardiovascular autonomic control by spontaneous methods, such as heart rate variability (HRV), systolic blood pressure variability (SBPV) and baroreflex sensitivity (BRS), in healthy adults. The revised Cochrane risk-of-bias tool (RoB-2) was used to assess the risk of bias in each study. Main results: Twenty-seven studies were included in the qualitative synthesis. Whole-body heating protocols caused a reduction in cardiac vagal modulation in fourteen studies, and two studies reported both increased sympathetic modulation and vagal withdrawal. Contrariwise, local heating protocols and sauna bathing seem to increase cardiac vagal modulation. A reduction of BRS was reported in most of the studies that used whole-body heating protocols. However, heating effects on BRS remain controversial due to methodological differences among baroreflex analysis and heating protocols. Significance: Whole-body heat stress may increase sympathetic and reduce vagal modulation to the heart in healthy adults. On the other hand, local heating therapy and sauna bathing seem to increase cardiac vagal modulation, opposing sympathetic modulation. Nonetheless, further studies should investigate acute and chronic effects of thermal therapy on cardiovascular autonomic control.
“…Regarding the risk of bias due to deviations from the intended interventions, three studies (Brenner et al 1997, Yamamoto et al 2007, Zhu et al 2020 with a small sample size (n 8) did not report statistical power data or sample size calculations. Concerning the missing outcome data, no articles were ranked as 'high risk'.…”
Section: Risk Of Bias and Quality Of The Studiesmentioning
Objective: To conduct a systematic review about the possible effects of passive heating protocols on cardiovascular autonomic control in healthy individuals. Approach: The studies were obtained from MEDLINE (PubMed), LILACS (BVS), EUROPE PMC (PMC) and SCOPUS databases, simultaneously. Studies were considered eligible if they employed passive heating protocols and investigated the cardiovascular autonomic control by spontaneous methods, such as heart rate variability (HRV), systolic blood pressure variability (SBPV) and baroreflex sensitivity (BRS), in healthy adults. The revised Cochrane risk-of-bias tool (RoB-2) was used to assess the risk of bias in each study. Main results: Twenty-seven studies were included in the qualitative synthesis. Whole-body heating protocols caused a reduction in cardiac vagal modulation in fourteen studies, and two studies reported both increased sympathetic modulation and vagal withdrawal. Contrariwise, local heating protocols and sauna bathing seem to increase cardiac vagal modulation. A reduction of BRS was reported in most of the studies that used whole-body heating protocols. However, heating effects on BRS remain controversial due to methodological differences among baroreflex analysis and heating protocols. Significance: Whole-body heat stress may increase sympathetic and reduce vagal modulation to the heart in healthy adults. On the other hand, local heating therapy and sauna bathing seem to increase cardiac vagal modulation, opposing sympathetic modulation. Nonetheless, further studies should investigate acute and chronic effects of thermal therapy on cardiovascular autonomic control.
“…Therefore, many scholars have improved some environmental parameters on the basis of standard ones to meet the needs of extreme environments [8][9][10][11][12][13] or specific functions. 1,10,[14][15][16][17][18][19][20][21][22][23][24][25][26][27] Table 1 summarizes the features of some environmental chambers.…”
Section: Introduction To Environmental Chambersmentioning
Environmental chambers are a kind of equipment to simulate various conventional and extreme environments, which are usually applied to create various environmental conditions and conduct various studies related to environmental parameters. Through our review of literature of the past 30 years, environmental chambers have been mainly used in the following four aspects: pollutants’ emission characterization, human thermal comfort research, products and materials development and transformation and the reaction and behaviour of other living bodies such as animals and plants. In this paper, the current application of environmental chambers is summarized based on the research objectives, conditions and technical means. The purpose of this paper is to provide a review of the use of environmental chambers for research and analyze the current application of environmental chambers for the future application of environmental chambers and explore the direction of its future transformation and application.
“…hospital patients, elderly, children and pregnant women). [7][8][9][10][11][12] Multiple studies on the thermal comfort of sensitive populations (such as patients, the elderly and children) have been published in recent years (see Table 1 for details). These studies have reported differences between the predicted neutral values and the actual neutral values.…”
In this study, on-site measurements of the summer air-conditioning environment in obstetric clinics of six hospitals in Guangzhou, China, and subjective questionnaire surveys of pregnant women regarding hot and humid environments were carried out. A total of 723 valid questionnaires were obtained. In order to determine the appropriate metabolic rate, three methods were used in this study to obtain three different metabolic rate values, including ASHRAE 55-2020 for healthy adults in a sedentary state 1.0 met, pregnant women after 5 months of pregnancy 1.2 met based on medical tests and the resting metabolic rate of pregnant women 0.66 met. Linear fitting was performed with three predicted mean votes (PMVs) and thermal sensation vote (TSV). The mean TSV (MTSV) and PMV models were established to estimate the actual thermal neutral value (25.3°C) and the predicted thermal neutral value (26.1°C) for pregnant women. The PMV model for pregnant women was linearly corrected, and the corrected PMV model coincided with the actual thermal sensory MTSV model. The corrected PMV estimate was 0.60 PMV + 0.17, and the corrected thermal neutral estimate was 25.3°C. Finally, a simplified model of the relationship between the PMV for pregnant women and the relative humidity, mean radiant temperature, wind speed and air temperature was obtained.
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