View clinical trials related to Heat Exposure.
Filter by:As the ongoing progression of climate change exposes individuals to elevated temperatures and an escalating frequency of extreme heat events, the risk of more intense and prolonged heat waves raises significant concerns for public health, particularly among vulnerable populations. The physiological response to acute heat stress involves involuntary thermolytic reactions that may strain the cardiovascular system, especially in individuals with pre-existing vulnerabilities. Heat acclimation has been identified as a potential strategy to enhance thermoregulation and mitigate the adverse effects of heat stress. While existing research primarily focuses on athletes and military, this study aims to investigate the impact of a practical heat acclimation strategy, combining passive and active heat exposure, on thermophysiological, cardiovascular and metabolic parameters in healthy overweight adults. The study targets a population at increased risk for heat-related complications, seeking to provide realistic guidelines for broader application when a heat wave appears on the weather forecast.
The aim of this study was to determine the effect of hot application applied to the sacral region during first stage of labor on women's pain level and labor process.
The main objective of the study is to evaluate the physiological-biochemical effects of physical training under artificially altered climatic conditions (using a hypoxic thermoclimatic chamber) in particular to determine the effect of such training on exercise capacity and physiological response, including the effect of training in high-performance athletes. The study will evaluate the effects of physical training and the simultaneous application of hypoxia and heat/cold on aerobic and anaerobic capacity and the physiological response of the human body. The aim of the study is to find the most favourable environmental conditions for physical training in order to maximise physical performance.
The global populace is at growing risk of heat-related illness due to climate change and accompanying increases in the intensity and regularity of extremely hot temperatures. In heat-exposed persons, heat gain from the environment and metabolism initially exceeds the rate of heat dissipation from the skin. Heat is stored in the body, causing core and skin temperatures to rise, which in turn triggers autonomically mediated elevations in cutaneous blood flow and sweating to facilitate heat loss. If conditions are compensable, heat loss increases until it balances total heat gain. At this point, the rate of heat storage falls to zero (i.e., heat balance is achieved) and body temperature stabilizes, albeit at a level elevated from thermoneutral conditions. If, however, the maximal achievable rate of heat dissipation is insufficient to offset heat gain, conditions are uncompensable, and prolonged exposure will cause a continual rise in core temperature that can compromise health if left unchecked. The environmental limits of compensability (i.e., the temperatures/humidities above which heat balance can not be maintained) are therefore an important determinant of survival during prolonged heat exposure. Evaluating this limit and how it can be modified (e.g., by behavior or individual factors like age or sex) is an increasingly important and active field of study. Contemporary evaluations of the environmental limits of compensability utilize "ramping protocols" in which participants are exposed to increasing levels of temperature or humidity (in 5-10 min stages) while core temperature is monitored. It is generally observed that core temperature is relatively stable (or rises slightly) in the early stages of exposure but undergoes an abrupt and rapid increase as heat stress becomes more severe. The conditions (e.g., wet-bulb temperature or wet-bulb globe temperature) at this "inflection point" are taken as the limits of compensability. That is, it is assumed that inflection corresponds to the demarcation point, below which core temperature would remain stable for prolonged periods (theoretically indefinitely if hydration is maintained) but above which heat loss is insufficient to offset heat gain, causing core temperature to rise continuously. Despite the increasing use of these protocols, no study has clearly demonstrated their validity for identifying the environmental limits of compensability. The goal of this project is therefore to assess the validity of ramping protocols for determining the ambient conditions above which thermal compensation is not possible. Enrolled participants will complete four experimental trials in a climate-controlled chamber: one ramping protocol followed by three randomized fixed-condition exposures. In the ramping protocol, participants will rest in 42°C with 28% relative humidity (RH) for 70 min, after which RH will be increased 3% every 10 min until 70% RH is achieved. The core (esophageal) temperature inflection point will be determined. For the fixed-condition exposures, participants will rest in i) 42°C with RH ~5% below their individual inflection point (below-inflection condition), ii) 42°C with RH ~5% above their individual inflection point (above-inflection condition), and iii) 26°C with 45% RH (control condition). Comparing the rate of change in esophageal temperature between each fixed-condition exposure will provide important insight into the validity of ramping protocols for identifying the limits of compensability.
Aging is associated with impairments in heat loss responses of skin blood flow and sweating leading to reductions in whole-body heat loss. Consequently, older adults store more body heat and experience greater elevations in core temperature during heat exposure at rest and during exercise. This maladaptive response occurs in adults as young as 40 years of age. Recently, heat acclimation associated with repeated bouts of exercise in the heat performed over 7 successive days has been shown to enhance whole-body heat loss in older adults, leading to a reduction in body heat storage. However, performing exercise in the heat may not be well tolerated or feasible for many older adults. Passive heat acclimation, such as the use of warm-water immersion may be an effective, alternative method to enhance heat-loss capacity in older adults. Thus, the following study aims to assess the effectiveness of a 7-day warm-water immersion (~40°C) protocol in enhancing whole-body heat loss in older adults. Warm-water immersion will consist of a one-hour immersion in warm water with core temperature clamped at 38.5°C. Improvements in whole-body heat loss will be assessed during an incremental exercise protocol performed in dry heat (i.e., 40°C, ~15% relative humidity) prior to and following the 7-day passive heat acclimation protocol. The incremental exercise protocol will consist of three 30 minute exercise bouts performed at increasing fixed rates of metabolic heat production (i.e., 150, 200, and 250 W/m2), each separated by 15-minutes of recovery, with exception final recovery will be 1-hour in duration) performed in a direct calorimeter (a device that provides a precise measurement of the heat dissipated by the human body).
The goal of this clinical trial is to compare the efficiency of water biking training in hot (35°C) versus neutral (25°C) temperature water to elicite heat acclimation in healthy recreative athletes.
The purpose of the project is to estimate the air temperature in the lungs after a change from room temperature (25℃) to an environment with a constant temperature of 88-92℃ in resp. lung-healthy persons and persons with bronchiectasis.
The purpose of this study is to examine the human thermoregulatory impact of applying a commercially available menthol gel (BioFreeze) to the skin prior to moderate intensity walking under heated conditions. Experimental Visits will consist of 30 min of treadmill walking at a moderate pace (3.5 mph, 5% grade) under hot conditions (38°C, 60%RH) and will be randomized and counterbalanced for BioFreeze or a hypoallergenic gel (control) application. Gels will be applied to areas commonly exposed during outdoor activity in warm conditions (shoulder to wrist, mid thigh to ankle). Accordingly, participants will wear shorts and a tank top shirt during exercise. Core temperature, skin temperature, galvanic skin response, laser doppler blood flow, and heart rate will be continuously recorded throughout the exercise bout via an integrated analog to digital converter. Sweat will be collected during exercise using commercially available absorbent patches. Thermal sensation will be assessed throughout exercise via the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) thermal sensation likert scale (cold to hot). Lastly, nude body weight will be recorded pre and post exercise for sweat rate determination. The BioFreeze and control trials will be separated by a 7-14 day washout period.
The purpose of this study is to examine the human thermoregulatory impact of applying a commercially available capsaicin gel to the skin prior to moderate intensity walking under heated conditions. Experimental Visits will consist of 30 min of treadmill walking at a moderate pace (3.5 mph, 5% grade) under hot conditions (38°C, 60%RH) and will be randomized and counterbalanced for capsaicin gel or a hypoallergenic gel (control) application. Gels will be applied to areas commonly exposed during outdoor activity in warm conditions (shoulder to wrist, mid thigh to ankle). Accordingly, participants will wear shorts and a tank top shirt during exercise. Core temperature, skin temperature, galvanic skin response, laser doppler blood flow, and heart rate will be continuously recorded throughout the exercise bout via an integrated analog to digital converter. Sweat will be collected during exercise using commercially available absorbent patches. Thermal sensation will be assessed throughout exercise via the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) thermal sensation likert scale (cold to hot). Lastly, nude body weight will be recorded pre and post exercise for sweat rate determination. The capsaicin and control trials will be separated by a 7-14 day washout period
Insulin resistance and hyperglycemia predispose individuals with type 2 diabetes mellitus (T2DM) to endothelial dysfunction and a greater risk of cardiovascular diseases (CVD). Increased CVD risk in individuals with T2DM persists despite optimal pharmacological therapy, highlighting the need to identify complementary lifestyle interventions that improve cardiometabolic functions in this population. Evidence from animal models suggests that heat exposure improves metabolic functions. Notably, weekly heat exposure for 16 weeks blunts hyperinsulinemia and hyperglycemia induced by a high fat diet in mice. In parallel, studies in humans have shown that heat exposure improves vascular endothelial function. Based on such findings, it has been suggested that heat therapy may represent an effective lifestyle intervention to improve cardiometabolic functions. However, only 1 study has examined the impact of a heat therapy intervention on individuals with T2DM, demonstrating that 6 weeks of heat exposure reduces fasting plasma glucose and hemoglobin A1C. No study has considered potential vascular benefits of heat therapy in individuals with T2DM. This project will investigate cardiometabolic responses to repeated heat exposure in men and women with T2DM. We will test the hypothesis that 12 weeks of heat therapy improves postprandial fatty acid handling, insulin sensitivity and endothelial function in individuals with T2DM.