Body Temperature Changes

Extreme heat events are becoming more frequent, intense, and prolonged, increasing the risk of heat-related illness among workers performing physically demanding work in hot environments. Current occupational heat-stress guidelines aim to limit excessive increases in core body temperature and physiological strain through the use of work-rest schedules. However, these guidelines do not provide clear direction on the safe, maximum duration of continuous work that can be performed before heat-mitigation controls should be implemented, known as the initial stay time. Recent work has generated initial stay time recommendations for young and older workers performing moderate-intensity work in the heat, but these estimates were developed under normoxic conditions. In many occupational settings, workers may be exposed to additional environmental stressors such as hypoxia, including work at altitude or in oxygen-reduced environments. Hypoxia can increase cardiovascular strain, reduce arterial oxygen saturation, and alter exercise tolerance, potentially compromising the effectiveness of heat-stress guidance developed under normal oxygen conditions. Older workers may be especially vulnerable due to age-related reductions in thermoregulatory and cardiovascular function. To date, it remains unclear whether hypoxia alters physiological strain during work in the heat or whether current initial stay time and recovery recommendations remain protective under combined heat and hypoxic stress. The primary objective of this study is to determine whether exposure to hypoxia increases physiological strain during moderate-intensity work in the heat in young and older males. Specifically, investigators will assess whether normoxia-derived initial stay times and recovery recommendations for work at 29°C wet-bulb globe (37.5°C, 35% RH) temperature remain effective when workers are exposed to hypoxia equivalent to 14% inspired oxygen (simulating \~3000 m in altitude). Healthy young and older males will complete simulated occupational heat exposure under two conditions: heat alone and combined heat plus hypoxia. Participants will perform moderate-intensity treadmill work based on age-specific initial stay times, followed by prescribed work-rest cycles and seated recovery. Measures of core temperature, cardiovascular strain, oxygen saturation, skin temperature, hydration status, perceptual responses, mood, symptoms of environmental stress, and cognitive function will be assessed to determine whether hypoxia modifies responses to work in the heat. This study will provide important evidence on whether occupational heat-stress guidance requires refinement when workers are exposed to combined heat and hypoxic stress.

Extreme heat events are becoming more frequent, intense, and prolonged, increasing the risk of heat-related illness among workers exposed to hot environments. Current occupational heat-stress guidelines are designed to limit excessive increases in core body temperature and physiological strain during work in the heat through the use of work-rest schedules. However, these guidelines are largely based on single-day heat exposures and assume that workers recover in cool indoor environments between shifts. During heat events, many workers may instead recover in homes or accommodations that remain overheated, particularly in the absence of air conditioning. Inadequate overnight cooling may impair the body's ability to dissipate heat, increase physiological strain, and reduce tolerance to heat exposure on subsequent workdays. Older adults may be especially vulnerable due to age-related impairments in heat-loss capacity. To date, the effects of recovering in an overheated indoor environment on physiological strain and thermoregulatory function during repeated occupational heat exposure remain poorly understood, limiting the development of evidence-based recommendations to protect workers during prolonged heat events. The primary objective of this study is to determine whether overnight recovery in an overheated indoor environment increases physiological strain during repeated occupational heat exposure in older adults. Specifically, investigators will assess whether recovery at the recently proposed upper indoor temperature limit of 26°C and 45% relative humidity (RH) (PMID: 38329752) is sufficient to attenuate elevations in core temperature during subsequent work in the heat compared with recovery in an overheated indoor environment (31°C, 45% RH) representative of conditions commonly experienced during extreme heat events. Healthy older adults will complete two consecutive days and nights of simulated moderate-intensity occupational heat exposure, with overnight recovery occurring in either the 26°C or 31°C condition. Measures of core temperature, cardiovascular strain, heat-loss capacity, hydration status, sleep quality, cognitive function, mood, and perceptual responses will be assessed to determine the impact of overnight recovery conditions on responses to repeated heat exposure. Whole-body heat-loss capacity will also be evaluated before and after the exposure protocol as assessed during incremental, intermittent exercise protocol performed in an air calorimeter.

This study, in a quasi-experimental matched two-group pre-post design, investigates the effect of serial water-filtered whole-body hyperthermia on circadian core body temperature, the somatosensory system (nociception) and the movement evoked pain in healthy and patients with chronic primary pain (e.g., fibromyalgia). The intervention lasts 3 weeks with two treatment sessions per week.

Obesity has become a global public health crisis, with 810 million adults classified as obese (BMI ≥ 30 kg/m²) worldwide in 2020. This number is projected to rise to 1.53 billion by 2035. China faces a particularly severe challenge, with one of the highest rates and fastest growth in obesity prevalence globally. Obesity is a well-established risk factor for numerous chronic diseases, including cancer, cardiovascular disease, and diabetes. As such, weight loss is essential for improving health outcomes and preventing related complications. Lifestyle interventions-primarily dietary modifications and physical activity-are the cornerstone of obesity treatment, aiming to reduce weight by addressing energy intake and expenditure. Accumulating evidence indicates that energy imbalance is a key driver of obesity. However, resting metabolic rate (RMR), which accounts for approximately 60-75% of total energy expenditure, often declines during lifestyle interventions due to metabolic adaptation. This adaptive decrease in RMR can undermine weight loss efforts. While both body composition and core body temperature are known to influence RMR, their specific roles in metabolic adaptation during lifestyle interventions remain poorly understood. This study aims to investigate the individual contributions of changes in body composition and fluctuations in core body temperature to the observed reduction in RMR during such interventions. By combining body composition analysis and continuous core temperature monitoring, the study seeks to uncover mechanisms underlying metabolic adaptation and identify potential targets for enhancing weight loss strategies.

The goal of this clinical trial is to learn if cold water drinking could promote body composition and further extend healthy lifespan in Chinese older adults. The main questions it aims to answer are: 1. Does cold water drinking lower the body fat percentage? 2. Will cold water drinking positively extend lifespan in a long-term Researchers will compare cold water intervention group to a control group (drinking 37℃ water instead) to see if cold water drinking works to promote health and slow down ageing process. Participants will: 1. Drink 4℃ or 37℃ water 4 times (9a.m., 12p.m., 15p.m., 18p.m.) every day for 6 months. 2. Visit the institute and health checkup department for tests and checkup at baseline, the end of the 3rd month, and the end of 6th month.

This single-blind, randomized controlled trial aims to investigate the effect of Kinesio Taping (KT) applied to lumbar paravertebral muscles with different tensions (25% and 75%) on local body temperature. The study will compare the changes in local body temperature before and after KT application using infrared thermography. Participants will be randomly allocated to one of three groups with randomization stratified by sex: 25% tension KT, 75% tension KT, and a control group. Temperature measurements will be taken at four time points: before the application, 15 minutes, 45 minutes, and 24 hours post-application. The data will be analyzed using statistical methods to evaluate the impact of KT tension on local body temperature. This study will provide insights into the physiological effects of KT under different tension levels.

The aim of this project is to test the rate of cooling following exercise in the heat utilising the CRYOGENX Cryosuit device i) against passive cooling, and ii) to quantify the rate of cooling and compare this rate with established cooling intervention thresholds i.e. -0.11 to 0.15°C.min-1. As this project is to determine the efficacy of the intervention in populations equivalent to sporting and military personnel, these aims will be tested in young (18-40 year old) healthy male and female participants whom participate in regular physical activity. As a commercially funded project, the experimental design implemented will closely replicate that of the independent investigation into the efficacy of the CAERvest® device.