Temperature最新文献

Sweating is a vital thermoregulatory mechanism in humans for maintaining thermal balance during exercise and exposure to hot environments. The development of models that predict sweat rate based on body temperature has been ongoing for over half a century. Here, we compared predicted water loss rates (WLR) from these models to actual observations collected during 780 participant-exposures in three independent laboratory-based experiments. In these experiments, male participants aged 19-50 years cycled or walked at various intensities (metabolic heat productions between 200 and 970 W), in air temperatures ranging from -40°C to 50°C, relative humidities (14% to 95%), and air velocities (<0.2 to 10 m/s), while wearing different clothing ensembles (thermal insulation 0.20 to 3.75 clo). The models' performances were evaluated by the coefficient of determination (R²) and Root Mean Square Error (RMSE). Performance varied greatly with a maximum R² value of 0.5 and RMSE values ranging from 10.4 to 4.9 g/min. Models with a lower sweat onset core temperature setpoint performed better and most models generally underestimated the water loss at higher WLR. Optimization of the core and skin temperature setpoints suggests preferred core temperature setpoints within a narrow range (36.2°C to 36.6°C). Even with optimized inputs, R² values were around 0.5, meaning only 50% of the variance in observed WLR was explained by the models. Better model consideration of relations between body temperature and sweat rate, and the incorporation of non-thermal exercise-induced sweat promotion, may reduce model underpredictions at higher exercise intensities.

The associated factors for exertional heat stroke among amateur golfers remain poorly understood. We conducted a case-control study to examine exertional heat exhaustion (EHE) - related symptoms among amateur golfers in Japan using a self-administered questionnaire. Retrospective case-control study design. A web-based questionnaire was administered from September to November 2024. Data were collected on basic attributes, lifestyle habits, perceived health factors, perceived playing conditions, changes in eating behavior, and EHE-related symptoms. We performed a case-control analysis using a multivariate conditional logistic regression model. The explanatory variables included lifestyle habits, health factors, playing conditions, and eating behavior; the objective variables were EHE-related symptoms. Our study included 194 participants with EHE-related symptoms and 252 control participants. The following factors were significantly associated with EHE symptoms: perceived dehydration (adjusted odds ratio [AOR], 4.65, 95% confidence intervals (CI) 3.08-7.03); sleep deprivation (AOR, 4.38, 95% CI 2.84-6.77); loss of appetite (AOR, 4.32, 95% CI 2.84-6.58); accumulated fatigue (AOR, 3.26 95% CI 1.17-1.31); mental stress (AOR, 2.71, 95% CI 1.78-4.12); average rounds of golf (AOR 1.88, 95% CI 1.14-3.13); increased sports drink consumption (AOR 2.07, 95% CI 1.20-3.56); increased consumption of salt tablets and candies (AOR 1.99, 95% CI 1.29-3.05); and increased dietary supplement intake (AOR, 1.88, 95% CI 1.14-3.11).These findings suggest that amateur golfers should assess their physical condition before play and adjust their schedules accordingly, particularly in hot weather, to minimize the risk of heat-related illnesses.

The effects of exposure to extreme heat and cold temperatures on human health have mostly been studied in high-income countries. We examined this association by exploring the effect of extreme temperatures on mortality due to heatstroke and exposure to cold in India and by states. We used temperature data from the Indian Meteorological Department (IMD) and mortality data from the National Crime Records Bureau (NCRB) to examine trends in overall, gender, and age-specific mortality. We used structural breaks analysis to observe changes in India's mortality trends during 2001-2019. We examined the time trends in the relationship between extreme temperature and mortality for 24 Indian states from 2001 to 2014. We used panel regression and spline regression models. Between 2001 and 2019, India reported 19,693 and 15,197 deaths due to heatstroke and cold exposure, respectively. Top three states with the greatest number of deaths due to heatstroke were Andhra Pradesh, Uttar Pradesh, and Punjab; for cold exposure it was Uttar Pradesh, Punjab, and Bihar. Working-age men were significantly more susceptible to heatstroke. Spline regression results indicated that mortality varied across different temperature bins for both extreme summer and winter temperatures. Our findings demonstrate an urgent need to strengthen welfare and social support systems and invest in built environment and livelihood interventions to counter the avoidable mortality from extreme temperature events.

Heat exposure after exercise may enhance recovery of physical performance but can also impose additional physiological stress on athletes. This study investigated the effects of post-exercise infrared sauna (IRS) on adrenal and autonomic nervous system (ANS) responses and examined how these responses adapt over time during a 6-week training intervention. Forty female team-sport athletes were pair-matched into an IRS-group and a control group (CON). Participants completed jumping exercises followed by IRS (10 min, 50 °C) or passive recovery and physiological assessments during two experimental trials: in the first (EX1) and in the last (EX2) week of the training intervention. The ANS responses were assessed by nocturnal heart rate (HR) and heart rate variability recorded before and after exercise session. Saliva cortisol concentrations, muscle soreness, and perceived recovery were assessed in the morning, before and after the exercise sessions. Cortisol increased by 5.1 ± 8.6 nmol/l the morning after EX1 in the IRS-group (p = 0.017), but not in the CON-group. Furthermore, a greater pre-post change in cortisol concentration was observed following EX1 (4.6 ± 10.4 nmol/l) compared to EX2 (-1.8 ± 7.6 nmol/l). The IRS-group showed a higher post-session HR in EX1 compared to the CON-group (61 ± 8 bpm vs. 55 ± 6 bpm; p = 0.019). Increased muscle soreness was observed at EX1 post36h only in the CON-group. Post-exercise IRS initially elevated physiological stress responses in female athletes. After six weeks of regular IRS use, athletes' ANS balance and cortisol response adapted, suggesting effective physiological adjustment to the heat intervention within six weeks.

Changes in thermoregulation, notably the emergence of hot flashes, occur during the menopause transition in association with reproductive hormonal changes. Hot flashes constitute the most characteristic symptom of menopause (prevalence of 50-80%), and have a substantial negative effect on quality of life. Here, we review the endocrine changes associated with menopause and the thermoregulatory system and its sensitivity to female sex hormones. We then review current knowledge on the underlying neural mechanisms of hot flashes and how the reproductive and thermoregulatory systems interact in females. We consider the kisspeptin-neurokinin B-dynorphin (KNDy) neuron complex, which becomes hyperactive when estradiol levels decrease. KNDy neurons project from the arcuate nucleus to thermoregulatory areas within the hypothalamic preoptic area, where heat loss mechanisms are triggered, including cutaneous vasodilation and sweating - characteristics of the hot flash. We describe the physiology and measurement of hot flashes and discuss the mixed research findings about thresholds for sweating in symptomatic individuals. We consider the unique situation of hot flashes that arise during sleep, and discuss the relationships between the environment, exercise, and body mass index with hot flashes. We also discuss the unique situation of surgical menopause (with oophorectomy) and cancer therapy, conditions that are associated with frequent, severe, hot flashes. We then provide an overview of treatments of hot flashes, including hormone therapy and targeted neurokinin B-antagonists, recently developed to target the neural mechanism of hot flashes. Finally, we highlight gaps in knowledge about menopausal thermoregulation and hot flashes and suggest future directions for research.

A heat tolerance test (HTT) can aid in return-to-play decision making following exertional heat stroke (EHS). The HTT uses rectal temperature (T_REC, >38.5°C) and heart rate thresholds (HR; >150 bpm) to identify "heat intolerance." Unfortunately, T_REC is prohibited in some clinical settings (e.g. secondary schools), making a standard HTT unusable. Recently, gait sensors were used to identify heat illness, but have never been correlated with T_REC during a HTT. No research has compared gait or noninvasive body temperature sites to T_REC to determine their surrogacy for T_REC during a HTT. Eighteen subjects underwent a standard HTT (12 men, 6 women; age: 22 ± 2y; height: 168.3 ± 8.5 cm; mass: 76.6 ± 14.8 kg). Rectal, oral, aural, forehead, and axillary temperatures, gait metrics, and HR were measured every 5 minutes during a HTT. Temperature sites were invalid if bias (i.e. difference from T_REC) was >±0.27°C. Spearman correlations examined the relationship between T_REC and gait variables. Mean aural, oral, axillary, and forehead bias were -0.19 ± 0.56°C, 0.70 ± 0.53°C, 0.85 ± 0.45°C, and 1.38 ± 0.69°C, respectively (F_2,35 = 42.3, p < 0.001). Aural, oral, forehead, and axillary measurements exceeded our validity threshold 48 ± 30% (169 of 353), 87 ± 16% (307 of 353), 91 ± 15% (321 of 353), and 93 ± 10% (328 of 353) of the time, respectively. T_REC was significantly negatively correlated to shock (r =-0.28, p < 0.001), impact g (r =-0.28, p < 0.001), and braking g (r=-0.24, p < 0.001), and positively correlated with pronation excursion (r = 0.30, p < 0.001). Clinicians should use T_REC during an HTT as no alternative, valid temperature site was found. Some gait variables showed promise for tracking T_REC during a HTT, but more research is necessary.