Foot immersion with and without neck cooling reduces self-reported environmental symptoms in older adults exposed to simulated indoor overheating.

While foot immersion and neck cooling have been recommended for protecting heat-vulnerable groups, recent evidence does not support their efficacy for mitigating increases in physiological heat strain in older adults. However, their influence on self-reported environmental symptoms and mood-state remains unclear. Seventeen older adults (nine females, median [interquartile range] age: 72 [69-74]) completed three randomized heat exposures (6-h; 38°C, 35% relative humidity) with no cooling (control), foot immersion to mid-calf in 20°C water for the final 40-min of each hour (foot immersion), or foot immersion with a wet towel (20°C) around the neck (foot immersion with neck cooling).

Agreement between measured and self-reported physiological strain in young adults and older adults with and without common chronic diseases during simulated occupational heat stress.

While monitoring physiological strain is recommended to safeguard workers during heat exposure, it is logistically challenging. The perceptual strain index (PeSI) is a subjective estimate thought to reflect the physiological strain index (PSI) that requires no direct monitoring. However, advanced age and chronic diseases (hypertension/type 2 diabetes [T2D]) influence the perception of heat stress, potentially limiting the utility of the PeSI.

Brain-derived neurotrophic factor in older adults exposed to simulated indoor overheating.

Purpose: Brain-derived neurotrophic factor (BDNF) is a neuroprotective growth factor that increases in young adults during short, intense bouts of passive heat stress. However, this may not reflect the response in heat-vulnerable populations exposed to air temperatures more consistent with indoor overheating during hot weather and heatwaves, especially as the BDNF response to acute stressors may diminish with increasing age. We therefore evaluated the ambient and body temperature-dependent responses of BDNF in older adults during daylong passive heating.

An exploratory investigation of heart rate and heart rate variability responses to daylong heat exposure in young and older adults.

Heart rate variability (HRV) has shown potential as a tool for monitoring thermal strain, but there is limited data to support its efficacy in older adults during prolonged heat exposures. We compared HRV between young (19-31 years,  = 20) and older (61-78 years,  = 39) adults during 9 h of heat exposure (40 °C, 9% RH). We also explored whether heart rate (HR) and/or HRV could be used to distinguish older adults who achieved elevated thermal strain, defined as either (1) an increase in core temperature >1.

The effect of foot immersion and neck cooling on cardiac autonomic function in older adults exposed to indoor overheating: a randomized crossover trial.

Foot immersion and neck cooling are recommended cooling strategies for protecting heat-vulnerable persons during heat waves. While we recently showed that these strategies do not limit core temperature increases in older adults during prolonged heat exposure, we did observe small reductions in heart rate. Expanding on these findings, we examined the effects of foot immersion with and without neck cooling on cardiac autonomic function.

Time to reach equilibrium deep body temperatures in young and older adults resting in the heat: a descriptive secondary analysis.

It is commonly thought that steady-state thermoregulatory responses are achieved within 30-90 min of compensable heat stress. However, this assumption is based on measurements of whole body heat exchange during exercise, which stabilize (equilibrate) more rapidly than deep body temperatures, especially under resting conditions. To support the design of ecologically relevant heat exposure studies, we quantified equilibrium times for deep body temperature, as indexed by rectal temperature, in young and older adults resting in the heat.

Exploring the contribution of inter-individual factors to the development of physiological heat strain in older adults exposed to simulated indoor overheating.

Older adults are at elevated risk of heat-related mortality due to age-associated declines in thermoregulatory and cardiovascular function. However, the inter-individual factors that exacerbate physiological heat strain during heat exposure remain unclear, making it challenging to identify more heat-vulnerable subgroups. We therefore explored factors contributing to inter-individual variability in physiological responses of older adults exposed to simulated hot weather.

An exploratory survey of on-site heat stress management practices in the Canadian mining industry.

With climate change fueling more frequent and intense periods of hot weather, heat stress management programs are becoming increasingly important for protecting the health and safety of workers in the Canadian mining industry. While the inclusion of heat-mitigation measures such as those provided by the American College of Governmental Industrial Hygienists (ACGIH) Threshold Limit Values (TLVs) are commonly employed by industry, there is a need to develop more comprehensive industry-specific measures for heat stress prevention and management. To better understand current heat management practices and identify opportunities for improvement, an exploratory survey of 51 employees responsible for health and safety at underground mining ( = 35), and surface operations ( = 16) (e.

Exercise intensity- and body region-specific differences in sweating in middle-aged to older men with and without type 2 diabetes.

Type 2 diabetes (T2D) is associated with reduced whole body sweating during exercise-heat stress. However, it is unclear if this impairment is related to exercise intensity and whether it occurs uniformly across body regions. We evaluated whole body (direct calorimetry) and local (ventilated-capsule technique; chest, back, forearm, thigh) sweat rates in physically active men with type 2 diabetes [T2D; aged 59 (7) yr; V̇o 32.

A critical review of the effectiveness of electric fans as a personal cooling intervention in hot weather and heatwaves.

Health agencies worldwide have historically cautioned that electric fans accelerate body-heat gain during hot weather and heatwaves (typically in air temperatures ≥35°C). However, guidance published since 2021 has suggested that fans can still cool the body in air temperatures up to 40°C by facilitating sweat evaporation, and therefore are an inexpensive yet sustainable alternative to air conditioning. In a critical analysis of the reports cited to support this claim, we found that although fan use improves sweat evaporation, these benefits are of insufficient magnitude to exert meaningful reductions in body core temperature in air temperatures exceeding 35°C.

Experimental research in environmentally induced hyperthermic older persons: A systematic quantitative literature review mapping the available evidence.

The heat-related health burden is expected to persist and worsen in the coming years due to an aging global population and climate change. Defining the breadth and depth of our understanding of age-related changes in thermoregulation can identify underlying causes and strategies to protect vulnerable individuals from heat. We conducted the first systematic quantitative literature review to provide context to the historical experimental research of healthy older adults - compared to younger adults or unhealthy age matched cases - during exogenous heat strain, focusing on factors that influence thermoregulatory function (e.

Agreement between measured and self-reported physiological strain in males and females during simulated occupational heat stress.

Rationale: Monitoring physiological strain is recommended to safeguard workers during heat exposure, but is logistically challenging. The perceptual strain index (PeSI) is a subjective estimate thought to reflect the physiological strain index (PSI) that requires no physiological monitoring. However, sex is known to influence perceptions of heat stress, potentially limiting the utility of the PeSI.

Effect of daylong exposure to indoor overheating on autophagy and the cellular stress response in older adults.

To protect vulnerable populations during heat waves, public health agencies recommend maintaining indoor air temperature below ∼24-28 °C. While we recently demonstrated that maintaining indoor temperatures ≤26 °C mitigates the development of hyperthermia and cardiovascular strain in older adults, the cellular consequences of prolonged indoor heat stress are poorly understood. We therefore evaluated the cellular stress response in 16 adults (six females) aged 66-78 years during 8 h rest in ambient conditions simulating homes maintained at 22 °C (control) and 26 °C (indoor temperature upper limit proposed by health agencies), as well as non-air-conditioned domiciles during hot weather and heat waves (31 and 36 °C, respectively; all 45% relative humidity).

Hormonal intrauterine devices and heat exchange during exercise.

Synthetic progestins in oral contraceptives are thought to blunt heat dissipation by reducing skin blood flow and sweating. However, whether progestin-releasing intrauterine devices (IUDs) modulate heat loss during exercise-heat stress is unknown. We used direct calorimetry to measure whole-body total (dry + evaporative) heat loss in young, physically active women (mean (SD); aged 24 (4) years, 39.

Effects of Daylong Exposure to Indoor Overheating on Thermal and Cardiovascular Strain in Older Adults: A Randomized Crossover Trial.

Background: Health agencies recommend that homes of heat-vulnerable occupants (e.g., older adults) be maintained below 24-28°C to prevent heat-related mortality and morbidity.

The utility of heart rate and heart rate variability to identify limits of tolerance to moderate-intensity work in the heat: a secondary analysis.

We investigated the utility of heart rate (HR) and heart rate variability (HRV) for identifying individuals who may terminate work early due to excessive heat strain. Forty-eight men and women (median = 36 years; Q1 = 20 years; Q3 = 54 years) attempted 180 min of moderate-intensity work at a fixed metabolic rate (∼200 W/m; ∼3.5 METs) in a hot environment (wet-bulb globe temperature: 32 °C).

Physiological responses to 9 hours of heat exposure in young and older adults. Part III: Association with self-reported symptoms and mood state.

Older adults are at greater risk of heat-related morbidity and mortality during heat waves, which is commonly linked to impaired thermoregulation. However, little is known about the influence of increasing age on the relation between thermal strain and perceptual responses during daylong heat exposure. We evaluated thermal and perceptual responses in 20 young (19-31 yr) and 39 older adults (20 with hypertension and/or type 2 diabetes; 61-78 yr) resting in the heat for 9 h (heat index: 37°C).

Hot Topic: A Systematic Review and Content Analysis of Heat-Related Messages During the 2021 Heat Dome in Canada.

Context: During the summer of 2021, western Canada experienced a deadly heat event. From the first heat alert to postevent reporting, thousands of media articles were published that reference the heat event. However, a gap remains in understanding how this communication chain-from the release of a public heat alert to information shared through media outlets to the public-currently operates to disseminate heat-related messaging across Canada.

Dose-dependent nonthermal modulation of whole body heat exchange during dynamic exercise in humans.

To maintain heat balance during exercise, humans rely on skin blood flow and sweating to facilitate whole body dry and evaporative heat exchange. These responses are modulated by the rise in body temperature (thermal factors), as well as several nonthermal factors implicated in the cardiovascular response to exercise (i.e.

Brief ambient cooling preserves autophagy in peripheral blood mononuclear cells from older adults during 9 h of heat exposure.

Heat waves can cause dangerous elevations in body temperature that can compromise cellular function and increase the risk of heat stroke and major cardiovascular events. Visiting a cooling center or other air-conditioned location is commonly recommended by health agencies to protect heat-vulnerable older persons but the associated cellular effects remain underexplored. We evaluated cellular stress responses in peripheral blood mononuclear cells (PBMC) from 19 older adults [71 (SD 2) yr; 9 females] before and after a 9-h heat exposure [40.

Indoor overheating influences self-reported symptoms and mood-state in older adults during a simulated heatwave: Effects of mid-day cooling centre use.

Unlabelled: Public health agencies recommend that older adults without home air-conditioning visit cooling centres to mitigate physiological strain from high ambient temperatures during heat waves. However, there is little evidence regarding their influence on self-reported environmental symptoms and mood-state after returning to the heat.

Methods: Forty adults (64-79 years) underwent a daylong laboratory-based indoor overheating simulation (9-hours, heat index: 37 °C) with (cooling, n = 20) or without (control, n = 20) a 2-hour air-conditioning intervention (hours 5-6).

Physiological responses to 9 hours of heat exposure in young and older adults. Part II: Autophagy and the acute cellular stress response.

With rising global temperatures, heat-related mortality is increasing, particularly among older adults. Although this is often attributed to declines in thermoregulatory function, little is known regarding the effect of age on the cellular processes associated with mitigating heat-induced cytotoxicity. We compared key components of the cellular stress response in 19 young (19-31 yr; 10 female) and 37 older adults (61-78 yr; 10 female) during 9 h of heat exposure (40°C, 9% relative humidity).