Screening criteria for increased susceptibility to heat stress during work or leisure in hot environments in healthy individuals aged 31–70 years

Abstract

Population aging and global warming generate important public health risks, as older adults have increased susceptibility to heat stress (SHS). We defined and validated sex-specific screening criteria for SHS during work and leisure activities in hot environments in individuals aged 31-70 years using age, anthropometry, and cardiorespiratory fitness. A total of 123 males and 44 females [44 ± 14 years; 22.9 ± 7.4% body fat; 40.3 ± 8.6 peak oxygen uptake (mlO/kg/min)] participated, separated into the Analysis (n = 111) and Validation (n = 56) groups. Within these groups, participants were categorized into YOUNG (19-30 years; n = 47) and OLDER (31-70 years; n = 120). All participants performed exercise in the heat inside a direct calorimeter. Screening criteria for OLDER participants were defined from the Analysis group and were cross-validated in the Validation group. Results showed that 30% of OLDER individuals in the Analysis group were screened as SHS positive. A total of 274 statistically valid (p < 0.05) criteria were identified suggesting that OLDER participants were at risk for SHS when demonstrating two or more of the following (males/females): age ≥ 53.0/55.8 years; body mass index ≥29.5/25.7 kg/m; body fat percentage ≥ 28.8/34.9; body surface area ≤2.0/1.7 m; peak oxygen uptake ≤48.3/41.4 mlO/kg fat free mass/min. In the Validation group, McNemar χ comparisons confirmed acceptable validity for the developed criteria. We conclude that the developed criteria can effectively screen individuals 31-70 years who are at risk for SHS during work and leisure activities in hot environments and can provide simple and effective means to mitigate the public health risks caused by heat exposure.

Workers' health and productivity under occupational heat strain: a systematic review and meta-analysis

“…Our estimate that 35% of individuals working in heat stress conditions experience occupational heat strain is in line with the 30% (95% CI 24-36) prevalence reported for increased susceptibility to heat stress (an inability to mitigate hyperthermia) when working or exercising in hot environments, 139 and with epidemiological data 140,141 for morbidity and mortality during extreme heat events. When compared with normative values for healthy, [142][143][144] obese, 145 or acutely-ill 146 adults, the average core temperature of 37•6°C estimated for individuals working a shift under heat stress is considered borderline hyperthermia or pyrexia.…”

“…While core temperature thresholds for hyperthermia, fever, and heat injury vary across individuals, 144 those who are older, obese, unfit, have chronic disease, or experience acute illness or infection are at a high risk for heatinduced pathologies (eg, heat cramps, heat exhaustion, and heat stroke). 1,7,139,147 We used the standard definitions of kidney disease and acute kidney injury proposed by the KDIGO clinical practice guidelines workgroup 24 and found that 15% of individuals working in heat stress have these conditions, which is markedly higher than the prevalence rates reported for kidney disease (10%) 148 and acute kidney injury in high-income (2%) 149,150 and low-income (3-9%) 151,152 countries. Taken together, these results raise serious concerns for the kidney function of individuals who typically or frequently work in heat stress conditions, because even a single episode of acute kidney injury can lead to chronic kidney disease, with substantial socioeconomic and public health outcomes.…”

Oral Glutamine Supplement Reduces Subjective Fatigue Ratings during Repeated Bouts of Firefighting Simulations

“…The authors further concluded that safety programs and strategies should be developed in response to high occurrences of heat-related injury in tropical regions [69]. In addition, efforts have been made to identify the characteristics of those susceptible to heat-related injury to prevent public health risks [70]. This may include older workers and those working for successive days in the heat [71].…”

Superoxide and NADPH oxidase do not modulate skin blood flow in older exercising adults with and without type 2 diabetes

“…High aerobic fitness levels can counteract age-related impairments in whole-body heat loss during exercise (Flouris et al, 2018;Stapleton et al, 2015). Habitual physical activity can also reduce age-related oxidative stress and enhance endothelium-dependent vasodilation (Pierce et al, 2011;Walker et al, 2014).…”