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Crank PJ, O'Lenick CR, Baniassadi A, Sailor DJ, Wilhelmi O, Hayden M. Sociodemographic Determinants of Extreme Heat and Ozone Risk Among Older Adults in 3 Sun Belt Cities. J Gerontol A Biol Sci Med Sci 2024; 79:glae164. [PMID: 39073887 DOI: 10.1093/gerona/glae164] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2023] [Indexed: 07/31/2024] Open
Abstract
BACKGROUND Vulnerable populations across the United States are frequently exposed to extreme heat, which is becoming more intense due to a combination of climate change and urban-induced warming. Extreme heat can be particularly detrimental to the health and well-being of older citizens when it is combined with ozone. Although population-based studies have demonstrated associations between ozone, extreme heat, and human health, few studies focused on the role of social and behavioral factors that increase indoor risk and exposure among older adults. METHODS We conducted a household survey that aimed to understand how older adults are affected by extreme heat and ozone pollution inside and outside of their homes across Houston, Phoenix, and Los Angeles. We examine contributing factors to the risk of self-reported health effects using a generalized linear mixed-effects regression model of telephone survey data of 909 older adults in 2017. RESULTS We found an increased occurrence of self-reported symptoms for extreme heat with preexisting respiratory health conditions and a lack of air conditioning access; self-reported ozone symptoms were more likely with preexisting respiratory health conditions. The risk of heat-related symptoms was slightly higher in Los Angeles than Houston and Phoenix. We found several demographic, housing, and behavioral characteristics that influenced the risk of heat- and ozone-related symptoms. CONCLUSIONS The increased risk among older adults based on specific social and behavioral factors identified in this study can inform public health policy and help cities tailor their heat and ozone response plans to the specific needs of this vulnerable population.
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Affiliation(s)
- Peter J Crank
- Department of Geography and Environmental Management, University of Waterloo, Waterloo, Ontario, Canada
| | - Cassandra R O'Lenick
- Center for Environmental Medicine, Asthma and Lung Biology, University of North Carolina-Chapel Hill, Chapel Hill, North Carolina, USA
| | - Amir Baniassadi
- Department of Medicine, Harvard Medical School, Boston, Massachusetts, USA
- Marcus Institute for Aging Research, Hebrew SeniorLife, Boston, Massachusetts, USA
| | - David J Sailor
- Urban Climate Research Center, Arizona State University, Tempe, Arizona, USA
- School of Geographical Sciences and Urban Planning, Arizona State University, Tempe, Arizona, USA
| | - Olga Wilhelmi
- NSF National Center for Atmospheric Research, Boulder, Colorado, USA
| | - Mary Hayden
- Lyda Hill Institute for Human Resilience, University of Colorado-Colorado Springs, Colorado Springs, Colorado, USA
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2
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Singh G, Peterson B, Jay O, Stevens CJ. The effect of synthetic grass sports surfaces on the thermal environment: A systematic review. INTERNATIONAL JOURNAL OF BIOMETEOROLOGY 2024; 68:1235-1252. [PMID: 38691211 PMCID: PMC11272752 DOI: 10.1007/s00484-024-02679-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/05/2023] [Revised: 04/04/2024] [Accepted: 04/08/2024] [Indexed: 05/03/2024]
Abstract
There are concerns regarding high surface temperatures on synthetic grass sports surfaces influencing the surrounding thermal environment, potentially increasing heat stress and impacting athlete safety. As such, studies have investigated changes to the thermal environment surrounding synthetic grass surfaces in comparison to both natural grass, and synthetic surfaces with different features, but this body of research has not been systematically reviewed. Therefore, this systematic review aimed to (i) determine if there are differences in the thermal environment surrounding synthetic grass surfaces compared with natural grass surfaces, and (ii) determine if there are differences in the thermal environment between different types of synthetic grass surfaces. A systematic review adhering to the PRISMA guidelines was performed. The eligibility criteria required investigations to report at least one of the following environmental parameters on or directly above both a synthetic surface and a comparator group of either natural grass or an alternative synthetic grass surface used in sport: Air temperature, mean radiant temperature, humidity, wind velocity, unified heat stress indices (i.e. wet-bulb-globe temperature and heat index) and/or surface temperature. Twenty-three studies were identified. The only parameters that were consistently higher on synthetic grass compared to natural grass were the air temperature (range: 0.5-1.2 °C) and surface temperature (range: 9.4-33.7 °C), while the mean radiant temperature, humidity, wind velocity and wet-bulb-globe temperature remained similar or required more data to determine if any differences exist. Synthetic grass surfaces consisting of styrene butadiene rubber infill or a shock pad had increased surface temperatures, whereas surfaces with thermoplastic elastomer infill, Cool climate turf fibres or HydroChill had lower surface temperatures. This systematic review has demonstrated that air and surface temperatures can be increased on synthetic sports surfaces, compared to natural grass surfaces. However, it is uncertain whether the differences are enough to increase an individual's heat stress risk and cause concern for athlete safety. While modifications to the turf infill or fibres can reduce synthetic surface temperatures, the effect of these features on the thermal environment as a whole is unclear. This review was prospectively registered with the Open Science Framework (Open Science Framework registration https://doi.org/10.17605/OSF.IO/BTKGE ).
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Affiliation(s)
- Gurpreet Singh
- Physical Activity, Sport, and Exercise Research (PASER) Theme, Faculty of Health, Southern Cross University, Coffs Harbour, NSW, Australia.
| | - Benjamin Peterson
- School of Health, Medical and Applied Sciences, Central Queensland University, Rockhampton, Australia
| | - Ollie Jay
- Heat and Health Research Incubator, Faculty of Medicine and Health, University of Sydney, Camperdown, Australia
| | - Christopher J Stevens
- Physical Activity, Sport, and Exercise Research (PASER) Theme, Faculty of Health, Southern Cross University, Coffs Harbour, NSW, Australia
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3
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Topham TH, Smallcombe JW, Brown HA, Clark B, Woodward AP, Telford RD, Jay O, Périard JD. Biological sex does not independently influence core temperature change and sweating of children exercising in uncompensable heat stress. J Appl Physiol (1985) 2024; 136:1440-1449. [PMID: 38660730 DOI: 10.1152/japplphysiol.00877.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2023] [Revised: 04/03/2024] [Accepted: 04/21/2024] [Indexed: 04/26/2024] Open
Abstract
The purpose of this study was to investigate the influence of biological sex, independent of differences in aerobic fitness and body fatness, on the change in gastrointestinal temperature (ΔTgi) and whole body sweat rate (WBSR) of children exercising under uncompensable heat stress. Seventeen boys (means ± SD; 13.7 ± 1.3 yr) and 18 girls (13.7 ± 1.4 yr) walked for 45 min at a fixed rate of metabolic heat production per kg body mass (8 W·kg-1) in 40°C and 30% relative humidity. Sex and peak oxygen consumption (V̇o2peak) were entered into a Bayesian hierarchical general additive model (HGAM) for Tgi. Sex, V̇o2peak, and the evaporative requirement for heat balance (Ereq) were entered into a Bayesian hierarchical linear regression for WBSR. For 26 (12 M and 14 F) of the 35 children with measured body composition, body fat percentage was entered in a separate HGAM and hierarchical linear regression for Tgi and WBSR, respectively. Conditional on sex-specific mean V̇o2peak, ΔTgi was 1.00°C [90% credible intervals (Crl): 0.84, 1.16] for boys and 1.17°C [1.01, 1.33] for girls, with a difference of 0.17°C [-0.39, 0.06]. When sex differences in V̇o2peak were accounted for, the difference in ΔTgi between boys and girls was 0.01°C [-0.25, 0.22]. The difference in WBSR between boys and girls was 0.03 L·h-1 [-0.02, 0.07], when isolated from differences in Ereq. The difference in ΔTgi between boys and girls was -0.10°C [-0.38, 0.17] when sex differences in body fat (%) were accounted for. Biological sex did not independently influence the ΔTgi and WBSR of children exercising under uncompensable heat stress.NEW & NOTEWORTHY Limited studies have investigated the thermoregulatory responses of boys and girls exercising under uncompensable heat stress. Boys and girls often differ in physiological characteristics other than biological sex, such as aerobic fitness and body fat percentage, which may confound interpretations. We investigated the influence of biological sex on exercise thermoregulation in children, independent of differences in aerobic fitness and body fatness.
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Affiliation(s)
- Thomas H Topham
- Research Institute for Sport and Exercise (UCRISE), University of Canberra, Bruce, Australian Capital Territory, Australia
| | - James W Smallcombe
- Faculty of Medicine and Health, Heat and Health Research Incubator, The University of Sydney, Sydney, New South Wales, Australia
| | - Harry A Brown
- Research Institute for Sport and Exercise (UCRISE), University of Canberra, Bruce, Australian Capital Territory, Australia
| | - Brad Clark
- Research Institute for Sport and Exercise (UCRISE), University of Canberra, Bruce, Australian Capital Territory, Australia
| | - Andrew P Woodward
- Faculty of Health, University of Canberra, Bruce, Australian Capital Territory, Australia
| | - Richard D Telford
- Research Institute for Sport and Exercise (UCRISE), University of Canberra, Bruce, Australian Capital Territory, Australia
| | - Ollie Jay
- Faculty of Medicine and Health, Heat and Health Research Incubator, The University of Sydney, Sydney, New South Wales, Australia
| | - Julien D Périard
- Research Institute for Sport and Exercise (UCRISE), University of Canberra, Bruce, Australian Capital Territory, Australia
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4
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Park DY, Bittar-Carlini G, Kumar M, Jamil Y, Nanna MG. Seasonal variations in admissions for atrial fibrillation or atrial flutter in the Northeast and the Midwest regions of the United States. Proc AMIA Symp 2024; 37:560-568. [PMID: 38910792 PMCID: PMC11188794 DOI: 10.1080/08998280.2024.2346050] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2024] [Accepted: 04/01/2024] [Indexed: 06/25/2024] Open
Abstract
Background Previous studies conflict on whether seasonal variability exists in atrial fibrillation (AF) admissions, and contemporary studies are lacking. Methods We identified admissions for AF or atrial flutter in the Midwest and Northeast regions of the US from the National Inpatient Database for 2016 to 2020, grouped them into the four seasons (spring, summer, fall, winter), and compared the number of admissions. Subgroup analyses were performed stratified to sex, age, race, AF alone, and geographical regions. Results A total of 955,320 admissions for AF or atrial flutter occurred. The number of admissions was highest during winter (243,990, 25.5% of the total), followed by fall (239,250, 25.0% of the total), summer (236,910, 24.8% of the total), and spring (235,170, 24.6% of the total). The differences were statistically significant (P < 0.001). An increasing trend in the number of admissions was observed from March to February of the next year (P trend <0.001). Admissions were most common in the winter and least common in the spring in subgroups of both sexes, age ≥65 years, Whites, non-Whites, AF alone, Northeast region, and Midwest region. Conclusion Contemporary analysis of a national database demonstrates seasonal variability in the number of admissions for AF, with a slight increase observed during the winter.
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Affiliation(s)
- Dae Yong Park
- Department of Medicine, Cook County Health, Chicago, Illinois, USA
| | | | - Manoj Kumar
- Department of Medicine, Cook County Health, Chicago, Illinois, USA
| | - Yasser Jamil
- Department of Medicine, Yale School of Medicine, Connecticut, USA
| | - Michael G. Nanna
- Section of Cardiovascular Medicine, Department of Medicine, Yale School of Medicine, New Haven, Connecticut, USA
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5
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Beigtan M, Gonçalves M, Weon BM. Heat Transfer by Sweat Droplet Evaporation. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2024; 58:6532-6539. [PMID: 38538556 PMCID: PMC11025549 DOI: 10.1021/acs.est.4c00850] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/24/2024] [Revised: 03/03/2024] [Accepted: 03/12/2024] [Indexed: 04/17/2024]
Abstract
Sweating regulates the body temperature in extreme environments or during exercise. Here, we investigate the evaporative heat transfer of a sweat droplet at the microscale to unveil how the evaporation complexity of a sweat droplet would affect the body's ability to cool under specific environmental conditions. Our findings reveal that, depending on the relative humidity and temperature levels, sweat droplets experience imperfect evaporation dynamics, whereas water droplets evaporate perfectly at equivalent ambient conditions. At low humidity, the sweat droplet fully evaporates and leaves a solid deposit, while at high humidity, the droplet never reaches a solid deposit and maintains a liquid phase residue for both low and high temperatures. This unprecedented evaporation mechanism of a sweat droplet is attributed to the intricate physicochemical properties of sweat as a biofluid. We suppose that the sweat residue deposited on the surface by evaporation is continuously absorbing the surrounding moisture. This route leads to reduced evaporative heat transfer, increased heat index, and potential impairment of the body's thermoregulation capacity. The insights into the evaporative heat transfer dynamics at the microscale would help us to improve the knowledge of the body's natural cooling mechanism with practical applications in healthcare, materials science, and sports science.
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Affiliation(s)
- Mohadese Beigtan
- Soft
Matter Physics Laboratory, School of Advanced Materials Science and
Engineering, Sungkyunkwan University, Suwon 16419, South Korea
| | - Marta Gonçalves
- Soft
Matter Physics Laboratory, School of Advanced Materials Science and
Engineering, Sungkyunkwan University, Suwon 16419, South Korea
- Research
Center for Advanced Materials Technology, Sungkyunkwan University, Suwon 16419, South Korea
| | - Byung Mook Weon
- Soft
Matter Physics Laboratory, School of Advanced Materials Science and
Engineering, Sungkyunkwan University, Suwon 16419, South Korea
- Research
Center for Advanced Materials Technology, Sungkyunkwan University, Suwon 16419, South Korea
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Peel JS, McNarry MA, Heffernan SM, Nevola VR, Kilduff LP, Coates K, Dudley E, Waldron M. The effect of 8-day oral taurine supplementation on thermoregulation during low-intensity exercise at fixed heat production in hot conditions of incremental humidity. Eur J Appl Physiol 2024:10.1007/s00421-024-05478-3. [PMID: 38582816 DOI: 10.1007/s00421-024-05478-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2023] [Accepted: 03/22/2024] [Indexed: 04/08/2024]
Abstract
PURPOSE To determine the effect of taurine supplementation on sweating and core temperature responses, including the transition from compensable to uncompensable heat stress, during prolonged low-intensity exercise of a fixed-heat production (~ 200W/m2) in hot conditions (37.5 °C), at both fixed and incremental vapour-pressure. METHODS Fifteen females (n = 3) and males (n = 12; 27 ± 5 years, 78 ± 9 kg, V ˙ O2max 50.3 ± 7.8 mL/kg/min), completed a treadmill walking protocol (~ 200W/m2 heat production [Ḣprod]) in the heat (37.5 ± 0.1 °C) at fixed-(16-mmHg) and ramped-humidity (∆1.5-mmHg/5-min) following 1 week of oral taurine supplementation (50 mg/kg/bm) or placebo, in a double-blind, randomised, cross-over design. Participants were assessed for whole-body sweat loss (WBSL), local sweat rate (LSR), sweat gland activation (SGA), core temperature (Tcore), breakpoint of compensability (Pcrit) and calorimetric heat transfer components. Plasma volume and plasma taurine concentrations were established through pre- and post-trial blood samples. RESULTS Taurine supplementation increased WBSL by 26.6% and 5.1% (p = 0.035), LSR by 15.5% and 7.8% (p = 0.013), SGA (1 × 1 cm) by 32.2% and 29.9% (p < 0.001) and SGA (3 × 3 cm) by 22.1% and 17.1% (p = 0.015) during the fixed- and ramped-humidity exercise periods, respectively. Evaporative heat loss was enhanced by 27% (p = 0.010), heat-storage reduced by 72% (p = 0.024) and Pcrit was greater in taurine vs placebo (25.0-mmHg vs 21.7-mmHg; p = 0.002). CONCLUSION Taurine supplementation increased sweating responses during fixed Ḣprod in hot conditions, prior to substantial heat strain and before the breakpoint of compensability, demonstrating improved thermoregulatory capacity. The enhanced evaporative cooling and reduced heat-storage delayed the subsequent upward inflection in Tcore-represented by a greater Pcrit-and offers a potential dietary supplementation strategy to support thermoregulation.
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Affiliation(s)
- Jennifer S Peel
- A-STEM Centre, Faculty of Science and Engineering, Swansea University, Swansea, UK.
| | - Melitta A McNarry
- A-STEM Centre, Faculty of Science and Engineering, Swansea University, Swansea, UK
| | - Shane M Heffernan
- A-STEM Centre, Faculty of Science and Engineering, Swansea University, Swansea, UK
| | - Venturino R Nevola
- A-STEM Centre, Faculty of Science and Engineering, Swansea University, Swansea, UK
- Defence Science and Technology Laboratory (Dstl), Fareham, Hampshire, UK
| | - Liam P Kilduff
- A-STEM Centre, Faculty of Science and Engineering, Swansea University, Swansea, UK
- Welsh Institute of Performance Science, Swansea University, Swansea, UK
| | - Kathryn Coates
- Swansea University Medical School, Faculty of Medicine, Health and Life Science, Swansea University, Swansea, UK
| | - Ed Dudley
- Swansea University Medical School, Faculty of Medicine, Health and Life Science, Swansea University, Swansea, UK
| | - Mark Waldron
- A-STEM Centre, Faculty of Science and Engineering, Swansea University, Swansea, UK
- Welsh Institute of Performance Science, Swansea University, Swansea, UK
- School of Health and Behavioural Sciences, University of the Sunshine Coast, Sippy Downs, QLD, Australia
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7
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Topham TH, Smallcombe JW, Brown HA, Clark B, Woodward AP, Telford RD, Jay O, Périard JD. Influence of Biological Sex and Fitness on Core Temperature Change and Sweating in Children Exercising in Warm Conditions. Med Sci Sports Exerc 2024; 56:697-705. [PMID: 38051094 DOI: 10.1249/mss.0000000000003347] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/07/2023]
Abstract
PURPOSE This study aimed to investigate the associations of biological sex and aerobic fitness (i.e., V̇O 2peak ) on the change in gastrointestinal temperature (∆ Tgi ) and whole-body sweat rate (WBSR) of children exercising in warm conditions. METHODS Thirty-eight children (17 boys, mean ± SD = 13.7 ± 1.2 yr; 21 girls, 13.6 ± 1.8 yr) walked for 45 min at a fixed rate of metabolic heat production (8 W·kg -1 ) in 30°C and 40% relative humidity. Biological sex and relative V̇O 2peak were entered as predictors into a Bayesian hierarchical generalized additive model for Tgi . For a subsample of 13 girls with measured body composition, body fat percent was entered into a separate hierarchical generalized additive model for Tgi . Sex, V̇O 2peak , and the evaporative requirement for heat balance ( Ereq ) were entered into a Bayesian hierarchical linear regression for WBSR. RESULTS The mean ∆ Tgi for boys was 0.71°C (90% credible interval = 0.60-0.82) and for girls 0.78°C (0.68-0.88). A predicted 20 mL·kg -1 ·min -1 higher V̇O 2peak resulted in a 0.19°C (-0.03 to 0.43) and 0.24°C (0.07-0.40) lower ∆ Tgi in boys and girls, respectively. A predicted ~13% lower body fat in the subsample of girls resulted in a 0.15°C (-0.12 to 0.45) lower ∆ Tgi . When Ereq was standardized to the grand mean, the difference in WBSR between boys and girls was -0.00 L·h -1 (-0.06 to 0.06), and a 20-mL·kg -1 ·min -1 higher predicted V̇O 2peak resulted in a mean difference in WBSR of -0.07 L·h -1 (-0.15 to 0.00). CONCLUSIONS Biological sex did not independently influence ∆ Tgi and WBSR in children. However, a higher predicted V̇O 2peak resulted in a lower ∆ Tgi of children, which was not associated with a greater WBSR, but may be related to differences in body fat percent between high and low fitness individuals.
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Affiliation(s)
- Thomas H Topham
- Research Institute for Sport and Exercise (UCRISE), University of Canberra, Bruce, ACT, AUSTRALIA
| | - James W Smallcombe
- The University of Sydney, Heat and Health Research Incubator, Faculty of Medicine and Health, Sydney, NSW, AUSTRALIA
| | - Harry A Brown
- Research Institute for Sport and Exercise (UCRISE), University of Canberra, Bruce, ACT, AUSTRALIA
| | - Brad Clark
- Research Institute for Sport and Exercise (UCRISE), University of Canberra, Bruce, ACT, AUSTRALIA
| | | | - Richard D Telford
- Research Institute for Sport and Exercise (UCRISE), University of Canberra, Bruce, ACT, AUSTRALIA
| | - Ollie Jay
- The University of Sydney, Heat and Health Research Incubator, Faculty of Medicine and Health, Sydney, NSW, AUSTRALIA
| | - Julien D Périard
- Research Institute for Sport and Exercise (UCRISE), University of Canberra, Bruce, ACT, AUSTRALIA
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8
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Taylor KM, Giersch GEW, Caldwell AR, Epstein Y, Charkoudian N. Relation of body surface area-to-mass ratio to risk of exertional heat stroke in healthy men and women. J Appl Physiol (1985) 2024; 136:549-554. [PMID: 38234291 PMCID: PMC11219003 DOI: 10.1152/japplphysiol.00597.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2023] [Revised: 12/15/2023] [Accepted: 01/09/2024] [Indexed: 01/19/2024] Open
Abstract
Risk of exertional heat stroke (EHS) is an ongoing challenge for United States military personnel, for athletes and for individuals with occupational stressors that involve prolonged activity in hot environments. Higher body mass index (BMI) is significantly associated with increased risk for EHS in activity duty U.S. Soldiers. During exercise, heat is generated primarily by contracting skeletal muscle (and other metabolically active body mass) and dissipated based on body surface area (BSA). Thus, in compensable environments, a higher BSA·mass-1 may be a benefit to heat dissipation and decrease the risk of EHS. The purpose of the present analysis was to test the hypothesis that BSA·mass-1 ratio is an important biophysical characteristic contributing to the risk of EHS. We employed a matched case-control approach, where each individual with a diagnosis of EHS was matched to five controls who were never diagnosed with EHS but were in the same unit and had the same job title. We used a multivariate conditional logistic regression model including variables of BSA·mass-1, sex, age, military rank, and race. BSA·mass-1 significantly predicted EHS risk (P = 0.006), such that people with higher BSA·mass-1 were at lower risk of developing EHS when controlling for other potential factors such as age and race. This relationship persisted after adjustment for other anthropometric measures of body size including weight, BMI, and BSA. These data suggest that biophysical factors play an important role in EHS risk, particularly in a healthy military-aged cohort of men and women.NEW & NOTEWORTHY With the impacts of climate change yielding higher average ambient temperatures over time, the incidence of EHS for individuals participating in outdoor activities may consequently increase. With the larger sample size in this study compared with prior research in this field, we were able to use various methods that had not been applied before. For example, we were able to mutually adjust for different measurements of body size to understand which metric had the highest association with EHS risk. Understanding factors that may be modifiable may be important for developing interventions to counteract the increased risk of EHS associated with climate change.
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Affiliation(s)
- Kathryn M Taylor
- Military Performance Division, U.S. Army Research Institute of Environmental Medicine, Natick, Massachusetts, United States
| | - Gabrielle E W Giersch
- Thermal and Mountain Medicine Division, U.S. Army Research Institute of Environmental Medicine, Natick, Massachusetts, United States
| | - Aaron R Caldwell
- Thermal and Mountain Medicine Division, U.S. Army Research Institute of Environmental Medicine, Natick, Massachusetts, United States
| | - Yoram Epstein
- School of Public Health, Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Nisha Charkoudian
- Thermal and Mountain Medicine Division, U.S. Army Research Institute of Environmental Medicine, Natick, Massachusetts, United States
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9
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Hendry E, McCallister B, Elman DJ, Freeman R, Borsook D, Elman I. Validity of mental and physical stress models. Neurosci Biobehav Rev 2024; 158:105566. [PMID: 38307304 PMCID: PMC11082879 DOI: 10.1016/j.neubiorev.2024.105566] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2023] [Revised: 01/13/2024] [Accepted: 01/27/2024] [Indexed: 02/04/2024]
Abstract
Different stress models are employed to enhance our understanding of the underlying mechanisms and explore potential interventions. However, the utility of these models remains a critical concern, as their validities may be limited by the complexity of stress processes. Literature review revealed that both mental and physical stress models possess reasonable construct and criterion validities, respectively reflected in psychometrically assessed stress ratings and in activation of the sympathoadrenal system and the hypothalamic-pituitary-adrenal axis. The findings are less robust, though, in the pharmacological perturbations' domain, including such agents as adenosine or dobutamine. Likewise, stress models' convergent- and discriminant validity vary depending on the stressors' nature. Stress models share similarities, but also have important differences regarding their validities. Specific traits defined by the nature of the stressor stimulus should be taken into consideration when selecting stress models. Doing so can personalize prevention and treatment of stress-related antecedents, its acute processing, and chronic sequelae. Further work is warranted to refine stress models' validity and customize them so they commensurate diverse populations and circumstances.
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Affiliation(s)
- Erin Hendry
- Center for Autonomic and Peripheral Nerve Disorders, Harvard Medical School, Boston, MA, USA; Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA
| | - Brady McCallister
- Center for Autonomic and Peripheral Nerve Disorders, Harvard Medical School, Boston, MA, USA
| | - Dan J Elman
- Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA
| | - Roy Freeman
- Center for Autonomic and Peripheral Nerve Disorders, Harvard Medical School, Boston, MA, USA; Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA
| | - David Borsook
- Departments of Psychiatry and Radiology, Massachusetts General Hospital, Harvard Medical School, Department of Anesthesiology, Harvard Medical School, Boston, MA, USA.
| | - Igor Elman
- Department of Psychiatry, Cambridge Health Alliance, Harvard Medical School, Cambridge, MA, USA
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10
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Giannaros C, Agathangelidis I, Galanaki E, Cartalis C, Kotroni V, Lagouvardos K, Giannaros TM, Matzarakis A. Hourly values of an advanced human-biometeorological index for diverse populations from 1991 to 2020 in Greece. Sci Data 2024; 11:76. [PMID: 38228665 PMCID: PMC10791640 DOI: 10.1038/s41597-024-02923-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2023] [Accepted: 01/05/2024] [Indexed: 01/18/2024] Open
Abstract
Existing assessments of the thermal-related impact of the environment on humans are often limited by the use of data that are not representative of the population exposure and/or not consider a human centred approach. Here, we combine high resolution regional retrospective analysis (reanalysis), population data and human energy balance modelling, in order to produce a human thermal bioclimate dataset capable of addressing the above limitations. The dataset consists of hourly, population-weighted values of an advanced human-biometeorological index, namely the modified physiologically equivalent temperature (mPET), at fine-scale administrative level and for 10 different population groups. It also includes the main environmental drivers of mPET at the same spatiotemporal resolution, covering the period from 1991 to 2020. The study area is Greece, but the provided code allows for the ease replication of the dataset in countries included in the domains of the climate reanalysis and population data, which focus over Europe. Thus, the presented data and code can be exploited for human-biometeorological and environmental epidemiological studies in the European continent.
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Affiliation(s)
- Christos Giannaros
- National and Kapodistrian University of Athens, Department of Physics, 15784, Athens, Greece.
| | - Ilias Agathangelidis
- National and Kapodistrian University of Athens, Department of Physics, 15784, Athens, Greece
| | - Elissavet Galanaki
- National Observatory of Athens, Institute for Environmental Research and Sustainable Development, Palea Penteli, 15236, Athens, Greece
| | - Constantinos Cartalis
- National and Kapodistrian University of Athens, Department of Physics, 15784, Athens, Greece
| | - Vassiliki Kotroni
- National Observatory of Athens, Institute for Environmental Research and Sustainable Development, Palea Penteli, 15236, Athens, Greece
| | - Konstantinos Lagouvardos
- National Observatory of Athens, Institute for Environmental Research and Sustainable Development, Palea Penteli, 15236, Athens, Greece
| | - Theodore M Giannaros
- National Observatory of Athens, Institute for Environmental Research and Sustainable Development, Palea Penteli, 15236, Athens, Greece
| | - Andreas Matzarakis
- German Meteorological Service (DWD), Research Centre Human Biometeorology, D-79085, Freiburg, Germany
- University of Freiburg, Institute of Earth and Environmental Sciences, D-79104, Freiburg, Germany
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11
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Wallace PJ, Hartley GL, Nowlan JG, Ljubanovich J, Sieh N, Taber MJ, Gagnon DD, Cheung SS. Endurance capacity impairment in cold air ranging from skin cooling to mild hypothermia. J Appl Physiol (1985) 2024; 136:58-69. [PMID: 37942528 DOI: 10.1152/japplphysiol.00663.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2023] [Revised: 10/20/2023] [Accepted: 11/06/2023] [Indexed: 11/10/2023] Open
Abstract
We tested the effects of cold air (0°C) exposure on endurance capacity to different levels of cold strain ranging from skin cooling to core cooling of Δ-1.0°C. Ten males completed a randomized, crossover, control study consisting of a cycling time to exhaustion (TTE) at 70% of their peak power output following: 1) 30-min of exposure to 22°C thermoneutral air (TN), 2) 30-min exposure to 0°C air leading to a cold shell (CS), 3) 0°C air exposure causing mild hypothermia of -0.5°C from baseline rectal temperature (HYPO-0.5°C), and 4) 0°C air exposure causing mild hypothermia of -1.0°C from baseline rectal temperature (HYPO-1.0°C). The latter three conditions tested TTE in 0°C air. Core temperature and seven-site mean skin temperature at the start of the TTE were: TN (37.0 ± 0.2°C, 31.2 ± 0.8°C), CS (37.1 ± 0.3°C, 25.5 ± 1.4°C), HYPO-0.5°C (36.6 ± 0.4°C, 22.3 ± 2.2°C), HYPO-1.0°C (36.4 ± 0.5°C, 21.4 ± 2.7°C). There was a significant condition effect (P ≤ 0.001) for TTE, which from TN (23.75 ± 13.75 min) to CS (16.22 ± 10.30 min, Δ-30.9 ± 21.5%, P = 0.055), HYPO-0.5°C (8.50 ± 5.23 min, Δ-61.4 ± 19.7%, P ≤ 0.001), and HYPO-1.0°C (6.50 ± 5.60 min, Δ-71.6 ± 16.4%, P ≤ 0.001). Furthermore, participants had a greater endurance capacity in CS compared with HYPO-0.5°C (P = 0.046), and HYPO-1.0°C (P = 0.007), with no differences between HYPO-0.5°C and HYPO-1.0°C (P = 1.00). Endurance capacity impairment at 70% peak power output occurs early in cold exposure with skin cooling, with significantly larger impairments with mild hypothermia up to Δ-1.0°C.NEW & NOTEWORTHY We developed a novel protocol that cooled skin temperature, or skin plus core temperature (Δ-0.5°C or Δ-1.0 °C), to determine a dose-response of cold exposure on endurance capacity at 70% peak power output. Skin cooling significantly impaired exercise tolerance time by ∼31%, whereas core cooling led to a further reduction of 30%-40% with no difference between Δ-0.5°C and Δ-1.0°C. Overall, simply cooling the skin impaired endurance capacity, but this impairment is further magnified by core cooling.
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Affiliation(s)
- Phillip J Wallace
- Environmental Ergonomics Laboratory, Department of Kinesiology, Brock University, St. Catharines, Ontario, Canada
| | - Geoffrey L Hartley
- Department of Physical and Health Education, Nipissing University, North Bay, Ontario, Canada
| | - Josh G Nowlan
- Environmental Ergonomics Laboratory, Department of Kinesiology, Brock University, St. Catharines, Ontario, Canada
| | - Johnathan Ljubanovich
- Environmental Ergonomics Laboratory, Department of Kinesiology, Brock University, St. Catharines, Ontario, Canada
| | - Nina Sieh
- Environmental Ergonomics Laboratory, Department of Kinesiology, Brock University, St. Catharines, Ontario, Canada
| | - Michael J Taber
- Environmental Ergonomics Laboratory, Department of Kinesiology, Brock University, St. Catharines, Ontario, Canada
- N2M Consulting Inc., St. Catharines, Ontario, Canada
| | - Dominique D Gagnon
- School of Kinesiology and Health Sciences, Laurentian University, Sudbury, Ontario, Canada
- Faculty of Sports and Health Sciences, University of Jyväskylä, Jyväskylä, Finland
- Clinic for Sports and Exercise Medicine, Department of Sports and Exercise Medicine, Faculty of Medicine, University of Helsinki Mäkelänkatu, Helsinki, Finland
| | - Stephen S Cheung
- Environmental Ergonomics Laboratory, Department of Kinesiology, Brock University, St. Catharines, Ontario, Canada
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12
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Renaghan E, Wittels HL, Feigenbaum LA, Wishon MJ, Chong S, Wittels ED, Hendricks S, Hecocks D, Bellamy K, Girardi J, Lee S, Vo T, McDonald SM, Wittels SH. Exposures to Elevated Core Temperatures during Football Training: The Impact on Autonomic Nervous System Recovery and Function. Sports (Basel) 2023; 12:8. [PMID: 38251282 PMCID: PMC10819443 DOI: 10.3390/sports12010008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2023] [Revised: 12/14/2023] [Accepted: 12/20/2023] [Indexed: 01/23/2024] Open
Abstract
Exercising with elevated core temperatures may negatively affect autonomic nervous system (ANS) function. Additionally, longer training duration under higher core temperatures may augment these negative effects. This study evaluated the relationship between exercise training duration and 24 h ANS recovery and function at ≥37 °C, ≥38 °C and ≥39 °C core temperature thresholds in a sample of male Division I (D1) collegiate American football athletes. Fifty athletes were followed over their 25-week season. Using armband monitors (Warfighter MonitorTM, Tiger Tech Solutions, Inc., Miami, FL, USA), core temperature (°C) and 24 h post-exercise baseline heart rate (HR), HR recovery and heart rate variability (HRV) were measured. For HRV, two time-domain indices were measured: the root mean square of the standard deviation of the NN interval (rMSSD) and the standard deviation of the NN interval (SDNN). Linear regression models were performed to evaluate the associations between exercise training duration and ANS recovery (baseline HR and HRV) and function (HR recovery) at ≥37 °C, ≥38 °C and ≥39 °C core temperature thresholds. On average, the athletes were 21.3 (± 1.4) years old, weighed 103.0 (±20.2) kg and had a body fat percentage of 15.4% (±7.8%, 3.0% to 36.0%). The duration of training sessions was, on average, 161.1 (±40.6) min and they ranged from 90.1 to 339.6 min. Statistically significant associations between training duration and 24 h ANS recovery and function were observed at both the ≥38.0 °C (baseline HR: β = 0.10 ± 0.02, R2 = 0.26, p < 0.0000; HR recovery: β = -0.06 ± 0.02, R2 = 0.21, p = 0.0002; rMSSD: β = -0.11 ± 0.02, R2 = 0.24, p < 0.0000; and SDNN: β = -0.16 ± 0.04, R2 = 0.22, p < 0.0000) and ≥39.0 °C thresholds (β = 0.39 ± 0.05, R2 = 0.62, p < 0.0000; HR recovery: β = -0.26 ± 0.04, R2 = 0.52, p < 0.0000; rMSSD: β = -0.37 ± 0.05, R2 = 0.58, p < 0.0000; and SDNN: β = -0.67 ± 0.09, R2 = 0.59, p < 0.0000). With increasing core temperatures, increases in slope steepness and strengths of the associations were observed, indicating accelerated ANS deterioration. These findings demonstrate that exercise training under elevated core temperatures (≥38 °C) may negatively influence ANS recovery and function 24 h post exercise and progressively worsen.
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Affiliation(s)
- Eric Renaghan
- Department of Athletics, Sports Science, University of Miami, Miami, FL 33146, USA; (E.R.); (L.A.F.)
| | - Harrison L. Wittels
- Tiger Tech Solutions, Inc., Miami, FL 33156, USA; (H.L.W.); (M.J.W.); (S.C.); (E.D.W.); (S.H.); (D.H.); (S.H.W.)
| | - Luis A. Feigenbaum
- Department of Athletics, Sports Science, University of Miami, Miami, FL 33146, USA; (E.R.); (L.A.F.)
- Department of Physical Therapy, Miller School of Medicine, University of Miami, Miami, FL 33146, USA;
| | - Michael J. Wishon
- Tiger Tech Solutions, Inc., Miami, FL 33156, USA; (H.L.W.); (M.J.W.); (S.C.); (E.D.W.); (S.H.); (D.H.); (S.H.W.)
| | - Stephanie Chong
- Tiger Tech Solutions, Inc., Miami, FL 33156, USA; (H.L.W.); (M.J.W.); (S.C.); (E.D.W.); (S.H.); (D.H.); (S.H.W.)
| | - Eva D. Wittels
- Tiger Tech Solutions, Inc., Miami, FL 33156, USA; (H.L.W.); (M.J.W.); (S.C.); (E.D.W.); (S.H.); (D.H.); (S.H.W.)
| | - Stephanie Hendricks
- Tiger Tech Solutions, Inc., Miami, FL 33156, USA; (H.L.W.); (M.J.W.); (S.C.); (E.D.W.); (S.H.); (D.H.); (S.H.W.)
| | - Dustin Hecocks
- Tiger Tech Solutions, Inc., Miami, FL 33156, USA; (H.L.W.); (M.J.W.); (S.C.); (E.D.W.); (S.H.); (D.H.); (S.H.W.)
| | - Kyle Bellamy
- Department of Athletics, Nutrition, University of Miami, Miami, FL 33146, USA;
| | - Joe Girardi
- Department of Physical Therapy, Miller School of Medicine, University of Miami, Miami, FL 33146, USA;
| | - Stephen Lee
- United States Army Research Laboratory, Adelphi, MD 20783, USA;
| | - Tri Vo
- Navy Medical Center—San Diego, San Diego, CA 92134, USA;
| | - Samantha M. McDonald
- Tiger Tech Solutions, Inc., Miami, FL 33156, USA; (H.L.W.); (M.J.W.); (S.C.); (E.D.W.); (S.H.); (D.H.); (S.H.W.)
- School of Kinesiology and Recreation, Illinois State University, Normal, IL 61761, USA
| | - S. Howard Wittels
- Tiger Tech Solutions, Inc., Miami, FL 33156, USA; (H.L.W.); (M.J.W.); (S.C.); (E.D.W.); (S.H.); (D.H.); (S.H.W.)
- Department of Anesthesiology, Mount Sinai Medical Center, Miami, FL 33140, USA
- Department of Anesthesiology, Wertheim School of Medicine, Florida International University, Miami, FL 33199, USA
- Miami Beach Anesthesiology Associates, Miami, FL 33140, USA
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13
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Vanos J, Guzman-Echavarria G, Baldwin JW, Bongers C, Ebi KL, Jay O. A physiological approach for assessing human survivability and liveability to heat in a changing climate. Nat Commun 2023; 14:7653. [PMID: 38030628 PMCID: PMC10687011 DOI: 10.1038/s41467-023-43121-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2023] [Accepted: 11/01/2023] [Indexed: 12/01/2023] Open
Abstract
Most studies projecting human survivability limits to extreme heat with climate change use a 35 °C wet-bulb temperature (Tw) threshold without integrating variations in human physiology. This study applies physiological and biophysical principles for young and older adults, in sun or shade, to improve current estimates of survivability and introduce liveability (maximum safe, sustained activity) under current and future climates. Our physiology-based survival limits show a vast underestimation of risks by the 35 °C Tw model in hot-dry conditions. Updated survivability limits correspond to Tw~25.8-34.1 °C (young) and ~21.9-33.7 °C (old)-0.9-13.1 °C lower than Tw = 35 °C. For older female adults, estimates are ~7.2-13.1 °C lower than 35 °C in dry conditions. Liveability declines with sun exposure and humidity, yet most dramatically with age (2.5-3.0 METs lower for older adults). Reductions in safe activity for younger and older adults between the present and future indicate a stronger impact from aging than warming.
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Affiliation(s)
- Jennifer Vanos
- School of Sustainability, Arizona State University, Tempe, AZ, USA.
| | - Gisel Guzman-Echavarria
- School of Geographical Sciences and Urban Planning, Arizona State University, Tempe, AZ, USA
| | - Jane W Baldwin
- Department of Earth System Science, University of California Irvine, Irvine, CA, USA
- Lamont-Doherty Earth Observatory, Palisades, NY, USA
| | - Coen Bongers
- Department of Medical Sciences, Radboud university medical center, Nijmegen, The Netherlands
- Heat and Health Research Incubator, University of Sydney, Sydney, NSW, Australia
| | - Kristie L Ebi
- Center for Health and the Global Environment, University of Washington, Seattle, WA, USA
| | - Ollie Jay
- Heat and Health Research Incubator, University of Sydney, Sydney, NSW, Australia
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14
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Ogden HB, Rawcliffe AJ, Delves SK, Roberts A. Are young military personnel at a disproportional risk of heat illness? BMJ Mil Health 2023; 169:559-564. [PMID: 35241622 PMCID: PMC10715519 DOI: 10.1136/bmjmilitary-2021-002053] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2021] [Accepted: 01/08/2022] [Indexed: 11/04/2022]
Abstract
Heat illnesses (HI) define a continuum of conditions where patients become incapacitated due to uncompensable heat stress. In the military, HI has a significant health, financial and operational burden that requires vigilant management. Military training and operations regularly expose personnel to known HI risk factors, meaning that prevalence remains high despite stringent attempts to reduce risk to as low as reasonably practicable. While prepubertal children and elderly adults are widely demonstrated to be at greater risk of classic HI than young adults due to impaired physiological and/or behavioural thermoregulation, in military personnel, it is young recruit-age individuals (16-19 years) who consistently experience the highest prevalence of exertional HI. Mechanistically, controlled laboratory studies have never directly compared thermoregulation between young recruit-age individuals and other groups of adults, though research highlighting impaired thermoregulation in prepubertal children potentially has some relevance to late-developing young recruit-age personnel. Aside from potential age-related differences in thermoregulation, a major consideration must also be given to the increased prevalence of organisational risk factors for HI in younger military personnel (eg, education, physical load, rank, job roles), which is likely to be the primary explanation behind age-related trends in HI prevalence, at least in the military. The aims of this article are to review: (i) the epidemiology of HI between young recruit-age individuals and older military personnel; (ii) the theoretical basis for age-associated differences in thermoregulatory function and (iii) pertinent areas for future research.
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Affiliation(s)
- Henry B Ogden
- Army Recruit Health and Performance Research, UK Ministry of Defence, Upavon, Wiltshire, UK
| | - A J Rawcliffe
- Army Recruit Health and Performance Research, UK Ministry of Defence, Upavon, Wiltshire, UK
| | - S K Delves
- Environmental Medicine and Science, Institute of Naval Medicine, Gosport, UK
| | - A Roberts
- Army Recruit Health and Performance Research, UK Ministry of Defence, Upavon, Wiltshire, UK
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15
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Rivas E, Foster J, Crandall CG, Finnerty CC, Suman-Vejas OE. Key Exercise Concepts in the Rehabilitation from Severe Burns. Phys Med Rehabil Clin N Am 2023; 34:811-824. [PMID: 37806699 PMCID: PMC10731385 DOI: 10.1016/j.pmr.2023.05.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/10/2023]
Abstract
This article presents information on the benefits of exercise in counteracting the detrimental effects of bed rest, and/or severe burns. Exercise is key for maintaining physical function, lean body mass, metabolic recovery, and psychosocial health after major burn injuries. The details of an exercise training program conducted in severely burned persons are presented, as well as information on the importance of proper regulation of body temperature during exercise or physical activity. The sections on exercise and thermoregulation are followed by a section on the role of exercise in scarring and contractures. Finally, gaps in the current knowledge of exercise, thermoregulation, and contractures are presented.
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Affiliation(s)
- Eric Rivas
- Microgravity Research, In-Space Solutions, Axiom Space Headquarters, 1290 Hercules Avenue, Houston, TX 77058, USA
| | - Josh Foster
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Institute for Exercise and Environmental Medicine (IEEM), Texas Health Presbyterian Hospital Dallas, 5323 Harry Hines Boulevard, Dallas, TX 75390, USA
| | - Craig G Crandall
- Division of Cardiology, Department of Internal Medicine, University of Texas Southwestern Medical Center, Institute for Exercise and Environmental Medicine (IEEM), Texas Health Presbyterian Hospital Dallas, 7232 Greenville Avenue, Suite 435, Dallas, TX 75231, USA
| | - Celeste C Finnerty
- Department of Surgery, Division of Surgical Sciences, University of Texas Medical Branch, 301 University Boulevard, Galveston, TX 77555-1220, USA
| | - Oscar E Suman-Vejas
- Department of Surgery, Division of Surgical Sciences, University of Texas Medical Branch, 301 University Boulevard, Galveston, TX 77555-1220, USA.
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16
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Vecellio DJ, Kong Q, Kenney WL, Huber M. Greatly enhanced risk to humans as a consequence of empirically determined lower moist heat stress tolerance. Proc Natl Acad Sci U S A 2023; 120:e2305427120. [PMID: 37812703 PMCID: PMC10589700 DOI: 10.1073/pnas.2305427120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2023] [Accepted: 08/15/2023] [Indexed: 10/11/2023] Open
Abstract
As heatwaves become more frequent, intense, and longer-lasting due to climate change, the question of breaching thermal limits becomes pressing. A wet-bulb temperature (Tw) of 35 °C has been proposed as a theoretical upper limit on human abilities to biologically thermoregulate. But, recent-empirical-research using human subjects found a significantly lower maximum Tw at which thermoregulation is possible even with minimal metabolic activity. Projecting future exposure to this empirical critical environmental limit has not been done. Here, using this more accurate threshold and the latest coupled climate model results, we quantify exposure to dangerous, potentially lethal heat for future climates at various global warming levels. We find that humanity is more vulnerable to moist heat stress than previously proposed because of these lower thermal limits. Still, limiting warming to under 2 °C nearly eliminates exposure and risk of widespread uncompensable moist heatwaves as a sharp rise in exposure occurs at 3 °C of warming. Parts of the Middle East and the Indus River Valley experience brief exceedances with only 1.5 °C warming. More widespread, but brief, dangerous heat stress occurs in a +2 °C climate, including in eastern China and sub-Saharan Africa, while the US Midwest emerges as a moist heat stress hotspot in a +3 °C climate. In the future, moist heat extremes will lie outside the bounds of past human experience and beyond current heat mitigation strategies for billions of people. While some physiological adaptation from the thresholds described here is possible, additional behavioral, cultural, and technical adaptation will be required to maintain healthy lifestyles.
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Affiliation(s)
- Daniel J. Vecellio
- Center for Healthy Aging, Pennsylvania State University, University Park, PA16802
| | - Qinqin Kong
- Earth, Atmospheric, and Planetary Sciences Department and the Institute for a Sustainable Future, Purdue University, West Lafayette, IN47907
| | - W. Larry Kenney
- Center for Healthy Aging, Pennsylvania State University, University Park, PA16802
- Department of Kinesiology, Pennsylvania State University, University Park, PA16802
- Graduate Program in Physiology, Pennsylvania State University, University Park, PA16802
| | - Matthew Huber
- Earth, Atmospheric, and Planetary Sciences Department and the Institute for a Sustainable Future, Purdue University, West Lafayette, IN47907
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17
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Niclou A, Sarma M, Levy S, Ocobock C. To the extreme! How biological anthropology can inform exercise physiology in extreme environments. Comp Biochem Physiol A Mol Integr Physiol 2023; 284:111476. [PMID: 37423419 DOI: 10.1016/j.cbpa.2023.111476] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2023] [Revised: 07/03/2023] [Accepted: 07/04/2023] [Indexed: 07/11/2023]
Abstract
The fields of biological anthropology and exercise physiology are closely related and can provide mutually beneficial insights into human performance. These fields often use similar methods and are both interested in how humans function, perform, and respond in extreme environments. However, these two fields have different perspectives, ask different questions, and work within different theoretical frameworks and timescales. Biological anthropologists and exercise physiologists can greatly benefit from working together when examining human adaptation, acclimatization, and athletic performance in the extremes of heat, cold, and high-altitude. Here we review the adaptations and acclimatizations in these three different extreme environments. We then examine how this work has informed and built upon exercise physiology research on human performance. Finally, we present an agenda for moving forward, hopefully, with these two fields working more closely together to produce innovative research that improves our holistic understanding of human performance capacities informed by evolutionary theory, modern human acclimatization, and the desire to produce immediate and direct benefits.
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Affiliation(s)
- Alexandra Niclou
- Pennington Biomedical Research Center, Baton Rouge, LA, United States of America. https://twitter.com/fiat_luxandra
| | - Mallika Sarma
- Human Space Flight Lab, Johns Hopkins School of Medicine, Baltimore, MD, United States of America. https://twitter.com/skyy_mal
| | - Stephanie Levy
- Department of Anthropology, CUNY Hunter College, New York, NY, United States of America; New York Consortium in Evolutionary Primatology, New York, NY, United States of America. https://twitter.com/slevyscience
| | - Cara Ocobock
- University of Notre Dame Department of Anthropology, Notre Dame, IN, United States of America; Eck Institute for Global Health, Institute for Educational Initiatives, University of Notre Dame, United States of America.
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18
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Wang J, Jiang C, Yang G, Bai G, Yu S. Study on thermal health and its safety management mode for the working environment. Front Public Health 2023; 11:1227630. [PMID: 37670839 PMCID: PMC10475595 DOI: 10.3389/fpubh.2023.1227630] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2023] [Accepted: 07/31/2023] [Indexed: 09/07/2023] Open
Abstract
Thermal health concerns have gained significant attention due to the heightened health risks faced by workers who are exposed to extreme thermal environments for prolonged periods. To ensure the occupational health and safety of such workers, and to enhance work efficiency, it is imperative to examine the characteristics of thermal health in the working environment. This study proposes three key elements of thermal health in the working environment, namely thermal health states, absence of heat-related illnesses, and heat adaptability, which can be used to develop a safety management framework for thermal health. By exploring the interconnections between these elements, the study summarizes their features and outlines the necessary precautions to safeguard them. The PDCA (plan/do/check/action) cycle management mode is utilized as a framework, with the three components of thermal health forming the core, to establish a safety management mode for thermal health. To ensure that employees work in a safe, healthy, comfortable, and productive environment, the assessment and control objectives of the thermal environment are regularly revised through the use of labor protection technology and thermal environment control technology. This paper presents a PDCA cycle safety management mode based on the characteristics of thermal health, which offers novel insights and approaches for assessing and managing workers' thermal health.
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Affiliation(s)
- Jue Wang
- Key Laboratory of Mine Thermodynamic Disasters and Control of Ministry of Education, Liaoning Technical University, Fuxin, Liaoning, China
- School of Safety Science and Engineering, Liaoning Technical University, Fuxin, Liaoning, China
- School of Civil Engineering, Liaoning Technical University, Fuxin, Liaoning, China
| | - Cheng Jiang
- School of Civil Engineering, Liaoning Technical University, Fuxin, Liaoning, China
| | - Guang Yang
- School of Civil Engineering, Liaoning Technical University, Fuxin, Liaoning, China
| | - Gang Bai
- Key Laboratory of Mine Thermodynamic Disasters and Control of Ministry of Education, Liaoning Technical University, Fuxin, Liaoning, China
- School of Safety Science and Engineering, Liaoning Technical University, Fuxin, Liaoning, China
| | - Shixuan Yu
- School of Civil Engineering, Liaoning Technical University, Fuxin, Liaoning, China
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19
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Willingham BD, Rentería LI, Ragland TJ, Ormsbee MJ. The effects of betaine supplementation on fluid balance and heat tolerance during passive heat stress in men. Physiol Rep 2023; 11:e15792. [PMID: 37604644 PMCID: PMC10442523 DOI: 10.14814/phy2.15792] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2023] [Revised: 08/01/2023] [Accepted: 08/01/2023] [Indexed: 08/23/2023] Open
Abstract
INTRODUCTION Consuming intracellular osmolytes, like betaine (BET), may attenuate symptoms of heat stress. The purpose of this study was to examine the effects of BET supplementation on fluid balance and heat tolerance after a 7-day loading period and during passive heat exposure. METHODS A double-blind, placebo controlled, crossover study compared BET or placebo consumption (50 mg·kg-1 , twice daily) for 7 days in young, recreationally active men (N = 11). RESULTS During the loading period, no significant interactions were found for any marker of fluid balance between or within conditions. During heat exposure, significant time effects but no condition x time interactions, were found for plasma characteristics (i.e., volume, osmolality, sodium, albumin, and total protein). Plasma volume was significantly increased by min 30 in both conditions (PLA: +6.9. ± 5.0%, BET: +10.2 ± 7.4%) and remained elevated for the remainder of the experimental trial, but was not significantly different between conditions. After 60 min of passive heat exposure, both conditions experienced a similar increase in core temperature (PLA: +0.32 ± 0.22°C, BET: +0.31 ± 0.21°C; p = 0.912). CONCLUSIONS Supplemental BET did not improve markers of fluid balance or heat tolerance during 7 days of loading or during passive heat exposure.
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Affiliation(s)
- Brandon D. Willingham
- Department of KinesiologyCoastal Carolina UniversityConwaySouth CarolinaUSA
- Institute of Sports Sciences & Medicine, Nutrition, and Integrative PhysiologyFlorida State UniversityFloridaUSA
| | - Liliana I. Rentería
- Institute of Sports Sciences & Medicine, Nutrition, and Integrative PhysiologyFlorida State UniversityFloridaUSA
| | - Tristan J. Ragland
- Institute of Sports Sciences & Medicine, Nutrition, and Integrative PhysiologyFlorida State UniversityFloridaUSA
- Department of Kinesiology and HealthRutgers UniversityNew BrunswickNew JerseyUSA
| | - Michael J. Ormsbee
- Institute of Sports Sciences & Medicine, Nutrition, and Integrative PhysiologyFlorida State UniversityFloridaUSA
- Discipline of Biokinetics, Exercise, and Leisure SciencesUniversity of KwaZulu‐NatalDurbanSouth Africa
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20
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Hillen B, Andrés López D, Marzano-Felisatti JM, Sanchez-Jimenez JL, Cibrián Ortiz de Anda RM, Nägele M, Salvador-Palmer MR, Pérez-Soriano P, Schömer E, Simon P, Priego-Quesada JI. Acute physiological responses to a pyramidal exercise protocol and the associations with skin temperature variation in different body areas. J Therm Biol 2023; 115:103605. [PMID: 37329763 DOI: 10.1016/j.jtherbio.2023.103605] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2023] [Revised: 05/08/2023] [Accepted: 05/27/2023] [Indexed: 06/19/2023]
Abstract
This study aimed to examine the skin temperature (Tsk) variations in five regions of interest (ROI) to assess whether possible disparities between the ROI's Tsk could be associated with specific acute physiological responses during cycling. Seventeen participants performed a pyramidal load protocol on a cycling ergometer. We synchronously measured Tsk in five ROI with three infrared cameras. We assessed internal load, sweat rate, and core temperature. Reported perceived exertion and calves' Tsk showed the highest correlation (r = -0.588; p < 0.01). Mixed regression models revealed that the heart rate and reported perceived exertion were inversely related to calves' Tsk. The exercise duration was directly associated with the nose tip and calf Tsk but inversely related to the forehead and forearm Tsk. The sweat rate was directly related to forehead and forearm Tsk. The association of Tsk with thermoregulatory or exercise load parameters depends on the ROI. The parallel observation of the face and calf Tsk could indicate simultaneously the observation of acute thermoregulatory needs and individual internal load. The separate Tsk analyses of individual ROI appear more suitable to examine specific physiological response than a mean Tsk of several ROI during cycling.
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Affiliation(s)
- Barlo Hillen
- Department of Sports Medicine, Disease Prevention and Rehabilitation, Institute of Sports Science, Johannes Gutenberg University of Mainz, Germany.
| | - Daniel Andrés López
- Research Group of Computational Geometry, Institute of Computer Science, Johannes Gutenberg University of Mainz, Germany
| | - Joaquín Martín Marzano-Felisatti
- Department of Physical Education and Sports, Faculty of Physical Activity and Sports Sciences, GIBD (Research Group in Sports Biomechanics), University of Valencia, Spain
| | - José Luis Sanchez-Jimenez
- Department of Physical Education and Sports, Faculty of Physical Activity and Sports Sciences, GIBD (Research Group in Sports Biomechanics), University of Valencia, Spain
| | - Rosa Maria Cibrián Ortiz de Anda
- Department of Physiology. Faculty of Medicine and Odontology, GIFIME (Biophysics and Medical Physics Group), University of Valencia, Spain
| | | | - Maria Rosario Salvador-Palmer
- Department of Physiology. Faculty of Medicine and Odontology, GIFIME (Biophysics and Medical Physics Group), University of Valencia, Spain
| | - Pedro Pérez-Soriano
- Department of Physical Education and Sports, Faculty of Physical Activity and Sports Sciences, GIBD (Research Group in Sports Biomechanics), University of Valencia, Spain
| | - Elmar Schömer
- Research Group of Computational Geometry, Institute of Computer Science, Johannes Gutenberg University of Mainz, Germany
| | - Perikles Simon
- Department of Sports Medicine, Disease Prevention and Rehabilitation, Institute of Sports Science, Johannes Gutenberg University of Mainz, Germany
| | - Jose Ignacio Priego-Quesada
- Department of Physical Education and Sports, Faculty of Physical Activity and Sports Sciences, GIBD (Research Group in Sports Biomechanics), University of Valencia, Spain; Department of Physiology. Faculty of Medicine and Odontology, GIFIME (Biophysics and Medical Physics Group), University of Valencia, Spain.
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21
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Yüzen D, Graf I, Tallarek AC, Hollwitz B, Wiessner C, Schleussner E, Stammer D, Padula A, Hecher K, Arck PC, Diemert A. Increased late preterm birth risk and altered uterine blood flow upon exposure to heat stress. EBioMedicine 2023:104651. [PMID: 37355458 PMCID: PMC10363435 DOI: 10.1016/j.ebiom.2023.104651] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2023] [Revised: 05/26/2023] [Accepted: 05/30/2023] [Indexed: 06/26/2023] Open
Abstract
BACKGROUND Climate change, in particular the exposure to heat, impacts on human health and can trigger diseases. Pregnant people are considered a vulnerable group given the physiological changes during pregnancy and the potentially long-lasting consequences for the offspring. Evidence published to date on higher risk of pregnancy complications upon heat stress exposure are from geographical areas with high ambient temperatures. Studies from geographic regions with temperate climates are sparse; however, these areas are critical since individuals may be less equipped to adapt to heat stress. This study addresses a significant gap in knowledge due to the temperature increase documented globally. METHODS Birth data of singleton pregnancies (n = 42,905) from a tertiary care centre in Hamburg, Germany, between 1999 and 2021 were retrospectively obtained and matched with climate data from the warmer season (March to September) provided by the adjacent federal meteorological station of the German National Meteorological Service to calculate the relative risk of heat-associated preterm birth. Heat events were defined by ascending temperature percentiles in combination with humidity over exposure periods of up to 5 days. Further, ultrasound data documented in a longitudinal prospective pregnancy cohort study (n = 612) since 2012 were used to identify pathophysiological causes of heat-induced preterm birth. FINDINGS Both extreme heat and prolonged periods of heat exposure increased the relative risk of preterm birth (RR: 1.59; 95% CI: 1.01-2.43; p = 0.045; RR: 1.20; 95% CI: 1.02-1.40; p = 0.025). We identified a critical period of heat exposure during gestational ages 34-37 weeks that resulted in increased risk of late preterm birth (RR: 1.67; 95% CI: 1.14-1.43; p = 0.009). Pregnancies with a female fetus were more prone to heat stress-associated preterm birth. We found heat exposure was associated with altered vascular resistance within the uterine artery. INTERPRETATION Heat stress caused by high ambient temperatures increases the risk of preterm birth in a geographical region with temperate climate. Prenatal routine care should be revised in such regions to provide active surveillance for women at risk. FUNDING Found in acknowledgements.
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Affiliation(s)
- Dennis Yüzen
- Department of Obstetrics and Fetal Medicine, Laboratory for Experimental Feto-Maternal Medicine, University Medical Centre of Hamburg-Eppendorf, Germany; Institute of Immunology, University Medical Centre of Hamburg-Eppendorf, Germany
| | - Isabel Graf
- Department of Obstetrics and Fetal Medicine, Laboratory for Experimental Feto-Maternal Medicine, University Medical Centre of Hamburg-Eppendorf, Germany
| | - Ann-Christin Tallarek
- Department of Obstetrics and Fetal Medicine, University Medical Centre of Hamburg-Eppendorf, Germany
| | - Bettina Hollwitz
- Department of Obstetrics and Fetal Medicine, University Medical Centre of Hamburg-Eppendorf, Germany
| | - Christian Wiessner
- Institute of Medical Biometry and Epidemiology, University Medical Centre of Hamburg-Eppendorf, Germany
| | | | - Detlef Stammer
- Centre for Earth System Research and Sustainability (CEN), University Hamburg, Germany
| | - Amy Padula
- Division of Maternal-Fetal Medicine, Department of Obstetrics, University of California, San Francisco, USA
| | - Kurt Hecher
- Department of Obstetrics and Fetal Medicine, University Medical Centre of Hamburg-Eppendorf, Germany
| | - Petra Clara Arck
- Department of Obstetrics and Fetal Medicine, Laboratory for Experimental Feto-Maternal Medicine, University Medical Centre of Hamburg-Eppendorf, Germany.
| | - Anke Diemert
- Department of Obstetrics and Fetal Medicine, University Medical Centre of Hamburg-Eppendorf, Germany
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22
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de Korte JQ, Eijsvogels TMH, Hopman MTE, Bongers CCWG. Thermoregulatory, Cardiovascular and Perceptual Responses of Spectators of a Simulated Football Match in Hot and Humid Environmental Conditions. Sports (Basel) 2023; 11:sports11040078. [PMID: 37104152 PMCID: PMC10140829 DOI: 10.3390/sports11040078] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2023] [Revised: 03/17/2023] [Accepted: 03/29/2023] [Indexed: 04/03/2023] Open
Abstract
Major sporting events are often scheduled in thermally challenging environments. The heat stress may impact athletes but also spectators. We examined the thermal, cardiovascular, and perceptual responses of spectators watching a football match in a simulated hot and humid environment. A total of 48 participants (43 ± 9 years; n = 27 participants <50 years and n = 21 participants ≥50 years, n = 21) watched a 90 min football match in addition to a 15 min baseline and 15 min halftime break, seated in an environmental chamber (Tair = 31.9 ± 0.4 °C; RH = 76 ± 4%). Gastrointestinal temperature (Tgi), skin temperature (Tskin), and heart rate (HR) were measured continuously throughout the match. Mean arterial pressure (MAP) and perceptual parameters (i.e., thermal sensation and thermal comfort) were scored every 15 min. Tri (37.3 ± 0.4 °C to 37.4 ± 0.3 °C, p = 0.11), HR (76 ± 15 bpm to 77 ± 14 bpm, p = 0.96) and MAP (97 ± 10 mm Hg to 97 ± 10 mm Hg, p = 0.67) did not change throughout the match. In contrast, an increase in Tskin (32.9 ± 0.8 °C to 35.4 ± 0.3 °C, p < 0.001) was found. Further, 81% of participants reported thermal discomfort and 87% a (slightly) warm thermal sensation at the end of the match. Moreover, the thermal or cardiovascular responses were not affected by age (all p-values > 0.05). Heat stress induced by watching a football match in simulated hot and humid conditions does not result in substantial thermal or cardiovascular strain, whereas a significant perceptual strain was observed.
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Affiliation(s)
- Johannus Q. de Korte
- Department of Medical Biosciences, Radboud University Medical Center, 6500VC Nijmegen, The Netherlands
| | - Thijs M. H. Eijsvogels
- Department of Medical Biosciences, Radboud University Medical Center, 6500VC Nijmegen, The Netherlands
| | - Maria T. E. Hopman
- Department of Medical Biosciences, Radboud University Medical Center, 6500VC Nijmegen, The Netherlands
| | - Coen C. W. G. Bongers
- Department of Medical Biosciences, Radboud University Medical Center, 6500VC Nijmegen, The Netherlands
- School of Sport and Exercise, Health Promotion & Performance, HAN University of Applied Sciences, 6525AJ Nijmegen, The Netherlands
- Correspondence:
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23
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Pan R, Xie M, Chen M, Zhang Y, Ma J, Zhou J. The impact of heat waves on the mortality of Chinese population: A systematic review and meta-analysis. Medicine (Baltimore) 2023; 102:e33345. [PMID: 37000079 PMCID: PMC10063284 DOI: 10.1097/md.0000000000033345] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/14/2022] [Revised: 03/01/2023] [Accepted: 03/02/2023] [Indexed: 04/01/2023] Open
Abstract
BACKGROUND Many studies had shown that with global warming, heat waves may increase the mortality risk of Chinese populations. However, these findings are not consistent. Therefore, we elucidated the associations by meta-analysis and quantified the magnitude of these risks, as well as the underlying factors. METHODS We searched the China National Knowledge Infrastructure (CNKI), Wanfang database, PubMed, EMBASE, and Web of Science for literature screening up to Nov 10, 2022, to analyze the effect of heat waves on mortality in the Chinese population. Literature screening and data extraction were performed independently by two researchers and the data were merged by meta-analysis. In addition, we conducted subgroup analysis by sex, age, years of education, region, and number of events to explore the source of heterogeneity. RESULTS Fifteen related studies on the impact on heat waves of the death of Chinese people were included in this study. The results of the meta-analysis showed that heat waves were significantly associated with increased mortality from non-accidental deaths, cardiovascular diseases, stroke, respiratory diseases, and circulatory diseases in the Chinese population: non-accidental mortality (RR = 1.19, 95% CI: 1.13-1.27, P < .01), cardiovascular diseases (RR = 1.25, 95% CI: 1.14-1.38), stroke (RR = 1.11, 95% CI: 1.03-1.20), respiratory diseases (RR = 1.18, 95% CI: 1.09-1.28), and circulatory diseases (RR = 1.11, 95% CI: 1.06-1.17). Subgroup analyses showed that heat waves had a higher risk of non-accidental death for those with <6 years of education than for those with ≥6 years of education. Meta-regression analysis showed that the contribution of the study year to the inter studied heterogeneity was 50.57%. The sensitivity analysis showed that the exclusion of any single study did not materially alter the overall combined effect. The meta-analysis method indicated no obvious evidence of publication bias. CONCLUSIONS The results of the review indicated that heat waves were associated with increased mortality in the Chinese population, that attention should be paid to high-risk groups, and that public health policies and strategies should be implemented to more effectively respond to and adapt to climate change.
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Affiliation(s)
- Ranran Pan
- Department of Science and Education, Shuyang Hospital of Traditional Chinese Medicine, Shuyang, China
| | - Ming Xie
- Department of Science and Education, The Third Hospital of Changsha, Changsha, China
| | - Mengxiang Chen
- Key Laboratory of Molecular Epidemiology of Hunan Province, School of Medicine, Hunan Normal University, Changsha, China
| | - Yannan Zhang
- Jiangyin Center for Disease Control and Prevention, Jiangyin, China
| | - Jian Ma
- Huaian Center for Disease Control and Prevention, Huaian, China
| | - Junhua Zhou
- Key Laboratory of Molecular Epidemiology of Hunan Province, School of Medicine, Hunan Normal University, Changsha, China
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24
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Fang Z, Mao Y, Zhu Y, Lu J, Zheng Z, Chen X. Human thermal physiological response of wearing personal protective equipment: An educational building semi-open space experimental investigation. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 877:162779. [PMID: 36924973 PMCID: PMC10014506 DOI: 10.1016/j.scitotenv.2023.162779] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/08/2022] [Revised: 03/06/2023] [Accepted: 03/06/2023] [Indexed: 05/03/2023]
Abstract
With the outbreak and spread of the COVID-19 epidemic, HCWs are frequently required to wear personal protective equipment (PPE) for nucleic acid sample collection in semi-open transition spaces. Wearing PPE causes significant psychological and physical stress in HCWs. In this study, operative temperature (Top) and wet-bulb globe temperature (WBGT) were used to assess thermal conditions through field experiments, while multiple physiological parameters were measured in the subjects. The results indicated that the subjects showed statistically significant differences in thermal perception and physiological parameters with and without PPE. Using observed increases in heart rate (HR), auditory canal temperature (Tac), mean skin temperature (MST), and end-tidal CO2 pressure, subjects were shown to have an increased metabolic rate and heat storage while wearing PPE. Additionally, a decrease in oxygen concentration was also observed, and this decrease may be linked to fatigue and cognitive impairment. Moreover, HR, MST, and Tac showed a significant linear relationship, which increased with temperature and operative temperature, and the HR response was stronger with PPE than without PPE. The neutral, preferred, and acceptable temperatures were significantly lower with PPE than without PPE, and the deviations for neutral Top/WBGT were 9.5/7.1 °C and preferred Top/WBGT was 2.2/4.0 °C, respectively. Moreover, the upper limits of acceptable WBGT, 29.4 °C with PPE and 20.4 °C without PPE, differed significantly between the two phases. Furthermore, the recorded physiological parameter responses and thermal perception responses of the subjects while wearing PPE indicated that they were at risk of thermal stress. Overall, these results suggest that people who wear PPE should focus on their health and thermal stress. This study provides a reference for the development of strategies to counteract heat stress and improve thermal comfort.
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Affiliation(s)
- Zhaosong Fang
- School of Civil Engineering, Guangzhou University, Guangzhou, China
| | - Yudong Mao
- School of Civil Engineering, Guangzhou University, Guangzhou, China
| | - Yongcheng Zhu
- The Second Affiliated Hospital of Guangzhou Medical University, Guangzhou, China
| | - Jiaxin Lu
- School of Civil Engineering, Guangzhou University, Guangzhou, China
| | - Zhimin Zheng
- School of Civil Engineering, Guangzhou University, Guangzhou, China.
| | - Xiaohui Chen
- The Second Affiliated Hospital of Guangzhou Medical University, Guangzhou, China.
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25
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Yu H, Song Y, Wang Y, Wang X, Li H, Feng X, Yu M. The Impact of Temperature on 24-Hour Movement Behaviors among Chinese Freshmen Students. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2023; 20:4970. [PMID: 36981878 PMCID: PMC10049201 DOI: 10.3390/ijerph20064970] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/14/2023] [Revised: 03/08/2023] [Accepted: 03/09/2023] [Indexed: 06/18/2023]
Abstract
BACKGROUND Human populations worldwide have experienced substantial climate change issues. Gaps in scientific literature remain regarding the relationship between temperature and 24-hour movement behavior among people. The purpose of this study is to examine the impact of temperature on 24-hour movement behavior including physical activity (PA), sedentary behavior (SB) and sleep duration among university students living in Beijing, China. METHODS We conducted follow-up health surveys on 44,693 freshmen students enrolled at Tsinghua University from 2012 to 2018. PA and SB were measured by using the short version of the International Physical Activity Questionnaire (IPAQ-s); sleep duration was estimated by using The Pittsburgh Sleep Quality Index (CPSQI). Corresponding temperature data measured by the Beijing Meteorological Service were collected to include average daily temperature from the nearest weather station to Tsinghua university. The data were analyzed using linear individual fixed-effect regressions. RESULTS An increase in temperature (temperature range 2.29-28.73 °C) by 1 °C was associated with an increase in 0.66 weekly minutes of vigorous physical activity (VPA) (95% confidence interval [CI] = 0.49, 0.82), an increase in 0.56 weekly minutes of moderate physical activity (MPA)(95% CI = 0.32, 0.79), an increase in 1.21 weekly minutes of moderate to vigorous physical activity (MVPA) (95% CI = 0.90, 1.53), an increase in 0.55 weekly minutes of walking (95% CI = 0.31, 0.78), an increase in 1.76 weekly minutes of total PA (95% CI = 1.35, 2.17), and a reduction in 1.60 weekly minutes of sleeping (95% CI = -2.09, -1.11). There was no significant correlation between temperature and sedentary behavior among participants. CONCLUSIONS Temperature was significantly positively correlated with physical activity levels in the Chinese freshmen students, and significantly negatively correlated with sleep duration. Replication of this study is warranted among various populations within China. The evidence of this novel study focused on understanding the relationship between climate change and 24-hour movement behaviors among people for developing effective adaptation strategies to climate change to improve people's health behavior. This study has important implications for future study, as knowledge of the impact of temperature on movement behavior may help in the interpretation of their results and translate into improving people's health behavior.
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Affiliation(s)
- Hongjun Yu
- Department of Physical Education, Tsinghua University, Beijing 100084, China
| | - Yiling Song
- Department of Physical Education, Tsinghua University, Beijing 100084, China
| | - Yangyang Wang
- Department of Physical Education, Tsinghua University, Beijing 100084, China
| | - Xiaoxin Wang
- Department of Physical Education, Tsinghua University, Beijing 100084, China
| | - Haoxuan Li
- Department of Physical Education, Tsinghua University, Beijing 100084, China
| | - Xiaolu Feng
- Department of Sports Science, College of Education, Zhejiang University, Hangzhou 310058, China
| | - Miao Yu
- Renmin University of China Libraries, Beijing 100872, China
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26
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Gifford RM, Taylor N, Stacey M, Woods DR. Sex, gender or occupational psychology: what matters most to preventing heat-related illnesses and improving outcomes for women in ground close combat? BMJ Mil Health 2023; 169:75-77. [PMID: 32345677 DOI: 10.1136/bmjmilitary-2020-001480] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2020] [Revised: 04/05/2020] [Accepted: 04/06/2020] [Indexed: 01/27/2023]
Abstract
Since the advent of women in ground close combat (WGCC) roles, the impact on women of the attendant risk of heat stress and heat illness has been considered. Much emphasis has been placed on sex differences in thermal physiology. This article considers the application of evidence of sex-associated thermoregulatory variation to the occupational and environmental setting of WGCC, and weighs the relative importance of physiological differences arising from biological sex, and behaviour associated with gender normatives. Quantifying the risk of heat illness to WGCC should draw on data from their real-world occupational context.
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Affiliation(s)
- Robert M Gifford
- British Heart Foundation Centre for Cardiovascular Science, University of Edinburgh, Edinburgh, UK.,Academic Department of Military Medicine, HQ Joint Medical Group, Birmingham, UK
| | - N Taylor
- Academic Department of Military Medicine, HQ Joint Medical Group, Birmingham, UK
| | - M Stacey
- Academic Department of Military Medicine, HQ Joint Medical Group, Birmingham, UK
| | - D R Woods
- Academic Department of Military Medicine, HQ Joint Medical Group, Birmingham, UK.,Research Institute for Sport, Physical Activity and Leisure, Leeds Beckett University Carnegie Faculty, Leeds, UK
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27
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Corbett J, Wright J, Tipton MJ. Sex differences in response to exercise heat stress in the context of the military environment. BMJ Mil Health 2023; 169:94-101. [PMID: 32094215 DOI: 10.1136/jramc-2019-001253] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2019] [Revised: 08/08/2019] [Accepted: 08/11/2019] [Indexed: 01/26/2023]
Abstract
Women can now serve in ground close combat (GCC) roles, where they may be required to operate alongside men in hot environments. However, relative to the average male soldier, female soldiers are less aerobically fit, with a smaller surface area (A D), lower mass (m) with higher body fat and a larger A D/m ratio. This increases cardiovascular strain, reduces heat exchange with the environment and causes a greater body temperature increase for a given heat storage, although a large A D/m ratio can be advantageous. Physical employment standards for GCC roles might lessen the magnitude of fitness and anthropometric differences, yet even when studies control for these factors, women sweat less than men at high work rates. Therefore, the average female soldier in a GCC role is likely to be at a degree of disadvantage in many hot environments and particularly during intense physical activity in hot-arid conditions, although heat acclimation may mitigate some of this effect. Any thermoregulatory disadvantage may be exacerbated during the mid-luteal phase of the menstrual cycle, although the data are equivocal. Likewise, sex differences in behavioural thermoregulation and cognition in the heat are not well understood. Interestingly, there is often lower reported heat illness incidence in women, although the extent to which this is influenced by behavioural factors or historic differences in role allocation is unclear. Indeed, much of the extant literature lacks ecological validity and more work is required to fully understand sex differences to exercise heat stress in a GCC context.
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Affiliation(s)
- Jo Corbett
- School of Sport, Health and Exercise Science, University of Portsmouth, Portsmouth, UK
| | - J Wright
- School of Sport, Health and Exercise Science, University of Portsmouth, Portsmouth, UK.,Reserach Associate, British Army, London, UK
| | - M J Tipton
- School of Sport, Health and Exercise Science, University of Portsmouth, Portsmouth, UK
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28
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Hinchliffe A, Alguacil J, Bijoux W, Kogevinas M, Menegaux F, Parent ME, Pérez Gomez B, Uuksulainen S, Turner MC. Occupational heat exposure and prostate cancer risk: A pooled analysis of case-control studies. ENVIRONMENTAL RESEARCH 2023; 216:114592. [PMID: 36272590 DOI: 10.1016/j.envres.2022.114592] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/14/2022] [Revised: 09/23/2022] [Accepted: 10/11/2022] [Indexed: 06/16/2023]
Abstract
BACKGROUND Heat exposures occur in many occupations. Heat has been linked to key carcinogenic processes, however, evidence for associations with cancer risk is sparse. We examined potential associations between occupational heat exposure and prostate cancer risk in a multi-country study. METHODS We analysed a large, pooled dataset of 3142 histologically confirmed prostate cancer cases and 3512 frequency-matched controls from three countries: Canada, France, and Spain. Three exposure indices: ever exposure, lifetime cumulative exposure and duration of exposure, were developed using the Finnish Job-Exposure Matrix, FINJEM, applied to the lifetime occupational history of participants. We estimated odds ratios (ORs) and 95% confidence intervals (CIs), using conditional logistic regression models stratified by 5-year age groups and study, adjusting for potential confounders. Potential interactions with exposure to other occupational agents were also explored. RESULTS Overall, we found no association for ever occupational heat exposure (OR 0.97; 95% CI 0.87, 1.09), nor in the highest categories of lifetime cumulative exposure (OR 1.04; 95% CI 0.89, 1.23) or duration (OR 1.03; 95% CI 0.88, 1.22). When using only the Spanish case-control study and a Spanish Job Exposure Matrix (JEM), some weakly elevated ORs were observed. CONCLUSIONS Findings from this study provide no clear evidence for an association between occupational heat exposure and prostate cancer risk.
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Affiliation(s)
- Alice Hinchliffe
- Barcelona Institute for Global Health (ISGlobal), Barcelona, Spain; Universitat Pompeu Fabra (UPF), Barcelona, Spain
| | - Juan Alguacil
- Consortium for Biomedical Research in Epidemiology & Public Health (CIBER Epidemiología y Salud Pública - CIBERESP), Madrid, Spain; Centro de Investigación en Recursos Naturales, Salud y Medio Ambiente (RENSMA), Universidad de Huelva, Huelva, Spain
| | - Wendy Bijoux
- Paris-Saclay University, UVSQ, Gustave Roussy, Inserm, CESP, Team "Exposome and Heredity", 94807, Villejuif, France
| | - Manolis Kogevinas
- Barcelona Institute for Global Health (ISGlobal), Barcelona, Spain; Universitat Pompeu Fabra (UPF), Barcelona, Spain; Consortium for Biomedical Research in Epidemiology & Public Health (CIBER Epidemiología y Salud Pública - CIBERESP), Madrid, Spain; IMIM (Hospital Del Mar Medical Research Institute), Carrer Del Dr. Aiguader, 88, 08003, Barcelona, Spain
| | - Florence Menegaux
- Paris-Saclay University, UVSQ, Gustave Roussy, Inserm, CESP, Team "Exposome and Heredity", 94807, Villejuif, France
| | - Marie-Elise Parent
- Centre Armand-Frappier Santé Biotechnologie, Institut National de La Recherche Scientifique, Laval, Quebec, H7V 1B7, Canada; Department of Social and Preventive Medicine, School of Public Health, University of Montreal, Montreal, Quebec, H3N 1X9, Canada; University of Montreal Hospital Research Center, Montreal, Quebec, H2X 0A9, Canada
| | - Beatriz Pérez Gomez
- Consortium for Biomedical Research in Epidemiology & Public Health (CIBER Epidemiología y Salud Pública - CIBERESP), Madrid, Spain; Department of Epidemiology for Chronic Diseases, National Center of Epidemiology, Instituto de Salud Carlos III, Madrid, Spain
| | | | - Michelle C Turner
- Barcelona Institute for Global Health (ISGlobal), Barcelona, Spain; Universitat Pompeu Fabra (UPF), Barcelona, Spain; Consortium for Biomedical Research in Epidemiology & Public Health (CIBER Epidemiología y Salud Pública - CIBERESP), Madrid, Spain.
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29
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Giersch GEW, Taylor KM, Caldwell AR, Charkoudian N. Body mass index, but not sex, influences exertional heat stroke risk in young healthy men and women. Am J Physiol Regul Integr Comp Physiol 2023; 324:R15-R19. [PMID: 36342147 DOI: 10.1152/ajpregu.00168.2022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Exertional heat stroke (EHS) remains a persistent threat for individuals working or playing in the heat, including athletes and military and emergency service personnel. However, influence of biological sex and/or body mass index (BMI) on the risk of EHS remain poorly understood. The purpose of this study was to retrospectively assess the influence of sex and BMI on risk of EHS in the active-duty US Army. We analyzed data from 2016 to 2021, using a matched case-control approach, where each individual with a diagnosis of EHS was matched to five controls based on calendar time, unit ID, and job category, to capture control individuals who were matched to EHS events by location, time, and activity. We used a multivariate logistic regression model mutually adjusted for sex, BMI, and age to compare 745 (n = 61 F) individuals (26 ± 7 yr) with a diagnosed EHS to 4,290 (n = 384 F) case controls (25 ± 5 yr). Group average BMI were similar: 26.6 ± 3.1 (EHS) and 26.5 ± 3.6 kg/m2 (CON). BMI was significantly (P < 0.0001) associated with higher risk of EHS with a 3% increase in risk of EHS for every unit increase in BMI. Notably, sex was not associated with any difference in risk for EHS (P = 0.54). These data suggest that young healthy people with higher BMI have significantly higher risk of EHS, but, contrary to what some have proposed, this risk was not higher in young women.
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Affiliation(s)
- Gabrielle E W Giersch
- Thermal and Mountain Medicine Division, United States Army Research Institute of Environmental Medicine, Natick, Massachusetts
| | - Kathryn M Taylor
- Military Performance Division, United States Army Research Institute of Environmental Medicine, Natick, Massachusetts
| | - Aaron R Caldwell
- Thermal and Mountain Medicine Division, United States Army Research Institute of Environmental Medicine, Natick, Massachusetts
| | - Nisha Charkoudian
- Thermal and Mountain Medicine Division, United States Army Research Institute of Environmental Medicine, Natick, Massachusetts
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Carlson JM, Zanobetti A, Ettinger de Cuba S, Poblacion AP, Fabian PM, Carnes F, Rhee J, Lane KJ, Sandel MT, Janulewicz PA. Critical windows of susceptibility for the effects of prenatal exposure to heat and heat variability on gestational growth. ENVIRONMENTAL RESEARCH 2023; 216:114607. [PMID: 36279910 DOI: 10.1016/j.envres.2022.114607] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/08/2022] [Revised: 10/11/2022] [Accepted: 10/14/2022] [Indexed: 06/16/2023]
Abstract
BACKGROUND Studies have shown that prenatal heat exposure may impact fetal growth, but few studies have examined the critical windows of susceptibility. As extreme heat events and within season temperature variability is expected to increase in frequency, it is important to understand how this may impact gestational growth. OBJECTIVES We investigated associations between various measures of weekly prenatal heat exposure (mean and standard deviation (SD) of temperature and heat index (HI), derived using temperature in °C and dew point) and term birthweight or odds of being born small for gestational age (SGA) to identify critical windows of susceptibility. METHODS We analyzed data from mother-child dyads (n = 4442) in the Boston-based Children's HealthWatch cohort. Birthweights were collected from survey data and electronic health records. Daily temperature and HI values were obtained from 800 m gridded spatial climate datasets aggregated by the PRISM Climate Group. Distributed lag-nonlinear models were used to assess the effect of the four weekly heat metrics on measures of gestational growth (birthweight, SGA, and birthweight z-scores). Analyses were stratified by child sex and maternal homelessness status during pregnancy. RESULTS HI variability was significantly associated with decreased term birthweight during gestational weeks 10-29 and with SGA for weeks 9-26. Cumulative effects for these time periods were -287.4 g (95% CI: -474.1 g, -100.8 g for birthweight and 4.7 (95% CI: 1.6, 14.1) for SGA. Temperature variability was also significantly associated with decreased birthweight between weeks 15 and 26. The effects for mean heat measures on term birthweight and SGA were not significant for any gestational week. Stratification by sex revealed a significant effect on term birthweight in females between weeks 23-28 and in males between weeks 9-26. Strongest effects of HI variability on term birthweight were found in children of mothers who experienced homelessness during pregnancy. Weekly HI variability was the heat metric most strongly associated with measures of gestational growth. The effects observed were largest in males and those who experienced homelessness during pregnancy. DISCUSSION Given the impact of heat variability on birthweight and risk of SGA, it is important for future heat warnings to incorporate measure of heat index and temperature variability.
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Affiliation(s)
- Jeffrey M Carlson
- Department of Environmental Health, Boston University School of Public Health, Boston, MA, USA.
| | - Antonella Zanobetti
- Department of Environmental Health, Harvard T.H. Chan School of Public Health, Boston, MA, USA
| | - Stephanie Ettinger de Cuba
- Department of Pediatrics, School of Medicine, Boston University, Boston, MA, USA; Children's HealthWatch, USA
| | - Ana P Poblacion
- Children's HealthWatch, USA; Department of Pediatrics, Boston Medical Center, Boston, MA, USA
| | - Patricia M Fabian
- Department of Environmental Health, Boston University School of Public Health, Boston, MA, USA
| | - Fei Carnes
- Department of Environmental Health, Boston University School of Public Health, Boston, MA, USA
| | - Jongeun Rhee
- Department of Environmental Health, Harvard T.H. Chan School of Public Health, Boston, MA, USA
| | - Kevin J Lane
- Department of Environmental Health, Boston University School of Public Health, Boston, MA, USA
| | - Megan T Sandel
- Department of Environmental Health, Boston University School of Public Health, Boston, MA, USA; Department of Pediatrics, School of Medicine, Boston University, Boston, MA, USA
| | - Patricia A Janulewicz
- Department of Environmental Health, Boston University School of Public Health, Boston, MA, USA
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Wolf ST, Vecellio DJ, Kenney WL. Adverse heat-health outcomes and critical environmental limits (Pennsylvania State University Human Environmental Age Thresholds project). Am J Hum Biol 2023; 35:e23801. [PMID: 36125292 PMCID: PMC9840654 DOI: 10.1002/ajhb.23801] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2022] [Revised: 06/24/2022] [Accepted: 07/29/2022] [Indexed: 02/04/2023] Open
Abstract
BACKGROUND The earth's climate is warming and the frequency, duration, and severity of heat waves are increasing. Meanwhile, the world's population is rapidly aging. Epidemiological data demonstrate exponentially greater increases in morbidity and mortality during heat waves in adults ≥65 years. Laboratory data substantiate the mechanistic underpinnings of age-associated differences in thermoregulatory function. However, the specific combinations of environmental conditions (i.e., ambient temperature and absolute/relative humidity) above which older adults are at increased risk of heat-related morbidity and mortality are less clear. METHODS This review was conducted to (1) examine the recent (past 3 years) literature regarding heat-related morbidity and mortality in the elderly and discuss projections of future heat-related morbidity and mortality based on climate model data, and (2) detail the background and unique methodology of our ongoing laboratory-based projects aimed toward identifying the specific environmental conditions that result in elevated risk of heat illness in older adults, and the implications of using the data toward the development of evidence-based safety interventions in a continually-warming climate (PSU HEAT; Human Environmental Age Thresholds). RESULTS The recent literature demonstrates that extreme heat continues to be increasingly detrimental to the health of the elderly and that this is apparent across the world, although the specific environmental conditions above which older adults are at increased risk of heat-related morbidity and mortality remain unclear. CONCLUSION Characterizing the environmental conditions above which risk of heat-related illnesses increase remains critical to enact policy decisions and mitigation efforts to protect vulnerable people during extreme heat events.
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Affiliation(s)
- S. Tony Wolf
- Department of Kinesiology, The Pennsylvania State University, University Park, PA, 16802
| | - Daniel J. Vecellio
- Center for Healthy Aging, The Pennsylvania State University, University Park, PA, 16802
| | - W. Larry Kenney
- Department of Kinesiology, The Pennsylvania State University, University Park, PA, 16802
- Center for Healthy Aging, The Pennsylvania State University, University Park, PA, 16802
- Graduate Program in Physiology, The Pennsylvania State University, University Park, PA, 16802
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Guzman-Echavarria G, Middel A, Vanos J. Beyond heat exposure - new methods to quantify and link personal heat exposure, stress, and strain in diverse populations and climates: The journal Temperature toolbox. Temperature (Austin) 2022; 10:358-378. [PMID: 37554380 PMCID: PMC10405775 DOI: 10.1080/23328940.2022.2149024] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2022] [Revised: 10/31/2022] [Accepted: 11/12/2022] [Indexed: 11/21/2022] Open
Abstract
Fine-scale personal heat exposure (PHE) information can help prevent or minimize weather-related deaths, illnesses, and reduced work productivity. Common methods to estimate heat risk do not simultaneously account for the intensity, frequency, and duration of thermal exposures, nor do they include inter-individual factors that modify physiological response. This study demonstrates new whole-body net thermal load estimations to link PHE to heat stress and strain over time. We apply a human-environment heat exchange model to examine how time-varying net thermal loads differ across climate contexts, personal attributes, and spatiotemporal scales. First, we investigate summertime climatic PHE impacts for three US cities: Phoenix, Miami, and New York. Second, we model body morphology and acclimatization for three profiles (middle-aged male/female; female >65 years). Finally, we quantify model sensitivity using representative data at synoptic and micro-scales. For all cases, we compare required and potential evaporative heat losses that can lead to dangerous thermal exposures based on (un)compensable heat stress. Results reveal misclassifications in heat stress or strain due to incomplete environmental data and assumed equivalent physiology and activities between people. Heat strain is most poorly represented by PHE alone for the elderly, non-acclimatized, those engaged in strenuous activities, and when negating solar radiation. Moreover, humid versus dry heat across climates elicits distinct thermal responses from the body. We outline criteria for inclusive PHE evaluations connecting heat exposure, stress, and strain while using physiological-based methods to avoid misclassifications. This work underlines the value of moving from "one-size-fits-all" thermal indices to "fit-for-purpose" approaches using personalized information.
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Affiliation(s)
- Gisel Guzman-Echavarria
- School of Geographical Sciences and Urban Planning, Arizona State University, Tempe, AZ, USA
| | - Ariane Middel
- School of Arts, Media and Engineering, Arizona State University, Tempe, AZ, USA
- School of Computing and Augmented Intelligence, Arizona State University,Tempe, AZ, USA
| | - Jennifer Vanos
- School of Sustainability, Arizona State University, Tempe, AZ, USA
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Individual variability in achievement of short-term heat acclimation during a fixed intensity protocol. J Therm Biol 2022; 110:103373. [DOI: 10.1016/j.jtherbio.2022.103373] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2021] [Revised: 10/04/2022] [Accepted: 10/12/2022] [Indexed: 12/05/2022]
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Peel JS, McNarry MA, Heffernan SM, Nevola VR, Kilduff LP, Waldron M. Measurement of thermal sweating at rest and steady-state exercise in healthy adults: Inter-day reliability and relationships with components of partitional calorimetry. PLoS One 2022; 17:e0278652. [PMID: 36455061 PMCID: PMC9714830 DOI: 10.1371/journal.pone.0278652] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2022] [Accepted: 11/21/2022] [Indexed: 12/03/2022] Open
Abstract
OBJECTIVE Inter-day reliability of sweat measurements, including the absorbent patch and modified iodine-paper techniques, at rest and exercise were evaluated. We further evaluated the effect of iodine paper size and the method of establishing sweat gland activation (sweat gland counting or surface area covered) on reliability. Furthermore, the relationships between all measurement techniques and metabolic heat production [Ḣprod] and evaporative requirement for heat balance [Ėreq] were determined. METHOD Twelve participants were assessed for whole-body sweat loss (WBSL), local sweat rate (LSR; absorbent patch) and sweat gland activation (SGA; iodine-paper) during rest and sub-maximal cycling at ~200, ~250 and ~300 W/m2 Ḣprod in the heat. Variations in iodine paper (1 x 1 cm-9 x 9 cm) were used to quantify SGA by counting sweat glands or surface area covered. The 'optimal' area of SGA was also determined based on the highest density of recruited glands. RESULTS All measures of the sweating response were positively related with Ḣprod and Ėreq (r = 0.53-0.84), with the 9 x 9 cm and 6 x 6 cm iodine paper sizes being the strongest (r = 0.66-0.84) for SGA. Superior inter-day reliability was found for all measures during exercise (CV% = 6-33.2) compared to rest (CV% = 33.5-77.9). The iodine-paper technique was most reliable at 9 x 9 cm (CV% = 15.9) or when the 1 x 1 cm (CV% = 17.6) and 3 x 3 cm (CV% = 15.5) optimal SGA was determined, particularly when measuring the sweat gland number. SIGNIFICANCE WBSL, LSR and SGA measurement techniques are sufficiently reliable to detect changes in thermal sweating typically reported. We recommend 9 x 9 cm paper sizes or 1 x 1 cm-3 x 3 cm optimal areas, using either gland counting or surface area to determine SGA.
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Affiliation(s)
- Jennifer S. Peel
- Faculty of Science and Engineering, A-STEM Centre, Swansea University, Swansea, United Kingdom
- * E-mail:
| | - Melitta A. McNarry
- Faculty of Science and Engineering, A-STEM Centre, Swansea University, Swansea, United Kingdom
| | - Shane M. Heffernan
- Faculty of Science and Engineering, A-STEM Centre, Swansea University, Swansea, United Kingdom
| | - Venturino R. Nevola
- Faculty of Science and Engineering, A-STEM Centre, Swansea University, Swansea, United Kingdom
- Defence Science and Technology Laboratory (Dstl), Fareham, Hampshire, United Kingdom
| | - Liam P. Kilduff
- Faculty of Science and Engineering, A-STEM Centre, Swansea University, Swansea, United Kingdom
- Welsh Institute of Performance Science, Swansea University, Swansea, United Kingdom
| | - Mark Waldron
- Faculty of Science and Engineering, A-STEM Centre, Swansea University, Swansea, United Kingdom
- Welsh Institute of Performance Science, Swansea University, Swansea, United Kingdom
- School of Health and Behavioural Sciences, University of the Sunshine Coast, Queensland, Australia
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Ferreira FC, Padilha MCSV, Tobadini E, Bellocchi C, Carandina A, Montano N, Soares PPS, Rodrigues GD. Women have a greater cardiac vagal withdrawal to heat stress compared to men. Temperature (Austin) 2022; 10:444-453. [PMID: 38130655 PMCID: PMC10732604 DOI: 10.1080/23328940.2022.2135354] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2022] [Accepted: 10/07/2022] [Indexed: 10/31/2022] Open
Abstract
The heated environment shifts the sympatho-vagal balance toward sympathetic predominance and vagal withdrawal. Women's heart is more reliant on vagal autonomic control, while men's heart is more dependent on sympathetic control. However, sex differences in cardiovascular autonomic responses to heat stress remain unknown. We aimed to investigate the cardiovascular autonomic regulation under heat stress between sexes. Thirty-two young participants (27 ± 4 years old; 16 women) were enrolled in a single visit, resting for 30min at baseline (thermal reference condition TC; ∼24°C) and 30min under a heated environment (HOT; ∼38°C). Blood pressure (BP), skin temperature, electrocardiogram, and respiratory oscillations were continuously recorded. The heart rate variability (HRV) was assessed by spectral analysis (low-frequency [LFnu; sympathetic and vagal] and high-frequency [HFnu; vagal]), and symbolic analysis (0 V% [sympathetic] and 2UV%, and 2LV% [vagal]). The spontaneous baroreflex sensitivity (BRS) was calculated by the gain between BP and R-R within the LF band (αLF). The estimated maximal aerobic capacity and body surface area were employed as covariates in sex comparisons. The effects of HOT were the following: 1) Women have a greater cardiac vagal withdrawal to heat stress compared to men; 2) Sex differences on cardiac autonomic response to heat stress exist after controlling for the effect of estimated physical fitness and body surface area. Therefore, heat stress provokes a higher vagal withdrawal to the heart in women compared to men. It could be attributed to sex per se since significant differences between men and women were not modified after covariate analysis.
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Affiliation(s)
- Felipe C. Ferreira
- Laboratory of Experimental and Applied Exercise Physiology, Department of Physiology and Pharmacology, Fluminense Federal University, Niterói, Brazil
| | - Michelle Cristina S. V. Padilha
- Laboratory of Experimental and Applied Exercise Physiology, Department of Physiology and Pharmacology, Fluminense Federal University, Niterói, Brazil
| | - Eleonora Tobadini
- Department of Clinical Sciences and Community Health, University of Milan, 20122Milan, Italy
- Department of Internal Medicine, Fondazione IRCCS Ca’ Granda Ospedale Maggiore Policlinico, 20122Milan, Italy
| | - Chiara Bellocchi
- Department of Clinical Sciences and Community Health, University of Milan, 20122Milan, Italy
- Department of Internal Medicine, Fondazione IRCCS Ca’ Granda Ospedale Maggiore Policlinico, 20122Milan, Italy
| | - Angelica Carandina
- Department of Clinical Sciences and Community Health, University of Milan, 20122Milan, Italy
- Department of Internal Medicine, Fondazione IRCCS Ca’ Granda Ospedale Maggiore Policlinico, 20122Milan, Italy
| | - Nicola Montano
- Department of Clinical Sciences and Community Health, University of Milan, 20122Milan, Italy
- Department of Internal Medicine, Fondazione IRCCS Ca’ Granda Ospedale Maggiore Policlinico, 20122Milan, Italy
| | - Pedro Paulo S. Soares
- Laboratory of Experimental and Applied Exercise Physiology, Department of Physiology and Pharmacology, Fluminense Federal University, Niterói, Brazil
| | - Gabriel D. Rodrigues
- Laboratory of Experimental and Applied Exercise Physiology, Department of Physiology and Pharmacology, Fluminense Federal University, Niterói, Brazil
- Department of Clinical Sciences and Community Health, University of Milan, 20122Milan, Italy
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Périard JD, DeGroot D, Jay O. Exertional heat stroke in sport and the military: epidemiology and mitigation. Exp Physiol 2022; 107:1111-1121. [PMID: 36039024 PMCID: PMC9826288 DOI: 10.1113/ep090686] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2022] [Accepted: 08/12/2022] [Indexed: 01/11/2023]
Abstract
NEW FINDINGS What is the topic of this review? Exertional heat stroke epidemiology in sport and military settings, along with common risk factors and strategies and policies designed to mitigate its occurrence. What advances does it highlight? Individual susceptibility to exertional heat stroke risk is dependent on the interaction of intrinsic and extrinsic factors. Heat policies in sport should assess environmental conditions, as well as the characteristics of the athlete, clothing/equipment worn and activity level of the sport. Exertional heat stroke risk reduction in the military should account for factors specific to training and personnel. ABSTRACT Exertional heat illness occurs along a continuum, developing from the relatively mild condition of muscle cramps, to heat exhaustion, and in some cases to the life-threatening condition of heat stroke. The development of exertional heat stroke (EHS) is associated with an increase in core temperature stemming from inadequate heat dissipation to offset the rate of metabolically generated heat. Susceptibility to EHS is linked to the interaction of several factors including environmental conditions, individual characteristics, health conditions, medication and drug use, behavioural responses, and sport/organisational requirements. Two settings in which EHS is commonly observed are competitive sport and the military. In sport, the exact prevalence of EHS is unclear due to inconsistent exertional heat illness terminology, diagnostic criteria and data reporting. In contrast, exertional heat illness surveillance in the military is facilitated by standardised case definitions, a requirement to report all heat illness cases and a centralised medical record repository. To mitigate EHS risk, several strategies can be implemented by athletes and military personnel, including heat acclimation, ensuring adequate hydration, cold-water immersion and mandated work-to-rest ratios. Organisations may also consider developing sport or military task-specific heat stress policies that account for the evaporative heat loss requirement of participants, relative to the evaporative capacity of the environment. This review examines the epidemiology of EHS along with the strategies and policies designed to reduce its occurrence in sport and military settings. We highlight the nuances of identifying individuals at risk of EHS and summarise the benefits and shortcomings of various mitigation strategies.
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Affiliation(s)
- Julien D. Périard
- Research Institute for Sport and ExerciseUniversity of CanberraCanberraAustralia
| | - David DeGroot
- Army Heat CenterMartin Army Community HospitalFort BenningGAUSA
| | - Ollie Jay
- Thermal Ergonomics LaboratoryHeat and Health Research IncubatorFaculty of Medicine and HealthUniversity of SydneyCamperdownAustralia
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Cramer MN, Gagnon D, Laitano O, Crandall CG. Human temperature regulation under heat stress in health, disease, and injury. Physiol Rev 2022; 102:1907-1989. [PMID: 35679471 PMCID: PMC9394784 DOI: 10.1152/physrev.00047.2021] [Citation(s) in RCA: 59] [Impact Index Per Article: 29.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2021] [Revised: 05/10/2022] [Accepted: 05/28/2022] [Indexed: 12/30/2022] Open
Abstract
The human body constantly exchanges heat with the environment. Temperature regulation is a homeostatic feedback control system that ensures deep body temperature is maintained within narrow limits despite wide variations in environmental conditions and activity-related elevations in metabolic heat production. Extensive research has been performed to study the physiological regulation of deep body temperature. This review focuses on healthy and disordered human temperature regulation during heat stress. Central to this discussion is the notion that various morphological features, intrinsic factors, diseases, and injuries independently and interactively influence deep body temperature during exercise and/or exposure to hot ambient temperatures. The first sections review fundamental aspects of the human heat stress response, including the biophysical principles governing heat balance and the autonomic control of heat loss thermoeffectors. Next, we discuss the effects of different intrinsic factors (morphology, heat adaptation, biological sex, and age), diseases (neurological, cardiovascular, metabolic, and genetic), and injuries (spinal cord injury, deep burns, and heat stroke), with emphasis on the mechanisms by which these factors enhance or disturb the regulation of deep body temperature during heat stress. We conclude with key unanswered questions in this field of research.
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Affiliation(s)
- Matthew N Cramer
- Defence Research and Development Canada-Toronto Research Centre, Toronto, Ontario, Canada
| | - Daniel Gagnon
- Montreal Heart Institute and School of Kinesiology and Exercise Science, Université de Montréal, Montréal, Quebec, Canada
| | - Orlando Laitano
- Department of Applied Physiology and Kinesiology, University of Florida, Gainesville, Florida
| | - Craig G Crandall
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas and University of Texas Southwestern Medical Center, Dallas, Texas
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Continuous Thermoregulatory Responses to a Mass-Participation 89-km Ultramarathon Road Race. Int J Sports Physiol Perform 2022; 17:1574-1582. [PMID: 36070861 DOI: 10.1123/ijspp.2022-0043] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2022] [Revised: 05/20/2022] [Accepted: 06/27/2022] [Indexed: 11/18/2022]
Abstract
PURPOSE To continuously measure body core temperature (Tc) throughout a mass-participation ultramarathon in subelite recreational runners to quantify Tc magnitude and the influence of aerobic fitness and body fat. METHODS Twenty-three participants (19 men and 4 women; age 45 [9] y; body mass 72.0 [9.3] kg; body fat 26% [6%]; peak oxygen uptake 50 [6] mL·kg-1·min-1) had gastrointestinal temperature measured during an 89-km ultramarathon. Prerace-to-postrace changes in body mass, plasma sodium, and fluid and food recall quantified body water balance. RESULTS In maximal environmental conditions of 26.3 °C and 53% humidity, 21 of the 23 participants finished in 10:28 (01:10) h:min while replacing 49% (27%) of sweat losses, maintaining plasma sodium (140 [3] mmol·L-1), and dehydrating by 4.1% (1.3%). Mean maximum Tc was 39.0 (0.5) (range 38.2-40.1 °C) with 90% of race duration ≤39.0 °C. Mean maximum ΔTc was 1.9 (0.9) (0.9-2.7 °C) with 95% of race duration ≤2.0 °C. Over 0 to 45 km, associations between ΔTc and peak oxygen uptake (positive) and body fat (negative) were observed. Over 58 to 89 km, associations between Tc and peak oxygen uptake (negative) and body fat (positive) were observed. CONCLUSIONS Modest Tc responses were observed in recreational ultramarathon runners. Runners with higher levels of aerobic fitness and lower levels of body fat demonstrated the greatest changes in Tc during the first half of the race. Conversely, runners with lower levels of aerobic fitness and higher levels of body fat demonstrated the greatest absolute Tc in the final third of the race.
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Lanza K, Gohlke J, Wang S, Sheffield PE, Wilhelmi O. Climate change and physical activity: ambient temperature and urban trail use in Texas. INTERNATIONAL JOURNAL OF BIOMETEOROLOGY 2022; 66:1575-1588. [PMID: 35622168 PMCID: PMC9135991 DOI: 10.1007/s00484-022-02302-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/25/2022] [Revised: 03/18/2022] [Accepted: 04/30/2022] [Indexed: 06/15/2023]
Abstract
Individuals in the USA are insufficiently active, increasing their chronic disease risk. Extreme temperatures may reduce physical activity due to thermal discomfort. Cooler climate studies have suggested climate change may have a net positive effect on physical activity, yet research gaps remain for warmer climates and within-day physical activity patterns. We determined the association between ambient temperatures (contemporary and projected) and urban trail use in a humid subtropical climate. At a trail in Austin, TX, five electronic counters recorded hourly pedestrian and cyclist counts in 2019. Weather data were acquired from World Weather Online. Generalized additive models estimated the association between temperature and trail counts. We then combined the estimated exposure-response relation with weather projections from climate models for intermediate (RCP4.5) and high (RCP8.5) emissions scenarios by NASA NEX-GDDP. From summer to autumn to spring to winter, hourly trail counts shifted from bimodal (mid-morning and early-evening peaks) to one mid-day peak. Pedestrians were more likely to use the trail between 7 and 27 °C (45-81°F) with peak use at 17 °C (63°F) and cyclists between 15 and 33 °C (59-91°F) with peak use at 27 °C (81°F) than at temperature extremes. A net decrease in trail use was estimated by 2041-2060 (RCP4.5: pedestrians = - 4.5%, cyclists = - 1.1%; RCP8.5: pedestrians = - 6.6%, cyclists = - 1.6%) and 2081-2100 (RCP4.5: pedestrians = - 7.5%, cyclists = - 1.9%; RCP8.5: pedestrians = - 16%, cyclists = - 4.5%). Results suggest climate change may reduce trail use. We recommend interventions for thermal comfort at settings for physical activity.
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Affiliation(s)
- Kevin Lanza
- Department of Epidemiology, Human Genetics, and Environmental Sciences, UTHealth School of Public Health in Austin, 1616 Guadalupe St, Suite 6.300, Austin, TX, 78701, USA.
| | - Julia Gohlke
- Department of Population Health Sciences, Virginia Polytechnic Institute and State University, 205 Duck Pond Drive, Blacksburg, VA, 24061, USA
| | - Suwei Wang
- Department of Population Health Sciences, Duke University, 215 Morris Street, Durham, NC, 27701, USA
| | - Perry E Sheffield
- Departments of Environmental Medicine and Public Health and Pediatrics, Icahn School of Medicine at Mount Sinai, 1 Gustave L Levy Pl, EMPH Box 1057, New York, NY, 10029, USA
| | - Olga Wilhelmi
- Research Applications Laboratory, National Center for Atmospheric Research, P.O. Box 3000, Boulder, CO, 80307, USA
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Horseman M, Panahi L, Udeani G, Tenpas AS, Verduzco Jr. R, Patel PH, Bazan DZ, Mora A, Samuel N, Mingle AC, Leon LR, Varon J, Surani S. Drug-Induced Hyperthermia Review. Cureus 2022; 14:e27278. [PMID: 36039261 PMCID: PMC9403255 DOI: 10.7759/cureus.27278] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/22/2022] [Indexed: 11/26/2022] Open
Abstract
Humans maintain core body temperature via a complicated system of physiologic mechanisms that counteract heat/cold fluctuations from metabolism, exertion, and the environment. Overextension of these mechanisms or disruption of body temperature homeostasis leads to bodily dysfunction, culminating in a syndrome analogous to exertional heat stroke (EHS). The inability of this thermoregulatory process to maintain the body temperature is caused by either thermal stress or certain drugs. EHS is a syndrome characterized by hyperthermia and the activation of systemic inflammation. Several drug-induced hyperthermic syndromes may resemble EHS and share common mechanisms. The purpose of this article is to review the current literature and compare exertional heat stroke (EHS) to three of the most widely studied drug-induced hyperthermic syndromes: malignant hyperthermia (MH), neuroleptic malignant syndrome (NMS), and serotonin syndrome (SS). Drugs and drug classes that have been implicated in these conditions include amphetamines, diuretics, cocaine, antipsychotics, metoclopramide, selective serotonin reuptake inhibitors (SSRIs), tricyclic antidepressants (TCAs), and many more. Observations suggest that severe or fulminant cases of drug-induced hyperthermia may evolve into an inflammatory syndrome best described as heat stroke. Their underlying mechanisms, symptoms, and treatment approaches will be reviewed to assist in accurate diagnosis, which will impact the management of potentially life-threatening complications.
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Klous L, van Diemen F, Ruijs S, Gerrett N, Daanen H, de Weerd M, Veenstra B, Levels K. Efficiency of three cooling methods for hyperthermic military personnel linked to water availability. APPLIED ERGONOMICS 2022; 102:103700. [PMID: 35231652 DOI: 10.1016/j.apergo.2022.103700] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/14/2021] [Revised: 01/16/2022] [Accepted: 01/24/2022] [Indexed: 06/14/2023]
Abstract
PURPOSE Three feasible cooling methods for treatment of hyperthermic individuals in the military, that differed considerably in water volume needed (none to ~80 L), were evaluated. METHODS Ten male soldiers were cooled following exercise-induced hyperthermia (rectal temperature (Tre) ∼39.5 °C) using ventilation by fanning (1.7 m s-1), ventilation by fanning (1.7 m s-1) while wearing a wet t-shirt (250 mL-27 °C water) and tarp assisted cooling with oscillations (80 L of 27.2 ± 0.5 °C water; TACO). RESULTS Cooling rates were higher using TACO (0.116 ± 0.032 °C min-1) compared to ventilation (0.065 ± 0.011 °C min-1, P<0.001) and ventilation in combination with a wet t-shirt (0.074 ± 0.020 °C min-1, P=0.002). Time to cool (TTC) to Tre=38.2 °C for TACO was shorter (14 ± 4 min) compared to ventilation only (20 ± 5 min; P=0.018), but not to ventilation while wearing a wet t-shirt (18 ± 6 min; P=0.090). CONCLUSIONS TACO may be an acceptable, efficient and feasible cooling method in case of exertional heat stroke. However, in case of limited water availability, transportat should be prioritized, and cooling of any form should be implemented while waiting for and during transport.
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Affiliation(s)
- Lisa Klous
- Department of Human Movement Sciences, Faculty of Behavioural and Movement Sciences, Vrije Universiteit Amsterdam, Amsterdam Movement Sciences, Amsterdam, the Netherlands; Netherlands Organization for Applied Scientific Research (TNO), Department of Human Performance, Unit Defence, Safety and Security, Soesterberg, The Netherlands
| | - Femke van Diemen
- Department of Human Movement Sciences, Faculty of Behavioural and Movement Sciences, Vrije Universiteit Amsterdam, Amsterdam Movement Sciences, Amsterdam, the Netherlands
| | - Silke Ruijs
- Department of Human Movement Sciences, Faculty of Behavioural and Movement Sciences, Vrije Universiteit Amsterdam, Amsterdam Movement Sciences, Amsterdam, the Netherlands
| | - Nicola Gerrett
- Department of Human Movement Sciences, Faculty of Behavioural and Movement Sciences, Vrije Universiteit Amsterdam, Amsterdam Movement Sciences, Amsterdam, the Netherlands; Gentherm Inc., Michigan, USA
| | - Hein Daanen
- Department of Human Movement Sciences, Faculty of Behavioural and Movement Sciences, Vrije Universiteit Amsterdam, Amsterdam Movement Sciences, Amsterdam, the Netherlands
| | - Marijne de Weerd
- Institute of Training Medicine and Training Physiology, TGTF, Royal Netherlands Army, the Netherlands
| | - Bertil Veenstra
- Institute of Training Medicine and Training Physiology, TGTF, Royal Netherlands Army, the Netherlands
| | - Koen Levels
- Institute of Training Medicine and Training Physiology, TGTF, Royal Netherlands Army, the Netherlands.
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Topham TH, Smallcombe JW, Clark B, Brown HA, Telford RD, Jay O, Periard JD. The influence of sex and biological maturation on the sudomotor response to exercise-heat stress: Are girls disadvantaged? Am J Physiol Regul Integr Comp Physiol 2022; 323:R161-R168. [PMID: 35670483 DOI: 10.1152/ajpregu.00328.2021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Both adult females and children have been reported to have a lower sweating capacity and thus reduced evaporative heat loss potential which may increase their susceptibility to exertional hyperthermia in the heat. Compared to males, females have a lower maximal sweat rate and thus a theoretically lower maximum skin wettedness, due to a lower sweat output per gland. Similarly, children have been suggested to be disadvantaged in high ambient temperatures due to a lower sweat production and therefore reduced evaporative capacity, despite modifications of heat transfer due to physical attributes and possible evaporative efficiency. The reported reductions in sudomotor activity of females and children suggests a lower sweating capacity in girls. However, due to the complexities of isolating sex and maturation from the confounding effects of morphological differences (e.g., body surface area-to-mass ratio) and metabolic heat production, limited evidence exists supporting whether children and, more specifically, girls are at a thermoregulatory disadvantage. Furthermore, a limited number of child-adult comparison studies involve females and very few studies have directly compared regional and whole-body sudomotor activity between boys and girls. This mini review highlights the exercise-induced sudomotor response of females and children, summarises previous research investigating the sudomotor response to exercise in girls and suggests important areas for further research.
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Affiliation(s)
- Thomas H Topham
- Research Institute for Sport and Exercise, University of Canberra, Bruce, Australia
| | - James W Smallcombe
- The University of Sydney, Heat and Health Research Incubator, Faculty of Medicine and Health, Sydney, New South Wales, Australia
| | - Brad Clark
- Research Institute for Sport and Exercise, University of Canberra, Bruce, Australia
| | - Harry A Brown
- Research Institute for Sport and Exercise, University of Canberra, Bruce, Australia
| | - Richard D Telford
- Research Institute for Sport and Exercise, University of Canberra, Bruce, Australia
| | - Ollie Jay
- The University of Sydney, Heat and Health Research Incubator, Faculty of Medicine and Health, Sydney, New South Wales, Australia
| | - Julien D Periard
- Research Institute for Sport and Exercise, University of Canberra, Bruce, Australia
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Giersch G, Garcia C, Stachenfeld N, Charkoudian N. Are there sex differences in risk for exertional heat stroke? A translational approach. Exp Physiol 2022; 107:1136-1143. [PMID: 35598159 DOI: 10.1113/ep090402] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2022] [Accepted: 05/11/2022] [Indexed: 11/08/2022]
Abstract
NEW FINDINGS What is the topic of this review? This review discusses the current status of the literature in sex differences in exertional heat stroke. What advances does this review highlight? We utilize a translational model to explore possible physical and physiological differences with respect risk and treatment of exertional heat stroke. ABSTRACT Exertional heat stroke (EHS) is a potentially fatal condition brought about by a combination of physical activity and heat stress and resulting in central nervous system dysfunction and organ damage. EHS impacts several hundred individuals each year ranging from military personnel, athletes, to occupational workers. Understanding the pathophysiology and risk factors can aid in reducing EHS across the globe. While we know there are differences between sexes in mechanisms of thermoregulation, there is currently not a clear understanding if/how those differences impact EHS risk. The purpose of this review is to assess the current status of the literature surrounding EHS from risk factors to treatment using both animal and human models. We use a translational approach, considering both animal and human research to elucidate the possible influence of female sex hormones on temperature regulation and performance in the heat and highlight the specific areas with limited research. While more work is necessary to comprehensively understand these differences, the current research presented provides a good framework for future investigations. This article is protected by copyright. All rights reserved.
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Affiliation(s)
- Gabrielle Giersch
- Thermal and Mountain Medicine Division, U.S. Army Research Institute for Environmental Medicine, Natick, MA, USA.,Oak Ridge Institute for Science and Education, Belcamp, MD, USA
| | - Christian Garcia
- Department of Nutrition and Integrative Physiology, Florida State University, Tallahassee, FL, USA
| | - Nina Stachenfeld
- John B. Pierce Laboratory, Yale School of Medicine, New Haven, CT, USA
| | - Nisha Charkoudian
- Thermal and Mountain Medicine Division, U.S. Army Research Institute for Environmental Medicine, Natick, MA, USA
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44
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Sex Differences in VO 2max and the Impact on Endurance-Exercise Performance. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2022; 19:ijerph19094946. [PMID: 35564339 PMCID: PMC9105160 DOI: 10.3390/ijerph19094946] [Citation(s) in RCA: 23] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/07/2022] [Accepted: 04/15/2022] [Indexed: 02/04/2023]
Abstract
It was not until 1984 that women were permitted to compete in the Olympic marathon. Today, more women than men participate in road racing in all distances except the marathon where participation is near equal. From the period of 1985 to 2004, the women’s marathon record improved at a rate three times greater than men’s. This has led many to question whether women are capable of surpassing men despite the fact that there remains a 10–12% performance gap in all distance events. The progressive developments in sports performance research and training, beginning with A.V. Hill’s establishment of the concept of VO2max, have allowed endurance athletes to continue performance feats previously thought to be impossible. However, even today women are significantly underrepresented in sports performance research. By focusing more research on the female physiology and sex differences between men and women, we can better define how women differ from men in adapting to training and potentially use this information to improve endurance-exercise performance in women. The male advantage in endurance-exercise performance has commonly been attributed to their higher VO2max, even when expressed as mL/kg/min. It is widely known that oxygen delivery is the primary limiting factor in elite athletes when it comes to improving VO2max, but little research has explored the sex differences in oxygen delivery. Thus, the purpose of this review is to highlight what is known about the sex differences in the physiological factors contributing to VO2max, more specifically oxygen delivery, and the impacts on performance.
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Farré R, Rodríguez-Lázaro MA, Dinh-Xuan AT, Pons-Odena M, Navajas D, Gozal D. A Low-Cost, Easy-to-Assemble Device to Prevent Infant Hyperthermia under Conditions of High Thermal Stress. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2021; 18:ijerph182413382. [PMID: 34948991 PMCID: PMC8703827 DOI: 10.3390/ijerph182413382] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/18/2021] [Revised: 12/10/2021] [Accepted: 12/16/2021] [Indexed: 12/14/2022]
Abstract
High ambient temperature and humidity greatly increase the risk of hyperthermia and mortality, particularly in infants, who are especially prone to dehydration. World areas at high risk of heat stress include many of the low- and middle-income countries (LMICs) where most of their inhabitants have no access to air conditioning. This study aimed to design, evaluate, and test a novel low-cost and easy-to-assemble device aimed at preventing the risk of infant hyperthermia in LMICs. The device is based on optimizing negative heat transfer from a small amount of ice and transferring it directly to the infant by airflow of refrigerated air. As a proof of concept, a device was assembled mainly using recycled materials, and its performance was assessed under laboratory-controlled conditions in a climatic chamber mimicking realistic stress conditions of high temperature and humidity. The device, which can be assembled by any layperson using easily available materials, provided sufficient refrigerating capacity for several hours from just 1–2 kg of ice obtained from a domestic freezer. Thus, application of this novel device may serve to attenuate the adverse effects of heat stress in infants, particularly in the context of the evolving climatic change trends.
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Affiliation(s)
- Ramon Farré
- Unitat de Biofísica i Bioenginyeria, Facultat de Medicina i Ciències de la Salut, Universitat de Barcelona, 08036 Barcelona, Spain; (M.A.R.-L.); (D.N.)
- CIBER de Enfermedades Respiratorias, 28029 Madrid, Spain
- Institut Investigacions Biomèdiques August Pi Sunyer, 08036 Barcelona, Spain
- Correspondence:
| | - Miguel A. Rodríguez-Lázaro
- Unitat de Biofísica i Bioenginyeria, Facultat de Medicina i Ciències de la Salut, Universitat de Barcelona, 08036 Barcelona, Spain; (M.A.R.-L.); (D.N.)
| | - Anh Tuan Dinh-Xuan
- Service de Physiologie-Explorations Fonctionnelles, Hôpital Cochin, Assistance Publique-Hôpitaux de Paris (AP-HP), 75014 Paris, France;
| | - Martí Pons-Odena
- Immune and Respiratory Dysfunction Research Group, Institut de Recerca Sant Joan de Déu, Pediatric Intensive Care and Intermediate Care Department, Sant Joan de Déu University Hospital, Universitat de Barcelona, 08950 Esplugues de Llobregat, Spain;
| | - Daniel Navajas
- Unitat de Biofísica i Bioenginyeria, Facultat de Medicina i Ciències de la Salut, Universitat de Barcelona, 08036 Barcelona, Spain; (M.A.R.-L.); (D.N.)
- CIBER de Enfermedades Respiratorias, 28029 Madrid, Spain
- The Institute for Bioengineering of Catalonia (IBEC), The Barcelona Institute of Science and Technology (BIST), 08028 Barcelona, Spain
| | - David Gozal
- Department of Child Health, The University of Missouri School of Medicine, Columbia, MO 65201, USA;
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Effect of fatigue strength exercise on anterior thigh skin temperature rewarming after cold stress test. J Therm Biol 2021; 101:103098. [PMID: 34879916 DOI: 10.1016/j.jtherbio.2021.103098] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2021] [Revised: 08/20/2021] [Accepted: 09/14/2021] [Indexed: 11/21/2022]
Abstract
Although dynamic thermography skin temperature assessment has been used in medical field, scientific evidence in sports is scarce. The aim of the study was to assess changes in anterior thigh skin temperature in response to a cold stress test after a strength exercise fatiguing protocol. Ten physically active adults performed a familiarization session and two strength exercise sessions, one with dominant and the other with non-dominant lower limb. Participants performed bouts of 10 concentric and eccentric contractions of leg extensions in an isokinetic device until reaching around 30% of force loss. Infrared thermographic images were taken at baseline conditions and after the fatigue level from both thighs after being cooled using a cryotherapy system. ROIs included vastus medialis, rectus femoris, adductor and vastus lateralis. Skin temperature rewarming was assessed during 180s after the cooling process obtaining the coefficients of the following equation: ΔSkin temperature = β0 + β1 * ln(T), being β0 and β1 the constant and slope coefficients, respectively, T the time elapsed following the cold stress in seconds, and ΔSkin temperature the difference between the skin temperature at T respect and the pre-cooling moment. Lower β0 and higher β1 were found for vastus lateralis and rectus femoris in the intervention lower limb compared with baseline conditions (p < 0.05 and ES > 0.6). Adductor only showed differences in β0 (p = 0.01 and ES = 0.92). The regressions models obtained showed that β0 and β1 had a direct relationship with age and muscle mass, but an inverse relationship with the number of series performed until 30% of fatigue (R2 = 0.8). In conclusion, fatigue strength exercise results in a lower skin temperature and a faster thermal increase after a cold stress test.
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47
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Skin temperature measurement in individuals with spinal cord injury during and after exercise: Systematic review. J Therm Biol 2021; 105:103146. [DOI: 10.1016/j.jtherbio.2021.103146] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2021] [Revised: 11/14/2021] [Accepted: 11/29/2021] [Indexed: 11/24/2022]
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48
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Haematological, Biochemical and Hormonal Biomarkers of Heat Intolerance in Military Personnel. BIOLOGY 2021; 10:biology10101068. [PMID: 34681165 PMCID: PMC8533107 DOI: 10.3390/biology10101068] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/14/2021] [Revised: 10/15/2021] [Accepted: 10/15/2021] [Indexed: 01/31/2023]
Abstract
Simple Summary This study focuses on the biomarkers that are predictive of heat intolerance in military populations. Military personnel are at risk of exertional heat stroke when the body’s temperature increases during intense physical activity in hot weather. Exertional heat stroke (EHS) may accompany or precede heat intolerance, an unusual sensitivity to heat. However, it is unknown if blood biomarkers (haematological, biochemical and hormonal) are predictive of heat intolerance. We subjected a sample of Australian Defence Force personnel and civilian volunteers to a heat tolerance test (HTT), and blood samples were obtained pre-and post–HTT. The results showed that a history of EHS was associated with changes in creatinine and urea. The biochemical and hormonal biomarkers associated with heat intolerance were alanine amino transaminase, creatine kinase, cortisol and creatinine. Furthermore, creatinine and cortisol were identified as predictors and useful biomarkers of heat intolerance. This study also highlights the need for further exploration of genetic biomarkers to aid early identification and the return to duty process for military personnel who may be at risk of heat intolerance. Abstract Heat intolerance is the inability to withstand heat stress and this may occur due to exertional heat stroke (EHS). However, it is unknown if heat intolerance is associated with immune and hormonal disturbances. This study investigates haematological, biochemical and hormonal biomarkers related to heat intolerance and EHS in military and civilian volunteers. A quasi-experimental pre-and post-test design was used, with participants drawn from the Australian Defence Force (ADF) and the general populace. Blood samples were collected and analysed for biomarkers. Inferential statistics compared the biomarkers between the groups. Changes in alanine amino transaminase (p = 0.034), creatine kinase (0.044), cortisol (p = 0.041) and creatinine (p < 0.001) differed between the heat-intolerant and heat-tolerant groups. Participants with a history of EHS showed significant changes in creatinine (p = 0.022) and urea (p = 0.0031) compared to those without EHS history. Predictors of heat intolerance were increasing post-HTT creatinine and cortisol (OR = 1.177, p = 0.011 and OR = 1.015, p = 0.003 respectively). Conclusively, EHS history is associated with changes in creatinine and urea concentrations, while the predictors of heat intolerance are creatinine and cortisol. However, further exploration of other biomarkers, such as genetic polymorphism, is needed.
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Podlogar T, Bolčič T, Cirnski S, Verdel N, Debevec T. Commercially available carbohydrate drink with menthol fails to improve thermal perception or cycling exercise capacity in males. Eur J Sport Sci 2021; 22:1705-1713. [PMID: 34559601 DOI: 10.1080/17461391.2021.1986140] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
The purpose of this double-blinded, crossover randomized and counterbalanced study was to compare the effects of ingesting a tepid commercially available carbohydrate-menthol-containing sports drink (menthol) and an isocaloric carbohydrate-containing sports drink (placebo) on thermal perception and cycling endurance capacity "in a simulated home virtual cycling environment". It was hypothesized that the addition of menthol would improve indicators of thermal perception and improve endurance exercise capacity. Twelve healthy, endurance-trained males (age 29 ± 5 years, height 181 ± 6 cm, body mass 79 ± 2 kg and V̇O2max 57.3 ± 6.4 mL kg-1 min-1) completed two experimental trials on a stationary bicycle without external air flow. Each trial consisted of (1) cycling for 60 min at 90% of the first ventilatory threshold while receiving a fixed amount of menthol or placebo every 10 min followed immediately by (2) cycling until volitional exhaustion (TTE) at 105% of the intensity corresponding to the respiratory compensation point. TTE did not differ between both conditions (541 ± 177 and 566 ± 150 s for menthol and placebo; p > 0.05) and neither did ratings of perceived thermal comfort or thermal sensation (p > 0.05). Also, the rectal temperature at the end of TTE was comparable between menthol and placebo trials (38.7 ± 0.2°C and 38.7 ± 0.3°C, respectively; p > 0.05). The present results demonstrate that the addition of menthol to commercially available sports drink does not improve thermal comfort or endurance exercise capacity during ∼65 min of intense virtual cycling.
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Affiliation(s)
- Tim Podlogar
- Department of Automation, Biocybernetics and Robotics, Jožef Stefan Institute, Ljubljana, Slovenia.,Faculty of Health Sciences, University of Primorska, Izola, Slovenia
| | - Tina Bolčič
- Faculty of Sports, University of Ljubljana, Ljubljana, Slovenia
| | | | - Nina Verdel
- Swedish Winter Sports Research Centre, Mid Sweden University, Östersund, Sweden
| | - Tadej Debevec
- Department of Automation, Biocybernetics and Robotics, Jožef Stefan Institute, Ljubljana, Slovenia.,Faculty of Sports, University of Ljubljana, Ljubljana, Slovenia
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50
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Fukuhara K, Mikami Y, Hasegawa H, Nakashima D, Ikuta Y, Tajima F, Kimura H, Adachi N. Thermoregulatory responses in persons with lower-limb amputation during upper-limb endurance exercise in a hot and humid environment. Prosthet Orthot Int 2021; 45:401-409. [PMID: 34483329 PMCID: PMC9201935 DOI: 10.1097/pxr.0000000000000030] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/19/2021] [Accepted: 07/27/2021] [Indexed: 02/03/2023]
Abstract
BACKGROUND Persons with an amputation may have an increased heat strain due to reduced surface area. However, there is limited evidence on the thermoregulatory responses in persons with lower-limb amputation (LLA). Although a previous study reported no difference in their rectal temperatures (Tres) in a hot environment, suggesting compensatory sweating of the intact limb, we examined the thermoregulatory responses of such persons in a hot and humid environment. OBJECTIVE To compare the thermoregulatory responses-through changes in Tre, sweat, and oxygen uptake (O2)-between persons with LLA and able-bodied (AB) individuals, in hot and humid environments. STUDY DESIGN A nonrandomized control trial. METHODS Nine AB men (AB group) and nine persons with LLA group performed the arm ergometer exercise at 60% peak power output intensity for 60 min in a hot and humid environment, and they were tested before and after performing. The O2, Tre and skin temperature, and total body sweating, and local sweating during exercise were measured and compared between the groups. RESULTS The changes in O2 and Tre after the endurance exercise did not differ between the groups (ΔTre: AB group, 1.1°C ± 0.5°C; LLA group, 1.2°C ±0.3 °C; P = 0.65), whereas the amount of local sweating of the chest (group effect, P < 0.01 by two-way analysis of variance [group × time], the group effect size was medium, η2 = 0.10) and dehydration rate (AB group, 1.5% ± 0.5%; LLA group, 2.1% ± 0.5%; P = 0.03) were higher in the LLA than in the AB group. CONCLUSIONS We compared the thermoregulatory responses of persons with LLA with those of AB individuals in hot and humid environments. Core body temperatures of persons with LLAs during endurance exercise were not different from those of AB men even in hot and humid environments. We found compensatory increases in the sweat rate of the chest and increased dehydration rate in persons with LLA. More sweat potentially means that athletes with LLA need to drink more fulids.
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Affiliation(s)
- Kouki Fukuhara
- Department of Rehabilitation Medicine, Graduate School of Biomedical and Health Sciences, Hiroshima University, Japan
- Sports Medical Center, Hiroshima University Hospital, Japan
| | - Yukio Mikami
- Department of Rehabilitation Medicine, Wakayama Medical University, Japan
| | - Hiroshi Hasegawa
- Graduate School of Humanities and Social Sciences, Hiroshima University, Japan
| | | | - Yasunari Ikuta
- Sports Medical Center, Hiroshima University Hospital, Japan
| | - Fumihiro Tajima
- Department of Rehabilitation Medicine, Wakayama Medical University, Japan
| | - Hiroaki Kimura
- Department of Rehabilitation Medicine, Hiroshima University Hospital, Japan
| | - Nobuo Adachi
- Sports Medical Center, Hiroshima University Hospital, Japan
- Department of Orthopaedic Surgery, Graduate School of Biomedical and Health Sciences, Hiroshima University, Japan
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