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Barry H, Iglesies-Grau J, Chaseling GK, Paul J, Gosselin C, D'Oliviera-Sousa C, Juneau M, Harel F, Kaiser D, Pelletier-Galarneau M, Gagnon D. The Effect of Heat Exposure on Myocardial Blood Flow and Cardiovascular Function. Ann Intern Med 2024. [PMID: 38857500 DOI: 10.7326/m24-3504] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 06/12/2024] Open
Abstract
BACKGROUND Heat extremes are associated with greater risk for cardiovascular death. The pathophysiologic mechanisms mediating this association are unknown. OBJECTIVE To quantify the myocardial blood flow (MBF) requirements of heat exposure. DESIGN Experimental study. (ClinicalTrials.gov: NCT04549974). SETTING Laboratory-based. PARTICIPANTS 61 participants, comprising 20 healthy young adults (mean age, 28 years), 21 healthy older adults (mean age, 67 years), and 20 older adults with coronary artery disease (CAD) (mean age, 70 years). INTERVENTION Participants were heated until their core temperature increased 1.5 °C; MBF was measured before heat exposure and at every increase of 0.5 °C in core temperature. MEASUREMENTS The primary outcome was MBF measured by positron emission tomography-computed tomography. Secondary outcomes included heart rate, blood pressure, and body weight change. RESULTS At a core temperature increase of 1.5 °C, MBF increased in healthy young adults (change, 0.8 mL/min/g [95% CI, 0.5 to 1.0 mL/min/g]), healthy older adults (change, 0.7 mL/min/g [CI, 0.5 to 0.9 mL/min/g]), and older adults with CAD (change, 0.6 mL/min/g [CI, 0.3 to 0.8 mL/min/g]). This represented a 2.08-fold (CI, 1.75- to 2.41-fold), 1.79-fold (CI, 1.59- to 1.98-fold), and 1.64-fold (CI, 1.41- to 1.87-fold) change, respectively, from preexposure values. Imaging evidence of asymptomatic heat-induced myocardial ischemia was seen in 7 adults with CAD (35%) in post hoc analyses. LIMITATIONS In this laboratory-based study, heating was limited to about 100 minutes and participants were restricted in movement and fluid intake. Participants refrained from strenuous exercise and smoking; stopped alcohol and caffeine intake; and withheld β-blockers, calcium-channel blockers, and nitroglycerin before heating. CONCLUSION Heat exposure that increases core temperature by 1.5 °C nearly doubles MBF. Changes in MBF did not differ by age or presence of CAD, but some older adults with CAD may experience asymptomatic myocardial ischemia. PRIMARY FUNDING SOURCE Canadian Institutes of Health Research.
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Affiliation(s)
- Hadiatou Barry
- Montreal Heart Institute and Department of Pharmacology and Physiology, Faculty of Medicine, Université de Montréal, Montreal, Quebec, Canada (H.B.)
| | - Josep Iglesies-Grau
- Montreal Heart Institute and Department of Medicine, Université de Montréal, Montreal, Quebec, Canada (J.I.)
| | - Georgia K Chaseling
- Engagement and Co-Design Research Hub, School of Health Sciences, Faculty of Medicine and Health, University of Sydney, Sydney, New South Wales, Australia (G.K.C.)
| | - Jade Paul
- Montreal Heart Institute, Montreal, Quebec, Canada (J.P., C.G., M.J.)
| | - Camila Gosselin
- Montreal Heart Institute, Montreal, Quebec, Canada (J.P., C.G., M.J.)
| | - Caroline D'Oliviera-Sousa
- Department of Medical Imaging, Montreal Heart Institute, Montreal, Quebec, Canada (C.D., F.H., M.P.)
| | - Martin Juneau
- Montreal Heart Institute, Montreal, Quebec, Canada (J.P., C.G., M.J.)
| | - Francois Harel
- Department of Medical Imaging, Montreal Heart Institute, Montreal, Quebec, Canada (C.D., F.H., M.P.)
| | - David Kaiser
- Direction de Santé Publique du Centre Intégré Universitaire de Santé et de Services Sociaux du Centre-Sud-de-l'Île-de-Montréal, Montreal, Quebec, Canada (D.K.)
| | | | - Daniel Gagnon
- Montreal Heart Institute and School of Kinesiology and Exercise Science, Faculty of Medicine, Université de Montréal, Montreal, Quebec, Canada (D.G.)
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Lee BJ, Flood TR, Galan-Lopez N, McCormick JJ, King KE, Fujii N, Kenny GP. Changes in surrogate markers of intestinal epithelial injury and microbial translocation in young and older men during prolonged occupational heat stress in temperate and hot conditions. Eur J Appl Physiol 2024; 124:1049-1062. [PMID: 37815618 DOI: 10.1007/s00421-023-05329-7] [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: 04/06/2023] [Accepted: 09/16/2023] [Indexed: 10/11/2023]
Abstract
PURPOSE Exertional heat stress can cause damage to the intestinal epithelium and disrupt gastrointestinal barrier integrity, leading to microbial translocation (MT) linked to the development of heat stroke. This study aimed to assess age-related differences in markers of intestinal epithelial injury and MT following non-heat stress and high-heat stress exercise in healthy young and older men. METHODS Markers of intestinal epithelial injury (intestinal fatty acid-binding protein-'IFABP') and MT (soluble cluster of differentiation 14-'sCD14'; and lipopolysaccharide-binding protein-'LBP') were assessed in healthy young (18-30 y, n = 13) and older (50-70 y) men (n = 12). Blood samples were collected before, after 180 min of moderate-intensity (metabolic rate: 200 W/m2) walking and following 60 min recovery in either a non-heat stress [temperate: 21.9 °C, 35% relative humidity (RH)] or high-heat stress (hot: 41.4 °C, 35% RH) environment. RESULTS There were no differences in IFABP and sCD14 between the young and older groups in the temperate condition, while LBP was greater in the older group (+ 0.66 ug/mL; + 0.08 to + 1.24 ug/mL). In the hot condition, the older group experienced greater increases in IFABP compared to the young group (+ 712 pg/mL/hr; + 269 to + 1154 pg/mL/hr). However, there were no clear between-group differences for sCD14 (+ 0.24 ug/mL/hr, - 0.22 to + 0.70 ug/mL/hr) or LBP (+ 0.86 ug/mL/hr, - 0.73 to + 2.46 ug/mL/hr). CONCLUSION While older men may experience greater intestinal epithelial injury following exercise in the heat; this did not lead to a greater magnitude of microbial translocation relative to their younger counterparts.
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Affiliation(s)
- Ben J Lee
- Occupational and Environmental Physiology Group, Centre for Sport, Exercise, and Life Sciences, Coventry University, Coventry, UK
| | - Tessa R Flood
- Institute of Sport, Manchester Metropolitan University, Manchester, UK
| | - Natalia Galan-Lopez
- Occupational and Environmental Physiology Group, Centre for Sport, Exercise, and Life Sciences, Coventry University, Coventry, UK
- School of Sport, Exercise and Health Sciences, Loughborough University, Loughborough, UK
| | - James J McCormick
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, 125 University Ave., Room 367, Montpetit Hall, Ottawa, ON, K1N 6N5, Canada
| | - Kelli E King
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, 125 University Ave., Room 367, Montpetit Hall, Ottawa, ON, K1N 6N5, Canada
| | - Naoto Fujii
- Health and Sport Sciences, University of Tsukuba, Tsukuba, Japan
| | - Glen P Kenny
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, 125 University Ave., Room 367, Montpetit Hall, Ottawa, ON, K1N 6N5, Canada.
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Bachraty JP, Qiao J, Powers ES, Vandermark LW, Pryor JL, Pryor RR. Plateau in Core Temperature during Shorter but Not Longer Work/Rest Cycles in Heat. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2024; 21:371. [PMID: 38541370 PMCID: PMC10970706 DOI: 10.3390/ijerph21030371] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/29/2024] [Revised: 03/12/2024] [Accepted: 03/18/2024] [Indexed: 04/09/2024]
Abstract
This study compared physiological responses to two work/rest cycles of a 2:1 work-to-rest ratio in a hot environment. In a randomized crossover design, fourteen participants completed 120 min of walking and rest in the heat (36.3 ± 0.6 °C, 30.2 ± 4.0% relative humidity). Work/rest cycles were (1) 40 min work/20 min rest [40/20], or (2) 20 min work/10 min rest [20/10], both completing identical work. Core temperature (Tc), skin temperature (Tsk), heart rate (HR), nude body mass, and perception of work were collected. Comparisons were made between trials at equal durations of work using three-way mixed model ANOVA. Tc plateaued in [20/10] during the second hour of work (p = 0.93), while Tc increased in [40/20] (p < 0.01). There was no difference in maximum Tc ([40/20]: 38.08 ± 0.35 °C, [20/10]: 37.99 ± 0.27 °C, p = 0.22) or end-of-work Tsk ([40/20]: 36.1 ± 0.8 °C, [20/10]: 36.0 ± 0.7 °C, p = 0.45). End-of-work HR was greater in [40/20] (145 ± 25 b·min-1) compared to [20/10] (141 ± 27 b·min-1, p = 0.04). Shorter work/rest cycles caused a plateau in Tc while longer work/rest cycles resulted in a continued increase in Tc throughout the work, indicating that either work structure could be used during shorter work tasks, while work greater than 2 h in duration may benefit from shorter work/rest cycles to mitigate hyperthermia.
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Affiliation(s)
| | | | | | | | | | - Riana R. Pryor
- Center for Research and Education in Special Environments, Department of Exercise and Nutrition Sciences, University at Buffalo, Buffalo, NY 14214, USA (J.Q.); (E.S.P.)
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Bach AJE, Cunningham SJK, Morris NR, Xu Z, Rutherford S, Binnewies S, Meade RD. Experimental research in environmentally induced hyperthermic older persons: A systematic quantitative literature review mapping the available evidence. Temperature (Austin) 2024; 11:4-26. [PMID: 38567267 PMCID: PMC7615797 DOI: 10.1080/23328940.2023.2242062] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2023] [Accepted: 07/21/2023] [Indexed: 04/04/2024] Open
Abstract
The heat-related health burden is expected to persist and worsen in the coming years due to an aging global population and climate change. Defining the breadth and depth of our understanding of age-related changes in thermoregulation can identify underlying causes and strategies to protect vulnerable individuals from heat. We conducted the first systematic quantitative literature review to provide context to the historical experimental research of healthy older adults - compared to younger adults or unhealthy age matched cases - during exogenous heat strain, focusing on factors that influence thermoregulatory function (e.g. co-morbidities). We identified 4,455 articles, with 147 meeting eligibility criteria. Most studies were conducted in the US (39%), Canada (29%), or Japan (12%), with 71% of the 3,411 participants being male. About 71% of the studies compared younger and older adults, while 34% compared two groups of older adults with and without factors influencing thermoregulation. Key factors included age combined with another factor (23%), underlying biological mechanisms (18%), age independently (15%), influencing health conditions (15%), adaptation potential (12%), environmental conditions (9%), and therapeutic/pharmacological interventions (7%). Our results suggest that controlled experimental research should focus on the age-related changes in thermoregulation in the very old, females, those with overlooked chronic heat-sensitive health conditions (e.g. pulmonary, renal, mental disorders), the impact of multimorbidity, prolonged and cumulative effects of extreme heat, evidence-based policy of control measures (e.g. personal cooling strategies), pharmaceutical interactions, and interventions stimulating protective physiological adaptation. These controlled studies will inform the directions and use of limited resources in ecologically valid fieldwork studies.
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Affiliation(s)
- Aaron J. E. Bach
- School of Medicine and Dentistry, Griffith University, Gold Coast, QLD, Australia
- Cities Research Institute, Griffith University, Gold Coast, QLD, Australia
| | - Sarah J. K. Cunningham
- School of Medicine and Dentistry, Griffith University, Gold Coast, QLD, Australia
- Cities Research Institute, Griffith University, Gold Coast, QLD, Australia
| | - Norman R. Morris
- School of Health Sciences and Social Work, Griffith University, Gold Coast, QLD, Australia
- Metro North Hospital and Health Service, The Prince Charles Hospital. Allied Health Research Collaborative, Brisbane, QLD, Australia
- Menzies Health Institute Queensland, Griffith University, Gold Coast, QLD, Australia
| | - Zhiwei Xu
- School of Medicine and Dentistry, Griffith University, Gold Coast, QLD, Australia
- Cities Research Institute, Griffith University, Gold Coast, QLD, Australia
| | - Shannon Rutherford
- School of Medicine and Dentistry, Griffith University, Gold Coast, QLD, Australia
- Cities Research Institute, Griffith University, Gold Coast, QLD, Australia
| | - Sebastian Binnewies
- School of Information and Communication Technology, Griffith University, Gold Coast, QLD, Australia
| | - Robert D. Meade
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, ON, Canada
- Harvard T.H. Chan School of Public Health, Harvard University, Boston, MA, USA
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5
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Koch Esteves N, Khir AW, González‐Alonso J. Lower limb hyperthermia augments functional hyperaemia during small muscle mass exercise similarly in trained elderly and young humans. Exp Physiol 2023; 108:1154-1171. [PMID: 37409754 PMCID: PMC10988472 DOI: 10.1113/ep091275] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2023] [Accepted: 06/23/2023] [Indexed: 07/07/2023]
Abstract
NEW FINDINGS What is the central question of the study? Ageing is postulated to lead to underperfusion of human limb tissues during passive and exertional hyperthermia, but findings to date have been equivocal. Thus, does age have an independent adverse effect on local haemodynamics during passive single-leg hyperthermia, single-leg knee-extensor exercise and their combination? What is the main finding and its importance? Local hyperthermia increased leg blood flow over three-fold and had an additive effect during knee-extensor exercise with no absolute differences in leg perfusion between the healthy, exercise-trained elderly and the young groups. Our findings indicate that age per se does not compromise lower limb hyperaemia during local hyperthermia and/or small muscle mass exercise. ABSTRACT Heat and exercise therapies are recommended to improve vascular health across the lifespan. However, the haemodynamic effects of hyperthermia, exercise and their combination are inconsistent in young and elderly people. Here we investigated the acute effects of local-limb hyperthermia and exercise on limb haemodynamics in nine healthy, trained elderly (69 ± 5 years) and 10 young (26 ± 7 years) adults, hypothesising that the combination of local hyperthermia and exercise interact to increase leg perfusion, albeit to a lesser extent in the elderly. Participants underwent 90 min of single whole-leg heating, with the contralateral leg remaining as control, followed by 10 min of low-intensity incremental single-leg knee-extensor exercise with both the heated and control legs. Temperature profiles and leg haemodynamics at the femoral and popliteal arteries were measured. In both groups, heating increased whole-leg skin temperature and blood flow by 9.5 ± 1.2°C and 0.7 ± 0.2 L min-1 (>3-fold), respectively (P < 0.0001). Blood flow in the heated leg remained 0.7 ± 0.6 and 1.0 ± 0.8 L min-1 higher during exercise at 6 and 12 W, respectively (P < 0.0001). However, there were no differences in limb haemodynamics between cohorts, other than the elderly group exhibiting a 16 ± 6% larger arterial diameter and a 51 ± 6% lower blood velocity following heating (P < 0.0001). In conclusion, local hyperthermia-induced limb hyperperfusion and/or small muscle mass exercise hyperaemia are preserved in trained older people despite evident age-related structural and functional alterations in their leg conduit arteries.
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Affiliation(s)
- Nuno Koch Esteves
- Division of Sport, Health, and Exercise Sciences, Department of Life SciencesBrunel University LondonUxbridgeUK
| | | | - José González‐Alonso
- Division of Sport, Health, and Exercise Sciences, Department of Life SciencesBrunel University LondonUxbridgeUK
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6
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Meade RD, Notley SR, Akerman AP, McGarr GW, Richards BJ, McCourt ER, King KE, McCormick JJ, Boulay P, Sigal RJ, Kenny GP. Physiological responses to 9 hours of heat exposure in young and older adults. Part I: Body temperature and hemodynamic regulation. J Appl Physiol (1985) 2023; 135:673-687. [PMID: 37439239 DOI: 10.1152/japplphysiol.00227.2023] [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: 04/11/2023] [Revised: 06/23/2023] [Accepted: 07/10/2023] [Indexed: 07/14/2023] Open
Abstract
Aging is associated with an elevated risk of heat-related mortality and morbidity, attributed, in part, to declines in thermoregulation. However, comparisons between young and older adults have been limited to brief exposures (1-4 h), which may not adequately reflect the duration or severity of the heat stress experienced during heat waves. We therefore evaluated physiological responses in 20 young (19-31 yr; 10 females) and 39 older (61-78 yr; 11 females) adults during 9 h of rest at 40°C and 9% relative humidity. Whole body heat exchange and storage were measured with direct calorimetry during the first 3 h and final 3 h. Core temperature (rectal) was monitored continuously. The older adults stored 88 kJ [95% confidence interval (CI): 29, 147] more heat over the first 3 h of exposure (P = 0.006). Although no between-group differences were observed after 3 h [young: 37.6°C (SD 0.2°C) vs. older: 37.7°C (0.3°C); P = 0.216], core temperature was elevated by 0.3°C [0.1, 0.4] (adjusted for baseline) in the older group at hour 6 [37.6°C (0.2°C) vs. 37.9°C (0.2°C); P < 0.001] and by 0.2°C [0.0, 0.3] at hour 9 [37.7°C (0.3°C) vs. 37.8°C (0.3°C)], although the latter comparison was not significant after multiplicity correction (P = 0.061). Our findings indicate that older adults sustain greater increases in heat storage and core temperature during daylong exposure to hot dry conditions compared with their younger counterparts. This study represents an important step in the use of ecologically relevant, prolonged exposures for translational research aimed at quantifying the physiological and health impacts of hot weather and heat waves on heat-vulnerable populations.NEW & NOTEWORTHY We found greater increases in body heat storage and core temperature in older adults than in their younger counterparts during 9 h of resting exposure to hot dry conditions. Furthermore, the age-related increase in core temperature was exacerbated in older adults with common heat-vulnerability-linked health conditions (type 2 diabetes and hypertension). Impairments in thermoregulatory function likely contribute to the increased risk of heat-related illness and injury seen in older adults during hot weather and heat waves.
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Affiliation(s)
- Robert D Meade
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, Ontario, Canada
- Harvard T.H. Chan School of Public Health, Harvard University, Boston, Massachusetts, United States
| | - Sean R Notley
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, Ontario, Canada
| | - Ashley P Akerman
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, Ontario, Canada
| | - Gregory W McGarr
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, Ontario, Canada
| | - Brodie J Richards
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, Ontario, Canada
| | - Emma R McCourt
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, Ontario, Canada
| | - Kelli E King
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, Ontario, Canada
| | - James J McCormick
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, Ontario, Canada
| | - Pierre Boulay
- Faculty of Physical Activity Sciences, University of Sherbrooke, Sherbrooke, Quebec, Canada
| | - Ronald J Sigal
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, Ontario, Canada
- Department of Medicine, Faculty of Medicine, University of Calgary, Calgary, Alberta, Canada
- Department of Cardiac Sciences, Faculty of Medicine, University of Calgary, Calgary, Alberta, Canada
- Department of Community Health Sciences, Faculty of Medicine, University of Calgary, Calgary, Alberta, Canada
- Faculty of Kinesiology, University of Calgary, Calgary, Alberta, Canada
- Clinical Epidemiology Program, Ottawa Hospital Research Institute, Ottawa, Ontario, Canada
| | - Glen P Kenny
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, Ontario, Canada
- Clinical Epidemiology Program, Ottawa Hospital Research Institute, Ottawa, Ontario, Canada
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7
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McKenna ZJ, Foster J, Atkins WC, Belval LN, Watso JC, Jarrard CP, Orth BD, Crandall CG. Age alters the thermoregulatory responses to extreme heat exposure with accompanying activities of daily living. J Appl Physiol (1985) 2023; 135:445-455. [PMID: 37410904 PMCID: PMC10538984 DOI: 10.1152/japplphysiol.00285.2023] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2023] [Revised: 06/15/2023] [Accepted: 06/27/2023] [Indexed: 07/08/2023] Open
Abstract
Older adults are at greater risk for heat-related morbidity and mortality, due in part to age-related reductions in heat dissipating capabilities. Previous studies investigating the impact of age on responses to heat stress used approaches that lack activities of daily living and therefore may not accurately depict the thermal/physiological strain that would occur during actual heatwaves. We sought to compare the responses of young (18-39 yr) and older (≥65 yr) adults exposed to two extreme heat simulations. Healthy young (n = 20) and older (n = 20) participants underwent two 3-h extreme heat exposures on different days: 1) DRY (47°C and 15% humidity) and 2) HUMID (41°C and 40% humidity). To mimic heat generation comparable with activities of daily living, participants performed 5-min bouts of light physical activity dispersed throughout the heat exposure. Measurements included core and skin temperatures, heart rate, blood pressure, local and whole body sweat rate, forearm blood flow, and perceptual responses. Δ core temperature (Young: 0.68 ± 0.27°C vs. Older: 1.37 ± 0.42°C; P < 0.001) and ending core temperature (Young: 37.81 ± 0.26°C vs. Older: 38.15 ± 0.43°C; P = 0.005) were greater in the older cohort during the DRY condition. Δ core temperature (Young: 0.58 ± 0.25°C vs. Older: 1.02 ± 0.32°C; P < 0.001), but not ending core temperature (Young: 37.67 ± 0.34°C vs. Older: 37.83 ± 0.35°C; P = 0.151), was higher in the older cohort during the HUMID condition. We demonstrated that older adults have diminished thermoregulatory responses to heat stress with accompanying activities of daily living. These findings corroborate previous reports and confirm epidemiological data showing that older adults are at a greater risk for hyperthermia.NEW & NOTEWORTHY Using an experimental model of extreme heat exposure that incorporates brief periods of light physical activity to simulate activities of daily living, the extent of thermal strain reported herein more accurately represents what would occur during actual heatwave conditions. Despite matching metabolic heat generation and environmental conditions, we show that older adults have augmented core temperature responses, likely due to age-related reductions in heat dissipating mechanisms.
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Affiliation(s)
- Zachary J McKenna
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, Dallas, Texas, United States
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas, United States
| | - Josh Foster
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, Dallas, Texas, United States
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas, United States
| | - Whitley C Atkins
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, Dallas, Texas, United States
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas, United States
| | - Luke N Belval
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, Dallas, Texas, United States
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas, United States
| | - Joseph C Watso
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, Dallas, Texas, United States
- Department of Applied Clinical Research, University of Texas Southwestern Medical Center, Dallas, Texas, United States
| | - Caitlin P Jarrard
- Cardiovascular and Applied Physiology Laboratory, Department of Nutrition and Integrative Physiology, Florida State University, Tallahassee, Florida, United States
| | - Bonnie D Orth
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, Dallas, Texas, United States
| | - Craig G Crandall
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, Dallas, Texas, United States
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas, United States
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Venugopal V, Lennqvist R, Latha PK, Shanmugam R, Krishnamoorthy M, Selvaraj N, Balakrishnan R, Omprashant R, Purty AJ, Bazroy J, Glaser J, Jakobsson K. Occupational Heat Stress and Kidney Health in Salt Pan Workers. Kidney Int Rep 2023; 8:1363-1372. [PMID: 37441492 PMCID: PMC10334398 DOI: 10.1016/j.ekir.2023.04.011] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2022] [Revised: 04/08/2023] [Accepted: 04/10/2023] [Indexed: 07/15/2023] Open
Abstract
Introduction Work in heat affects millions of workers. Although kidney function in agricultural workers is increasingly researched, nonagricultural studies are scarce. In coastal salt pans, the absence of occupational exposures to pesticides and other toxicants allows assessment of heat stress alone. Methods Seven Indian salt pans were surveyed from 2017 to 2020. Job-specific workload was assessed. Heat stress was characterized as exceeding the wet bulb globe temperature (WBGT)-threshold limit value (TLV) for high and moderate workloads. Preshift and postshift heart rates (HRs), tympanic temperatures, and urine specific gravity (USG) were measured for 352 workers, as were sweat rates (SwR), serum creatinine (SCr), serum uric acid, and urine dipstick. Estimated glomerular filtration rate (eGFR; ml/min per 1.73 m2) was computed. Heat-strain symptoms were assessed using questionnaires. Results The mean WBGT was 30.5 ± 1.3 °C (summer) and 27.8 ± 1.9 °C (winter). Water intake during the workday was low, median was one Litre, and most workers (87%) exceeded the TLV for heat stress. Dehydration-related symptoms were frequent in those with high-heat stress, as were cross-shift increases in temperature (≥1°C; 15%), a high USG (≥1.020; 28%), and a high SwR (≥1 l/h; 53%). An eGFR of 60 to 89 ml/min per 1.73 m2 was observed in 41% of all workers examined, and 7% had eGFR below 60 ml/min per 1.73 m2. The odds ratio for eGFR <90 ml/min per 1.73 m2 in workers exceeding the TLV, compared to workers below this limit, adjusted for age and gender was 2.9 (95% CI: 1.3-6.4). Conclusion Workplace interventions to prevent heat stress and dehydration in the salt pans and other at-risk industries are urgently required. The findings strengthen the notion that high-heat stress and limited hydration is a risk factor for kidney dysfunction.
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Affiliation(s)
- Vidhya Venugopal
- Department of Environmental Health Engineering, Sri Ramachandra Institute of Higher Education and Research, Chennai, India
| | - Robin Lennqvist
- School of Public Health and Community Medicine, Institute of Medicine, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - PK Latha
- Department of Environmental Health Engineering, Sri Ramachandra Institute of Higher Education and Research, Chennai, India
| | - Rekha Shanmugam
- Department of Environmental Health Engineering, Sri Ramachandra Institute of Higher Education and Research, Chennai, India
| | - Manikandan Krishnamoorthy
- Department of Environmental Health Engineering, Sri Ramachandra Institute of Higher Education and Research, Chennai, India
| | - Nandhini Selvaraj
- Department of Environmental Health Engineering, Sri Ramachandra Institute of Higher Education and Research, Chennai, India
| | - Rajagurusamy Balakrishnan
- Department of Environmental Health Engineering, Sri Ramachandra Institute of Higher Education and Research, Chennai, India
| | - R. Omprashant
- Department of Environmental Health Engineering, Sri Ramachandra Institute of Higher Education and Research, Chennai, India
| | - Anil Jacob Purty
- Department of Community Medicine, Pondicherry Institute of Medical Sciences, Puducherry, India
| | - Joy Bazroy
- Department of Community Medicine, Pondicherry Institute of Medical Sciences, Puducherry, India
| | | | - Kristina Jakobsson
- School of Public Health and Community Medicine, Institute of Medicine, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
- La Isla Network, Washington, USA
- Department of Occupational and Environmental Medicine, Sahlgrenska University Hospital, Gothenburg, Sweden
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Meade RD, Notley SR, Akerman AP, McCormick JJ, King KE, Sigal RJ, Kenny GP. Efficacy of Cooling Centers for Mitigating Physiological Strain in Older Adults during Daylong Heat Exposure: A Laboratory-Based Heat Wave Simulation. ENVIRONMENTAL HEALTH PERSPECTIVES 2023; 131:67003. [PMID: 37262028 DOI: 10.1289/ehp11651] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
BACKGROUND Health agencies, including the U.S. Centers for Disease Control and Prevention and the World Health Organization, recommend that heat-vulnerable older adults without home air-conditioning should visit cooling centers or other air-conditioned locations (e.g., a shopping mall) during heat waves. However, experimental evidence supporting the effectiveness of brief air-conditioning is lacking. OBJECTIVE We evaluated whether brief exposure to an air-conditioned environment, as experienced in a cooling center, was effective for limiting physiological strain in older adults during a daylong laboratory-based heat wave simulation. METHODS Forty adults 64-79 years of age underwent a 9-h simulated heat wave (heat index: 37°C) with (cooling group, n=20) or without (control group, n=20) a cooling intervention consisting of 2-h rest in an air-conditioned room (∼23°C, hours 5-6). Core and skin temperatures, whole-body heat exchange and storage, cardiovascular function, and circulating markers of acute inflammation were assessed. RESULTS Core temperature was 0.8°C (95% CI: 0.6, 0.9) lower in the cooling group compared with the control group at the end of the cooling intervention (p<0.001; hour 6), and it remained 0.3°C (95% CI: 0.2, 0.4) lower an hour after returning to the heat (p<0.001; hour 7). Despite this, core temperatures in each group were statistically equivalent at hours 8 and 9, within ±0.3°C (p≤0.005). Cooling also acutely reduced demand on the heart and improved indices of cardiovascular autonomic function (p≤0.021); however, these outcomes were not different between groups at the end of exposure (p≥0.58). DISCUSSION Brief air-conditioning exposure during a simulated heat wave caused a robust but transient reduction in core temperature and cardiovascular strain. These findings provide important experimental support for national and international guidance that cooling centers are effective for limiting physiological strain during heat waves. However, they also show that the physiological impacts of brief cooling are temporary, a factor that has not been considered in guidance issued by health agencies. https://doi.org/10.1289/EHP11651.
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Affiliation(s)
- Robert D Meade
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, Ontario, Canada
- Harvard T.H. Chan School of Public Health, Harvard University, Boston, Massachusetts, USA
| | - Sean R Notley
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, Ontario, Canada
| | - Ashley P Akerman
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, Ontario, Canada
| | - James J McCormick
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, Ontario, Canada
| | - Kelli E King
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, Ontario, Canada
| | - Ronald J Sigal
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, Ontario, Canada
- Department of Medicine, Faculties of Medicine and Kinesiology, University of Calgary, Calgary, Alberta, Canada
- Department of Cardiac Sciences, Faculties of Medicine and Kinesiology, University of Calgary, Calgary, Alberta, Canada
- Department of Community Health Sciences, Faculties of Medicine and Kinesiology, University of Calgary, Calgary, Alberta, Canada
- Clinical Epidemiology Program, Ottawa Hospital Research Institute, Ottawa, Ontario, Canada
| | - Glen P Kenny
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, Ontario, Canada
- Clinical Epidemiology Program, Ottawa Hospital Research Institute, Ottawa, Ontario, Canada
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10
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Pacheco P, Mera E, Fuentes V. Intensive Urbanization, Urban Meteorology and Air Pollutants: Effects on the Temperature of a City in a Basin Geography. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2023; 20:3941. [PMID: 36900952 PMCID: PMC10001953 DOI: 10.3390/ijerph20053941] [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: 01/13/2023] [Revised: 02/11/2023] [Accepted: 02/16/2023] [Indexed: 06/18/2023]
Abstract
A qualitative study of thermal transfers is carried out from a record of measurements (time series) of meteorological variables (temperature, relative humidity and magnitude of wind speeds) and pollutants (PM10, PM2.5 and CO) in six localities located at different heights in the geographic basin of Santiago de Chile. The measurements were made in two periods, 2010-2013 and 2017-2020 (a total of 2,049,336 data), the last period coinciding with a process of intense urbanization, especially high-rise construction. The measurements, in the form of hourly time series, are analyzed on the one hand according to the theory of thermal conduction discretizing the differential equation of the temporal variation in the temperature and, on the other hand, through the theory of chaos that provides the entropies (S). Both procedures demonstrate, comparatively, that the last period of intense urbanization presents an increase in thermal transfers and temperature, which affects urban meteorology and makes it more complex. As shown by the chaotic analysis, there is a faster loss of information for the period 2017-2020. The consequences of the increase in temperature on human health and learning processes are studied.
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11
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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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12
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Savioli G, Zanza C, Longhitano Y, Nardone A, Varesi A, Ceresa IF, Manetti AC, Volonnino G, Maiese A, La Russa R. Heat-Related Illness in Emergency and Critical Care: Recommendations for Recognition and Management with Medico-Legal Considerations. Biomedicines 2022; 10:biomedicines10102542. [PMID: 36289804 PMCID: PMC9599879 DOI: 10.3390/biomedicines10102542] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2022] [Revised: 09/22/2022] [Accepted: 10/06/2022] [Indexed: 11/30/2022] Open
Abstract
Hyperthermia is an internal body temperature increase above 40.5 °C; normally internal body temperature is kept constant through natural homeostatic mechanisms. Heat-related illnesses occur due to exposure to high environmental temperatures in conditions in which an organism is unable to maintain adequate homeostasis. This can happen, for example, when the organism is unable to dissipate heat adequately. Heat dissipation occurs through evaporation, conduction, convection, and radiation. Heat disease exhibits a continuum of signs and symptoms ranging from minor to major clinical pictures. Minor clinical pictures include cramps, syncope, edema, tetany, and exhaustion. Major clinical pictures include heatstroke and life-threatening heat stroke and typically are expressed in the presence of an extremely high body temperature. There are also some categories of people at greater risk of developing these diseases, due to exposure in particular geographic areas (e.g., hot humid environments), to unchangeable predisposing conditions (e.g., advanced age, young age (i.e., children), diabetes, skin disease with reduced sweating), to modifiable risk factors (e.g., alcoholism, excessive exercise, infections), to partially modifiable risk factors (obesity), to certain types of professional activity (e.g., athletes, military personnel, and outdoor laborers) or to the effects of drug treatment (e.g., beta-blockers, anticholinergics, diuretics). Heat-related illness is largely preventable.
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Affiliation(s)
- Gabriele Savioli
- Emergency Department, IRCCS Policlinico San Matteo, 27100 Pavia, Italy
- Doctoral Program Experimental Medicine, Department of Clinical-Surgical, Diagnostic and Pediatric Sciences, University of Pavia, 27100 Pavia, Italy
| | - Christian Zanza
- Foundation “Ospedale Alba-Bra”, Department of Emergency Medicine, Anesthesia and Critical Care Medicine, Michele and Pietro Ferrero Hospital, 12060 Verduno, Italy
- Correspondence:
| | - Yaroslava Longhitano
- Foundation “Ospedale Alba-Bra”, Department of Emergency Medicine, Anesthesia and Critical Care Medicine, Michele and Pietro Ferrero Hospital, 12060 Verduno, Italy
| | - Alba Nardone
- Department of Internal Medicine, Università degli Studi of Pavia, 27100 Pavia, Italy
| | - Angelica Varesi
- Department of Internal Medicine, Università degli Studi of Pavia, 27100 Pavia, Italy
| | | | - Alice Chiara Manetti
- Department of Surgical, Medical and Molecular Pathology and Critical Care Medicine, Institute of Legal Medicine, University of Pisa, 56126 Pisa, Italy
| | - Gianpietro Volonnino
- Department of Anatomy, Histology, Forensic Medicine and Orthopedics, Sapienza University, 00185 Rome, Italy
| | - Aniello Maiese
- Department of Surgical, Medical and Molecular Pathology and Critical Care Medicine, Institute of Legal Medicine, University of Pisa, 56126 Pisa, Italy
| | - Raffaele La Russa
- Department of Clinical and Experimental Medicine, University of Foggia, 71122 Foggia, Italy
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13
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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: 57] [Impact Index Per Article: 28.5] [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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14
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Li PL, Yick KL, Yip J, Ng SP. Influence of Upper Footwear Material Properties on Foot Skin Temperature, Humidity and Perceived Comfort of Older Individuals. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2022; 19:10861. [PMID: 36078575 PMCID: PMC9518374 DOI: 10.3390/ijerph191710861] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/12/2022] [Revised: 08/17/2022] [Accepted: 08/30/2022] [Indexed: 06/15/2023]
Abstract
Studying the in-shoe microclimate of older individuals is important for enhancing their foot comfort and preventing foot diseases. However, there is a lack of scientific work that explores the thermo-physiological wear comfort of older individuals with different footwear. This study aims to examine the effects of upper footwear materials on changes and distributions in the foot skin temperature and relative humidity for older individuals. Forty older individuals are recruited to perform sitting and walking activities under four experimental conditions in a conditioning chamber. The findings indicate that footwear upper constructed of highly permeable mesh fabric with large air holes shows fewer changes in foot skin temperature (ranging from 1.3 to 3.3 °C) and relative humidity (ranging from -13.3 to 5.7%) throughout the entire foot during dynamic walking, as well as higher subjective ratings on perceived thermal comfort when compared to footwear made of synthetic leather and composite layers. The findings serve to enhance current understanding of designing footwear with optimum comfort for older adults.
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Affiliation(s)
- Pui-Ling Li
- School of Fashion and Textiles, The Hong Kong Polytechnic University, Hung Hom, Hong Kong SAR, China
- Laboratory for Artificial Intelligence in Design, Hong Kong Science Park, New Territories, Hong Kong SAR, China
| | - Kit-Lun Yick
- School of Fashion and Textiles, The Hong Kong Polytechnic University, Hung Hom, Hong Kong SAR, China
- Laboratory for Artificial Intelligence in Design, Hong Kong Science Park, New Territories, Hong Kong SAR, China
| | - Joanne Yip
- School of Fashion and Textiles, The Hong Kong Polytechnic University, Hung Hom, Hong Kong SAR, China
- Laboratory for Artificial Intelligence in Design, Hong Kong Science Park, New Territories, Hong Kong SAR, China
| | - Sun-Pui Ng
- School of Professional Education and Executive Development, The Hong Kong Polytechnic University, Hung Hom, Hong Kong SAR, China
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15
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Sugg MM, Runkle JD, Dow K, Barnes J, Stevens S, Pearce J, Bossak B, Curtis S. Individually experienced heat index in a coastal Southeastern US city among an occupationally exposed population. INTERNATIONAL JOURNAL OF BIOMETEOROLOGY 2022; 66:1665-1681. [PMID: 35759147 DOI: 10.1007/s00484-022-02309-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/17/2022] [Revised: 04/13/2022] [Accepted: 05/24/2022] [Indexed: 06/15/2023]
Abstract
Recent studies have characterized individually experienced temperatures or individually experienced heat indices, including new exposure metrics that capture dimensions of exposure intensity, frequency, and duration. Yet, few studies have examined the personal thermal exposure in underrepresented groups, like outdoor workers, and even fewer have assessed corresponding changes in physiologic heat strain. The objective of this paper is to examine a cohort of occupationally exposed grounds and public safety workers (n = 25) to characterize their heat exposure and resulting heat strain. In addition, a secondary aim of this work is to compare individually heat index exposure (IHIE) across exposure metrics, fixed-site in situ weather stations, and raster-derived urban heat island (UHI) measurements in Charleston, SC, a humid coastal climate in the Southeastern USA. A Bland-Altman (BA) analysis was used to assess the level of agreement between the personal IHIE measurements and weather-station heat index (HI) and Urban Heat Island (UHI) measurements. Linear mixed-effect models were used to determine the association between individual risk factors and in situ weather station measurements significantly associated with IHIE measurements. Multivariable stepwise Cox proportional hazard modeling was used to identify the individual and workplace factors associated with time to heat strain in workers. We also examined the non-linear association between heat strain and exposure metrics using generalized additive models. We found significant heterogeneity in IHIE measurements across participants. We observed that time to heat strain was positively associated with a higher IHIE, older age, being male, and among Caucasian workers. Important nonlinear associations between heat strain occurrence and the intensity, frequency, and duration of personal heat metrics were observed. Lastly, our analysis found that IHIE measures were significantly similar for weather station HI, although differences were more pronounced for temperature and relative humidity measurements. Conversely, our IHIE findings were much lower than raster-derived UHI measurements. Real-time monitoring can offer important insights about unfolding temperature-health trends and emerging behaviors during thermal extreme events, which have significant potential to provide situational awareness.
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Affiliation(s)
- Margaret M Sugg
- Department of Geography and Planning, Appalachian State University, Boone, NC, USA.
| | - Jennifer D Runkle
- North Carolina Institute for Climate Studies, North Carolina State University, Asheville, NC, USA
| | - Kirstin Dow
- Department of Geography, University of South Carolina at Columbia, Columbia, SC, USA
| | | | - Scott Stevens
- North Carolina Institute for Climate Studies, North Carolina State University, Asheville, NC, USA
| | - John Pearce
- Department of Public Health Services, Medical University of South Carolina, Charleston, SC, USA
| | - Brian Bossak
- Department of Health and Human Performance, College of Charleston, Charleston, SC, USA
| | - Scott Curtis
- Department of Physics and Lt. Col. James B. Near, Jr., USAF, '77 Center for Climate Studies, The Citadel, Charleston, SC, USA
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16
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Schmidt MD, Notley SR, Meade RD, Akerman AP, Rutherford MM, Kenny GP. Revisiting regional variation in the age-related reduction in sweat rate during passive heat stress. Physiol Rep 2022; 10:e15250. [PMID: 35411704 PMCID: PMC9001962 DOI: 10.14814/phy2.15250] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2022] [Accepted: 03/17/2022] [Indexed: 06/14/2023] Open
Abstract
Aging is associated with attenuated sweat gland function, which has been suggested to occur in a peripheral-to-central manner. However, evidence supporting this hypothesis remains equivocal. We revisited this hypothesis by evaluating the sweat rate across the limbs and trunk in young and older men during whole-body, passive heating. A water-perfused suit was used to raise and clamp esophageal temperature at 0.6°C (low-heat strain) and 1.2°C (moderate-heat strain) above baseline in 14 young (24 (SD 5) years) and 15 older (69 (4) years) men. Sweat rate was measured at multiple sites on the trunk (chest, abdomen) and limbs (biceps, forearm, quadriceps, calf) using ventilated capsules (3.8 cm2 ). Sweat rates, expressed as the average of 5 min of stable sweating at low- and moderate-heat strain, were compared between groups (young, older) and regions (trunk, limbs) within each level of heat strain using a linear mixed-effects model with nested intercepts (sites nested within region nested within participant). At low-heat strain, the age-related reduction in sweat rate (older-young values) was greater at the trunk (0.65 mg/cm2 /min [95% CI 0.44, 0.86]) compared to the limbs (0.42 mg/cm2 /min [0.22, 0.62]; interaction: p = 0.010). At moderate-heat strain, sweat rate was lower in older compared to young (main effect: p = 0.025), albeit that reduction did not differ between regions (interaction: p = 0.888). We conclude that, contrary to previous suggestions, the age-related decline in sweat rate was greater at the trunk compared to the limbs at low-heat strain, with no evidence of regional variation in that age-related decline at moderate-heat strain.
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Affiliation(s)
- Madison D. Schmidt
- Human and Environmental Physiology Research UnitSchool of Human KineticsUniversity of OttawaOttawaOntarioCanada
| | - Sean R. Notley
- Human and Environmental Physiology Research UnitSchool of Human KineticsUniversity of OttawaOttawaOntarioCanada
| | - Robert D. Meade
- Human and Environmental Physiology Research UnitSchool of Human KineticsUniversity of OttawaOttawaOntarioCanada
- Harvard T.H. Chan School of Public HealthHarvard UniversityBostonMassachusettsUSA
| | - Ashley P. Akerman
- Human and Environmental Physiology Research UnitSchool of Human KineticsUniversity of OttawaOttawaOntarioCanada
| | - Maura M. Rutherford
- Human and Environmental Physiology Research UnitSchool of Human KineticsUniversity of OttawaOttawaOntarioCanada
| | - Glen P. Kenny
- Human and Environmental Physiology Research UnitSchool of Human KineticsUniversity of OttawaOttawaOntarioCanada
- Clinical Epidemiology ProgramOttawa Hospital Research InstituteOttawaOntarioCanada
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17
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Tochihara Y. A review of Japanese-style bathing: its demerits and merits. J Physiol Anthropol 2022; 41:5. [PMID: 35168673 PMCID: PMC8848820 DOI: 10.1186/s40101-022-00278-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2021] [Accepted: 01/27/2022] [Indexed: 01/06/2023] Open
Abstract
Japanese-style bathing (JSB), which involves soaking in hot water up to the shoulders in deep bathtubs for a long time in the evening to night, is unique. Many experimental and epidemiological studies and surveys have shown that JSB improve sleep quality, especially shortens sleep onset latency in winter. In addition, repeated JSB lead the improvement of depressive symptoms. JSB is a simple and low-cost non-pharmacological measure to sleep difficulty in winter and mental disorders, especially for the elderly. On the contrary, drowning, while soaking in a bathtub, is the most common of accidental death at home in Japan. It is estimated that approximately 19,000 Japanese individuals die annually while taking a bath, mostly during winter, and most victims are elderly people. Elderly Japanese people tend to prefer a higher-risk JSB because the temperature inside the house during winter, especially the dressing room/bathroom temperature, is very low. Since the physiological thermal effect of the elderly associated with bathing is relatively lower among the elderly than the young, the elderly prefer to take a long hot bath. This elderly’s favorite style of JSB results in larger increased blood pressure in dressing rooms and larger decreased in blood pressure during hot bathing. A sudden drop in blood pressure while immersed in the bathtub leads to fainting and drowning. Furthermore, elderly people are less sensitive to cold air or hot water, therefore, it is difficult to take appropriate measures to prevent large fluctuations in blood pressure. To ensure a safe and comfortable winter bathing, the dressing room/bathroom temperature needs to be maintained at 20 °C or higher, and several degrees higher would be recommended for the elderly.
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Affiliation(s)
- Yutaka Tochihara
- Department of Human Science, Faculty of Design, Kyushu University, 4-9-1 Shiobaru, Minami-ku, Fukuoka, 815-8540, Japan.
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18
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Abstract
The human population is at the centre of research on global environmental change. On the one hand, population dynamics influence the environment and the global climate system through consumption-based carbon emissions. On the other hand, the health and well-being of the population are already being affected by climate change. A knowledge of population dynamics and population heterogeneity is thus fundamental to improving our understanding of how population size, composition, and distribution influence global environmental change and how these changes affect population subgroups differentially by demographic characteristics and spatial distribution. The increasing relevance of demographic research on the topic, coupled with availability of theoretical concepts and advancement in data and computing facilities, has contributed to growing engagement of demographers in this field. In the past 25 years, demographic research has enriched climate change research-with the key contribution being in moving beyond the narrow view that population matters only in terms of population size-by putting a greater emphasis on population composition and distribution, through presenting both empirical evidence and advanced population forecasting to account for demographic and spatial heterogeneity. What remains missing in the literature is research that investigates how global environmental change affects current and future demographic processes and, consequently, population trends. If global environmental change does influence fertility, mortality, and migration, then population estimates and forecasts need to adjust for climate feedback in population projections. Indisputably, this is the area of new research that directly requires expertise in population science and contribution from demographers.
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Affiliation(s)
- Raya Muttarak
- International Institute for Applied Systems Analysis, Wittgenstein Centre for Demography and Global Human Capital (IIASA, OeAW, University of Vienna)
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19
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Extreme Heat and Cardiovascular Health: What a Cardiovascular Health Professional Should Know. Can J Cardiol 2021; 37:1828-1836. [PMID: 34802857 DOI: 10.1016/j.cjca.2021.08.008] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2021] [Revised: 07/23/2021] [Accepted: 08/09/2021] [Indexed: 01/22/2023] Open
Abstract
As global temperatures continue to rise, extreme heat events are becoming more frequent and intense. Extreme heat affects cardiovascular health as it is associated with a greater risk of adverse cardiovascular events, especially for adults with preexisting cardiovascular diseases. Nonetheless, the pathophysiology underlying the association between extreme heat and cardiovascular risk remains understudied. Furthermore, specific recommendations to mitigate the effects of extreme heat on cardiovascular health remain limited to guide clinical practice within the context of a warming climate. The overall objective of this review article is to raise awareness that extreme heat poses a risk for cardiovascular health. Specifically, the review discusses why cardiovascular healthcare professionals should care about extreme heat, how extreme heat affects cardiovascular health, and recommendations to minimise the cardiovascular consequences of extreme heat. Future research directions are also provided to further our understating of the cardiovascular health consequences of extreme heat. A better awareness and understanding of the cardiovascular consequences of extreme heat will help cardiovascular health professionals assess the risk and optimise the care of their patients exposed to an increasingly warm climate.
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20
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Shakeel CS, Hassan U, Ilyas F, Zariwala MM, Ilyas SM, Khan SJ. A prelude to wearable technology for the measurement and restoration of core body temperature and heart rate in athletes suffering from hypothermia. Proc Inst Mech Eng H 2021; 236:56-64. [PMID: 34632881 DOI: 10.1177/09544119211051176] [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: 11/16/2022]
Abstract
An individual who is in good physical health tends to exhibit an internal core temperature of 37°C and a heart rate of 60-100 beats per minute. Increase in the temperature of the surrounding environment can serve as the basis for the onset of the condition of Hypothermia. Hypothermia acts as one of the most significant barriers being faced by winter athletes and starts initially with an increase in the heart and breathing rate. However, if the condition persists it can lead to reduction in the heart and breathing rate and ultimately results in cardiac failure. Although, jackets are commercially available, they tend to operate manually and furthermore, do not serve the primary purpose of counteracting the condition of hypothermia, particularly experienced by athletes taking part in winter sports. The objective of this study is to design a heating jacket that enables effective counteraction of the condition of Hypothermia. It enables precise measurement of the of core body temperature with the aid of a pyroelectric sensor. Along with this, a pulse rate sensor for detecting the accurate heart rate has been incorporated on the index finger. Five heating pads would get activated to attain optimal temperature, in case the core body temperature of <37°C is detected. If the condition of hypothermia advances to the moderate stage, two additional heating pads will get activated and provide extra warmth to attain normal heart rate along with core body temperature. Overall, this wearable technology serves as a definitive solution to counteract the condition of hypothermia only when the internal parameters exhibit that you actually have it. The results of the study exhibited that this prototype can be utilized for detecting and treating the condition of Hypothermia.
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Affiliation(s)
- Choudhary Sobhan Shakeel
- Department of Biomedical Engineering, Faculty of Engineering, Science, Technology and Management (ZUFESTM), Ziauddin University, Karachi, Pakistan
| | - Umer Hassan
- Department of Biomedical Engineering, Faculty of Engineering, Science, Technology and Management (ZUFESTM), Ziauddin University, Karachi, Pakistan
| | - Fatema Ilyas
- Department of Biomedical Engineering, Faculty of Engineering, Science, Technology and Management (ZUFESTM), Ziauddin University, Karachi, Pakistan
| | - Munira Muhammadi Zariwala
- Department of Biomedical Engineering, Faculty of Engineering, Science, Technology and Management (ZUFESTM), Ziauddin University, Karachi, Pakistan
| | - Salman Muhammad Ilyas
- Department of Biomedical Engineering, Faculty of Engineering, Science, Technology and Management (ZUFESTM), Ziauddin University, Karachi, Pakistan
| | - Saad Jawaid Khan
- Department of Biomedical Engineering, Faculty of Engineering, Science, Technology and Management (ZUFESTM), Ziauddin University, Karachi, Pakistan
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21
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Tochihara Y, Yamashita K, Fujii K, Kaji Y, Wakabayashi H, Kitahara H. Thermoregulatory and cardiovascular responses in the elderly towards a broad range of gradual air temperature changes. J Therm Biol 2021; 99:103007. [PMID: 34420637 DOI: 10.1016/j.jtherbio.2021.103007] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2021] [Revised: 05/08/2021] [Accepted: 05/18/2021] [Indexed: 11/19/2022]
Abstract
This study aimed to determine age-related differences in thermoregulatory and cardiovascular responses to a wide range of gradual ambient temperature (Ta) changes. Morphologically matched normotensive elderly and young males participated. The participants wearing only shorts rested during the 3-h experiment. After 30 min of baseline at 28 °C, Ta increased linearly to 43 °C in 30 min (warming) and then gradually decreased to 13 °C in 60 min (cooling). Ta was rewarmed to 28 °C in 30 min (rewarming), and that temperature was maintained for an additional 30 min (second baseline). During the warming phase, there were no age-related differences in blood pressure (BP) and rectal temperature (Tre), despite a significantly lower cutaneous vascular conductance and heart rate in the elderly (P < 0.05). At the end of the cooling phase, systolic blood pressure (SBP) in the elderly was significantly higher than the young (155.8 ± 16.1 and 125.0 ± 12.5 mmHg, P < 0.01). There was a consistent age group difference in SBP during rewarming. Mean skin temperature was significantly lower in the elderly during rewarming (P < 0.05). Tre decreased more in the elderly and was significantly lower at the end of the experiment than the younger participants (36.78 ± 0.34 and 37.01 ± 0.15 °C, P < 0.05). However, there were no age group differences in thermal sensation. In conclusion, even normotensive elderly participants have a greater and more persistent BP response to cold than younger adults, suggesting that the elderly might be at a higher risk of cardiac events during cooling and subsequent rewarming.
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Affiliation(s)
- Yutaka Tochihara
- Environmental Ergonomics Laboratory, Department of Human Science, Faculty of Design, Kyushu University, Fukuoka, Japan
| | - Kazuaki Yamashita
- Environmental Ergonomics Laboratory, Department of Human Science, Faculty of Design, Kyushu University, Fukuoka, Japan; Toa, Kitakyushu, Japan
| | - Kenji Fujii
- Yamaguchi Prefectural Industrial Technology Institute, Ube, Japan
| | - Yumi Kaji
- Assisted Living Facility La Paz, Fukuoka, Japan
| | - Hitoshi Wakabayashi
- Environmental Ergonomics Laboratory, Department of Human Science, Faculty of Design, Kyushu University, Fukuoka, Japan; Laboratory of Environmental Ergonomics, Faculty of Engineering, Hokkaido University, Sapporo, Japan.
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22
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Knechtle B, McGrath C, Goncerz O, Villiger E, Nikolaidis PT, Marcin T, Sousa CV. The Role of Environmental Conditions on Master Marathon Running Performance in 1,280,557 Finishers the 'New York City Marathon' From 1970 to 2019. Front Physiol 2021; 12:665761. [PMID: 34079472 PMCID: PMC8165243 DOI: 10.3389/fphys.2021.665761] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2021] [Accepted: 04/14/2021] [Indexed: 01/29/2023] Open
Abstract
Aim: This study investigated the influence of weather conditions on running performance in female and male age group runners in the largest marathon in the world, the “New York City Marathon.” Methods: The analysis included data from 1,280,557 finishers the “New York City Marathon” from the years 1970 to 2019. Linear mixed models for men and women finishers with race time (min) as dependent variable and 5-year age groups, temperature, wind and relative humidity tertiles (low, medium, high) as independent factors and finisher as random intercept was performed. Additional models with an interaction between age groups and one weather variable each were performed. Results: Temperature was positively associated with race time while wind speed and humidity were negatively associated (p < 0.001). Men were significantly greater affected wind speed and humidity than women (p < 0.001 for interaction) but not by temperature (p = 0.17 for interaction). With an average of 8 min longer race time, high temperature had the greatest effect on race time. The effect of high humidity on race time was significantly increased in 40–59 years old men and 25–65 years old women. High temperatures had an increased effect on race time in 30–64 years old men and 40–64 years old women. The inverse association between race time and high wind speed was pronounced in finishers with younger age. Conclusion: Performance was lower on days with high temperature, low humidity and low wind speed. Men seemed to benefit more from higher humidity and wind speed than women. Aged (70 +) finishers were not greater affected by high temperatures.
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Affiliation(s)
- Beat Knechtle
- Institute of Primary Care, University of Zurich, Zurich, Switzerland.,Medbase St. Gallen Am Vadianplatz, St. Gallen, Switzerland
| | - Carlyn McGrath
- Bouve College of Health Sciences, Northeastern University, Boston, MA, United States
| | - Olivia Goncerz
- Bouve College of Health Sciences, Northeastern University, Boston, MA, United States
| | - Elias Villiger
- Medbase St. Gallen Am Vadianplatz, St. Gallen, Switzerland
| | | | - Thimo Marcin
- Research Department, Berner Reha Zentrum, Bern, Switzerland
| | - Caio Victor Sousa
- Bouve College of Health Sciences, Northeastern University, Boston, MA, United States
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23
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Belval LN, Giersch GEW, Adams WM, Hosokawa Y, Jardine JF, Katch RK, Stearns RL, Casa DJ. Age- and Sex-Based Differences in Exertional Heat Stroke Incidence in a 7-Mile Road Race. J Athl Train 2021; 55:1224-1229. [PMID: 33176353 DOI: 10.4085/1062-6050-539-19] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
CONTEXT Sex, age, and wet-bulb globe temperature (WBGT) have been proposed risk factors for exertional heat stroke (EHS) despite conflicting laboratory and epidemiologic evidence. OBJECTIVE To examine differences in EHS incidence while accounting for sex, age, and environmental conditions. DESIGN Observational study. SETTING Falmouth Road Race, a warm-weather 7-mi (11.26-km) running road race. PATIENTS OR OTHER PARTICIPANTS We reviewed records from patients treated for EHS at medical tents. MAIN OUTCOME MEASURE(S) The relative risk (RR) of EHS between sexes and across ages was assessed with males as the reference population. Multivariate linear regression analyses were calculated to determine the relative contribution of sex, age, and WBGT to the incidence of EHS. RESULTS Among 343 EHS cases, the female risk of EHS was lower overall (RR = 0.71; 95% confidence interval [CI] = 0.58, 0.89; P = .002) and for age groups 40 to 49 years (RR = 0.43; 95% CI = 0.24, 0.77; P = .005) and 50 to 59 years (RR = 0.31; 95% CI = 0.13, 0.72; P = .005). The incidence of EHS did not differ between sexes in relation to WBGT (P > .05). When sex, age, and WBGT were considered in combination, only age groups <14 years (β = 2.41, P = .008), 15 to 18 years (β = 3.83, P < .001), and 19 to 39 years (β = 2.24, P = .014) significantly accounted for the variance in the incidence of EHS (R2 = .10, P = .006). CONCLUSIONS In this unique investigation of EHS incidence in a road race, we found a 29% decreased EHS risk in females compared with males. However, when sex was considered with age and WBGT, only younger age accounted for an increased incidence of EHS. These results suggest that road race medical organizers should consider participant demographics when organizing the personnel and resources needed to treat patients with EHS. Specifically, organizers of events with greater numbers of young runners (aged 19 to 39 years) and males should prioritize ensuring that medical personnel are adequately prepared to handle patients with EHS.
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Affiliation(s)
- Luke N Belval
- Institute for Exercise and Environmental Medicine, University of Texas Southwestern and Texas Health Presbyterian Hospital Dallas
| | - Gabrielle E W Giersch
- Korey Stringer Institute, Department of Kinesiology, University of Connecticut, Storrs
| | - William M Adams
- Department of Kinesiology, University of North Carolina at Greensboro
| | - Yuri Hosokawa
- Faculty of Sport Sciences, Waseda University, Saitama, Japan
| | - John F Jardine
- Korey Stringer Institute, Department of Kinesiology, University of Connecticut, Storrs.,Falmouth Road Race, MA
| | - Rachel K Katch
- Korey Stringer Institute, Department of Kinesiology, University of Connecticut, Storrs
| | - Rebecca L Stearns
- Korey Stringer Institute, Department of Kinesiology, University of Connecticut, Storrs
| | - Douglas J Casa
- Korey Stringer Institute, Department of Kinesiology, University of Connecticut, Storrs
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24
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Moon J. The effect of the heatwave on the morbidity and mortality of diabetes patients; a meta-analysis for the era of the climate crisis. ENVIRONMENTAL RESEARCH 2021; 195:110762. [PMID: 33515577 DOI: 10.1016/j.envres.2021.110762] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/21/2020] [Revised: 01/06/2021] [Accepted: 01/14/2021] [Indexed: 06/12/2023]
Abstract
INTRODUCTION From the perspective of public health, the climate crisis is also causing many health problems worldwide. In contrast with the cardiovascular, respiratory, and urinary system, the adverse effects of heatwaves on the endocrine system, particularly in people with diabetes mellitus (DM), are not well established to date. In this study, the author investigated the morbidity and mortality changes of DM patients during heatwave periods, using the meta-analysis method. METHODS The author searched MEDLINE, EMBASE, and the Cochrane Library until March 12, 2020. The quality of each included study was assessed using the National Institutes of Health (NIH) Quality Assessment tools. The meta-analysis was conducted using the studies with a relative risk (RR) estimate and odds ratio (OR) estimate. The subgroup analysis and the meta-ANOVA analysis were conducted using various covariates, including lag days considered. RESULTS Only 36 articles were included in the meta-analysis. The pooled RR of mortality and of morbidity for diabetics under the heatwave were 1.18 (95% CI 1.13-1.25) and 1.10 (95% CI 1.06-1.14). For mortality studies, whether or not the lag days considered were 10 days or more was only a significant covariate for the meta-ANOVA analysis (Q = 3.17, p = 0.075). For morbidity studies, the definition of the heatwave (Q = 65.94, p < 0.0001), whether or not the maximum temperature was 40 °C or more (Q = 4.78, p = 0.0288), and the type of morbidity (Q = 60.23, p < 0.0001) were significant covariates for the analysis. DISCUSSION The mortality and morbidity risks of diabetes patients under the heatwave were mildly increased by about 18 percent for mortality and 10 percent for overall morbidity. The mortality risk of diabetics can increase more when lag days of 10 days or more are considered than when lag days of less than 10 days are considered. These valuable findings can be used in developing public health strategies to cope with heatwaves in the current era of aggravating global warming and climate crisis.
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Affiliation(s)
- Jinyoung Moon
- Seoul National University Graduate School of Public Health, Department of Environmental Health Science, Gwanak-ro 1, Gwanak-gu, Seoul, 08826, Republic of Korea; Department of Occupational and Environmental Medicine, Seoul Saint Mary's Hospital, Republic of Korea.
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25
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Gravel H, Chaseling GK, Barry H, Debray A, Gagnon D. Cardiovascular control during heat stress in older adults: time for an update. Am J Physiol Heart Circ Physiol 2020; 320:H411-H416. [PMID: 33275528 DOI: 10.1152/ajpheart.00536.2020] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
It is generally accepted that older adults display an impaired cardiovascular response to heat stress, and it has been suggested that this impaired response contributes to their increased risk of mortality during extreme heat events. Seminal studies have shown that cutaneous vasodilation, the redistribution of blood flow from visceral organs, and the increase in cardiac output are blunted in older adults during passive heating. The blunted rise of cardiac output was initially attributed to an inability to maintain stroke volume, suggesting that cardiac systolic and/or diastolic function does not adequately respond to the constraints of heat stress in older adults. Recent studies evaluated potential mechanisms underlying these seminal findings and their results challenge some of these initial observations. Notably, stroke volume is maintained during heat exposure in older adults and studies have provided evidence for preserved cardiac systolic and diastolic functions in this population. Nonetheless, a blunted increase in cardiac output during heat exposure remains a consistent observation in older adults, although it is now attributed to a blunted increase in heart rate. Recent studies have also evaluated the possibility that the attenuated capacity of aged skin to vasodilate contributes to a blunted increase in cardiac output during heat stress. The objective of this Mini-Review is to highlight these recent advances and challenge the long-standing view that the control of stroke volume during heat exposure is compromised in older adults. By doing so, our intent is to stimulate future studies to evaluate several unanswered questions in this area of research.
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Affiliation(s)
- Hugo Gravel
- Cardiovascular Prevention and Rehabilitation Centre, Montreal Heart Institute, Montreal, Quebec, Canada.,Research Centre, Montreal Heart Institute, Montreal, Quebec, Canada.,Department of Pharmacology and Physiology, Université de Montréal, Montreal, Quebec, Canada
| | - Georgia K Chaseling
- Cardiovascular Prevention and Rehabilitation Centre, Montreal Heart Institute, Montreal, Quebec, Canada.,Research Centre, Montreal Heart Institute, Montreal, Quebec, Canada.,Department of Pharmacology and Physiology, Université de Montréal, Montreal, Quebec, Canada
| | - Hadiatou Barry
- Cardiovascular Prevention and Rehabilitation Centre, Montreal Heart Institute, Montreal, Quebec, Canada.,Research Centre, Montreal Heart Institute, Montreal, Quebec, Canada.,Department of Pharmacology and Physiology, Université de Montréal, Montreal, Quebec, Canada
| | - Amélie Debray
- Cardiovascular Prevention and Rehabilitation Centre, Montreal Heart Institute, Montreal, Quebec, Canada.,Research Centre, Montreal Heart Institute, Montreal, Quebec, Canada.,Department of Medicine, Université de Montréal, Montreal, Quebec, Canada
| | - Daniel Gagnon
- Cardiovascular Prevention and Rehabilitation Centre, Montreal Heart Institute, Montreal, Quebec, Canada.,Research Centre, Montreal Heart Institute, Montreal, Quebec, Canada.,Department of Pharmacology and Physiology, Université de Montréal, Montreal, Quebec, Canada.,School of Kinesiology and Exercise Science, Université de Montréal, Montreal, Quebec, Canada
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26
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Meade RD, Akerman AP, Notley SR, McGinn R, Poirier P, Gosselin P, Kenny GP. Physiological factors characterizing heat-vulnerable older adults: A narrative review. ENVIRONMENT INTERNATIONAL 2020; 144:105909. [PMID: 32919284 DOI: 10.1016/j.envint.2020.105909] [Citation(s) in RCA: 90] [Impact Index Per Article: 22.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/16/2020] [Revised: 05/24/2020] [Accepted: 06/17/2020] [Indexed: 05/26/2023]
Abstract
More frequent and intense periods of extreme heat (heatwaves) represent the most direct challenge to human health posed by climate change. Older adults are particularly vulnerable, especially those with common age-associated chronic health conditions (e.g., cardiovascular disease, hypertension, obesity, type 2 diabetes, chronic kidney disease). In parallel, the global population is aging and age-associated disease rates are on the rise. Impairments in the physiological responses tasked with maintaining homeostasis during heat exposure have long been thought to contribute to increased risk of health disorders in older adults during heatwaves. As such, a comprehensive overview of the provisional links between age-related physiological dysfunction and elevated risk of heat-related injury in older adults would be of great value to healthcare officials and policy makers concerned with protecting heat-vulnerable sectors of the population from the adverse health impacts of heatwaves. In this narrative review, we therefore summarize our current understanding of the physiological mechanisms by which aging impairs the regulation of body temperature, hemodynamic stability and hydration status. We then examine how these impairments may contribute to acute pathophysiological events common during heatwaves (e.g., heatstroke, major adverse cardiovascular events, acute kidney injury) and discuss how age-associated chronic health conditions may exacerbate those impairments. Finally, we briefly consider the importance of physiological research in the development of climate-health programs aimed at protecting heat-vulnerable individuals.
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Affiliation(s)
- Robert D Meade
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, Ontario, Canada
| | - Ashley P Akerman
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, Ontario, Canada
| | - Sean R Notley
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, Ontario, Canada
| | - Ryan McGinn
- Department of Anesthesiology and Pain Medicine, The Ottawa Hospital, University of Ottawa, Ottawa, ON, Canada
| | - Paul Poirier
- Institut Universitaire de Cardiologie et de Pneumologie de Québec, Université Laval, Québec, Québec, Canada
| | - Pierre Gosselin
- Institut National de Santé Publique du Québec and Université Laval, Québec, Québec, Canada
| | - Glen P Kenny
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, Ontario, Canada; Clinical Epidemiology Program, Ottawa Hospital Research Institute, Ottawa, Ontario, Canada.
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27
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Chapman CL, Johnson BD, Parker MD, Hostler D, Pryor RR, Schlader Z. Kidney physiology and pathophysiology during heat stress and the modification by exercise, dehydration, heat acclimation and aging. Temperature (Austin) 2020; 8:108-159. [PMID: 33997113 PMCID: PMC8098077 DOI: 10.1080/23328940.2020.1826841] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2020] [Revised: 09/17/2020] [Accepted: 09/17/2020] [Indexed: 02/06/2023] Open
Abstract
The kidneys' integrative responses to heat stress aid thermoregulation, cardiovascular control, and water and electrolyte regulation. Recent evidence suggests the kidneys are at increased risk of pathological events during heat stress, namely acute kidney injury (AKI), and that this risk is compounded by dehydration and exercise. This heat stress related AKI is believed to contribute to the epidemic of chronic kidney disease (CKD) occurring in occupational settings. It is estimated that AKI and CKD affect upwards of 45 million individuals in the global workforce. Water and electrolyte disturbances and AKI, both of which are representative of kidney-related pathology, are the two leading causes of hospitalizations during heat waves in older adults. Structural and physiological alterations in aging kidneys likely contribute to this increased risk. With this background, this comprehensive narrative review will provide the first aggregation of research into the integrative physiological response of the kidneys to heat stress. While the focus of this review is on the human kidneys, we will utilize both human and animal data to describe these responses to passive and exercise heat stress, and how they are altered with heat acclimation. Additionally, we will discuss recent studies that indicate an increased risk of AKI due to exercise in the heat. Lastly, we will introduce the emerging public health crisis of older adults during extreme heat events and how the aging kidneys may be more susceptible to injury during heat stress.
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Affiliation(s)
- Christopher L. Chapman
- Center for Research and Education in Special Environments, Department of Exercise and Nutrition Sciences, University at Buffalo, Buffalo, NY, USA
- Department of Human Physiology, University of Oregon, Eugene, OR, USA
| | - Blair D. Johnson
- Department of Kinesiology, School of Public Health, Indiana University, Bloomington, IN, USA
| | - Mark D. Parker
- Department of Physiology and Biophysics, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo, NY, USA
- Department of Ophthalmology, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo, NY, USA
| | - David Hostler
- Center for Research and Education in Special Environments, Department of Exercise and Nutrition Sciences, University at Buffalo, Buffalo, NY, USA
| | - Riana R. Pryor
- Center for Research and Education in Special Environments, Department of Exercise and Nutrition Sciences, University at Buffalo, Buffalo, NY, USA
| | - Zachary Schlader
- Department of Kinesiology, School of Public Health, Indiana University, Bloomington, IN, USA
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28
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Foster J, Hodder SG, Lloyd AB, Havenith G. Individual Responses to Heat Stress: Implications for Hyperthermia and Physical Work Capacity. Front Physiol 2020; 11:541483. [PMID: 33013476 PMCID: PMC7516259 DOI: 10.3389/fphys.2020.541483] [Citation(s) in RCA: 55] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2020] [Accepted: 08/18/2020] [Indexed: 12/11/2022] Open
Abstract
Background Extreme heat events are increasing in frequency, severity, and duration. It is well known that heat stress can have a negative impact on occupational health and productivity, particularly during physical work. However, there are no up-to-date reviews on how vulnerability to heat changes as a function of individual characteristics in relation to the risk of hyperthermia and work capacity loss. The objective of this narrative review is to examine the role of individual characteristics on the human heat stress response, specifically in relation to hyperthermia risk and productivity loss in hot workplaces. Finally, we aim to generate practical guidance for industrial hygienists considering our findings. Factors included in the analysis were body mass, body surface area to mass ratio, body fat, aerobic fitness and training, heat adaptation, aging, sex, and chronic health conditions. Findings We found the relevance of any factor to be dynamic, based on the work-type (fixed pace or relative to fitness level), work intensity (low, moderate, or heavy work), climate type (humidity, clothing vapor resistance), and variable of interest (risk of hyperthermia or likelihood of productivity loss). Heat adaptation, high aerobic fitness, and having a large body mass are the most protective factors during heat exposure. Primary detrimental factors include low fitness, low body mass, and lack of heat adaptation. Aging beyond 50 years, being female, and diabetes are less impactful negative factors, since their independent effect is quite small in well matched participants. Skin surface area to mass ratio, body composition, hypertension, and cardiovascular disease are not strong independent predictors of the heat stress response. Conclusion Understanding how individual factors impact responses to heat stress is necessary for the prediction of heat wave impacts on occupational health and work capacity. The recommendations provided in this report could be utilized to help curtail hyperthermia risk and productivity losses induced by heat.
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Affiliation(s)
- Josh Foster
- Environmental Ergonomics Research Centre, Loughborough University, Loughborough, United Kingdom
| | - Simon G Hodder
- Environmental Ergonomics Research Centre, Loughborough University, Loughborough, United Kingdom
| | - Alex B Lloyd
- Environmental Ergonomics Research Centre, Loughborough University, Loughborough, United Kingdom
| | - George Havenith
- Environmental Ergonomics Research Centre, Loughborough University, Loughborough, United Kingdom
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29
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Macartney MJ, Meade RD, Notley SR, Herry CL, Seely AJE, Kenny GP. Fluid Loss during Exercise-Heat Stress Reduces Cardiac Vagal Autonomic Modulation. Med Sci Sports Exerc 2020; 52:362-369. [PMID: 31469711 DOI: 10.1249/mss.0000000000002136] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
PURPOSE Sweat-induced fluid loss during prolonged exercise-heat stress can compromise cardiovascular and thermoregulatory function, although its effects on cardiac autonomic modulation remain unclear. We therefore examined heart rate variability (HRV) and recovery (HRRec), as surrogates of cardiac autonomic modulation, during and after prolonged exercise in the heat with and without fluid replacement. METHODS Eleven young and healthy men performed 90 min of semi-recumbent cycling in dry heat (40°C; 20% relative humidity) at a fixed rate of metabolic heat production (600 W; ~46% V˙O2peak) followed by 40-min resting recovery without fluid replacement (No-FR; ~3.4% reduction in body mass). On a separate day, participants completed the same protocol with fluid replacement (FR; 500-700 mL timed boluses) to offset sweat losses. Esophageal temperature and ECG were recorded throughout, with measurements analyzed over 10-min averaged epochs during baseline, each 30-min interval during exercise and 20-min interval during recovery. RESULTS Esophageal temperature and heart rate were elevated in No-FR relative to FR throughout exercise (all P ≤ 0.02). The HRV indices reflecting vagal influence of heart rate including the cardiac vagal index (CVI = log10[16 × SD1 × SD2]) and root-mean-square of successive differences were attenuated throughout exercise relative to baseline in both conditions (all P < 0.05), with the magnitude of the reduction greater in the No-FR condition (all P < 0.05). Further, sample entropy was reduced throughout all time points measured during exercise in the No-FR relative to FR condition (all P ≤ 0.03). CONCLUSIONS Our unique observations indicate that while prolonged exercise heat stress attenuates the vagal influence and complexity of cardiac rhythms, that reduction is further exacerbated by fluid loss, highlighting the importance of fluid replacement in such conditions.
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Affiliation(s)
- Michael J Macartney
- School of Health Sciences, College of Health and Medicine, University of Tasmania, Hobart, AUSTRALIA
| | - Robert D Meade
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, ON, CANADA
| | - Sean R Notley
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, ON, CANADA
| | - Christophe L Herry
- Ottawa Hospital Research Institute, University of Ottawa, Ottawa, ON, CANADA
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30
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Cramer MN, Hieda M, Huang M, Moralez G, Crandall CG. Dietary nitrate supplementation does not influence thermoregulatory or cardiovascular strain in older individuals during severe ambient heat stress. Exp Physiol 2020; 105:1730-1741. [PMID: 32816341 DOI: 10.1113/ep088834] [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: 06/08/2020] [Accepted: 08/17/2020] [Indexed: 12/16/2022]
Abstract
NEW FINDINGS What is the central question of this study? Does dietary nitrate supplementation with beetroot juice attenuate thermoregulatory and cardiovascular strain in older adults during severe heat stress? What is the main finding and its importance? A 7-day nitrate supplementation regimen lowered resting mean arterial pressure in thermoneutral conditions. During heat stress, core and mean skin temperatures, vasodilatory responses, sweat loss, heart rate and left ventricular function were unchanged, and mean arterial pressure was only transiently reduced, post-supplementation. These data suggest nitrate supplementation with beetroot juice does not mitigate thermoregulatory or cardiovascular strain in heat-stressed older individuals. ABSTRACT This study tested the hypothesis that dietary nitrate supplementation with concentrated beetroot juice attenuates thermoregulatory and cardiovascular strain in older individuals during environmental heat stress. Nine healthy older individuals (six females, three males; aged 67 ± 5 years) were exposed to 42.5 ± 0.1°C and 34.0 ± 0.5% relative humidity conditions for 120 min before (CON) and after 7 days of dietary nitrate supplementation with concentrated beetroot juice (BRJ; 280 ml, ∼16.8 mmol of nitrate daily). Core and skin temperatures, body mass changes (indicative of whole-body sweat loss), skin blood flow and cutaneous vascular conductance, forearm blood flow and vascular conductance, heart rate, arterial blood pressures and indices of cardiac function were measured. The 7-day beetroot juice regimen increased plasma nitrate/nitrite levels from 27.4 ± 15.2 to 477.0 ± 102.5 μmol l-1 (P < 0.01) and lowered resting mean arterial pressure from 90 ± 7 to 83 ± 10 mmHg at baseline under thermoneutral conditions (P = 0.02). However, during subsequent heat stress, no differences in core and skin temperatures, skin blood flow and vascular conductance, forearm blood flow and vascular conductance, whole-body sweat loss, heart rate, and echocardiographic indices of systolic function and diastolic filling were evident following nitrate supplementation (all P > 0.05). Mean arterial pressure was lower in BRJ vs. CON during heat stress (treatment-by-time interaction: P = 0.02). Overall, these findings suggest that dietary nitrate supplementation with concentrated beetroot juice does not attenuate thermoregulatory or cardiovascular strain in older individuals exposed to severe ambient heat stress.
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Affiliation(s)
- Matthew N Cramer
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas and University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Michinari Hieda
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas and University of Texas Southwestern Medical Center, Dallas, TX, USA.,School of Medicine, Kyushu University, Fukuoka, Japan
| | - Mu Huang
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas and University of Texas Southwestern Medical Center, Dallas, TX, USA.,Applied Clinical Research, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Gilbert Moralez
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas and University of Texas Southwestern Medical Center, Dallas, TX, USA.,Applied Clinical Research, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Craig G Crandall
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas and University of Texas Southwestern Medical Center, Dallas, TX, USA
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31
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Kuzmenko NV, Pliss MG, Galagudza MM, Tsyrlin VA. Effects of Hyper- and Hypothermia on Hemodynamic Parameters in People of Different Age Groups: Meta-Analysis. ADVANCES IN GERONTOLOGY 2020. [DOI: 10.1134/s2079057020020095] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
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Notley SR, Meade RD, Akerman AP, Poirier MP, Boulay P, Sigal RJ, Flouris AD, Kenny GP. Evidence for age‐related differences in heat acclimatisation responsiveness. Exp Physiol 2020; 105:1491-1499. [DOI: 10.1113/ep088728] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2020] [Accepted: 06/23/2020] [Indexed: 12/12/2022]
Affiliation(s)
- Sean R. Notley
- Human and Environmental Physiology Research UnitSchool of Human KineticsFaculty of Health SciencesUniversity of Ottawa Ottawa Canada
| | - Robert D. Meade
- Human and Environmental Physiology Research UnitSchool of Human KineticsFaculty of Health SciencesUniversity of Ottawa Ottawa Canada
| | - Ashley P. Akerman
- Human and Environmental Physiology Research UnitSchool of Human KineticsFaculty of Health SciencesUniversity of Ottawa Ottawa Canada
| | - Martin P. Poirier
- Human and Environmental Physiology Research UnitSchool of Human KineticsFaculty of Health SciencesUniversity of Ottawa Ottawa Canada
| | - Pierre Boulay
- Faculté des sciences de l'activité physiqueUniversité de Sherbrooke Sherbrooke Canada
| | - Ronald J. Sigal
- Human and Environmental Physiology Research UnitSchool of Human KineticsFaculty of Health SciencesUniversity of Ottawa Ottawa Canada
- Departments of MedicineCardiac Sciences and Community Health Sciences Faculties of Medicine and KinesiologyUniversity of Calgary Calgary Canada
- Clinical Epidemiology ProgramOttawa Hospital Research Institute Ottawa Canada
| | - Andreas D. Flouris
- FAME LaboratoryDepartment of Exercise ScienceUniversity of Thessaly Trikala Greece
| | - Glen P. Kenny
- Human and Environmental Physiology Research UnitSchool of Human KineticsFaculty of Health SciencesUniversity of Ottawa Ottawa Canada
- Clinical Epidemiology ProgramOttawa Hospital Research Institute Ottawa Canada
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Millyard A, Layden JD, Pyne DB, Edwards AM, Bloxham SR. Impairments to Thermoregulation in the Elderly During Heat Exposure Events. Gerontol Geriatr Med 2020; 6:2333721420932432. [PMID: 32596421 PMCID: PMC7297481 DOI: 10.1177/2333721420932432] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2020] [Revised: 05/06/2020] [Accepted: 05/14/2020] [Indexed: 12/11/2022] Open
Abstract
Heat waves represent a public health risk to elderly people, and typically result in an increased rate of hospital admissions and deaths. Studies of thermoregulation in this cohort have generally focused on single elements such as sweating capacity. Sweating capacity and skin blood flow reduce with age, reducing ability to dissipate heat. Perception of effort during heat exposure is emerging as an area that needs further investigation as the elderly appear to lack the ability to adequately perceive increased physiological strain during heat exposure. The role of the gut and endotoxemia in heat stress has received attention in young adults, while the elderly population has been neglected. This shortcoming offers another potential avenue for identifying effective integrated health interventions to reduce heat illnesses. Increasing numbers of elderly individuals in populations worldwide are likely to increase the incidence of heat wave-induced deaths if adequate interventions are not developed, evaluated, and implemented. In this narrative-style review we identify and discuss health-related interventions for reducing the impact of heat illnesses in the elderly.
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Affiliation(s)
| | | | - David B Pyne
- University of Canberra, Australian Capital Territory, Australia
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Dennis M, Cook PA, James P, Wheater CP, Lindley SJ. Relationships between health outcomes in older populations and urban green infrastructure size, quality and proximity. BMC Public Health 2020; 20:626. [PMID: 32375720 PMCID: PMC7201616 DOI: 10.1186/s12889-020-08762-x] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2019] [Accepted: 04/22/2020] [Indexed: 01/03/2023] Open
Abstract
Background There is a growing body of literature supporting positive associations between natural environments and better health. The type, quality and quantity of green and blue space (‘green-space’) in proximity to the home might be particularly important for less mobile populations, such as for some older people. However, considerations of measurement and definition of green-space, beyond single aggregated metrics, are rare. This constitutes a major source of uncertainty in current understanding of public health benefits derived from natural environments. We aimed to improve our understanding of how such benefits are conferred to different demographic groups through a comprehensive evaluation of the physical and spatial characteristics of urban green infrastructure. Methods We employed a green infrastructure (GI) approach combining a high-resolution spatial dataset of land-cover and function with area-level demographic and socio-economic data. This allowed for a comprehensive characterization of a densely populated, polycentric city-region. We produced multiple GI attributes including, for example, urban vegetation health. We used a series of step-wise multi-level regression analyses to test associations between population chronic morbidity and the functional, physical and spatial components of GI across an urban socio-demographic gradient. Results GI attributes demonstrated associations with health in all socio-demographic contexts even where associations between health and overall green cover were non-significant. Associations varied by urban socio-demographic group. For areas characterised by having higher proportions of older people (‘older neighbourhoods’), associations with better health were exhibited by land-cover diversity, informal greenery and patch size in high income areas and by proximity to public parks and recreation land in low income areas. Quality of GI was a significant predictor of good health in areas of low income and low GI cover. Proximity of publicly accessible GI was also significant. Conclusions The influence of urban GI on population health is mediated by green-space form, quantity, accessibility, and vegetation health. People in urban neighbourhoods that are characterised by lower income and older age populations are disproportionately healthy if their neighbourhoods contain accessible, good quality public green-space. This has implications for strategies to decrease health inequalities and inform international initiatives, such as the World Health Organisation’s Age-Friendly Cities programme.
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Affiliation(s)
- Matthew Dennis
- Department of Geography, School of Environment Education and Development, University of Manchester, Arthur Lewis Building, Manchester, M13 9PL, UK.
| | - Penny A Cook
- School of Health and Society, University of Salford, The Crescent, Allerton Building, Salford, M5 4WT, UK
| | - Philip James
- School of Science, Engineering and Environment, University of Salford, The Crescent, Peel Building, Salford, M5 4WT, UK
| | - C Philip Wheater
- School of Science and the Environment, Manchester Metropolitan University, Chester Street, John Dalton Building, Manchester, M1 5GD, UK
| | - Sarah J Lindley
- Department of Geography, School of Environment Education and Development, University of Manchester, Arthur Lewis Building, Manchester, M13 9PL, UK
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35
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Poirier MP, Notley SR, Boulay P, Sigal RJ, Friesen BJ, Malcolm J, Flouris AD, Kenny GP. Type 2 diabetes does not exacerbate body heat storage in older adults during brief, extreme passive heat exposure. Temperature (Austin) 2020; 7:263-269. [PMID: 33123619 DOI: 10.1080/23328940.2020.1736760] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Aging exacerbates hyperthermia and cardiovascular strain during passive heat exposure, but it remains unclear whether those effects worsen in older adults with type 2 diabetes (T2D). We examined these responses in unacclimatized, physically active, older individuals with (n = 13, mean ± SD age: 60 ± 8 years, HbA1c: 7.0 ± 1.0%) and without (Control, n = 30, 62 ± 6 years) well-controlled T2D during a brief, 3-h passive exposure to extreme heat (44°C, 30% relative humidity). Metabolic heat production, dry heat gain, total heat gain (metabolic heat production + dry heat gain), evaporative heat loss, body heat storage (summation of heat gain/loss), rectal and mean skin temperatures as well as heart rate were measured continuously. No between-group differences were observed for metabolic heat production (T2D vs. Control; 53 ± 5 vs. 55 ± 7 W/m2), dry heat gain (48 ± 9 vs. 47 ± 11 W/m2), total heat gain (101 ± 10 vs. 102 ± 14 W/m2) and evaporative heat loss (83 ± 10 vs. 85 ± 12 W/m2) over the 3 h (all P > 0.05). Consequently, the changes in body heat storage (380 ± 93 vs. 358 ± 172 kJ, P = 0.67) were similar between groups. Moreover, no between-group differences in rectal and mean skin temperatures or heart rate were measured. We conclude that unacclimatized, physically active, older adults with well-controlled T2D do not experience greater hyperthermia and cardiovascular strain compared to their healthy counterparts while resting in extreme heat for a brief, 3-h period.
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Affiliation(s)
- Martin P Poirier
- Human and Environmental Physiology Research Unit, School of Human Kinetics, Faculty of Health Sciences, University of Ottawa, Ottawa, Canada
| | - Sean R Notley
- Human and Environmental Physiology Research Unit, School of Human Kinetics, Faculty of Health Sciences, University of Ottawa, Ottawa, Canada
| | - Pierre Boulay
- Faculté des Sciences de l'activité Physique, Université de Sherbrooke, Sherbrooke, Canada
| | - Ronald J Sigal
- Human and Environmental Physiology Research Unit, School of Human Kinetics, Faculty of Health Sciences, University of Ottawa, Ottawa, Canada.,Departments of Medicine, Cardiac Sciences and Community Health Sciences, Faculties of Medicine and Kinesiology, University of Calgary, Division of Endocrinology and Metabolism, RRDTC, Calgary, Canada.,Clinical Epidemiology Program, Ottawa Hospital Research Institute, Ottawa, Canada
| | - Brian J Friesen
- Human and Environmental Physiology Research Unit, School of Human Kinetics, Faculty of Health Sciences, University of Ottawa, Ottawa, Canada
| | - Janine Malcolm
- Division of Endocrinology and Metabolism, Department of Medicine, University of Ottawa, Ottawa, Canada
| | - Andreas D Flouris
- FAME Laboratory, Department of Exercise Science, University of Thessaly, Trikala, Greece
| | - Glen P Kenny
- Human and Environmental Physiology Research Unit, School of Human Kinetics, Faculty of Health Sciences, University of Ottawa, Ottawa, Canada.,Clinical Epidemiology Program, Ottawa Hospital Research Institute, Ottawa, Canada
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36
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Cramer MN, Huang M, Moralez G, Crandall CG. Keeping older individuals cool in hot and moderately humid conditions: wetted clothing with and without an electric fan. J Appl Physiol (1985) 2020; 128:604-611. [PMID: 32027545 DOI: 10.1152/japplphysiol.00786.2019] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
The present study evaluated whether wearing a water-soaked t-shirt, with or without electric fan use, mitigates thermal and cardiovascular strain in older individuals exposed to hot and moderately humid conditions. Nine healthy older individuals (68 ± 4 yr; five women) completed three 120-min heat exposures (42.4 ± 0.2°C, 34.2 ± 0.9% relative humidity) on separate days while wearing a dry t-shirt (CON), a t-shirt soaked with 500 ml of tap water (WET), or a t-shirt soaked with 500 ml of tap water while facing an electric fan (2.4 ± 0.4 m/s; WET+FAN). Measurements included core and skin temperatures, evaporative mass losses, heart rate, and blood pressure. In the WET condition, elevations in core temperature were attenuated compared with DRY from 30 to 120 min and compared with WET+FAN from 30 to 90 min (P < 0.05). Evaporative mass losses (inclusive of sweat and water losses from the shirt) were greatest in WET+FAN, followed by WET, and then DRY (P < 0.01). Sweat losses were lowest in WET, followed by DRY, and then WET+FAN (P < 0.01). Heart rate was lower only at 60 min in WET versus DRY (P = 0.01). No differences in mean arterial pressure were observed (P = 0.51). In conclusion, wearing a water-soaked t-shirt without, but not with, electric fan use is an effective heat management strategy to mitigate thermal strain and lower sweat losses in older individuals exposed to hot and moderately humid conditions.NEW & NOTEWORTHY In older individuals exposed to hot and moderately humid environments, electric fan use coupled with a water-soaked t-shirt exacerbates sweat losses without mitigating heat strain compared with a dry t-shirt. However, wearing a water-soaked t-shirt without fan use reduces sweat losses and attenuates heat strain compared with a dry t-shirt and a fan/water-soaked t-shirt combination. These findings suggest wearing a water-soaked t-shirt is an effective heat-management strategy for older individuals during heat waves when air conditioning is inaccessible.
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Affiliation(s)
- Matthew N Cramer
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas and University of Texas Southwestern Medical Center, Dallas, Texas
| | - Mu Huang
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas and University of Texas Southwestern Medical Center, Dallas, Texas.,Applied Clinical Research, University of Texas Southwestern Medical Center, Dallas, Texas
| | - Gilbert Moralez
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas and University of Texas Southwestern Medical Center, Dallas, Texas.,Applied Clinical Research, University of Texas Southwestern Medical Center, Dallas, Texas
| | - 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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Venugopal V, Krishnamoorthy M, Venkatesan V, Jaganathan V, Shanmugam R, Kanagaraj K, Paul SFD. Association between occupational heat stress and DNA damage in lymphocytes of workers exposed to hot working environments in a steel industry in Southern India. Temperature (Austin) 2020; 6:346-359. [PMID: 31934606 DOI: 10.1080/23328940.2019.1632144] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2018] [Revised: 06/03/2019] [Accepted: 06/07/2019] [Indexed: 10/26/2022] Open
Abstract
Occupational heat stress apart from adverse heat-related health consequences also induces DNA damage in workers exposed to high working temperatures. We investigated the association between chronic heat exposures and Micronuclei (MN) frequency in lymphocytes of 120 workers employed in the steel industry. There was a significant increase in the MN-frequency in exposed workers compared to the unexposed workers (X2 = 47.1; p < 0.0001). While exposed workers had higher risk of DNA damage (Adj. OR = 23.3, 95% CI 8.0-70.8) compared to the unexposed workers, among the exposed workers, the odds of DNA damage was much higher for the workers exposed to high-heat levels (Adj. OR = 81.4; 95% CI 21.3-310.1) even after adjusting for confounders. For exposed workers, years of exposure to heat also had a significant association with higher induction of MN (Adj. OR = 29.7; 95% CI 2.8-315.5). Exposures to chronic heat stress is a significant occupational health risk including damages in sub-cellular level, for workers. Developing protective interventions to reduce heat exposures is imperative in the rising temperature scenario to protect millions of workers across the globe.
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Affiliation(s)
- Vidhya Venugopal
- Department of Environmental Health Engineering, Sri Ramachandra Institute of Higher Education & Research (DU)
| | - Manikandan Krishnamoorthy
- Department of Environmental Health Engineering, Sri Ramachandra Institute of Higher Education & Research (DU)
| | - Vettriselvi Venkatesan
- Department of Human Genetics, Sri Ramachandra Institute of Higher Education & Research (DU), Chennai, India
| | - Vijayalakshmi Jaganathan
- Department of Human Genetics, Sri Ramachandra Institute of Higher Education & Research (DU), Chennai, India
| | - Rekha Shanmugam
- Department of Environmental Health Engineering, Sri Ramachandra Institute of Higher Education & Research (DU)
| | - Karthik Kanagaraj
- Department of Human Genetics, Sri Ramachandra Institute of Higher Education & Research (DU), Chennai, India
| | - Solomon F D Paul
- Department of Human Genetics, Sri Ramachandra Institute of Higher Education & Research (DU), Chennai, India
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Kaltsatou A, Flouris AD, Herry CL, Notley SR, Seely AJE, Beatty HW, Kenny GP. Age differences in cardiac autonomic regulation during intermittent exercise in the heat. Eur J Appl Physiol 2020; 120:453-465. [PMID: 31894413 DOI: 10.1007/s00421-019-04290-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2019] [Accepted: 12/18/2019] [Indexed: 12/19/2022]
Abstract
PURPOSE This study aimed to detect potential differences in heart-rate variability (HRV) during a moderate-intensity intermittent exercise in the heat among physically active young (25.8 ± 1.9 years), middle-aged (43.5 ± 2.8 years), and older (62.9 ± 3.7 years) men. METHODS Thirty-three participants (11/group) performed four successive bouts of 15-min cycling at a moderate fixed rate of metabolic heat production of ~ 400 W; each separated by a 15-min recovery with 1 h of final recovery in a hot and dry environment (35 °C, 20% relative humidity). Twelve HRV indices were computed that have been commonly described in the literature, and characterized various domains of the variability and complexity of heart rate. RESULTS Cardiac autonomic regulation during intermittent exercise in the heat, as well as during pre-exercise rest and recovery was significantly affected by age, as changes were observed among the three different aged groups in five indices (p ≤ 0.05). Similarly, time influenced cardiac autonomic regulation as three indices showed changes across time (p ≤ 0.05) during intermittent exercise, whilst five indices displayed significant changes (p ≤ 0.05) during rest and recovery in the heat. CONCLUSIONS This study supports that moderate-intensity intermittent exercise in the heat is associated with significant cardiac autonomic dysregulation in older men, as compared to young and middle-aged men, yet it highlights the importance of developing preventative health strategies for heat-related illness in aged individuals.
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Affiliation(s)
- Antonia Kaltsatou
- FAME Laboratory, Department of Physical Education and Sport Science, University of Thessaly, 42100, Trikala, Greece
| | - Andreas D Flouris
- FAME Laboratory, Department of Physical Education and Sport Science, University of Thessaly, 42100, Trikala, Greece
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, 125 University Private, Room 367, Montpetit Hall, Ottawa, ON, K1N 6N5, Canada
| | - Christophe L Herry
- Clinical Epidemiological Program of the Ottawa Hospital Research Institute, Ottawa, ON, Canada
| | - Sean R Notley
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, 125 University Private, Room 367, Montpetit Hall, Ottawa, ON, K1N 6N5, Canada
| | - Andrew J E Seely
- Clinical Epidemiological Program of the Ottawa Hospital Research Institute, Ottawa, ON, Canada
- Thoracic Surgery and Critical Care Medicine, Ottawa Hospital Research Institute, University of Ottawa, Ottawa, ON, Canada
| | - Heather Wright Beatty
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, 125 University Private, Room 367, Montpetit Hall, Ottawa, ON, K1N 6N5, Canada
| | - Glen P Kenny
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, 125 University Private, Room 367, Montpetit Hall, Ottawa, ON, K1N 6N5, Canada.
- Clinical Epidemiological Program of the Ottawa Hospital Research Institute, Ottawa, ON, Canada.
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D’Souza AW, Notley SR, Meade RD, Kenny GP. Intermittent sequential pneumatic compression does not enhance whole-body heat loss in elderly adults during extreme heat exposure. Appl Physiol Nutr Metab 2019; 44:1383-1386. [DOI: 10.1139/apnm-2019-0364] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Lower-limb intermittent sequential pneumatic compression (ISPC) improves circulation and vascular function in elderly adults. We evaluated the hypothesis that ISPC would also augment whole-body heat loss (WBHL) in elderly adults (aged 69 ± 4 years) resting in extreme heat (40 °C). While ISPC increased mean arterial pressure (91 ± 9 mm Hg) relative to no-ISPC (83 ± 5 mm Hg; P = 0.013) at the end of the exposure, no influence on WBHL was observed (81 ± 7 and 86 ± 11 W for ISPC and no-ISPC, respectively, P = 0.310). Novelty When assessed in elderly adults during an extreme heat exposure, intermittent sequential pneumatic compression augmented mean arterial pressure but did not enhance whole-body heat loss.
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Affiliation(s)
- Andrew W. D’Souza
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, ON K1N 6N5, Canada
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, ON K1N 6N5, Canada
| | - Sean R. Notley
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, ON K1N 6N5, Canada
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, ON K1N 6N5, Canada
| | - Robert D. Meade
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, ON K1N 6N5, Canada
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, ON K1N 6N5, Canada
| | - Glen P. Kenny
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, ON K1N 6N5, Canada
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40
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Carrillo AE, Flouris AD, Herry CL, Notley SR, Macartney MJ, Seely AJE, Wright Beatty HE, Kenny GP. Age-related reductions in heart rate variability do not worsen during exposure to humid compared to dry heat: A secondary analysis. Temperature (Austin) 2019; 6:341-345. [PMID: 31934605 DOI: 10.1080/23328940.2019.1684791] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2019] [Revised: 10/21/2019] [Accepted: 10/21/2019] [Indexed: 10/25/2022] Open
Abstract
We conducted a secondary analysis to investigate whether age-related attenuations in heart rate variability (HRV) worsen during exposure to moderate, dry (36.5°C, 20% RH) or humid (36.5°C, 60% RH) heat conditions that resulted in greater body heat storage among older compared to young participants, and during humid compared to dry heat, regardless of age. Six HRV indices [heart rate (HR), coefficient of variation (CoV), detrended fluctuation analysis: α1, low frequency power, high frequency power, and low/high frequency ratio] were assessed in 10 young (21 ± 3 y) and 9 older (65 ± 5 y) adults for 15-min prior to (baseline), and at the end of a 120-min exposure to dry and humid heat while seated at rest. Our results demonstrated a condition (dry and humid) x time (baseline and end) interaction effect on HR (p = 0.047) such that HR gradually increased during humid heat exposure yet remained similar during dry heat exposure across groups. We also found an age-related attenuation in CoV at baseline for both the dry (young: 0.097 ± 0.023%; older: 0.054 ± 0.016%) and humid (young: 0.093 ± 0.034%; older: 0.056 ± 0.014%) heat conditions (p < 0.02). Those age-related attenuations in CoV, however, were not magnified throughout the exposure nor different between conditions (p > 0.05). While older adults stored more heat during a brief 120-min exposure to dry heat compared to their young counterparts, this was not paralleled by further age-related impairments in HRV even when body heat storage and cardiovascular strain were exacerbated by exposure to humid heat.
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Affiliation(s)
- Andres E Carrillo
- FAME Laboratory, Department of Exercise Science, University of Thessaly, Trikala, Greece.,Department of Movement Science, Chatham University, Pittsburgh, PA, USA
| | - Andreas D Flouris
- FAME Laboratory, Department of Exercise Science, University of Thessaly, Trikala, Greece.,Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, ON, Canada
| | - Christophe L Herry
- Clinical Epidemiology Program, Ottawa Hospital Research Institute, Ottawa, ON, Canada
| | - Sean R Notley
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, ON, Canada
| | - Michael J Macartney
- School of Health Sciences, College of Health and Medicine, University of Tasmania, Hobart, Australia
| | - Andrew J E Seely
- Clinical Epidemiology Program, Ottawa Hospital Research Institute, Ottawa, ON, Canada.,Thoracic Surgery and Critical Care Medicine, The Ottawa Hospital, Ottawa, ON, Canada
| | - Heather E Wright Beatty
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, ON, Canada
| | - Glen P Kenny
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, ON, Canada.,Clinical Epidemiology Program, Ottawa Hospital Research Institute, Ottawa, ON, Canada
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Superoxide and NADPH oxidase do not modulate skin blood flow in older exercising adults with and without type 2 diabetes. Microvasc Res 2019; 125:103886. [DOI: 10.1016/j.mvr.2019.103886] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2019] [Revised: 05/09/2019] [Accepted: 06/11/2019] [Indexed: 11/15/2022]
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Morabito M, Messeri A, Noti P, Casanueva A, Crisci A, Kotlarski S, Orlandini S, Schwierz C, Spirig C, Kingma BRM, Flouris AD, Nybo L. An Occupational Heat-Health Warning System for Europe: The HEAT-SHIELD Platform. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2019; 16:ijerph16162890. [PMID: 31412559 PMCID: PMC6718993 DOI: 10.3390/ijerph16162890] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/30/2019] [Revised: 08/08/2019] [Accepted: 08/09/2019] [Indexed: 12/20/2022]
Abstract
Existing heat–health warning systems focus on warning vulnerable groups in order to reduce mortality. However, human health and performance are affected at much lower environmental heat strain levels than those directly associated with higher mortality. Moreover, workers are at elevated health risks when exposed to prolonged heat. This study describes the multilingual “HEAT-SHIELD occupational warning system” platform (https://heatshield.zonalab.it/) operating for Europe and developed within the framework of the HEAT-SHIELD project. This system is based on probabilistic medium-range forecasts calibrated on approximately 1800 meteorological stations in Europe and provides the ensemble forecast of the daily maximum heat stress. The platform provides a non-customized output represented by a map showing the weekly maximum probability of exceeding a specific heat stress condition, for each of the four upcoming weeks. Customized output allows the forecast of the personalized local heat-stress-risk based on workers’ physical, clothing and behavioral characteristics and the work environment (outdoors in the sun or shade), also taking into account heat acclimatization. Personal daily heat stress risk levels and behavioral suggestions (hydration and work breaks recommended) to be taken into consideration in the short term (5 days) are provided together with long-term heat risk forecasts (up to 46 days), all which are useful for planning work activities. The HEAT-SHIELD platform provides adaptation strategies for “managing” the impact of global warming.
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Affiliation(s)
- Marco Morabito
- Institute of BioEconomy-National Research Council, 50019 Florence, Italy.
- Centre of Bioclimatology-University of Florence, 50144 Florence, Italy.
| | | | - Pascal Noti
- Federal Office of Meteorology and Climatology, MeteoSwiss, Zurich Airport, 8058 Zurich, Switzerland
| | - Ana Casanueva
- Federal Office of Meteorology and Climatology, MeteoSwiss, Zurich Airport, 8058 Zurich, Switzerland
- Meteorology Group, Dept. Applied Mathematics and Computer Sciences, University of Cantabria, 39005 Santander, Spain
| | - Alfonso Crisci
- Institute of BioEconomy-National Research Council, 50019 Florence, Italy
| | - Sven Kotlarski
- Federal Office of Meteorology and Climatology, MeteoSwiss, Zurich Airport, 8058 Zurich, Switzerland
| | - Simone Orlandini
- Centre of Bioclimatology-University of Florence, 50144 Florence, Italy
- Department of Agricultural, Food, Environmental and Forestry Sciences and Technologies, University of Florence, 50144 Florence, Italy
| | - Cornelia Schwierz
- Federal Office of Meteorology and Climatology, MeteoSwiss, Zurich Airport, 8058 Zurich, Switzerland
| | - Christoph Spirig
- Federal Office of Meteorology and Climatology, MeteoSwiss, Zurich Airport, 8058 Zurich, Switzerland
| | - Boris R M Kingma
- Department of Nutrition, Exercise and Sports, University of Copenhagen, 2100 Copenhagen, Denmark
- Unit Defense, Safety and Security, The Netherlands Organisation of Applied Scientific Research, 3769DE Soesterberg, The Netherlands
| | - Andreas D Flouris
- FAME Laboratory, Department of Exercise Science, University of Thessaly, 42100 Karies, Greece
| | - Lars Nybo
- Department of Nutrition, Exercise and Sports, University of Copenhagen, 2100 Copenhagen, Denmark
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43
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Fujii N, Hatam K, McGarr GW, Meade RD, Boulay P, Nishiyasu T, Kenny GP. Exogenous Activation of Protease-Activated Receptor 2 Attenuates Cutaneous Vasodilatation and Sweating in Older Men Exercising in the Heat. Skin Pharmacol Physiol 2019; 32:235-243. [PMID: 31220834 DOI: 10.1159/000500643] [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: 03/03/2019] [Accepted: 04/26/2019] [Indexed: 11/19/2022]
Abstract
BACKGROUND Protease-activated receptor 2 (PAR2) exists in the cutaneous vasculature and eccrine sweat glands. We previously showed that in young habitually active men, exogenous PAR2 activation via the agonist SLIGKV-NH2 had no effect on heat loss responses of cutaneous vasodilatation and sweating during rest or exercise in the heat. However, ageing is associated with altered mechanisms governing these responses. Thus, the effect of exogenous PAR2 activation on cutaneous vasodilatation and sweating in older individuals may differ from that in young adults. METHODS Local cutaneous vascular conductance (CVC) and sweat rate were measured in 9 older males (62 ± 4 years) at four forearm skin sites treated with the following: (1) lactated Ringer solution (control), (2) 0.05 mM, (3) 0.5 mM, or (4) 5 mM SLIGKV-NH2. Measurements were performed while participants rested in a non-heat-stress environment (25°C) for ∼60 min and an additional 50 min thereafter in the heat (40°C). Participants then performed 50 min of cycling at a fixed metabolic heat load of 200 W/m2 (to maintain the same thermal drive for heat loss between participants) followed by a 30-min recovery. RESULTS CVC during non-heat-stress resting was elevated from the control site with 5 mM SLIGKV-NH2 (p ≤ 0.05), but this response was not observed during ambient heat exposure. By contrast, 5 mM SLIGKV-NH2 lowered CVC during the early stage (10 and 20 min) of exercise compared to the control site (all p ≤ 0.05). Although sweating during non-heat-stressed and heat-stressed resting was not affected by any dose of SLIGKV-NH2, it was reduced with all SLIGKV-NH2 doses relative to the control site during and following exercise (all p ≤ 0.05). CONCLUSION We show that while exogenous PAR2 activation induces cutaneous vasodilatation at rest under non-heat-stressed conditions, it attenuates cutaneous vasodilatation and sweating during and following an exercise-induced heat stress in older men.
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Affiliation(s)
- Naoto Fujii
- Human and Environmental Physiology Research Unit, University of Ottawa, Ottawa, Ontario, Canada, .,Faculty of Health and Sport Sciences, University of Tsukuba, Tsukuba, Japan,
| | - Kion Hatam
- Human and Environmental Physiology Research Unit, University of Ottawa, Ottawa, Ontario, Canada
| | - Gregory W McGarr
- Human and Environmental Physiology Research Unit, University of Ottawa, Ottawa, Ontario, Canada
| | - Robert D Meade
- Human and Environmental Physiology Research Unit, University of Ottawa, Ottawa, Ontario, Canada
| | - Pierre Boulay
- Faculty of Physical Activity Sciences, University of Sherbrooke, Sherbrooke, Québec, Canada
| | - Takeshi Nishiyasu
- Faculty of Health and Sport Sciences, University of Tsukuba, Tsukuba, Japan
| | - Glen P Kenny
- Human and Environmental Physiology Research Unit, University of Ottawa, Ottawa, Ontario, Canada
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McGarr GW, Fujii N, Muia CM, Nishiyasu T, Kenny GP. Separate and combined effects of K Ca and K ATP channel blockade with NOS inhibition on cutaneous vasodilation and sweating in older men during heat stress. Am J Physiol Regul Integr Comp Physiol 2019; 317:R113-R120. [PMID: 31091157 DOI: 10.1152/ajpregu.00075.2019] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Our objective in this study was to examine the separate and combined effects of potassium (K+) channels and nitric oxide synthase (NOS) on cutaneous vasodilation and sweating in older men during rest and exercise in the heat. In 13 habitually active men (61 ± 4 yr), cutaneous vascular conductance and local sweat rate were assessed at six dorsal forearm skin sites continuously perfused with either 1) lactated Ringer (control), 2) 10 mM NG-nitro-l-arginine methyl ester (l-NAME, NOS inhibitor), 3) 50 mM tetraethylammonium (TEA; Ca2+-activated K+ channel blocker), 4) 5 mM glybenclamide (GLY; ATP-sensitive K+ channel blocker), 5) 50 mM TEA + 10 mM l-NAME, and 6) 5 mM GLY + 10 mM l-NAME via microdialysis. Participants rested in non-heat stress (25°C) and heat stress (35°C) conditions for ∼60 min each, followed by 50 min of moderate-intensity cycling (∼55% V̇o2peak) and 30 min of recovery in the heat. During rest and exercise in the heat, l-NAME, TEA + l-NAME, and GLY + l-NAME attenuated CVC relative to control (all P ≤ 0.05), although l-NAME was not different from TEA + l-NAME or GLY + l-NAME (all P > 0.05). TEA attenuated CVC during rest, whereas GLY attenuated CVC during exercise (both P ≤ 0.05). Additionally, whereas neither l-NAME nor TEA altered sweating throughout the protocol (all P > 0.05), combined TEA + l-NAME attenuated sweating during exercise in the heat (P ≤ 0.05). We conclude that in habitually active older men blockade of KCa and KATP channels attenuates cutaneous vasodilation during rest and exercise in the heat, respectively, and these effects are NOS dependent. Furthermore, combined NOS inhibition and KCa channel blockade attenuates sweating during exercise in the heat.
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Affiliation(s)
- Gregory W McGarr
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa , Ottawa, Ontario , Canada
| | - Naoto Fujii
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa , Ottawa, Ontario , Canada.,Faculty of Health and Sport Sciences, University of Tsukuba , Tsukuba City , Japan
| | - Caroline M Muia
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa , Ottawa, Ontario , Canada
| | - Takeshi Nishiyasu
- Faculty of Health and Sport Sciences, University of Tsukuba , Tsukuba City , Japan
| | - Glen P Kenny
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa , Ottawa, Ontario , Canada
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45
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Meade RD, Notley SR, D’Souza AW, Dervis S, Boulay P, Sigal RJ, Kenny GP. Interactive effects of age and hydration state on human thermoregulatory function during exercise in hot-dry conditions. Acta Physiol (Oxf) 2019; 226:e13226. [PMID: 30480873 DOI: 10.1111/apha.13226] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2018] [Revised: 11/19/2018] [Accepted: 11/22/2018] [Indexed: 12/29/2022]
Abstract
AIM Ageing and hypohydration independently attenuate heat dissipation during exercise; however, the interactive effects of these factors remain unclear. We assessed the hypothesis that ageing suppresses hypohydration-induced reductions in whole-body heat loss during exercise in the heat. METHODS On two occasions, eight young (mean [SD]: 24 [4] years) and eight middle-aged (59 [5] years) men performed 30-minute bouts of light (heat production of 175 W m-2 ) and moderate (275 W m-2 ) cycling (separated by 15-minute rest) in the heat (40°C, 15% relative humidity) when euhydrated and hypohydrated (~4% reduction in body mass). Heat production and whole-body net heat exchange (evaporative heat loss + dry heat gain) were measured via indirect and direct calorimetry (respectively) and heat storage was calculated via their temporal summation. RESULTS Net heat exchange was reduced, while heat storage was elevated, in the middle-aged men during moderate exercise when euhydrated (both P ≤ 0.01). In the young, evaporative heat loss was attenuated in the hypohydrated vs euhydrated condition during light (199 ± 6 vs 211 ± 10 W m-2 ; P ≤ 0.01) and moderate (287 ± 15 vs 307 ± 13 W m-2 ; P ≤ 0.01) exercise, but was similar in the middle-aged men, averaging 223 ± 6 and 299 ± 15 W m-2 , respectively, across conditions (both P ≥ 0.32). Heat storage was thereby exacerbated by hypohydration in the young (both P < 0.01) but not the middle-aged (both P ≥ 0.32) during both exercise bouts and, as a result, was similar between groups when hypohydrated (both P ≥ 0.50). CONCLUSION Hypohydration attenuates heat loss via sweating in young but not middle-aged men, indicating that ageing impairs one's ability to mitigate further sweat-induced fluid loss during hypohydration.
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Affiliation(s)
- Robert D. Meade
- Human and Environmental Physiology Research Unit, School of Human Kinetics University of Ottawa Ottawa Ontario Canada
| | - Sean R. Notley
- Human and Environmental Physiology Research Unit, School of Human Kinetics University of Ottawa Ottawa Ontario Canada
| | - Andrew W. D’Souza
- Human and Environmental Physiology Research Unit, School of Human Kinetics University of Ottawa Ottawa Ontario Canada
| | - Sheila Dervis
- Human and Environmental Physiology Research Unit, School of Human Kinetics University of Ottawa Ottawa Ontario Canada
| | - Pierre Boulay
- Faculty of Physical Activity Sciences University of Sherbrooke Sherbrooke Quebec Canada
| | - Ronald J. Sigal
- Human and Environmental Physiology Research Unit, School of Human Kinetics University of Ottawa Ottawa Ontario Canada
- Departments of Medicine, Cardiac Sciences and Community Health Sciences, Faculties of Medicine and Kinesiology University of Calgary Calgary Alberta Canada
- Clinical Epidemiology Program Ottawa Hospital Research Institute Ottawa Ontario Canada
| | - Glen P. Kenny
- Human and Environmental Physiology Research Unit, School of Human Kinetics University of Ottawa Ottawa Ontario Canada
- Clinical Epidemiology Program Ottawa Hospital Research Institute Ottawa Ontario Canada
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46
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Fujii N, McGarr GW, Hatam K, Chandran N, Muia CM, Nishiyasu T, Boulay P, Ghassa R, Kenny GP. Heat shock protein 90 does not contribute to cutaneous vasodilatation in older adults during heat stress. Microcirculation 2019; 26:e12541. [DOI: 10.1111/micc.12541] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2018] [Accepted: 02/27/2019] [Indexed: 01/20/2023]
Affiliation(s)
- Naoto Fujii
- Human and Environmental Physiology Research Unit University of Ottawa Ottawa Ontario Canada
- Faculty of Health and Sport Sciences University of Tsukuba Tsukuba Japan
| | - Gregory W. McGarr
- Human and Environmental Physiology Research Unit University of Ottawa Ottawa Ontario Canada
| | - Kion Hatam
- Human and Environmental Physiology Research Unit University of Ottawa Ottawa Ontario Canada
| | - Nithila Chandran
- Human and Environmental Physiology Research Unit University of Ottawa Ottawa Ontario Canada
| | - Caroline M. Muia
- Human and Environmental Physiology Research Unit University of Ottawa Ottawa Ontario Canada
| | - Takeshi Nishiyasu
- Faculty of Health and Sport Sciences University of Tsukuba Tsukuba Japan
| | - Pierre Boulay
- Faculty of Physical Activity Sciences University of Sherbrooke Sherbrooke Quebec Canada
| | - Reem Ghassa
- Human and Environmental Physiology Research Unit University of Ottawa Ottawa Ontario Canada
| | - Glen P. Kenny
- Human and Environmental Physiology Research Unit University of Ottawa Ottawa Ontario Canada
- Clinical Epidemiology Program Ottawa Hospital Research Institute Ottawa Ontario Canada
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47
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Looney DP, Long ET, Potter AW, Xu X, Friedl KE, Hoyt RW, Chalmers CR, Buller MJ, Florian JP. Divers risk accelerated fatigue and core temperature rise during fully-immersed exercise in warmer water temperature extremes. Temperature (Austin) 2019; 6:150-157. [PMID: 31312674 PMCID: PMC6620004 DOI: 10.1080/23328940.2019.1599182] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2018] [Revised: 03/14/2019] [Accepted: 03/20/2019] [Indexed: 02/03/2023] Open
Abstract
Physiological responses to work in cold water have been well studied but little is known about the effects of exercise in warm water; an overlooked but critical issue for certain military, scientific, recreational, and professional diving operations. This investigation examined core temperature responses to fatiguing, fully-immersed exercise in extremely warm waters. Twenty-one male U.S. Navy divers (body mass, 87.3 ± 12.3 kg) were monitored during rest and fatiguing exercise while fully-immersed in four different water temperatures (Tw): 34.4, 35.8, 37.2, and 38.6°C (Tw34.4, Tw35.8, Tw37.2, and Tw38.6 respectively). Participants exercised on an underwater cycle ergometer until volitional fatigue or core temperature limits were reached. Core body temperature and heart rate were monitored continuously. Trial performance time decreased significantly as water temperature increased (Tw34.4, 174 ± 12 min; Tw35.8, 115 ± 13 min; Tw37.2, 50 ± 13 min; Tw38.6, 34 ± 14 min). Peak core body temperature during work was significantly lower in Tw34.4 water (38.31 ± 0.49°C) than in warmer temperatures (Tw35.8, 38.60 ± 0.55°C; Tw37.2, 38.82 ± 0.76°C; Tw38.6, 38.97 ± 0.65°C). Core body temperature rate of change increased significantly with warmer water temperature (Tw34.4, 0.39 ± 0.28°C·h−1; Tw35.8, 0.80 ± 0.19°C·h−1; Tw37.2, 2.02 ± 0.31°C·h−1; Tw38.6, 3.54 ± 0.41°C·h−1). Physically active divers risk severe hyperthermia in warmer waters. Increases in water temperature drastically increase the rate of core body temperature rise during work in warm water. New predictive models for core temperature based on workload and duration of warm water exposure are needed to ensure warm water diving safety.
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Affiliation(s)
- David P Looney
- Biophysics and Biomedical Modeling Division, United States Army Research Institute of Environmental Medicine (USARIEM), Natick, Massachusetts, USA
| | - Edwin T Long
- Navy Experimental Diving Unit (NEDU), Panama City, Florida, USA
| | - Adam W Potter
- Biophysics and Biomedical Modeling Division, United States Army Research Institute of Environmental Medicine (USARIEM), Natick, Massachusetts, USA.,Rutgers University, School of Biomedical and Health Sciences, Newark, New Jersey, USA
| | - Xiaojiang Xu
- Biophysics and Biomedical Modeling Division, United States Army Research Institute of Environmental Medicine (USARIEM), Natick, Massachusetts, USA
| | - Karl E Friedl
- Biophysics and Biomedical Modeling Division, United States Army Research Institute of Environmental Medicine (USARIEM), Natick, Massachusetts, USA
| | - Reed W Hoyt
- Biophysics and Biomedical Modeling Division, United States Army Research Institute of Environmental Medicine (USARIEM), Natick, Massachusetts, USA
| | - Christopher R Chalmers
- Biophysics and Biomedical Modeling Division, United States Army Research Institute of Environmental Medicine (USARIEM), Natick, Massachusetts, USA.,Oak Ridge Institute for Science and Education (ORISE), Oak Ridge, TN, USA
| | - Mark J Buller
- Biophysics and Biomedical Modeling Division, United States Army Research Institute of Environmental Medicine (USARIEM), Natick, Massachusetts, USA
| | - John P Florian
- Navy Experimental Diving Unit (NEDU), Panama City, Florida, USA
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48
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Strandberg TE, Strandberg A, Pitkälä K, Benetos A. Sauna bathing, health, and quality of life among octogenarian men: the Helsinki Businessmen Study. Aging Clin Exp Res 2018; 30:1053-1057. [PMID: 29188579 DOI: 10.1007/s40520-017-0855-z] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2017] [Accepted: 11/07/2017] [Indexed: 12/16/2022]
Abstract
BACKGROUND AND AIM Sauna-type bathing has increased worldwide, and it has been related to both harmful and beneficial effects. There are few studies of bathing in sauna in very old age. METHODS The series consists of 524 mostly home-living survivors of the Helsinki Businessmen Study (HBS, mean age 86 years, range 80-95), who in 2015 responded to a questionnaire survey about lifestyle (including sauna bathing), prevalent diseases, and health-related quality of life (HRQoL, RAND-36). RESULTS Of the men 57.6% (n = 302) reported all-year round and 17.6% (n = 92) part-year sauna bathing. Sauna was currently used mostly once a week, but 10% bathed more than twice a week. Median time in the hot room was 15 min at 80 °C. Among 45.7% of the men, the habit had decreased with ageing, and 130 (24.8%) did not attend sauna. However, 92.2% of the latter had discontinued an earlier habit, respective proportions 20.7% and 75.0% among all-year and part-year users. Overall, reasons for decreased sauna bathing were nonspecific or related to mobility problems or diverse health reasons (n = 63). The most frequent motivations for sauna were relaxation and hygienic reasons. Of the RAND-36 domains physical function, vitality, social functioning, and general health were significantly better among sauna users than non-users. These differences partly remained after adjusting for prevalent diseases and mobility-disability. CONCLUSIONS Regular sauna bathing was common among octogenarian men and was associated with better HRQoL. However, reverse causality must be taken into account in this cross-sectional study. The bathing habit seemed to be prudent and had decreased in almost half of the cohort.
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Affiliation(s)
- Timo E Strandberg
- University of Helsinki, Clinicum, and Helsinki University Hospital, Haartmaninkatu 4, PO Box 340, 00029, Helsinki, Finland.
- Center for Life Course Health Research, University of Oulu, Oulu, Finland.
| | - Arto Strandberg
- University of Helsinki, Clinicum, and Helsinki University Hospital, Haartmaninkatu 4, PO Box 340, 00029, Helsinki, Finland
| | - Kaisu Pitkälä
- University of Helsinki, Clinicum, and Helsinki University Hospital, Haartmaninkatu 4, PO Box 340, 00029, Helsinki, Finland
| | - Athanase Benetos
- University Hospital of Nancy, Université de Lorraine, Nancy, France
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Gagnon D, Romero SA, Cramer MN, Kouda K, Poh PYS, Ngo H, Jay O, Crandall CG. Folic acid supplementation does not attenuate thermoregulatory or cardiovascular strain of older adults exposed to extreme heat and humidity. Exp Physiol 2018; 103:1123-1131. [PMID: 29873123 DOI: 10.1113/ep087049] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2018] [Accepted: 05/29/2018] [Indexed: 01/28/2023]
Abstract
NEW FINDINGS What is the central question of this study? Does folic acid supplementation alleviate thermoregulatory and cardiovascular strain of older adults during exposure to extreme heat and humidity? What is the main finding and its importance? Folic acid supplementation for 6 weeks did not affect whole-limb blood flow/vasodilatation, core and skin temperatures, heart rate, blood pressure and cardiac output. Thus, 6 weeks of folic acid supplementation does not alleviate thermoregulatory or cardiovascular strain of healthy older adults exposed to extreme heat and humidity. ABSTRACT Folic acid supplementation reverses age-related reductions in cutaneous vasodilatation during passive heating. However, it is unknown if folic acid supplementation alleviates thermoregulatory and cardiovascular strain experienced by older adults during heat exposure. We evaluated the effect of folic acid supplementation on thermoregulatory and cardiovascular responses of nine healthy older adults (61-72 years, 3 males/6 females) exposed to extreme heat and humidity. Participants rested at 42°C while relative humidity was increased from 30% to 70% in 2% increments every 5 min. The protocol was performed before (CON) and after (FOLIC) 6 weeks of folic acid supplementation (5 mg day-1 ). Local cutaneous vascular conductance (CVC, laser-Doppler flowmetry), forearm vascular conductance (FVC, Doppler ultrasound), mean skin and oesophageal temperatures, heart rate, blood pressure and cardiac output were measured. Folic acid supplementation increased fasting serum folate concentrations (P < 0.01). Absolute CVC was greater throughout the protocol following supplementation (CON: 1.29 ± 0.16 units mmHg-1 vs. FOLIC: 1.65 ± 0.24 units mmHg-1 , P < 0.01). However, normalized CVC (CON: 54 ± 8% vs. FOLIC: 59 ± 7%, P = 0.22), FVC (CON: 3.47 ± 0.76 ml mmHg-1 vs. FOLIC: 3.40 ± 0.56 ml mmHg-1 , P = 0.93), mean skin (P = 0.81) and oesophageal (CON: 36.87 ± 0.28°C vs. folic: 36.90 ± 0.25°C, P = 0.98) temperatures, heart rate (CON: 83 ± 10 beats min-1 vs. FOLIC: 84 ± 8 beats min-1 , P = 0.64), blood pressure (P = 0.71) and cardiac output (P = 0.20) were unaffected by folic acid supplementation. These results demonstrate that 6 weeks of folic acid supplementation does not alleviate thermoregulatory or cardiovascular strain of healthy older adults exposed to extreme heat and humidity.
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Affiliation(s)
- Daniel Gagnon
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas and University of Texas Southwestern Medical Center, Dallas, TX, USA.,Cardiovascular Prevention and Rehabilitation Centre, Montreal Heart Institute, Montréal, QC, Canada.,Département de Pharmacologie et Physiologie, Faculté de Médecine, Université de Montréal, Montréal, QC, Canada
| | - Steven A Romero
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas and University of Texas Southwestern Medical Center, Dallas, TX, USA.,Department of Physiology and Anatomy, University of North Texas Health Science Center, Fort Worth, TX, USA
| | - Matthew N Cramer
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas and University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Ken Kouda
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas and University of Texas Southwestern Medical Center, Dallas, TX, USA.,Wakayama Medical University, Wakayama, Japan
| | - Paula Y S Poh
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas and University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Hai Ngo
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas and University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Ollie Jay
- Faculty of Health Sciences, University of Sydney, Lidcombe, Australia
| | - Craig G Crandall
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas and University of Texas Southwestern Medical Center, Dallas, TX, USA
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50
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Kenny GP, Flouris AD, Yagouti A, Notley SR. Towards establishing evidence-based guidelines on maximum indoor temperatures during hot weather in temperate continental climates. Temperature (Austin) 2018; 6:11-36. [PMID: 30906809 PMCID: PMC6422495 DOI: 10.1080/23328940.2018.1456257] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2017] [Accepted: 03/15/2018] [Indexed: 11/09/2022] Open
Abstract
Rising environmental temperatures represent a major threat to human health. The activation of heat advisories using evidence-based thresholds for high-risk outdoor ambient temperatures have been shown to be an effective strategy to save lives during hot weather. However, although the relationship between weather and human health has been widely defined by outdoor temperature, corresponding increases in indoor temperature during heat events can also be harmful to health especially in vulnerable populations. In this review, we discuss our current understanding of the relationship between outdoor temperature and human health and examine how human health can also be adversely influenced by high indoor temperatures during heat events. Our assessment of the existing literature revealed a high degree of variability in what can be considered an acceptable indoor temperature because there are differences in how different groups of people may respond physiologically and behaviorally to the same living environment. Finally, we demonstrate that both non-physiological (e.g., geographical location, urban density, building design) and physiological (e.g., sex, age, fitness, state of health) factors must be considered when defining an indoor temperature threshold for preserving human health in a warming global climate.
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Affiliation(s)
- Glen P. Kenny
- Human and Environmental Physiology Research Unit, Faculty of Health Sciences, University of Ottawa, Ottawa, Ontario, Canada
| | - Andreas D. Flouris
- FAME Laboratory, Department of Exercise Science, University of Thessaly, Trikala, Greece
| | | | - Sean R. Notley
- Human and Environmental Physiology Research Unit, Faculty of Health Sciences, University of Ottawa, Ottawa, Ontario, Canada
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