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Lee BJ, Russell SL, Meade RD, McCormick JJ, King KE, Kenny GP. Markers of enterocyte damage, microbial translocation, and systemic inflammation following 9 h of heat exposure in young and older adults. Appl Physiol Nutr Metab 2024; 49:1241-1251. [PMID: 38772045 DOI: 10.1139/apnm-2024-0094] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/23/2024]
Abstract
Heat stress induced damage to the gastrointestinal barrier can induce local and systemic inflammatory reactions implicated in heat-stroke. Gastrointestinal barrier damage has been shown to be greater in older relative to young adults following hyperthermia. However, comparisons between young and older adults have been limited to brief exposures (3 h), which may not reflect the duration of heat stress experienced during heat waves. We therefore evaluated markers of intestinal epithelial damage (log transformed intestinal fatty acid binding protein, IFABPLOG), microbial translocation (soluble cluster of differentiation 14, sCD14LOG), and systemic inflammation (tumour necrosis factor alpha, TNF-αLOG; interleukin 6, IL-6LOG; C-reactive protein, CRP) in 19 young (interquartile range: 21-27 years; 10 females) and 37 older (68-73 years; 10 females) adults before and after 9 h of rest in 40 °C (9% relative humidity). The magnitude of the increase in IFABPLOG was 0.38 log pg/mL (95% CI, 0.10, 0.65 log pg/mL) greater in the older relative to young cohort (P = 0.049) after 9 h heat exposure. At baseline both IL-6LOG and CRP concentrations were higher in the older (IL-6: 2.67 (1.5) log pg/mL, CRP: 0.28 (1.5) mg/mL) relative to the young (IL-6: 1.59 log pg/mL, SD 1.2; CRP: 0.11 mg/mL, SD 1.7) group (both P ≤ 0.001). The change in IL-6 and CRP was similar between groups following 9 h heat exposure (IL-6: P = 0.053; CRP: P = 0.241). Neither sCD14LOG and TNF-αLOG were different between groups at baseline nor altered after 9 h heat exposure. Our data indicate that age may modify intestinal epithelial injury following 9 h of passive heat exposure.
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Affiliation(s)
- Ben J Lee
- Occupational and Environmental Physiology Group, Centre for Physical Activity, Sport, Exercise Sciences, Coventry University, United Kingdom
| | - Sophie L Russell
- Clinical Sciences and Translational Medicine, Centre for Health and Life Sciences, Coventry University, Coventry, United Kingdom
| | - Robert D Meade
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, Canada
| | - James J McCormick
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, Canada
| | - Kelli E King
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, Canada
| | - Glen P Kenny
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, Canada
- Clinical Epidemiology Program, Ottawa Hospital Research Institute, Ottawa, ON, Canada
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Maddocks GM, Eisenstein M, Soh HT. Biosensors for Parkinson's Disease: Where Are We Now, and Where Do We Need to Go? ACS Sens 2024. [PMID: 39189973 DOI: 10.1021/acssensors.4c00790] [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: 08/28/2024]
Abstract
Parkinson's Disease is the second most common neurological disease in the United States, yet there is no cure, no pinpointed cause, and no definitive diagnostic procedure. Parkinson's is typically diagnosed when patients present with motor symptoms such as slowness of movement and tremors. However, none of these are specific to Parkinson's, and a confident diagnosis of Parkinson's is typically only achieved when 60-80% of dopaminergic neurons are no longer functioning, at which point much of the damage to the brain is irreversible. This Perspective details ongoing efforts and accomplishments in biosensor research with the goal of overcoming these issues for Parkinson's diagnosis and care, with a focus on the potential impact of early diagnosis and associated opportunities to pinpoint a cause and a cure. We critically analyze the strengths and shortcomings of current technologies and discuss the ideal characteristics of a diagnostic technology toolbox to guide future research decisions in this space. Finally, we assess what role biosensors can play in facilitating precision medicine for Parkinson's patients.
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Affiliation(s)
- Grace M Maddocks
- Department of Electrical Engineering, Stanford University, Stanford, California 94305, United States
| | - M Eisenstein
- Department of Electrical Engineering, Stanford University, Stanford, California 94305, United States
- Department of Radiology, Stanford University, Stanford, California 94305, United States
| | - H Tom Soh
- Department of Electrical Engineering, Stanford University, Stanford, California 94305, United States
- Department of Radiology, Stanford University, Stanford, California 94305, United States
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Blount H, Valenza A, Ward J, Caggiari S, Worsley PR, Filingeri D. The effect of female breast surface area on heat-activated sweat gland density and output. Exp Physiol 2024; 109:1330-1340. [PMID: 38847458 PMCID: PMC11291870 DOI: 10.1113/ep091850] [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: 02/26/2024] [Accepted: 05/08/2024] [Indexed: 08/02/2024]
Abstract
Female development includes significant morphological changes across the breast. Yet, whether differences in breast surface area (BrSA) modify sweat gland density and output remains unclear. The present study investigated the relationship between BrSA and sweat gland density and output in 22 young to middle-aged women (28± $\ \pm \ $ 10 years) of varying breast sizes (BrSA range: 147-561 cm2) during a submaximal run in a warm environment (32 ± $ \pm \ $ 0.6°C; 53 ± $ \pm \ $ 1.7% relative humidity). Local sweat gland density and local sweat rate (LSR) above and below the nipple and at the bra triangle were measured. Expired gases were monitored for the estimation of evaporative requirements for heat balance (Ereq, in W/m2). Associations between BrSA and (i) sweat gland density; (ii) LSR; and (iii) sweat output per gland for the breast sites were determined via correlation and regression analyses. Our results indicated that breast sweat gland density decreased linearly as BrSA increased (r = -0.76, P < 0.001), whereas sweat output per gland remained constant irrespective of BrSA (r = 0.29, P = 0.28). This resulted in LSR decreasing linearly as BrSA increased (r = -0.62, P = 0.01). Compared to the bra triangle, the breast had a 64% lower sweat gland density (P < 0.001), 83% lower LSR (P < 0.001) and 53% lower output per gland (P < 0.001). BrSA (R2 = 0.33, P = 0.015) explained a greater proportion of variance in LSR than Ereq (in W/m2) (R2 = 0.07, P = 0.538). These novel findings extend the known relationship between body morphology and sweat gland density and LSR, to the female breast. This knowledge could innovate user-centred design of sports bras by accommodating breast size-specific needs for sweat management, skin wetness perception and comfort.
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Affiliation(s)
- Hannah Blount
- ThermosenseLab, Skin Sensing Research Group, School of Health SciencesThe University of SouthamptonSouthamptonUK
| | - Alessandro Valenza
- ThermosenseLab, Skin Sensing Research Group, School of Health SciencesThe University of SouthamptonSouthamptonUK
- Sport and Exercise Sciences Research Unit, SPPEFF DepartmentUniversity of PalermoPalermoItaly
| | - Jade Ward
- ThermosenseLab, Skin Sensing Research Group, School of Health SciencesThe University of SouthamptonSouthamptonUK
| | - Silvia Caggiari
- PressureLab, Skin Sensing Research Group, School of Health SciencesThe University of SouthamptonSouthamptonUK
| | - Peter R. Worsley
- PressureLab, Skin Sensing Research Group, School of Health SciencesThe University of SouthamptonSouthamptonUK
| | - Davide Filingeri
- ThermosenseLab, Skin Sensing Research Group, School of Health SciencesThe University of SouthamptonSouthamptonUK
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Tsoutsoubi L, Ioannou LG, Ciuha U, Fisher JT, Possnig C, Simpson LL, Flouris AD, Lawley J, Mekjavic IB. Validation of formulae predicting stroke volume from arterial pressure: with particular emphasis on upright individuals in hot ambient conditions. Front Physiol 2024; 15:1398816. [PMID: 39050481 PMCID: PMC11266312 DOI: 10.3389/fphys.2024.1398816] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2024] [Accepted: 05/20/2024] [Indexed: 07/27/2024] Open
Abstract
Introduction During heatwaves, it is important to monitor workers' cardiovascular health since 35% of those working in hot environments experience symptoms of heat strain. Wearable technology has been popularized for monitoring heart rate (HR) during recreational activities, but it can also be used to monitor occupational heat strain based on core and skin temperatures and HR. To our knowledge, no devices estimate the cardiovascular strain directly based on stroke volume (SV) or cardiac output (CO). In addition to the hardware, there are limitations regarding the lack of suitable algorithms that would provide such an index based on relevant physiological responses. The validation of the formulae already existing in literature was the principle aim of the present study. Methods We monitored the cardiovascular responses of our participants to a supine and 60° head-up tilt at the same time each day. During the test, we measured blood pressure derived by finger photoplethysmography, which also provided beat-by-beat measures of SV and CO. Afterwards, we compared the SV derived from the photoplethysmography with the one calculated with the different equations that already exist in literature. Results The evaluation of the formulae was based on comparing the error of prediction. This residual analysis compared the sum of the squared residuals generated by each formula using the same data set. Conclusion Our findings suggest that estimating SV with existing formulae is feasible, showing a good correlation and a relatively small bias. Thus, simply measuring workers' blood pressure during breaks could estimate their cardiac strain.
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Affiliation(s)
- Lydia Tsoutsoubi
- Department of Automatics, Biocybernetics and Robotics, Jožef Stefan Institute, Ljubljana, Slovenia
| | - Leonidas G. Ioannou
- Department of Automatics, Biocybernetics and Robotics, Jožef Stefan Institute, Ljubljana, Slovenia
| | - Urša Ciuha
- Department of Automatics, Biocybernetics and Robotics, Jožef Stefan Institute, Ljubljana, Slovenia
| | - Jason T. Fisher
- Department of Automatics, Biocybernetics and Robotics, Jožef Stefan Institute, Ljubljana, Slovenia
- International Postgraduate School Józef Stefan, Ljubljana, Slovenia
| | - Carmen Possnig
- Department Sport Science, University of Innsbruck, Innsbruck, Austria
| | - Lydia L. Simpson
- Department Sport Science, University of Innsbruck, Innsbruck, Austria
| | - Andreas D. Flouris
- FAME Laboratory, Department of Physical Education and Sport Science, University of Thessaly, Trikala, Greece
| | - Justin Lawley
- Department Sport Science, University of Innsbruck, Innsbruck, Austria
| | - Igor B. Mekjavic
- Department of Automatics, Biocybernetics and Robotics, Jožef Stefan Institute, Ljubljana, Slovenia
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Kenny GP, Tetzlaff EJ, Journeay WS, Henderson SB, O’Connor FK. Indoor overheating: A review of vulnerabilities, causes, and strategies to prevent adverse human health outcomes during extreme heat events. Temperature (Austin) 2024; 11:203-246. [PMID: 39193048 PMCID: PMC11346563 DOI: 10.1080/23328940.2024.2361223] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2024] [Revised: 05/07/2024] [Accepted: 05/20/2024] [Indexed: 08/29/2024] Open
Abstract
The likelihood of exposure to overheated indoor environments is increasing as climate change is exacerbating the frequency and severity of hot weather and extreme heat events (EHE). Consequently, vulnerable populations will face serious health risks from indoor overheating. While the relationship between EHE and human health has been assessed in relation to outdoor temperature, indoor temperature patterns can vary markedly from those measured outside. This is because the built environment and building characteristics can act as an important modifier of indoor temperatures. In this narrative review, we examine the physiological and behavioral determinants that influence a person's susceptibility to indoor overheating. Further, we explore how the built environment, neighborhood-level factors, and building characteristics can impact exposure to excess heat and we overview how strategies to mitigate building overheating can help reduce heat-related mortality in heat-vulnerable occupants. Finally, we discuss the effectiveness of commonly recommended personal cooling strategies that aim to mitigate dangerous increases in physiological strain during exposure to high indoor temperatures during hot weather or an EHE. As global temperatures continue to rise, the need for a research agenda specifically directed at reducing the likelihood and impact of indoor overheating on human health is paramount. This includes conducting EHE simulation studies to support the development of consensus-based heat mitigation solutions and public health messaging that provides equitable protection to heat-vulnerable people exposed to high indoor temperatures.
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Affiliation(s)
- 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
| | - Emily J. Tetzlaff
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, ON, Canada
| | - W. Shane Journeay
- Departments of Medicine and Community Health and Epidemiology, Dalhousie Medicine New Brunswick and Dalhousie University, Saint John, NB, Canada
- Department of Medicine, Division of Physical Medicine and Rehabilitation, University of Toronto, Toronto, ON, Canada
- Department of Rehabilitative Care, Providence Healthcare-Unity Health Toronto, Toronto, ON, Canada
| | - Sarah B. Henderson
- Environmental Health Services, British Columbia Centre for Disease Control, Vancouver, BC, Canada
- National Collaborating Centre for Environmental Health, Vancouver, BC, Canada
| | - Fergus K. O’Connor
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, ON, Canada
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Dunn RA, Luk HY, Appell CR, Jiwan NC, Keefe MS, Rolloque JJS, Sekiguchi Y. Eccentric muscle-damaging exercise in the heat lowers cellular stress prior to and immediately following future exertional heat exposure. Cell Stress Chaperones 2024; 29:472-482. [PMID: 38735625 PMCID: PMC11131061 DOI: 10.1016/j.cstres.2024.05.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2024] [Revised: 04/22/2024] [Accepted: 05/04/2024] [Indexed: 05/14/2024] Open
Abstract
Muscle-damaging exercise (e.g., downhill running [DHR]) or heat exposure bouts potentially reduce physiological and/or cellular stress during future exertional heat exposure; however, the true extent of their combined preconditioning effects is unknown. Therefore, this study investigated the effect of muscle-damaging exercise in the heat on reducing physiological and cellular stress during future exertional heat exposure. Ten healthy males (mean ± Standard Definition; age, 23 ± 3 years; body mass, 78.7 ± 11.5 kg; height, 176.9 ± 4.7 cm) completed this study. Participants were randomly assigned into two preconditioning groups: (a) DHR in the heat (ambient temperature [Tamb], 35 °C; relative humidity [RH], 40%) and (b) DHR in thermoneutral (Tamb, 20 °C; RH, 20%). Seven days following DHR, participants performed a 45-min flat run in the heat (FlatHEAT [Tamb, 35 °C; RH, 40%]). During exercise, heart rate and rectal temperature (Trec) were recorded at baseline and every 5-min. Peripheral blood mononuclear cells were isolated to assess heat shock protein 72 (Hsp72) concentration between conditions at baseline, immediately post-DHR, and immediately pre-FlatHEAT and post-FlatHEAT. Mean Trec during FlatHEAT between hot (38.23 ± 0.38 °C) and thermoneutral DHR (38.26 ± 0.38 °C) was not significantly different (P = 0.68), with no mean heart rate differences during FlatHEAT between hot (172 ± 15 beats min-1) and thermoneutral conditions (174 ± 8 beats min-1; P = 0.58). Hsp72 concentration change from baseline to immediately pre-FlatHEAT was significantly lower in hot (-51.4%) compared to thermoneutral (+24.2%; P = 0.025) DHR, with Hsp72 change from baseline to immediately post-FlatHEAT also lower in hot (-52.6%) compared to thermoneutral conditions (+26.3%; P = 0.047). A bout of muscle-damaging exercise in the heat reduces cellular stress levels prior to and immediately following future exertional heat exposure.
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Affiliation(s)
- Ryan A Dunn
- Sports Performance Laboratory, Department of Kinesiology and Sport Management, Texas Tech University, Lubbock, TX, USA
| | - Hui-Ying Luk
- Applied Physiology Laboratory, Department of Kinesiology and Sport Management, Texas Tech University, Lubbock, TX, USA
| | - Casey R Appell
- Applied Physiology Laboratory, Department of Kinesiology and Sport Management, Texas Tech University, Lubbock, TX, USA
| | - Nigel C Jiwan
- Applied Physiology Laboratory, Department of Kinesiology and Sport Management, Texas Tech University, Lubbock, TX, USA
| | - Marcos S Keefe
- Sports Performance Laboratory, Department of Kinesiology and Sport Management, Texas Tech University, Lubbock, TX, USA
| | - Jan-Joseph S Rolloque
- Sports Performance Laboratory, Department of Kinesiology and Sport Management, Texas Tech University, Lubbock, TX, USA
| | - Yasuki Sekiguchi
- Sports Performance Laboratory, Department of Kinesiology and Sport Management, Texas Tech University, Lubbock, TX, USA.
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Dunn RA, Fry LA, Sekiguchi Y, Benjamin CL, Manning CN, Huggins RA, Stearns RL, Casa DJ. Effect of Heat Acclimatization, Heat Acclimation, and Intermittent Heat Training on Maximal Oxygen Uptake. Sports Health 2024:19417381241249470. [PMID: 38708678 DOI: 10.1177/19417381241249470] [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: 05/07/2024] Open
Abstract
BACKGROUND Maximal oxygen uptake (VO2max) is an important determinant of endurance performance. Heat acclimation/acclimatization (HA/HAz) elicits improvements in endurance performance. Upon heat exposure reduction, intermittent heat training (IHT) may alleviate HA/HAz adaptation decay; however, corresponding VO2max responses are unknown. HYPOTHESIS VO2max is maintained after HAz/HA; IHT mitigates decrements in aerobic power after HAz/HA. STUDY DESIGN Interventional study. LEVEL OF EVIDENCE Level 3. METHODS A total of 27 male endurance runners (mean ± SD; age, 36 ± 12 years; body mass, 73.03 ± 8.97 kg; height, 178.81 ± 6.39 cm) completed VO2max testing at 5 timepoints; baseline, post-HAz, post-HA, and weeks 4 and 8 of IHT (IHT4, IHT8). After baseline testing, participants completed HAz, preceded by 5 days of HA involving exercise to induce hyperthermia for 60 minutes in the heat (ambient temperature, 39.13 ± 1.37°C; relative humidity, 51.08 ± 8.42%). Participants were assigned randomly to 1 of 3 IHT groups: once-weekly, twice-weekly, or no IHT. Differences in VO2max, velocity at VO2max (vVO2), and maximal heart rate (HRmax) at all 5 timepoints were analyzed using repeated-measure analyses of variance with Bonferroni corrections post hoc. RESULTS No significant VO2max or vVO2 differences were observed between baseline, post-HAz, or post-HA (P = 0.36 and P = 0.09, respectively). No significant group or time effects were identified for VO2max or vVO2 at post-HA, IHT4, and IHT8 (P = 0.67 and P = 0.21, respectively). Significant HRmax differences were observed between baseline and post-HA tests (P < 0.01). No significant group or time HRmax differences shown for post-HA, IHT4, and IHT8 (P = 0.59). CONCLUSION VO2max was not reduced among endurance runners after HA/HAz and IHT potentially due to participants' similar aerobic training status and high aerobic fitness levels. CLINICAL RELEVANCE HAz/HA and IHT maintain aerobic power in endurance runners, with HAz/HA procuring reductions in HRmax.
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Affiliation(s)
- Ryan A Dunn
- Sports Performance Laboratory, Department of Kinesiology and Sport Management, Texas Tech University, Lubbock, Texas
| | - Lauren A Fry
- Korey Stringer Institute, Department of Kinesiology, University of Connecticut, Storrs, Connecticut
| | - Yasuki Sekiguchi
- Sports Performance Laboratory, Department of Kinesiology and Sport Management, Texas Tech University, Lubbock, Texas and Korey Stringer Institute, Department of Kinesiology, University of Connecticut, Storrs, Connecticut
| | - Courteney L Benjamin
- Korey Stringer Institute, Department of Kinesiology, University of Connecticut, Storrs, Connecticut and Department of Kinesiology, Samford University, Birmingham, Alabama
| | - Ciara N Manning
- Korey Stringer Institute, Department of Kinesiology, University of Connecticut, Storrs, Connecticut
| | - Robert A Huggins
- Korey Stringer Institute, Department of Kinesiology, University of Connecticut, Storrs, Connecticut
| | - Rebecca L Stearns
- Korey Stringer Institute, Department of Kinesiology, University of Connecticut, Storrs, Connecticut
| | - Douglas J Casa
- Korey Stringer Institute, Department of Kinesiology, University of Connecticut, Storrs, Connecticut
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Deshayes TA, Hsouna H, Braham MAA, Arvisais D, Pageaux B, Ouellet C, Jay O, Maso FD, Begon M, Saidi A, Gendron P, Gagnon D. Work-rest regimens for work in hot environments: A scoping review. Am J Ind Med 2024; 67:304-320. [PMID: 38345435 DOI: 10.1002/ajim.23569] [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: 10/02/2023] [Revised: 01/08/2024] [Accepted: 01/23/2024] [Indexed: 03/16/2024]
Abstract
BACKGROUND To limit exposures to occupational heat stress, leading occupational health and safety organizations recommend work-rest regimens to prevent core temperature from exceeding 38°C or increasing by ≥1°C. This scoping review aims to map existing knowledge of the effects of work-rest regimens in hot environments and to propose recommendations for future research based on identified gaps. METHODS We performed a search of 10 databases to retrieve studies focused on work-rest regimens under hot conditions. RESULTS Forty-nine articles were included, of which 35 were experimental studies. Most studies were conducted in laboratory settings, in North America (71%), on healthy young adults, with 94% of the 642 participants being males. Most studies (66%) employed a protocol duration ≤240 min (222 ± 162 min, range: 37-660) and the time-weighted average wet-bulb globe temperature was 27 ± 4°C (range: 18-34). The work-rest regimens implemented were those proposed by the American Conference of Governmental and Industrial Hygiene (20%), National Institute of Occupational Safety and Health (11%), or the Australian Army (3%). The remaining studies (66%) did not mention how the work-rest regimens were derived. Most studies (89%) focused on physical tasks only. Most studies (94%) reported core temperature, whereas only 22% reported physical and/or mental performance outcomes, respectively. Of the 35 experimental studies included, 77% indicated that core temperature exceeded 38°C. CONCLUSIONS Although work-rest regimens are widely used, few studies have investigated their physiological effectiveness. These studies were mainly short in duration, involved mostly healthy young males, and rarely considered the effect of work-rest regimens beyond heat strain during physical exertion.
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Affiliation(s)
- Thomas A Deshayes
- Montreal Heart Institute, Montréal, Québec, Canada
- École de kinésiologie et des sciences de l'activité physique (EKSAP), Faculté de médecine, Université de Montréal, Montréal, Québec, Canada
| | - Hsen Hsouna
- Montreal Heart Institute, Montréal, Québec, Canada
- École de kinésiologie et des sciences de l'activité physique (EKSAP), Faculté de médecine, Université de Montréal, Montréal, Québec, Canada
| | - Mounir A A Braham
- Département des sciences de l'activité physique, Université du Québec à Trois-Rivières, Trois-Rivières, Québec, Canada
- Département d'anatomie, Université du Québec à Trois-Rivières, Trois-Rivières, Québec, Canada
| | - Denis Arvisais
- Bibliothèque des sciences de la santé, Université de Montréal, Montréal, Québec, Canada
| | - Benjamin Pageaux
- École de kinésiologie et des sciences de l'activité physique (EKSAP), Faculté de médecine, Université de Montréal, Montréal, Québec, Canada
- Centre de recherche de l'Institut universitaire de gériatrie de Montréal (CRIUGM), Montréal, Québec, Canada
- Centre interdisciplinaire de recherche sur le cerveau et l'apprentissage (CIRCA), Montréal, Québec, Canada
| | - Capucine Ouellet
- Institut de recherche Robert-Sauvé en santé et en sécurité du travail (IRSST), Montréal, Québec, Canada
| | - Ollie Jay
- Heat and Health Research Incubator, University of Sydney, Sydney, New South Wales, Australia
| | - Fabien D Maso
- École de kinésiologie et des sciences de l'activité physique (EKSAP), Faculté de médecine, Université de Montréal, Montréal, Québec, Canada
- Centre interdisciplinaire de recherche sur le cerveau et l'apprentissage (CIRCA), Montréal, Québec, Canada
| | - Mickael Begon
- École de kinésiologie et des sciences de l'activité physique (EKSAP), Faculté de médecine, Université de Montréal, Montréal, Québec, Canada
- Centre de recherche du CHU Sainte-Justine, Montréal, Québec, Canada
| | - Alireza Saidi
- Institut de recherche Robert-Sauvé en santé et en sécurité du travail (IRSST), Montréal, Québec, Canada
| | - Philippe Gendron
- Département des sciences de l'activité physique, Université du Québec à Trois-Rivières, Trois-Rivières, Québec, Canada
| | - Daniel Gagnon
- Montreal Heart Institute, Montréal, Québec, Canada
- École de kinésiologie et des sciences de l'activité physique (EKSAP), Faculté de médecine, Université de Montréal, Montréal, Québec, 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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Rosbrook P, Sweet D, Qiao J, Looney DP, Margolis LM, Hostler D, Pryor RR, Pryor JL. Heat stress increases carbohydrate oxidation rates and oxygen uptake during prolonged load carriage exercise. Temperature (Austin) 2024; 11:170-181. [PMID: 38846526 PMCID: PMC11152092 DOI: 10.1080/23328940.2024.2322920] [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: 08/17/2023] [Accepted: 02/19/2024] [Indexed: 06/09/2024] Open
Abstract
Military missions are conducted in a multitude of environments including heat and may involve walking under load following severe exertion, the metabolic demands of which may have nutritional implications for fueling and recovery planning. Ten males equipped a military pack loaded to 30% of their body mass and walked in 20°C/40% relative humidity (RH) (TEMP) or 37°C/20% RH (HOT) either continuously (CW) for 90 min at the first ventilatory threshold or mixed walking (MW) with unloaded running intervals above the second ventilatory threshold between min 35 and 55 of the 90 min bout. Pulmonary gas, thermoregulatory, and cardiovascular variables were analyzed following running intervals. Final rectal temperature (MW: p < 0.001, g = 3.81, CW: p < 0.001, g = 4.04), oxygen uptake, cardiovascular strain, and energy expenditure were higher during HOT trials (p ≤ 0.05) regardless of exercise type. Both HOT trials elicited higher final carbohydrate oxidation (CHOox) than TEMP CW at min 90 (HOT MW: p < 0.001, g = 1.45, HOT CW: p = 0.009, g = 0.67) and HOT MW CHOox exceeded TEMP MW at min 80 and 90 (p = 0.049, g = 0.60 and p = 0.024, g = 0.73, respectively). There were no within-environment differences in substrate oxidation indicating that severe exertion work cycles did not produce a carryover effect during subsequent loaded walking. The rate of CHOox during 90 minutes of load carriage in the heat appears to be primarily affected by accumulated thermal load.
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Affiliation(s)
- Paul Rosbrook
- Center for Research & Education in Special Environments, University at Buffalo, Buffalo, USA
| | - Daniel Sweet
- Center for Research & Education in Special Environments, University at Buffalo, Buffalo, USA
| | - JianBo Qiao
- Center for Research & Education in Special Environments, University at Buffalo, Buffalo, USA
| | - David P. Looney
- Military Performance Division, United States Army Research Institute of Environmental Medicine, Natick, USA
| | - Lee M. Margolis
- Military Nutrition Division, United States Army Research Institute of Environmental Medicine, Natick, USA
| | - David Hostler
- Center for Research & Education in Special Environments, University at Buffalo, Buffalo, USA
| | - Riana R. Pryor
- Center for Research & Education in Special Environments, University at Buffalo, Buffalo, USA
| | - J. Luke Pryor
- Center for Research & Education in Special Environments, University at Buffalo, Buffalo, USA
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11
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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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12
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Henderson M, Halsey L. The metabolic upper critical temperature of the human thermoneutral zone. J Therm Biol 2022; 110:103380. [DOI: 10.1016/j.jtherbio.2022.103380] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2021] [Revised: 05/11/2022] [Accepted: 10/21/2022] [Indexed: 11/11/2022]
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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: 65] [Impact Index Per Article: 32.5] [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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Rykaczewski K. Thermophysiological aspects of wearable robotics: Challenges and opportunities. Temperature (Austin) 2022; 10:313-325. [PMID: 37554385 PMCID: PMC10405755 DOI: 10.1080/23328940.2022.2113725] [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: 06/16/2022] [Revised: 08/10/2022] [Accepted: 08/11/2022] [Indexed: 10/15/2022] Open
Abstract
Technological advancements in the last two decades have enabled development of a variety of mechanically supporting wearable robots (i.e. exoskeletons) that are transitioning to practice in medical and industrial settings. The feedback from industry and recent controlled studies is highlighting thermal discomfort as a major reason for the disuse of the devices and a substantial barrier to their long-term adoption. Furthermore, a brief overview of the devices and their intended applications reveals that many of the potential users are likely to face thermal comfort issues because of either high exertion or medically related high heat sensitivity. The aim of this review is to discuss these emerging thermal challenges and opportunities surrounding wearable robots. This review discusses mechanisms, potential solutions, and a platform for systematically measuring heat transfer inhibition caused by wearing of an exoskeleton. Lastly, the potential for substantial metabolic rate reduction provided by exoskeletons to reduce worker thermal strain in warm-to-hot conditions is also considered.
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Affiliation(s)
- Konrad Rykaczewski
- School for Engineering of Matter, Transport and Energy, Arizona State University, Tempe, AZ, US
- Julie Ann Wrigley Global Futures Laboratory, Arizona State University, Tempe, AZ, USA
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15
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Deshayes TA, Pancrate T, Goulet ED. Impact of dehydration on perceived exertion during endurance exercise: A systematic review with meta-analysis. J Exerc Sci Fit 2022; 20:224-235. [PMID: 35601980 PMCID: PMC9093000 DOI: 10.1016/j.jesf.2022.03.006] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2021] [Revised: 03/09/2022] [Accepted: 03/28/2022] [Indexed: 11/20/2022] Open
Abstract
Background Understanding the impact of stressors on the rating of perceived exertion (RPE) is relevant from a performance and exercise adherence/participation standpoint. Athletes and recreationally active individuals dehydrate during exercise. No attempt has been made to systematically determine the impact of exercise-induced dehydration (EID) on RPE. Objective The present meta-analysis aimed to determine the effect of EID on RPE during endurance exercise and examine the moderating effect of potential confounders. Data analyses Performed on raw RPE values using random-effects models weighted mean effect summaries and meta-regressions with robust standard errors, and with a practical meaningful effect set at 1 point difference between euhydration (EUH) and EID. Only controlled crossover studies measuring RPE with a Borg scale in healthy adults performing ≥30 min of continuous endurance exercise while dehydrating or drinking to maintain EUH were included. Results Sixteen studies were included, representing 147 individuals. Mean body mass loss with EUH was 0.5 ± 0.4%, compared to 2.3 ± 0.5% with EID (range 1.7-3.1%). Within an EID of 0.5-3% body mass, a maximum difference in RPE of 0.81 points (95% CI: 0.36-1.27) was observed between conditions. A meta-regression revealed that RPE increases by 0.21 points for each 1% increase in EID (95% CI: 0.12-0.31). Humidity, ambient temperature and aerobic capacity did not alter the relationship between EID and RPE. Conclusion Therefore, the effect of EID on RPE is unlikely to be practically meaningful until a body mass loss of at least 3%.
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Affiliation(s)
- Thomas A. Deshayes
- Faculty of Physical Activity Sciences, University of Sherbrooke, P.Q., Canada
- Research Center on Aging, University of Sherbrooke, P.Q., Canada
| | - Timothée Pancrate
- Faculty of Physical Activity Sciences, University of Sherbrooke, P.Q., Canada
| | - Eric D.B. Goulet
- Faculty of Physical Activity Sciences, University of Sherbrooke, P.Q., Canada
- Research Center on Aging, University of Sherbrooke, P.Q., Canada
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16
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King KE, McCormick JJ, Notley SR, Fujii N, Kenny GP. Serum klotho concentrations in young and older men during prolonged exercise in temperate and hot conditions. Curr Aging Sci 2022; 15:180-185. [PMID: 35249521 DOI: 10.2174/1874609815666220304200939] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2021] [Revised: 01/07/2022] [Accepted: 12/14/2022] [Indexed: 11/22/2022]
Abstract
BACKGROUND The protein klotho protects cellular function during various physiological stressors, such as exercise, however it is unknown how the age-related decline in klotho production affects responses during exercise, especially in the heat. OBJECTIVE Our objective was to determine the effect of exercise in temperate and hot environmental conditions on serum klotho concentrations in young and older men. METHODS 12 young (mean ± SD: 22 ± 3 years) and 12 older (59 ± 4 years) men performed 180 minutes of moderate-intensity treadmill walking (metabolic rate: 200 W/m2) in a temperate [wet-bulb globe temperature (WBGT) 16°C, achieved with 21.9°C, 35% relative humidity (RH)] and hot (WBGT 32°C, achieved with 41.4°C, 35% RH) environment. Serum klotho was assessed before and after exercise, as well as 60-min post-exercise recovery in the respective environments. RESULTS Absolute klotho concentrations were greater in young versus older men during all measured time points in the temperate (p = 0.032), but not the hot condition (p = 0.064). In the hot condition, the change in serum klotho from baseline was significantly higher after exercise in the heat (mean ± SEM: +251 ± 73 pg/mL) than the temperate (+75 ± 57 pg/mL) environment in both groups (p = 0.026). However, this elevation was not maintained during recovery. CONCLUSION We showed that prolonged exercise in a temperate environment does not elicit a klotho response in either group. In contrast, despite lower resting klotho levels, the older men showed a similar exercise-induced increase in serum klotho response as their younger counterparts.
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Affiliation(s)
- Kelli E King
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, Canada
| | - James J McCormick
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, Canada
| | - Sean R Notley
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, Canada
| | - Naoto Fujii
- Faculty of Health and Sport Sciences, University of Tsukuba, Japan
| | - Glen P Kenny
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, Canada
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17
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Gerrett N, Amano T, Inoue Y, Kondo N. Eccrine sweat glands' maximum ion reabsorption rates during passive heating in older adults (50-84 years). Eur J Appl Physiol 2021; 121:3145-3159. [PMID: 34370049 DOI: 10.1007/s00421-021-04766-6] [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: 02/10/2021] [Accepted: 07/05/2021] [Indexed: 11/29/2022]
Abstract
PURPOSE We examined whether eccrine sweat glands ion reabsorption rate declined with age in 35 adults aged 50-84 years. Aerobic fitness (VO2max) and salivary aldosterone were measured to see if they modulated ion reabsorption rates. METHODS During a passive heating protocol (lower leg 42 °C water submersion) the maximum ion reabsorption rates from the chest, forearm and thigh were measured, alongside other thermophysiological responses. The maximum ion reabsorption rate was defined as the inflection point in the slope of the relation between galvanic skin conductance and sweat rate. RESULTS The maximum ion reabsorption rate at the forearm, chest and thigh (0.29 ± 0.16, 0.33 ± 0.15, 0.18 ± 0.16 mg/cm2/min, respectively) were weakly correlated with age (r ≤ - 0.232, P ≥ 0.05) and salivary aldosterone concentrations (r ≤ - 0.180, P ≥ 0.179). A moderate positive correlation was observed between maximum ion reabsorption rate at the thigh and VO2max (r = 0.384, P = 0.015). Salivary aldosterone concentration moderately declined with age (r = - 0.342, P = 0.021). Whole body sweat rate and pilocarpine-induced sudomotor responses to iontophoresis increased with VO2max (r ≥ 0.323, P ≤ 0.027) but only moderate (r = - 0.326, P = 0.032) or no relations (r ≤ - 0.113, P ≥ 0.256) were observed with age. CONCLUSION The eccrine sweat glands' maximum ion reabsorption rate is not affected by age, spanning 50-84 years. Aldosterone concentration in an aged cohort does not appear to modulate the ion reabsorption rate. We provide further support for maintaining cardiorespiratory fitness to attenuate any decline in sudomotor function.
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Affiliation(s)
- N Gerrett
- Laboratory for Applied Human Physiology, Graduate School of Human Development and Environment, Kobe University, 3-11 Tsurukabuto, Nada-Ku, Kobe, 657-8501, Japan.,Department of Human Movement Sciences, Faculty of Behavioural and Movement Sciences, Amsterdam Movement Sciences, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands
| | - T Amano
- Laboratory for Exercise and Environmental Physiology, Faculty of Education, Niigata University, Niigata, Japan
| | - Y Inoue
- Laboratory for Human Performance Research, Osaka International University, Osaka, Japan
| | - Narihiko Kondo
- Laboratory for Applied Human Physiology, Graduate School of Human Development and Environment, Kobe University, 3-11 Tsurukabuto, Nada-Ku, Kobe, 657-8501, Japan.
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18
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Sippli K, Schmalzried P, Rieger MA, Voelter-Mahlknecht S. Challenges arising for older workers from participating in a workplace intervention addressing work ability: a qualitative study from Germany. Int Arch Occup Environ Health 2021; 94:919-933. [PMID: 33491100 PMCID: PMC8238737 DOI: 10.1007/s00420-020-01639-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2019] [Accepted: 12/18/2020] [Indexed: 11/26/2022]
Abstract
OBJECTIVE Studies examining what renders workplace interventions to sustain and promote work ability of older workers successful have largely neglected older workers´ perspective. This paper outlines the results of a study with regard to older workers´ experiences and expectations of a workplace intervention. Based on these findings, some reflections on how to improve the design and the implementation of workplace interventions for older workers are provided. METHODS Semi-structured interviews were conducted with older workers (N = 8) participating in a workplace intervention undertaken at one production site of a large manufacturing company in Baden-Wurttemberg/Germany. The interview guide included questions on participants´ experiences with and expectations of the intervention. The interviews were recorded, transcribed verbatim and analyzed using qualitative content analysis according to Mayring (2014). RESULTS Older workers´ reported some challenges they face due to their participation in the workplace intervention. These resulted from the work environment (physical challenges), the work process design (new long work cycle), the work organization (tight time allowances, little job rotation, change of teams, age stereotypes) and the management of the workplace intervention (bad information, feeling of occupational insecurity and lack of being valued). CONCLUSIONS The study shows that challenges arising for older workers from their participation in the workplace intervention may have counteracted the promotion of work ability. As findings suggest, some of these challenges might have been avoided either by considering workers´ perspective during design and implementation of an intervention or by referring to evidence on aging and work ability.
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Affiliation(s)
- Khira Sippli
- Institute of Occupational and Social Medicine and Health Services Research, University Hospital Tuebingen, Wilhelmstraße 27, 72074, Tübingen, Germany
- Institute for Applied Economic Research at the University Tuebingen, Schaffhausenstr. 73, 72072, Tuebingen, Germany
| | - Pia Schmalzried
- Institute of Occupational and Social Medicine and Health Services Research, University Hospital Tuebingen, Wilhelmstraße 27, 72074, Tübingen, Germany
| | - Monika A Rieger
- Institute of Occupational and Social Medicine and Health Services Research, University Hospital Tuebingen, Wilhelmstraße 27, 72074, Tübingen, Germany
| | - Susanne Voelter-Mahlknecht
- Institute of Occupational and Social Medicine and Health Services Research, University Hospital Tuebingen, Wilhelmstraße 27, 72074, Tübingen, Germany.
- Institute of Occupational Medicine, Charité-Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Augustenburger Platz 1, 13353, Berlin, Germany.
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19
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Knechtle B, Valero D, Villiger E, Alvero-Cruz JR, Nikolaidis PT, Cuk I, Rosemann T, Scheer V. Trends in Weather Conditions and Performance by Age Groups Over the History of the Berlin Marathon. Front Physiol 2021; 12:654544. [PMID: 34054573 PMCID: PMC8155689 DOI: 10.3389/fphys.2021.654544] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2021] [Accepted: 04/20/2021] [Indexed: 11/13/2022] Open
Abstract
The effect of different environmental conditions such as temperature, wind, barometric pressure, and precipitation has been well investigated in elite marathoners, but not by age categories (i.e., age group marathoners). The aim of the study was to investigate the potential influence of environmental conditions such as temperature, precipitation, and atmospheric pressure on marathon performance in age group marathoners competing in the ‘Berlin Marathon’ from 1974 to 2019. A total of 869,474 valid finisher records were available for analysis, of which 711,136 correspond to males and 158,338 to females. The influence of temperature, atmospheric pressure, and precipitation on marathon race times was investigated in age group marathoners grouped in 5-year-intervals. Within the 46 years of Berlin marathons under investigation, there was some level of precipitation for 18 years, and 28 years without any rain. Sunshine was predominant in 25 of the events, whilst in the other 21 years, cloud cover was predominant. Marathon race times were significantly and positively correlated with age (i.e., older runners were slower than younger runners) where the correlation was higher for males than for females. Marathon race times were significantly and positively correlated with both the hours of sunshine and the daily maximum temperature. The fastest marathon runners (meaning the minimum times) achieved the fastest race times on race days with higher maximum temperatures (i.e., 15–30°C). Daily maximum temperatures showed an influence on age group marathoners from age group 35–40 years and older. Higher precipitation levels impaired performance across most age groups. In summary, higher daily maximum temperatures (i.e., >15°C) and higher precipitation levels impaired performance of master marathoners (i.e., 35–40 years and older) competing in the ‘Berlin Marathon’ in the last 45 years. Master marathoners should start in marathon races with temperatures < 15°C and no precipitation in order to achieve a fast marathon race time.
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Affiliation(s)
- Beat Knechtle
- Medbase St. Gallen Am Vadianplatz, St. Gallen, Switzerland.,Institute of Primary Care, University Hospital Zurich, Zurich, Switzerland
| | - David Valero
- Ultra Sports Science Foundation, Pierre-Bénite, France
| | - Elias Villiger
- Institute of Primary Care, University Hospital Zurich, Zurich, Switzerland
| | - José R Alvero-Cruz
- Departamento de Fisiología Humana, Histología, Anatomia Patológica y Educación Física y Deportiva, University of Málaga, Málaga, Spain
| | - Pantelis T Nikolaidis
- School of Health and Caring Sciences, University of West Attica, Athens, Greece.,Laboratory of Exercise Testing, Hellenic Air Force Academy, Acharnes, Greece
| | - Ivan Cuk
- Faculty of Physical Education and Sports Management, Singidunum University, Belgrade, Serbia
| | - Thomas Rosemann
- Institute of Primary Care, University Hospital Zurich, Zurich, Switzerland
| | - Volker Scheer
- Ultra Sports Science Foundation, Pierre-Bénite, France
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20
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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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21
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Potter AW, Yermakova II, Hunt AP, Hancock JW, Oliveira AVM, Looney DP, Montgomery LD. Comparison of two mathematical models for predicted human thermal responses to hot and humid environments. J Therm Biol 2021; 97:102902. [PMID: 33863455 DOI: 10.1016/j.jtherbio.2021.102902] [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: 01/12/2021] [Revised: 03/02/2021] [Accepted: 03/03/2021] [Indexed: 11/28/2022]
Abstract
PURPOSE We compared the accuracy and design of two thermoregulatory models, the US Army's empirically designed Heat Strain Decision Aid (HSDA) and the rationally based Health Risk Prediction (HRP) for predicting human thermal responses during exercise in hot and humid conditions and wearing chemical protective clothing. METHODS Accuracy of the HSDA and HRP model predictions of core body and skin temperature (Tc, Ts) were compared to each other and relative to measured outcomes from eight male volunteers (age 24 ± 6 years; height 178 ± 5 cm; body mass 76.6 ± 8.4 kg) during intermittent treadmill marching in an environmental chamber (air temperature 29.3 ± 0.1 °C; relative humidity 56 ± 1%; wind speed 0.4 ± 0.1 m∙s-1) wearing three separate chemical protective ensembles. Model accuracies and precisions were evaluated by the bias, mean absolute error (MAE), and root mean square error (RMSE) compared to observed data mean ± SD and the calculated limits of agreement (LoA). RESULTS Average predictions of Tc were comparable and acceptable for each method, HSDA (Bias 0.02 °C; MAE 0.18 °C; RMSE 0.21 °C) and HRP (Bias 0.10 °C; MAE 0.25 °C; RMSE 0.34 °C). The HRP averaged predictions for Ts were within an acceptable agreement to observed values (Bias 1.01 °C; MAE 1.01 °C; RMSE 1.11 °C). CONCLUSION Both HSDA and HRP acceptably predict Tc and HRP acceptably predicts Ts when wearing chemical protective clothing during exercise in hot and humid conditions.
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Affiliation(s)
- Adam W Potter
- Biophysics and Biomedical Modeling Division, U.S. Army Research Institute of Environmental Medicine, 10 General Greene Avenue, Bldg 42 Natick, Massachusetts, 01760-5007, USA.
| | - Irena I Yermakova
- International Research-Training Centre for Information Technologies and Systems, National Academy of Sciences, Kiev, Ukraine.
| | - Andrew P Hunt
- School of Exercise and Nutrition Sciences, Queensland University of Technology, Brisbane, QLD, 4059, Australia; Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, QLD, 4059, Australia.
| | - Jason W Hancock
- Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, QLD, 4059, Australia.
| | - A Virgilio M Oliveira
- ADAI, LAETA, Department of Mechanical Engineering, University of Coimbra, Pólo II, 3030 - 788, Coimbra, Portugal; Coimbra Polytechnic - ISEC, Rua Pedro Nunes, Quinta da Nora, 3030-199, Coimbra, Portugal.
| | - David P Looney
- Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, QLD, 4059, Australia.
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22
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Ezure T, Amano S, Matsuzaki K. Aging-related shift of eccrine sweat glands toward the skin surface due to tangling and rotation of the secretory ducts revealed by digital 3D skin reconstruction. Skin Res Technol 2021; 27:569-575. [PMID: 33576542 PMCID: PMC8359204 DOI: 10.1111/srt.12985] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2020] [Accepted: 10/02/2020] [Indexed: 12/27/2022]
Abstract
Background Sweat gland function deteriorates with aging, leading to loss of heat tolerance. However, it is unclear whether and how the structure of sweat glands changes during aging, because the 3D structure is complex and inaccessible. Methods To clarify age‐dependent changes in sweat glands, we developed a method for 3D structure analysis of sweat glands by means of X‐ray micro‐CT observation of human skin specimens followed by 3D digital reconstruction on computer (digital 3D skin). Results Comparison of eccrine sweat glands of abdominal skin from young and old subjects showed that the density and volume of sweat glands do not change with aging. In contrast, the depth of the secretory coil from the skin surface is decreased in the aged group. Surprisingly, the secretory ducts appear tortuous or meandering though their length is unchanged. The secretory coils are located at the dermal‐adipose layer boundary in both groups, but the thickness of the dermal layer decreases with aging, and the depth of the coils is correlated with the dermal thickness. Conclusion Our results suggest that sweat glands twist and rotate with aging to maintain the position of the coil at the dermal‐adipose boundary, causing an overall shift toward the skin surface.
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Affiliation(s)
- Tomonobu Ezure
- Department of Plastic and Reconstructive Surgery, Shiseido Global Innovation Center, Kanagawa, Japan
| | - Satoshi Amano
- Department of Plastic and Reconstructive Surgery, Shiseido Global Innovation Center, Kanagawa, Japan
| | - Kyoichi Matsuzaki
- Department of Plastic and Reconstructive Surgery, School of Medicine, International University of Health and Welfare, Narita, Japan
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23
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Rogerson S, Brearley M, Meir R, Brooks L. Influence of age, geographical region, and work unit on heat strain symptoms: a cross-sectional survey of electrical utility workers. JOURNAL OF OCCUPATIONAL AND ENVIRONMENTAL HYGIENE 2020; 17:515-522. [PMID: 33196398 DOI: 10.1080/15459624.2020.1834112] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
This study assessed self-reported heat strain symptoms in workers of a state wide electrical utility distributor to determine risk differences between age groups, geographical work regions and work units. Out of a total 3,250 workers, 918 (∼28%) outdoor staff completed an online survey, which assessed the frequency of self-reported heat strain symptoms in the work and post-work settings, factors contributing to symptoms and symptom management. Heat strain symptoms were grouped into chronic low-grade cases and isolated high-grade cases based on the severity and frequency of symptoms. The risk (likelihood) of an employee being classified as either a chronic low-grade or isolated high-grade case was calculated and compared to the mean risk of all categories to determine risk difference, expressed as -1.00 to 1.00. For chronic low-grade cases, the 41-50 years age group had significantly increased risk (+0.08, p < 0.05) while the over 60 years age group had significantly decreased risk (-0.14, p < 0.05). Two of the three regions (p < 0.01) and three of the nine work units also demonstrated risk differences (p < 0.01) for chronic low-grade cases. Work units were the sole grouping to demonstrate risk difference for isolated high-risk cases. Work units with greater exposure to heat and higher requirement for protective clothing, such as Underground (+0.19, p < 0.05), Overhead - Predominantly Live Line (+0.18, p < 0.01), and Overhead - Distribution and Transmission (+0.11, p < 0.05) were at greater risk of reporting heat stress symptoms. This study demonstrates that the pattern of self-reported chronic low-grade heat strain cases differs to isolated high-grade cases within the electrical utility industry. Age, geographical location, and work unit independently alter the risk of chronic low-grade heat strain, while the risk of isolated high-grade heat strain was only related to work unit. These outcomes support implementation of a flexible and targeted approach to heat stress management in large and diverse organizations in which employees are routinely exposed to heat.
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Affiliation(s)
- Shane Rogerson
- Department of Health, Safety and Environment, Energy Queensland, Brisbane, Queensland, Australia
| | - Matt Brearley
- Thermal Hyperformance, Hervey Bay, Queensland, Australia
- National Critical Care and Trauma Response Centre, Royal Darwin Hospital, Darwin, Northern Territory, Australia
| | - Rudi Meir
- School of Health and Human Sciences, Southern Cross University, Lismore, New South Wales, Australia
| | - Lyndon Brooks
- School of Environment, Science and Engineering, Marine Ecology Research Centre (MERC), Southern Cross University, Lismore, New South Wales, Australia
- StatPlan Consulting Pty Ltd, Woodburn, New South Wales, Australia
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24
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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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25
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Williams ML. Global warming, heat-related illnesses, and the dermatologist. Int J Womens Dermatol 2020; 7:70-84. [PMID: 33537396 PMCID: PMC7838243 DOI: 10.1016/j.ijwd.2020.08.007] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2020] [Revised: 08/12/2020] [Accepted: 08/17/2020] [Indexed: 12/23/2022] Open
Abstract
Global warming, provoked by the greenhouse effect of high levels of atmospheric gases (most notably carbon dioxide and methane), directly threatens human health and survival. Individuals vary in their capacity to tolerate episodes of extreme heat. Because skin is the organ tasked with heat dissipation, it is important for dermatologists to be versed in the physiology of cutaneous heat dissipation and cognizant of clinical settings in which the skin’s thermoregulatory responses may be impaired. When the external temperature is lower than that of the skin, the skin releases internal heat through direct thermal exchange with the environment, a process that is aided by an expansion of cutaneous blood flow and eccrine sweating. Cooling through the evaporation of sweat is effective even when the external temperature exceeds that of skin. Many factors, including environmental and physiological (e.g., age and sex), and pathological (e.g., preexisting illnesses, disorders of eccrine function, and medications) considerations, affect the skin’s capacity to thermoregulate. Identification of individuals at increased risk for heat-related morbidity and mortality will become increasingly important in the care of patients.
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Affiliation(s)
- Mary L Williams
- Departments of Dermatology and Pediatrics, University of California San Francisco, San Francisco, CA, United States
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26
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Fujii N, McGarr GW, Amano T, Sigal RJ, Boulay P, Nishiyasu T, Kenny GP. Ageing augments β-adrenergic cutaneous vasodilatation differently in men and women, with no effect on β-adrenergic sweating. Exp Physiol 2020; 105:1720-1729. [PMID: 32818310 DOI: 10.1113/ep088583] [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: 02/28/2020] [Accepted: 08/10/2020] [Indexed: 11/08/2022]
Abstract
NEW FINDINGS What is the central question of this study? β-Adrenergic receptor activation modulates cutaneous vasodilatation and sweating in young adults. In this study, we assessed whether age-related differences in β-adrenergic regulation of these responses exist and whether they differ between men and women. What is the main finding and its importance? We showed that ageing augmented β-adrenergic cutaneous vasodilatation, although the pattern of response differed between men and women. Ageing had no effect on β-adrenergic sweating in men or women. Our findings advance our understanding of age-related changes in the regulation of cutaneous vasodilatation and sweating and provide new directions for research on the significance of enhanced β-adrenergic cutaneous vasodilatation in older adults. ABSTRACT β-Adrenergic receptor agonists, such as isoprenaline, can induce cutaneous vasodilatation and sweating in young adults. Given that cutaneous vasodilatation and sweating responses to whole-body heating and to pharmacological agonists, such as acetylcholine, ATP and nicotine, can differ in older adults, we assessed whether ageing also modulates β-adrenergic cutaneous vasodilatation and sweating and whether responses differ between men and women. In the context of the latter, prior reports showed that the effects of ageing on cutaneous vasodilatation (evoked with ATP and nicotine) and sweating (stimulated by acetylcholine) were sex dependent. Thus, in the present study, we assessed the role of β-adrenergic receptor activation on forearm cutaneous vasodilatation and sweating in 11 young men (24 ± 4 years of age), 11 young women (23 ± 5 years of age), 11 older men (61 ± 8 years of age) and 11 older women (60 ± 8 years of age). Initially, a high dose (100 µm) of isoprenaline was administered via intradermal microdialysis for 5 min to induce maximal β-adrenergic sweating. Approximately 60 min after the washout period, three incremental doses of isoprenaline were administered (1, 10 and 100 µm, each for 25 min) to assess dose-dependent cutaneous vasodilatation. Isoprenaline-mediated cutaneous vasodilatation was greater in both older men and older women relative to their young counterparts. Augmented cutaneous vasodilatory responses were observed at 1 and 10 µm in women and at 100 µm in men. Isoprenaline-mediated sweating was unaffected by ageing, regardless of sex. We show that ageing augments β-adrenergic cutaneous vasodilatation differently in men and women, without influencing β-adrenergic sweating.
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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, Ibaraki, Japan
| | - Gregory W McGarr
- Human and Environmental Physiology Research Unit, University of Ottawa, Ottawa, Ontario, Canada
| | - Tatsuro Amano
- Laboratory for Exercise and Environmental Physiology, Faculty of Education, Niigata University, Niigata, Niigata, Japan
| | - Ronald J Sigal
- Human and Environmental Physiology Research Unit, University of Ottawa, Ottawa, Ontario, Canada.,Department of Medicine, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada.,Ottawa Hospital Research Institute, Clinical Epidemiology Program, Ottawa, Ontario, Canada
| | - Pierre Boulay
- Faculty of Physical Activity Sciences, University of Sherbrooke, Sherbrooke, Quebec, Canada
| | - Takeshi Nishiyasu
- Faculty of Health and Sport Sciences, University of Tsukuba, Tsukuba, Ibaraki, Japan
| | - Glen P Kenny
- Human and Environmental Physiology Research Unit, University of Ottawa, Ottawa, Ontario, Canada.,Ottawa Hospital Research Institute, Clinical Epidemiology Program, Ottawa, Ontario, 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: 32] [Impact Index Per Article: 8.0] [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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28
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Westwood CS, Fallowfield JL, Delves SK, Nunns M, Ogden HB, Layden JD. Individual risk factors associated with exertional heat illness: A systematic review. Exp Physiol 2020; 106:191-199. [PMID: 32249985 DOI: 10.1113/ep088458] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2020] [Accepted: 03/30/2020] [Indexed: 12/17/2022]
Abstract
NEW FINDINGS What is the topic of this review? Exertional heat illness (EHI) remains a persistent problem for athletes and individuals. This threat remains despite numerous athletic position statements and occupational guidance policies. This review explores primary evidence that demonstrates a direct association between 'known' risk factors and EHI. What advances does it highlight? Primary evidence to support 'known' risk factors associated with EHI is not comprehensive. Furthermore, it is not evident that single individual factors predispose individuals to greater risk. In fact, the evidence indicates that EHI can manifest in non-hostile compensable environments when a combination of risk factors is prevalent. ABSTRACT Despite the widespread knowledge of exertional heat illness (EHI) and clear guidance for its prevention, the incidence of EHI remains high. We carried out a systematic review of available literature evaluating the scientific evidence underpinning the risk factors associated with EHI. Medline, PsycINFO, SportDiscus and Embase were searched from inception to January 2019 with no date limitation, with supplementary searches also being performed. Search terms included permutations of risk and heat illness, with only studies in English included. Study selection, data extraction and quality assessment, using the QUALSYST tool, were performed by two independent reviewers. Of 8898 articles identified by the searches, 42 were included in the systematic review as primary evidence demonstrating a link between a risk factor and EHI. The quality scores ranged from 57.50 to 100%, and studies were generally considered to be of strong quality. The majority of risks attributable to EHI were categorized as those associated with lifestyle factors. The findings from the systematic review suggest complex manifestation of EHI through multiple risk factors rather than any one factor in isolation. Further research is needed to explore the accumulation of risk factors to help in development of effective preventative measures.
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Affiliation(s)
- Caroline S Westwood
- School of Sport, Health and Wellbeing, Plymouth Marjon University, Plymouth, UK
| | | | | | - Michael Nunns
- Exeter Health Services and Delivery Research Evidence Synthesis Centre, Institute of Health Research, University of Exeter Medical School, University of Exeter, Exeter, UK
| | - Henry B Ogden
- School of Sport, Health and Wellbeing, Plymouth Marjon University, Plymouth, UK
| | - Joseph D Layden
- School of Sport, Health and Wellbeing, Plymouth Marjon University, Plymouth, UK
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29
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Notley SR, Flouris AD, Kenny GP. Occupational heat stress management: Does one size fit all? Am J Ind Med 2019; 62:1017-1023. [PMID: 30791115 DOI: 10.1002/ajim.22961] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2018] [Revised: 02/21/2019] [Accepted: 03/04/2019] [Indexed: 01/20/2023]
Abstract
Heat stress is a deadly occupational hazard that is projected to increase in severity with global warming. While upper limits for heat stress designed to protect all workers have been recommended by occupational safety institutes for some time, heat stress continues to compromise health and productivity. In our view, this is largely explained by the inability of existing guidelines to consider the inter-individual (age, sex, disease, others) and intra-individual (medication use, fitness, hydration, others) factors that cause extensive variability in physiological tolerance to a given heat stress. In conditions that do not exceed the recommended limits, this 'one size fits all' approach to heat stress management can lead to reductions in productivity in more heat-tolerant workers, while compromising safety in less heat-tolerant workers who may develop heat-related illness, even in temperate conditions. Herein, we discuss future directions in occupational heat stress management that consider this individual variability.
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Affiliation(s)
- Sean R. Notley
- Human and Environmental Physiology Research UnitSchool of Human Kinetics, University of Ottawa OttawaCanada
| | - Andreas D. Flouris
- Human and Environmental Physiology Research UnitSchool of Human Kinetics, University of Ottawa OttawaCanada
- FAME LaboratoryDepartment of Exercise Science, University of Thessaly TrikalaGreece
| | - Glen P. Kenny
- Human and Environmental Physiology Research UnitSchool of Human Kinetics, University of Ottawa OttawaCanada
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30
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Tan CCS, Chin LKK, Low ICC. Thermoregulation in the Aging Population and Practical Strategies to Overcome a Warmer Tomorrow. Proteomics 2019; 20:e1800468. [PMID: 31652021 DOI: 10.1002/pmic.201800468] [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] [Received: 05/09/2019] [Revised: 09/05/2019] [Indexed: 12/11/2022]
Abstract
As global temperatures continue to rise, improving thermal tolerance in the aged population is crucial to counteract age-associated impairments in thermoregulatory function. Impairments in reflex cutaneous vasodilation and sweating response can augment the vulnerability of older adults to heat-related injuries following exposure to heat stress. Mechanisms underlying a compromised cutaneous vasodilation are suggested to include reduced sympathetic neural drive, diminished cholinergic co-transmitter contribution, and altered second messenger signaling events. On the other hand, impairments in sweating response are ascribed to reduced sweat gland cholinergic sensitivity and altered cyclooxygenase and nitric oxide signaling. Several practical mitigation strategies such as exercise, passive heating, and behavioral adaptations are proposed as means to overcome heat stress and improve thermal tolerance in the aged. Aerobic exercise training is shown to be amongst the most effective ways to enhance thermoregulatory function. However, in elderly with limited exercise capability due to chronic diseases and mobility issues, passive heating can serve as a functional alternative as it has been shown to confer similar benefits to that of exercise training. Supplementary to exercise training and passive heating, behavioral adaptations can be applied to further enhance the heat-preparedness of the aged.
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Affiliation(s)
- Chee Chong Shawn Tan
- Department of Physiology, Yong Loo Lin School of Medicine (YLLSoM), National University of Singapore (NUS), Singapore, 117593, Singapore
| | - Li Kang Karen Chin
- Department of Physiology, Yong Loo Lin School of Medicine (YLLSoM), National University of Singapore (NUS), Singapore, 117593, Singapore
| | - Ivan Cherh Chiet Low
- Department of Physiology, Yong Loo Lin School of Medicine (YLLSoM), National University of Singapore (NUS), Singapore, 117593, Singapore
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31
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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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32
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Meade RD, Notley SR, Kenny GP. Aging and human heat dissipation during exercise-heat stress: an update and future directions. CURRENT OPINION IN PHYSIOLOGY 2019. [DOI: 10.1016/j.cophys.2019.07.003] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
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33
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Best A, Lieberman DE, Kamilar JM. Diversity and evolution of human eccrine sweat gland density. J Therm Biol 2019; 84:331-338. [PMID: 31466771 DOI: 10.1016/j.jtherbio.2019.07.024] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2019] [Revised: 07/22/2019] [Accepted: 07/25/2019] [Indexed: 01/08/2023]
Abstract
The human eccrine sweat gland is central to the evolution of the human genus, permitting an enormous thermoregulatory sweating capacity that was essential to the human niche of high physical activity in open, hot, semi-arid environments. Despite a century of research inventorying the structure and function of eccrine glands and the physiological responses of human heat acclimation, we do not have a clear understanding of how intraspecific differences in eccrine density affect thermoregulation. Similarly, existing data does not comprehensively catalogue modern human diversity in this trait, nor do we understand the relative influences of evolutionary forces and phenotypic plasticity in shaping this diversity.
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Affiliation(s)
- Andrew Best
- Department of Anthropology, University of Massachusetts Amherst, United States.
| | - Daniel E Lieberman
- Department of Human Evolutionary Biology, Harvard University, United States
| | - Jason M Kamilar
- Department of Anthropology, University of Massachusetts Amherst, United States; Graduate Program in Organismic and Evolutionary Biology, University of Massachusetts Amherst, United States
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34
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Baker LB. Physiology of sweat gland function: The roles of sweating and sweat composition in human health. Temperature (Austin) 2019; 6:211-259. [PMID: 31608304 PMCID: PMC6773238 DOI: 10.1080/23328940.2019.1632145] [Citation(s) in RCA: 258] [Impact Index Per Article: 51.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2019] [Revised: 06/06/2019] [Accepted: 06/08/2019] [Indexed: 12/21/2022] Open
Abstract
The purpose of this comprehensive review is to: 1) review the physiology of sweat gland function and mechanisms determining the amount and composition of sweat excreted onto the skin surface; 2) provide an overview of the well-established thermoregulatory functions and adaptive responses of the sweat gland; and 3) discuss the state of evidence for potential non-thermoregulatory roles of sweat in the maintenance and/or perturbation of human health. The role of sweating to eliminate waste products and toxicants seems to be minor compared with other avenues of excretion via the kidneys and gastrointestinal tract; as eccrine glands do not adapt to increase excretion rates either via concentrating sweat or increasing overall sweating rate. Studies suggesting a larger role of sweat glands in clearing waste products or toxicants from the body may be an artifact of methodological issues rather than evidence for selective transport. Furthermore, unlike the renal system, it seems that sweat glands do not conserve water loss or concentrate sweat fluid through vasopressin-mediated water reabsorption. Individuals with high NaCl concentrations in sweat (e.g. cystic fibrosis) have an increased risk of NaCl imbalances during prolonged periods of heavy sweating; however, sweat-induced deficiencies appear to be of minimal risk for trace minerals and vitamins. Additional research is needed to elucidate the potential role of eccrine sweating in skin hydration and microbial defense. Finally, the utility of sweat composition as a biomarker for human physiology is currently limited; as more research is needed to determine potential relations between sweat and blood solute concentrations.
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Affiliation(s)
- Lindsay B. Baker
- Gatorade Sports Science Institute, PepsiCo R&D Physiology and Life Sciences, Barrington, IL, USA
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35
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Notley SR, Lamarche DT, Meade RD, Flouris AD, Kenny GP. Revisiting the influence of individual factors on heat exchange during exercise in dry heat using direct calorimetry. Exp Physiol 2019; 104:1038-1050. [DOI: 10.1113/ep087666] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2019] [Accepted: 04/17/2019] [Indexed: 11/08/2022]
Affiliation(s)
- Sean R. Notley
- Human and Environmental Physiology Research UnitSchool of Human KineticsUniversity of Ottawa Ottawa ON Canada
| | - Dallon T. Lamarche
- Human and Environmental Physiology Research UnitSchool of Human KineticsUniversity of Ottawa Ottawa ON Canada
| | - Robert D. Meade
- Human and Environmental Physiology Research UnitSchool of Human KineticsUniversity of Ottawa Ottawa ON Canada
| | - Andreas D. Flouris
- Human and Environmental Physiology Research UnitSchool of Human KineticsUniversity of Ottawa Ottawa ON Canada
- FAME LaboratoryDepartment of Exercise ScienceUniversity of Thessaly Trikala Greece
| | - Glen P. Kenny
- Human and Environmental Physiology Research UnitSchool of Human KineticsUniversity of Ottawa Ottawa ON Canada
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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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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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Meade RD, Fujii N, McGarr GW, Alexander LM, Boulay P, Sigal RJ, Kenny GP. Local arginase inhibition does not modulate cutaneous vasodilation or sweating in young and older men during exercise. J Appl Physiol (1985) 2019; 126:1129-1137. [PMID: 30653418 PMCID: PMC6485684 DOI: 10.1152/japplphysiol.00657.2018] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2018] [Revised: 01/08/2019] [Accepted: 01/11/2019] [Indexed: 01/19/2023] Open
Abstract
Age-related impairments in cutaneous vascular conductance (CVC) and sweat rate (SR) during exercise may result from increased arginase activity, which can attenuate endogenous nitric oxide (NO) production. We therefore evaluated whether arginase inhibition modulates these heat-loss responses in young (n = 9, 23 ± 3 yr) and older (n = 9, 66 ± 6 yr) men during two 30-min bouts of moderate-intensity cycling (Ex1 and Ex2) in the heat (35°C). CVC and SR were measured at forearm skin sites perfused with 1) lactated Ringer's (control), 2) NG-nitro-L-arginine methyl ester (L-NAME; NO synthase-inhibited), or 3) Nω-hydroxy-nor-arginine and S-(2-boronoethyl)-l-cysteine (Nor-NOHA + BEC; arginase-inhibited). In both groups, CVC was reduced at L-NAME relative to control and Nor-NOHA + BEC (both P < 0.01). Likewise, SR was attenuated with L-NAME compared with control and Nor-NOHA + BEC during each exercise bout in the young men (all P ≤ 0.05); however, no influence of treatment on SR in the older men was observed (P = 0.14). Based on these findings, we then evaluated responses in 7 older men (64 ± 7 yr) during passively induced elevations in esophageal temperature (∆Tes) equal to those in Ex1 (0.6°C) and Ex2 (0.8°C). L-NAME reduced CVC by 18 ± 20% CVCmax at a ∆Tes of 0.8°C (P = 0.03) compared with control, whereas Nor-NOHA + BEC augmented CVC by 20 ± 18% CVCmax, on average, throughout heating (both P ≤ 0.03). SR was not influenced by either treatment (P = 0.80) Thus, arginase inhibition does not modulate CVC or SR during exercise in the heat but, consistent with previous findings, does augment CVC in older men during passive heating. NEW & NOTEWORTHY In the current study, we demonstrate that local arginase inhibition does not influence forearm cutaneous vasodilatory and sweating responses in young or older men during exercise-heat stress. Consistent with previous findings, however, we observed augmented cutaneous blood flow with arginase inhibition during whole-body passive heat stress. Thus, arginase differentially affects cutaneous vasodilation depending on the mode of heat stress but does not influence sweating during exercise or passive heating.
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Affiliation(s)
- Robert D Meade
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa , Ottawa, ON , Canada
| | - Naoto Fujii
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa , Ottawa, ON , Canada
- Faculty of Health and Sport Sciences, University of Tsukuba , Tsukuba City , Japan
| | - Gregory W McGarr
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa , Ottawa, ON , Canada
| | - Lacy M Alexander
- Department of Kinesiology, Noll Laboratory, Pennsylvania State University , University Park, Pennsylvania
| | - Pierre Boulay
- Faculty of Physical Activity Sciences, University of Sherbrooke , Sherbrooke, QC , Canada
| | - Ronald J Sigal
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa , Ottawa, ON , Canada
- Departments of Medicine, Cardiac Sciences, and Community Health Sciences, Faculties of Medicine and Kinesiology, University of Calgary , Calgary, AB , Canada
- Clinical Epidemiology Program, Ottawa Hospital Research Institute , 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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Potter AW, Hunt AP, Cadarette BS, Fogarty A, Srinivasan S, Santee WR, Blanchard LA, Looney DP. Heat Strain Decision Aid (HSDA) accurately predicts individual-based core body temperature rise while wearing chemical protective clothing. Comput Biol Med 2019; 107:131-136. [DOI: 10.1016/j.compbiomed.2019.02.004] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2018] [Revised: 02/07/2019] [Accepted: 02/08/2019] [Indexed: 11/16/2022]
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Sigal RJ, Armstrong MJ, Bacon SL, Boulé NG, Dasgupta K, Kenny GP, Riddell MC. Physical Activity and Diabetes. Can J Diabetes 2018; 42 Suppl 1:S54-S63. [PMID: 29650112 DOI: 10.1016/j.jcjd.2017.10.008] [Citation(s) in RCA: 100] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/29/2017] [Indexed: 12/15/2022]
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NOTLEY SEANR, MEADE ROBERTD, D’SOUZA ANDREWW, FRIESEN BRIANJ, KENNY GLENP. Heat Loss Is Impaired in Older Men on the Day after Prolonged Work in the Heat. Med Sci Sports Exerc 2018; 50:1859-1867. [DOI: 10.1249/mss.0000000000001643] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Fujii N, Pastore OL, McGarr GW, Meade RD, McNeely BD, Nishiyasu T, Kenny GP. Cyclooxygenase-1 and -2 modulate sweating but not cutaneous vasodilation during exercise in the heat in young men. Physiol Rep 2018; 6:e13844. [PMID: 30175553 PMCID: PMC6119687 DOI: 10.14814/phy2.13844] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2018] [Accepted: 08/02/2018] [Indexed: 12/16/2022] Open
Abstract
We recently reported that the nonselective cyclooxygenase (COX) inhibitor ketorolac attenuated sweating but not cutaneous vasodilation during moderate-intensity exercise in the heat. However, the specific contributions of COX-1 and COX-2 to the sweating response remained to be determined. We tested the hypothesis that COX-1 but not COX-2 contributes to sweating with no role for either COX isoform in cutaneous vasodilation during moderate-intensity exercise in the heat. In thirteen young males (22 ± 2 years), sweat rate and cutaneous vascular conductance were measured at three forearm skin sites that were continuously treated with (1) lactated Ringer's solution (Control), (2) 150 μmmol·L-1 celecoxib, a selective COX-2 inhibitor, or (3) 10 mmol L-1 ketorolac, a nonselective COX inhibitor. Participants first rested in a non heat stress condition (≥85 min, 25°C) followed by a further 70-min rest period in the heat (35°C). They then performed 50 min of moderate-intensity cycling (~55% peak oxygen uptake) followed by a 30-min recovery period. At the end of exercise, sweat rate was lower at the 150 μmol·L-1 celecoxib (1.51 ± 0.25 mg·min-1 ·cm-2 ) and 10 mmol·L-1 ketorolac (1.30 ± 0.30 mg·min-1 ·cm-2 ) treated skin sites relative to the Control site (1.89 ± 0.27 mg·min-1 ·cm-2 ) (both P ≤ 0.05). Additionally, sweat rate at the ketorolac site was attenuated relative to the celecoxib site (P ≤ 0.05). Neither celecoxib nor ketorolac influenced cutaneous vascular conductance throughout the experiment (both P > 0.05). We showed that both COX-1 and COX-2 contribute to sweating but not cutaneous vasodilation during moderate-intensity exercise in the heat in young men.
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Affiliation(s)
- Naoto Fujii
- Human and Environmental Physiology Research UnitUniversity of OttawaOttawaCanada
- Faculty of Health and Sport SciencesUniversity of TsukubaTsukubaJapan
| | - Olivia L. Pastore
- Human and Environmental Physiology Research UnitUniversity of OttawaOttawaCanada
| | - Gregory W. McGarr
- Human and Environmental Physiology Research UnitUniversity of OttawaOttawaCanada
| | - Robert D. Meade
- Human and Environmental Physiology Research UnitUniversity of OttawaOttawaCanada
| | - Brendan D. McNeely
- Human and Environmental Physiology Research UnitUniversity of OttawaOttawaCanada
| | - Takeshi Nishiyasu
- Faculty of Health and Sport SciencesUniversity of TsukubaTsukubaJapan
| | - Glen P. Kenny
- Human and Environmental Physiology Research UnitUniversity of OttawaOttawaCanada
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Intermittent living; the use of ancient challenges as a vaccine against the deleterious effects of modern life - A hypothesis. Med Hypotheses 2018; 120:28-42. [PMID: 30220336 DOI: 10.1016/j.mehy.2018.08.002] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2018] [Revised: 07/25/2018] [Accepted: 08/04/2018] [Indexed: 12/19/2022]
Abstract
Chronic non-communicable diseases (CNCD) are the leading cause of mortality in developed countries. They ensue from the sum of modern anthropogenic risk factors, including high calorie nutrition, malnutrition, sedentary lifestyle, social stress, environmental toxins, politics and economic factors. Many of these factors are beyond the span of control of individuals, suggesting that CNCD are inevitable. However, various studies, ours included, show that the use of intermittent challenges with hormetic effects improve subjective and objective wellbeing of individuals with CNCD, while having favourable effects on immunological, metabolic and behavioural indices. Intermittent cold, heat, fasting and hypoxia, together with phytochemicals in multiple food products, have widespread influence on many pathways related with overall health. Until recently, most of the employed challenges with hormetic effects belonged to the usual transient live experiences of our ancestors. Our hypothesis; we conclude that, whereas the total inflammatory load of multi-metabolic and psychological risk factors causes low grade inflammation and aging, the use of intermittent challenges, united in a 7-10 days lasting hormetic intervention, might serve as a vaccine against the deleterious effects of chronic low grade inflammation and it's metabolic and (premature) aging consequences.
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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: 23] [Impact Index Per Article: 3.8] [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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Leicht AS, Flouris AD, Kaltsatou A, Seely AJ, Herry CL, Wright Beatty HE, Kenny GP. Age alters cardiac autonomic modulations during and following exercise-induced heat stress in females. Temperature (Austin) 2018; 5:184-196. [PMID: 30377635 DOI: 10.1080/23328940.2018.1432918] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2017] [Revised: 01/26/2018] [Accepted: 02/07/2018] [Indexed: 12/19/2022] Open
Abstract
The aim of this study was to examine the effect of natural ageing on heart rate variability during and following exercise-induced heat stress in females. Eleven young (∼24 years) and 13 older (∼51 years), habitually active females completed an experimental session consisting of baseline rest, moderate intensity intermittent exercise (four 15-min bouts separated by 15-min recovery) and 1-hour of final recovery in a hot and dry (35°C, 20% relative humidity) environment. Respiratory and heart rate recordings were continuously logged with 10-min periods analysed at the end of: baseline rest; each of the exercise and recovery bouts; and during the 1-hour final recovery period. Comparisons over time during exercise and recovery, and between groups were conducted via two-way repeated-measures ANCOVAs with rest values as the covariate. During baseline rest, older females exhibited lower heart rate variability compared to young females with similar levels of respiration and most (∼71-79%) heart rate variability measures during repeated exercise and recovery. However, older females exhibited heart rate variability metrics suggestive of greater parasympathetic modulation (greater long axis of Poincare plot, cardiac vagal index; lower low-high frequency ratio) during repeated exercise with lower indices during the latter stage of prolonged recovery (less very low frequency component, Largest Lyapunov Exponent; greater cardiac sympathetic index). The current study documented several unique, age-dependent differences in heart rate variability, independent of respiration, during and following exercise-induced heat stress for females that may assist in the detection of normal heat-induced adaptations as well as individuals vulnerable to heat stress.
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Affiliation(s)
- Anthony S Leicht
- Sport and Exercise Science, James Cook University, Townsville, Australia
| | - Andreas D Flouris
- FAME Laboratory, Department of Exercise Science, University of Thessaly, Trikala, Greece
| | - Antonia Kaltsatou
- FAME Laboratory, Department of Exercise Science, University of Thessaly, Trikala, Greece
| | - Andrew J Seely
- Divisions of Thoracic Surgery and Critical Care Medicine, Ottawa Hospital Research Institute, University of Ottawa, Ottawa, Ontario, Canada
| | - Christophe L Herry
- Dynamical Analysis Lab, Clinical Epidemiology Program, Ottawa Hospital Research Institute, Ontario, Canada
| | | | - Glen P Kenny
- Human and Environmental Physiology Research Unit, University of Ottawa, Ontario, Canada
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Gagnon D, Romero SA, Cramer MN, Kouda K, Poh PYS, Ngo H, Jay O, Crandall CG. Age Modulates Physiological Responses during Fan Use under Extreme Heat and Humidity. Med Sci Sports Exerc 2018; 49:2333-2342. [PMID: 28609330 DOI: 10.1249/mss.0000000000001348] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
PURPOSE We examined the effect of electric fan use on cardiovascular and thermoregulatory responses of nine young (26 ± 3 yr) and nine aged (68 ± 4 yr) adults exposed to extreme heat and humidity. METHODS While resting at a temperature of 42°C, relative humidity increased from 30% to 70% in 2% increments every 5 min. On randomized days, the protocol was repeated without or with fan use. HR, core (Tcore) and mean skin (Tsk) temperatures were measured continuously. Whole-body sweat loss was measured from changes in nude body weight. Other measures of cardiovascular (cardiac output), thermoregulatory (local cutaneous and forearm vascular conductance, local sweat rate), and perceptual (thermal and thirst sensations) responses were also examined. RESULTS When averaged over the entire protocol, fan use resulted in a small reduction of HR (-2 bpm, 95% confidence interval [CI], -8 to 3), and slightly greater Tcore (+0.05°C; 95% CI, -0.13 to 0.23) and Tsk (+0.03°C; 95% CI, -0.36 to 0.42) in young adults. In contrast, fan use resulted in greater HR (+5 bpm; 95% CI, 0-10), Tcore (+0.20°C; 95% CI, 0.00-0.41), and Tsk (+0.47°C; 95% CI, 0.18-0.76) in aged adults. A greater whole-body sweat loss during fan use was observed in young (+0.2 kg; 95% CI, -0.2 to 0.6) but not aged (0.0 kg; 95% CI, -0.2 to 0.2) adults. Greater local sweat rate and cutaneous vascular conductance were observed with fan use in aged adults. Other measures of cardiovascular, thermoregulatory, and perceptual responses were unaffected by fan use in both groups. CONCLUSIONS During extreme heat and humidity, fan use elevates physiological strain in aged, but not young, adults.
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Affiliation(s)
- Daniel Gagnon
- 1Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas and University of Texas Southwestern Medical Center, Dallas, TX; 2Cardiovascular Prevention and Rehabilitation Centre, Montreal Heart Institute Research Centre, Montréal, QC, CANADA; 3Department of Pharmacology and Physiology, Faculty of Medicine, University of Montreal, Montreal, QC, CANADA; 4Wakayama Medical University, Wakayama, JAPAN; and 5Faculty of Health Sciences, University of Sydney, Lidcombe, AUSTRALIA
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Abstract
PURPOSE We evaluated physiological responses during exercise at a fixed evaporative requirement for heat balance (Ereq) but varying combinations of metabolic and environmental heat load. METHODS Nine healthy, physically active males (age: 46 ± 8 yr) performed four experimental sessions consisting of 75 min of semirecumbent cycling at various ambient temperatures. Whole-body dry heat loss (direct calorimetry) was monitored continuously as was heat production (indirect calorimetry), which was adjusted to achieve an Ereq of 400 W. The resultant metabolic heat productions and ambient temperatures for the sessions were as follows: (i) 440 W and 30°C (440 [30]), (ii) 388 W and 35°C (388 [35]), (iii) 317 W and 40°C (317 [40]), and (iv) 258 W and 45°C (258 [45]). Whole-body evaporative heat loss was determined via direct calorimetry. Esophageal (Tes) and mean skin (Tsk) temperatures as well as HR were monitored continuously. Mean body temperature (Tb) was calculated from Tes and Tsk. Physiological strain index (PSI) was determined from Tes and HR. RESULTS End-exercise evaporative heat loss and Tb were similar between conditions (both P ≥ 0.48). Tes was greater in 440 [30] (37.67°C ± 0.04°C) and 388 [35] (37.58°C ± 0.07°C) relative to both 317 [40] (37.35°C ± 0.06°C) and 258 [45] (37.20°C ± 0.07°C; all P ≤ 0.05). Further, Tsk was different between each condition (440 [30], 33.85°C ± 0.16°C; 388 [35], 34.53°C ± 0.08°C; 317 [40], 35.67°C ± 0.07°C; and 258 [45], 36.54°C ± 0.08°C; all P < 0.01). In 440 [30], HR was elevated by about 13 and 18 bpm relative to 317 [40] and 258 [45], respectively (both P < 0.01). Finally, PSI was greater in both 440 [30] and 388 [35] compared with 317 [40] and 258 [45] (all P ≤ 0.04). CONCLUSIONS Exercise at a fixed Ereq resulted in similar evaporative heat loss and Tb. However, the Tes, Tsk, HR, and PSI responses varied depending on the relative contribution of metabolic and environmental heat load.
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Affiliation(s)
- Robert D Meade
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Montpetit Hall, Ottawa, CANADA
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Flouris AD, McGinn R, Poirier MP, Louie JC, Ioannou LG, Tsoutsoubi L, Sigal RJ, Boulay P, Hardcastle SG, Kenny GP. Screening criteria for increased susceptibility to heat stress during work or leisure in hot environments in healthy individuals aged 31-70 years. Temperature (Austin) 2017; 5:86-99. [PMID: 29687046 PMCID: PMC5902215 DOI: 10.1080/23328940.2017.1381800] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2017] [Revised: 09/15/2017] [Accepted: 09/15/2017] [Indexed: 10/18/2022] Open
Abstract
Population aging and global warming generate important public health risks, as older adults have increased susceptibility to heat stress (SHS). We defined and validated sex-specific screening criteria for SHS during work and leisure activities in hot environments in individuals aged 31-70 years using age, anthropometry, and cardiorespiratory fitness. A total of 123 males and 44 females [44 ± 14 years; 22.9 ± 7.4% body fat; 40.3 ± 8.6 peak oxygen uptake (mlO2/kg/min)] participated, separated into the Analysis (n = 111) and Validation (n = 56) groups. Within these groups, participants were categorized into YOUNG (19-30 years; n = 47) and OLDER (31-70 years; n = 120). All participants performed exercise in the heat inside a direct calorimeter. Screening criteria for OLDER participants were defined from the Analysis group and were cross-validated in the Validation group. Results showed that 30% of OLDER individuals in the Analysis group were screened as SHS positive. A total of 274 statistically valid (p < 0.05) criteria were identified suggesting that OLDER participants were at risk for SHS when demonstrating two or more of the following (males/females): age ≥ 53.0/55.8 years; body mass index ≥29.5/25.7 kg/m2; body fat percentage ≥ 28.8/34.9; body surface area ≤2.0/1.7 m2; peak oxygen uptake ≤48.3/41.4 mlO2/kg fat free mass/min. In the Validation group, McNemar χ2 comparisons confirmed acceptable validity for the developed criteria. We conclude that the developed criteria can effectively screen individuals 31-70 years who are at risk for SHS during work and leisure activities in hot environments and can provide simple and effective means to mitigate the public health risks caused by heat exposure.
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Affiliation(s)
- Andreas D. Flouris
- FAME Laboratory, Department of Exercise Science, University of Thessaly, Trikala, Greece
- Human and Environmental Physiological Research Unit, School of Human Kinetics, Faculty of Health Sciences, University of Ottawa, Ontario, Canada
| | - Ryan McGinn
- Human and Environmental Physiological Research Unit, School of Human Kinetics, Faculty of Health Sciences, University of Ottawa, Ontario, Canada
| | - Martin P. Poirier
- Human and Environmental Physiological Research Unit, School of Human Kinetics, Faculty of Health Sciences, University of Ottawa, Ontario, Canada
| | - Jeffrey C. Louie
- Human and Environmental Physiological Research Unit, School of Human Kinetics, Faculty of Health Sciences, University of Ottawa, Ontario, Canada
| | - Leonidas G. Ioannou
- FAME Laboratory, Department of Exercise Science, University of Thessaly, Trikala, Greece
| | - Lydia Tsoutsoubi
- FAME Laboratory, Department of Exercise Science, University of Thessaly, Trikala, Greece
| | - Ronald J. Sigal
- Human and Environmental Physiological Research Unit, School of Human Kinetics, Faculty of Health Sciences, University of Ottawa, Ontario, Canada
- Departments of Medicine, Cardiac Sciences, and Community Health Sciences, Faculties of Medicine and Kinesiology, University of Calgary, Calgary, Canada
- Clinical Epidemiology Program, Ottawa Hospital Research Institute, Ottawa, Canada
| | - Pierre Boulay
- Faculty of Physical Activity Sciences, Department of Human Kinetics, University of Sherbrooke, Sherbrooke, Canada
| | | | - Glen P. Kenny
- Human and Environmental Physiological Research Unit, School of Human Kinetics, Faculty of Health Sciences, University of Ottawa, Ontario, Canada
- Clinical Epidemiology Program, Ottawa Hospital Research Institute, Ottawa, Canada
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Meade RD, D'Souza AW, Krishen L, Kenny GP. The physiological strain incurred during electrical utilities work over consecutive work shifts in hot environments: A case report. JOURNAL OF OCCUPATIONAL AND ENVIRONMENTAL HYGIENE 2017; 14:986-994. [PMID: 28825865 DOI: 10.1080/15459624.2017.1365151] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
PURPOSE In this article, we evaluated physiological strain in electrical utilities workers during consecutive work shifts in hot outdoor conditions. METHODS Four highly experienced electrical utilities workers were monitored during regularly scheduled work performed in hot conditions (∼34°C) on two consecutive days. Worker hydration (urine specific gravity) was assessed prior to and following work. The level of physical exertion was determined by video analysis. Body core temperature (Tcore) and heart rate (HR; presented as a percentage of maximum, %HRmax) were monitored continuously. Responses were reported for each worker individually and as a group mean ± standard deviation. RESULTS According to current guidelines, all workers were dehydrated prior to work on both days (urine specific gravity: day 1, 1.025 ± 0.005; day 2, 1.029 ± 0.004) and remained dehydrated following work (urine specific gravity: day 1, 1.027 ± 0.015; day 2, 1.032 ± 0.004) except for one worker on day 1 (urine specific gravity of 1.005). On day 1, the proportion of the work shift spent at rest (as defined by the American Conference for Governmental and Industrial Hygienists, ACGIH) was 51 ± 15% (range: 30-64%). Time spent resting increased in all workers on the second day reaching 66 ± 5% (range: 60-71%) of the work shift. Work shift average Tcore was 37.6 ± 0.1°C (range: 37.5-37.7°C) and 37.7 ± 0.2°C (range: 37.5-37.9°C) on days 1 and 2, respectively. Peak Tcore surpassed the ACGIH recommended threshold limit of 38.0°C for work in the heat in three workers on day 1 (38.1 ± 0.2°C, range: 37.8-38.2°C) while all workers exceeded this threshold on day 2 (38.4 ± 0.2°C, range: 38.2-38.7°C). By contrast, work shift average (day 1, 67 ± 7%HRmax, range: 59-74%HRmax; day 2, 65 ± 4%HRmax, range: 60-70%HRmax) and peak (day 1, 90 ± 6%HRmax, range: 83-98%HRmax; day 2, 87 ± 10%HRmax, range: 73-97%HRmax) HR were similar between days. CONCLUSION This case report demonstrates elevations in thermal strain over consecutive work shifts despite decreases in work effort in electrical utilities workers during regular work in the heat.
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Affiliation(s)
- Robert D Meade
- a Human and Environmental Physiology Research Unit, School of Human Kinetics , University of Ottawa , Ottawa , ON , Canada
| | - Andrew W D'Souza
- a Human and Environmental Physiology Research Unit, School of Human Kinetics , University of Ottawa , Ottawa , ON , Canada
| | - Lovely Krishen
- b Electrical Power Research Institute , Knoxville , Tennessee
| | - Glen P Kenny
- a Human and Environmental Physiology Research Unit, School of Human Kinetics , University of Ottawa , Ottawa , ON , Canada
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