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Cottle RM, Fisher KG, Leach OK, Wolf ST, Kenney WL. Critical environmental core temperature limits and heart rate thresholds across the adult age span (PSU HEAT Project). J Appl Physiol (1985) 2024; 137:145-153. [PMID: 38813613 DOI: 10.1152/japplphysiol.00117.2024] [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: 02/14/2024] [Revised: 05/16/2024] [Accepted: 05/17/2024] [Indexed: 05/31/2024] Open
Abstract
The frequency, duration, and severity of extreme heat events have increased and are projected to continue to increase throughout the next century. As a result, there is an increased risk of excessive heat- and cardiovascular-related morbidity and mortality during these extreme heat events. Therefore, the purposes of this investigation were to establish 1) critical environmental core temperature (Tc) limits for middle-aged adults (MA), 2) environmental thresholds that cause heart rate (HR) to progressively rise in MA and older (O) adults, and 3) examine critical environmental Tc limits and HR environmental thresholds across the adult age span. Thirty-three young (Y) (15 F; 23 ± 3 yr), 28 MA (17 F; 51 ± 6 yr), and 31 O (16 F; 70 ± 3 yr) subjects were exposed to progressive heat stress in an environmental chamber in a warm-humid (WH, 34-36°C, 50-90% rh) and a hot-dry (HD, 38°C-52°C, <30% rh) environment while exercising at a low metabolic rate reflecting activities of daily living (∼1.8 METs). In both environments, there was a main effect of age on the critical environmental Tc limit and environmental HR thresholds (main effect of age all P < 0.001). Across the lifespan, critical environmental Tc and HR thresholds decline linearly with age in HD environments (R2 ≥ 0.3) and curvilinearly in WH environments (R2 ≥ 0.4). These data support an age-associated shift in critical environmental Tc limits and HR thresholds toward lower environmental conditions and can be used to develop evidence-based safety guidelines to minimize future heat-related morbidity and mortality across the adult age span.NEW & NOTEWORTHY This study is the first to identify critical environmental core temperature and heart rate thresholds across the adult age spectrum. In addition, our data demonstrate that the rate of decline in Tc and HR limits with age is environmental-dependent. These findings provide strong empirical data for the development of safety guidelines and policy decisions to mitigate excessive heat- and cardiovascular-related morbidity and mortality for impending heat events.
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Affiliation(s)
- Rachel M Cottle
- Department of Kinesiology, The Pennsylvania State University, University Park, Pennsylvania, United States
- Center for Healthy Aging, College of Health and Human Development, The Pennsylvania State University, University Park, Pennsylvania, United States
| | - Kat G Fisher
- Department of Kinesiology, The Pennsylvania State University, University Park, Pennsylvania, United States
- Center for Healthy Aging, College of Health and Human Development, The Pennsylvania State University, University Park, Pennsylvania, United States
| | - Olivia K Leach
- Department of Kinesiology, The Pennsylvania State University, University Park, Pennsylvania, United States
| | - S Tony Wolf
- Department of Kinesiology, The Pennsylvania State University, University Park, Pennsylvania, United States
| | - W Larry Kenney
- Department of Kinesiology, The Pennsylvania State University, University Park, Pennsylvania, United States
- Center for Healthy Aging, College of Health and Human Development, The Pennsylvania State University, University Park, Pennsylvania, United States
- Graduate Program in Physiology, The Pennsylvania State University, University Park, Pennsylvania, United States
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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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3
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Tony Wolf S, Cottle RM, Fisher KG, Vecellio DJ, Larry Kenney W. Heat stress vulnerability and critical environmental limits for older adults. COMMUNICATIONS EARTH & ENVIRONMENT 2023; 4:486. [PMID: 38293008 PMCID: PMC10826365 DOI: 10.1038/s43247-023-01159-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2023] [Accepted: 12/05/2023] [Indexed: 02/01/2024]
Abstract
The present study examined heat stress vulnerability of apparently healthy older vs. young adults and characterized critical environmental limits for older adults in an indoor setting at rest (Rest) and during minimal activity associated with activities of daily living. Critical environmental limits are combinations of ambient temperature and humidity above which heat balance cannot be maintained (i.e., becomes uncompensable) for a given metabolic heat production. Here we exposed fifty-one young (23±4 yrs) and 49 older (71±6 yrs) adults to progressive heat stress across a wide range of environments in an environmental chamber during Minimal Activity (young and older subjects) and Rest (older adults only). Heat compensability curves were shifted leftward for older adults indicating age-dependent heat vulnerablity (p < 0.01). During Minimal Activity, critical environmental limits were lower in older compared to young adults (p < 0.0001) and lower than those at Rest (p < 0.0001). These data document heat vulnerability of apparently healthy older adults and to define critical environmental limits for indoor settings in older adults at rest and during activities of daily living, and can be used to develop evidence-based recommendations to minimize the deleterious impacts of extreme heat events in this population.
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Affiliation(s)
- S. Tony Wolf
- Department of Kinesiology, The Pennsylvania State University, University Park, PA 16802 USA
| | - Rachel M. Cottle
- Department of Kinesiology, The Pennsylvania State University, University Park, PA 16802 USA
- Center for Healthy Aging, The Pennsylvania State University, University Park, PA 16802 USA
| | - Kat G. Fisher
- Department of Kinesiology, The Pennsylvania State University, University Park, PA 16802 USA
| | - Daniel J. Vecellio
- Center for Healthy Aging, The Pennsylvania State University, University Park, PA 16802 USA
| | - W. Larry Kenney
- Department of Kinesiology, The Pennsylvania State University, University Park, PA 16802 USA
- Center for Healthy Aging, The Pennsylvania State University, University Park, PA 16802 USA
- Graduate Program in Physiology, The Pennsylvania State University, University Park, PA 16802 USA
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Vanos J, Guzman-Echavarria G, Baldwin JW, Bongers C, Ebi KL, Jay O. A physiological approach for assessing human survivability and liveability to heat in a changing climate. Nat Commun 2023; 14:7653. [PMID: 38030628 PMCID: PMC10687011 DOI: 10.1038/s41467-023-43121-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2023] [Accepted: 11/01/2023] [Indexed: 12/01/2023] Open
Abstract
Most studies projecting human survivability limits to extreme heat with climate change use a 35 °C wet-bulb temperature (Tw) threshold without integrating variations in human physiology. This study applies physiological and biophysical principles for young and older adults, in sun or shade, to improve current estimates of survivability and introduce liveability (maximum safe, sustained activity) under current and future climates. Our physiology-based survival limits show a vast underestimation of risks by the 35 °C Tw model in hot-dry conditions. Updated survivability limits correspond to Tw~25.8-34.1 °C (young) and ~21.9-33.7 °C (old)-0.9-13.1 °C lower than Tw = 35 °C. For older female adults, estimates are ~7.2-13.1 °C lower than 35 °C in dry conditions. Liveability declines with sun exposure and humidity, yet most dramatically with age (2.5-3.0 METs lower for older adults). Reductions in safe activity for younger and older adults between the present and future indicate a stronger impact from aging than warming.
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Affiliation(s)
- Jennifer Vanos
- School of Sustainability, Arizona State University, Tempe, AZ, USA.
| | - Gisel Guzman-Echavarria
- School of Geographical Sciences and Urban Planning, Arizona State University, Tempe, AZ, USA
| | - Jane W Baldwin
- Department of Earth System Science, University of California Irvine, Irvine, CA, USA
- Lamont-Doherty Earth Observatory, Palisades, NY, USA
| | - Coen Bongers
- Department of Medical Sciences, Radboud university medical center, Nijmegen, The Netherlands
- Heat and Health Research Incubator, University of Sydney, Sydney, NSW, Australia
| | - Kristie L Ebi
- Center for Health and the Global Environment, University of Washington, Seattle, WA, USA
| | - Ollie Jay
- Heat and Health Research Incubator, University of Sydney, Sydney, NSW, Australia
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Zhu W, Yang Y, Jiang J, Zhu Q, Qi J, Qin B, Fan J, Fu M, Li P. Value of the combination of a smartphone-compatible infrared camera and a hand-held doppler ultrasound in preoperative localization of perforators in flaps. Heliyon 2023; 9:e17372. [PMID: 37389045 PMCID: PMC10300357 DOI: 10.1016/j.heliyon.2023.e17372] [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: 09/28/2022] [Revised: 06/13/2023] [Accepted: 06/14/2023] [Indexed: 07/01/2023] Open
Abstract
This study was conducted to evaluate the effectiveness of the FLIR ONE PRO, a thermal imaging camera for smartphones, combined with handheld Doppler (HHD) in the localization of perforator arteries and to assess the efficacy of the FLIR ONE PRO in distinguishing perforators of the descending branch of the lateral circumflex femoral artery (LCFA) from other perforators of the anterolateral thigh perforator (ALTP) flap. We enrolled 29 free perforator flaps from 22 patients in our study. Before surgery, dynamic infrared thermography was performed using a FLIR ONE PRO to visualize hotspots on the flaps. Subsequently, HHD was used to further determine the perforators under the hotspots, which were ultimately identified and confirmed through intraoperative findings. Additionally, infrared images of the ALTP flap were analyzed using FLIR Tools. The performances of the FLIR ONE PRO and FLIR ONE PRO + HHD groups were evaluated by comparing the intraoperative findings. Using FLIR ONE PRO + HHD, 119 hotspots and 106 perforators were identified during surgery. Using FLIR ONE PRO + HHD, sensitivity and positive predictive value were 97.87% and 88.46%, respectively, in the young (age≤45 years). In the elderly group (age>45 years), these percentages were 93.22% and 82.09%, respectively. In addition, we found that the FLIR ONE PRO could be useful for differentiating perforators in the descending branch of the LCFA from other perforators within 5 min. The results showed a sensitivity of 96.15%, a specificity of 98.9%, a positive predictive value of 96.15%, and a negative predictive value of 98.9%. Compared to using FLIR ONE PRO alone, the combined application of HHD and FLIR ONE PRO had a higher value in perforator localization by increasing the positive predictive value. The FLIR ONE PRO may have significance in the rapid prediction of perforators deriving from the descending branch of the LCFA.
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Affiliation(s)
- Weiwen Zhu
- Department of Orthopedics, Trauma & Microsurgery, Joint Surgery, First Affiliated Hospital of Sun Yat-sen University, Zhongshan No. 2 Road, Guangzhou, 510080, China
| | - Yi Yang
- Department of Orthopedics, Trauma & Microsurgery, Joint Surgery, First Affiliated Hospital of Sun Yat-sen University, Zhongshan No. 2 Road, Guangzhou, 510080, China
| | - Jiyong Jiang
- Fourth District of Microsurgery and Hand Department, Heping Orthopedics Hospital, Jude Nan Road 112-120, Guangzhou, 510305, China
| | - Qingtang Zhu
- Department of Orthopedics, Trauma & Microsurgery, Joint Surgery, First Affiliated Hospital of Sun Yat-sen University, Zhongshan No. 2 Road, Guangzhou, 510080, China
| | - Jian Qi
- Department of Orthopedics, Trauma & Microsurgery, Joint Surgery, First Affiliated Hospital of Sun Yat-sen University, Zhongshan No. 2 Road, Guangzhou, 510080, China
| | - Bengang Qin
- Department of Orthopedics, Trauma & Microsurgery, Joint Surgery, First Affiliated Hospital of Sun Yat-sen University, Zhongshan No. 2 Road, Guangzhou, 510080, China
| | - Jingyuan Fan
- Department of Orthopedics, Trauma & Microsurgery, Joint Surgery, First Affiliated Hospital of Sun Yat-sen University, Zhongshan No. 2 Road, Guangzhou, 510080, China
| | - Ming Fu
- Department of Orthopedics, Trauma & Microsurgery, Joint Surgery, First Affiliated Hospital of Sun Yat-sen University, Zhongshan No. 2 Road, Guangzhou, 510080, China
| | - Ping Li
- Department of Orthopedics, Trauma & Microsurgery, Joint Surgery, First Affiliated Hospital of Sun Yat-sen University, Zhongshan No. 2 Road, Guangzhou, 510080, China
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Cramer MN, Gagnon D, Laitano O, Crandall CG. Human temperature regulation under heat stress in health, disease, and injury. Physiol Rev 2022; 102:1907-1989. [PMID: 35679471 PMCID: PMC9394784 DOI: 10.1152/physrev.00047.2021] [Citation(s) in RCA: 59] [Impact Index Per Article: 29.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2021] [Revised: 05/10/2022] [Accepted: 05/28/2022] [Indexed: 12/30/2022] Open
Abstract
The human body constantly exchanges heat with the environment. Temperature regulation is a homeostatic feedback control system that ensures deep body temperature is maintained within narrow limits despite wide variations in environmental conditions and activity-related elevations in metabolic heat production. Extensive research has been performed to study the physiological regulation of deep body temperature. This review focuses on healthy and disordered human temperature regulation during heat stress. Central to this discussion is the notion that various morphological features, intrinsic factors, diseases, and injuries independently and interactively influence deep body temperature during exercise and/or exposure to hot ambient temperatures. The first sections review fundamental aspects of the human heat stress response, including the biophysical principles governing heat balance and the autonomic control of heat loss thermoeffectors. Next, we discuss the effects of different intrinsic factors (morphology, heat adaptation, biological sex, and age), diseases (neurological, cardiovascular, metabolic, and genetic), and injuries (spinal cord injury, deep burns, and heat stroke), with emphasis on the mechanisms by which these factors enhance or disturb the regulation of deep body temperature during heat stress. We conclude with key unanswered questions in this field of research.
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Affiliation(s)
- Matthew N Cramer
- Defence Research and Development Canada-Toronto Research Centre, Toronto, Ontario, Canada
| | - Daniel Gagnon
- Montreal Heart Institute and School of Kinesiology and Exercise Science, Université de Montréal, Montréal, Quebec, Canada
| | - Orlando Laitano
- Department of Applied Physiology and Kinesiology, University of Florida, Gainesville, Florida
| | - Craig G Crandall
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas and University of Texas Southwestern Medical Center, Dallas, Texas
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Chang AY, Tan AX, Nadeau KC, Odden MC. Aging Hearts in a Hotter, More Turbulent World: The Impacts of Climate Change on the Cardiovascular Health of Older Adults. Curr Cardiol Rep 2022; 24:749-760. [PMID: 35438387 PMCID: PMC9017408 DOI: 10.1007/s11886-022-01693-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 03/17/2022] [Indexed: 12/28/2022]
Abstract
PURPOSE OF REVIEW Climate change has manifested itself in multiple environmental hazards to human health. Older adults and those living with cardiovascular diseases are particularly susceptible to poor outcomes due to unique social, economic, and physiologic vulnerabilities. This review aims to summarize those vulnerabilities and the resultant impacts of climate-mediated disasters on the heart health of the aging population. RECENT FINDINGS Analyses incorporating a wide variety of environmental data sources have identified increases in cardiovascular risk factors, hospitalizations, and mortality from intensified air pollution, wildfires, heat waves, extreme weather events, rising sea levels, and pandemic disease. Older adults, especially those of low socioeconomic status or belonging to ethnic minority groups, bear a disproportionate health burden from these hazards. The worldwide trends responsible for global warming continue to worsen climate change-mediated natural disasters. As such, additional investigation will be necessary to develop personal and policy-level interventions to protect the cardiovascular wellbeing of our aging population.
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Affiliation(s)
- Andrew Y Chang
- Department of Epidemiology and Population Health, Stanford University, Stanford, CA, USA.,Department of Medicine, Stanford University, Stanford, CA, USA.,Stanford Cardiovascular Institute, 150 Governor's Lane, Stanford, CA, 94305, USA
| | - Annabel X Tan
- Department of Epidemiology and Population Health, Stanford University, Stanford, CA, USA
| | - Kari C Nadeau
- Department of Epidemiology and Population Health, Stanford University, Stanford, CA, USA.,Department of Medicine, Stanford University, Stanford, CA, USA.,Stanford Cardiovascular Institute, 150 Governor's Lane, Stanford, CA, 94305, USA.,Woods Institute for the Environment, Stanford University, Stanford, CA, USA
| | - Michelle C Odden
- Department of Epidemiology and Population Health, Stanford University, Stanford, CA, USA. .,Stanford Cardiovascular Institute, 150 Governor's Lane, Stanford, CA, 94305, USA.
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Schmidt MD, Notley SR, Meade RD, Akerman AP, Rutherford MM, Kenny GP. Revisiting regional variation in the age-related reduction in sweat rate during passive heat stress. Physiol Rep 2022; 10:e15250. [PMID: 35411704 PMCID: PMC9001962 DOI: 10.14814/phy2.15250] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2022] [Accepted: 03/17/2022] [Indexed: 06/14/2023] Open
Abstract
Aging is associated with attenuated sweat gland function, which has been suggested to occur in a peripheral-to-central manner. However, evidence supporting this hypothesis remains equivocal. We revisited this hypothesis by evaluating the sweat rate across the limbs and trunk in young and older men during whole-body, passive heating. A water-perfused suit was used to raise and clamp esophageal temperature at 0.6°C (low-heat strain) and 1.2°C (moderate-heat strain) above baseline in 14 young (24 (SD 5) years) and 15 older (69 (4) years) men. Sweat rate was measured at multiple sites on the trunk (chest, abdomen) and limbs (biceps, forearm, quadriceps, calf) using ventilated capsules (3.8 cm2 ). Sweat rates, expressed as the average of 5 min of stable sweating at low- and moderate-heat strain, were compared between groups (young, older) and regions (trunk, limbs) within each level of heat strain using a linear mixed-effects model with nested intercepts (sites nested within region nested within participant). At low-heat strain, the age-related reduction in sweat rate (older-young values) was greater at the trunk (0.65 mg/cm2 /min [95% CI 0.44, 0.86]) compared to the limbs (0.42 mg/cm2 /min [0.22, 0.62]; interaction: p = 0.010). At moderate-heat strain, sweat rate was lower in older compared to young (main effect: p = 0.025), albeit that reduction did not differ between regions (interaction: p = 0.888). We conclude that, contrary to previous suggestions, the age-related decline in sweat rate was greater at the trunk compared to the limbs at low-heat strain, with no evidence of regional variation in that age-related decline at moderate-heat strain.
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Affiliation(s)
- Madison D. Schmidt
- Human and Environmental Physiology Research UnitSchool of Human KineticsUniversity of OttawaOttawaOntarioCanada
| | - Sean R. Notley
- Human and Environmental Physiology Research UnitSchool of Human KineticsUniversity of OttawaOttawaOntarioCanada
| | - Robert D. Meade
- Human and Environmental Physiology Research UnitSchool of Human KineticsUniversity of OttawaOttawaOntarioCanada
- Harvard T.H. Chan School of Public HealthHarvard UniversityBostonMassachusettsUSA
| | - Ashley P. Akerman
- Human and Environmental Physiology Research UnitSchool of Human KineticsUniversity of OttawaOttawaOntarioCanada
| | - Maura M. Rutherford
- Human and Environmental Physiology Research UnitSchool of Human KineticsUniversity of OttawaOttawaOntarioCanada
| | - Glen P. Kenny
- Human and Environmental Physiology Research UnitSchool of Human KineticsUniversity of OttawaOttawaOntarioCanada
- Clinical Epidemiology ProgramOttawa Hospital Research InstituteOttawaOntarioCanada
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9
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Fujii N, McGarr GW, Amano T, Boulay P, Nishiyasu T, Kenny GP. Does aging alter skin vascular function in humans when spatial variation is considered? Microcirculation 2021; 29:e12743. [PMID: 34874589 DOI: 10.1111/micc.12743] [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: 09/04/2021] [Revised: 11/10/2021] [Accepted: 12/01/2021] [Indexed: 11/30/2022]
Abstract
OBJECTIVE Reports evaluating age-related impairments in cutaneous vascular function assessed by either the venoarteriolar reflex (VAR) induced by venous congestion, or post-occlusive reactive hyperemia (PORH) activated by arterial occlusion, have yielded mixed findings. This may be due to region-specific variability that occurs when assessing local cutaneous vascular responses. We evaluated the hypothesis that aging attenuates VAR and PORH responses in forearm skin assessed across four adjacent sites, each separated by ~4 cm to account for inter-site variability. METHODS In twenty young (24 ± 4 years, 10 females) and twenty older (60 ± 7 years, 9 females) adults, VAR and PORH were achieved by a 3-min venous occlusion and 5-min arterial occlusion, each induced by inflating a pressure cuff to 45 and 240 mmHg, respectively. Cutaneous blood flow at all skin sites was measured by laser-Doppler flowmetry with the average response from all sites used for between-group comparisons. RESULTS VAR and PORH responses were similar between groups with the exception that the time required to achieve peak PORH was delayed in older adults (mean difference of 5.5 ± 4.4 s, p = 0.003, Cohen's d = 0.812). CONCLUSIONS We showed that aging had a negligible influence on VAR and PORH responses in forearm skin even when controlling for region-specific variability.
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Affiliation(s)
- Naoto Fujii
- Faculty of Health and Sport Sciences, University of Tsukuba, Tsukuba City, Japan
| | - Gregory W McGarr
- Human and Environmental Physiology Research Unit, University of Ottawa, Ottawa, ON, Canada
| | - Tatsuro Amano
- Laboratory for Exercise and Environmental Physiology, Faculty of Education, Niigata University, Niigata, Japan
| | - Pierre Boulay
- Faculty of Physical Activity Sciences, University of Sherbrooke, Sherbrooke, QC, Canada
| | - Takeshi Nishiyasu
- Faculty of Health and Sport Sciences, University of Tsukuba, Tsukuba City, Japan
| | - Glen P Kenny
- Human and Environmental Physiology Research Unit, University of Ottawa, Ottawa, ON, Canada
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10
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Vecellio DJ, Bardenhagen EK, Lerman B, Brown RD. The role of outdoor microclimatic features at long-term care facilities in advancing the health of its residents: An integrative review and future strategies. ENVIRONMENTAL RESEARCH 2021; 201:111583. [PMID: 34192557 DOI: 10.1016/j.envres.2021.111583] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/10/2020] [Revised: 05/18/2021] [Accepted: 06/21/2021] [Indexed: 06/13/2023]
Abstract
Projections show that Earth's climate will continue to warm concurrent with increases in the percentage of the world's elderly population. With an understanding that the body's resilience to the heat degrades as it ages, these coupled phenomena point to serious concerns of heat-related mortality in growing elderly populations. As many of the people in this age cohort choose to live in managed long-term care facilities, it's imperative that outdoor spaces of these communities be made thermally comfortable so that connections with nature and the promotion of non-sedentary activities are maintained. Studies have shown that simply being outside has a positive impact on a broad range of the psychosocial well-being of older adults. However, these spaces must be designed to afford accessibility, safety, and aesthetically pleasing experiences so that they are taken full advantage of. Here, we employ an integrative review to link ideas from the disciplines of climate science, health and physiology, and landscape architecture to explain the connections between heat, increased morbidity and mortality in aging adults, existing gaps in thermal comfort models, and key strategies in the development of useable, comfortable outdoor spaces for older adults. Integrative reviews allow for new frameworks or perspectives on a subject to be introduced. Uncovering the synergy of these three knowledge bases can contribute to guiding microclimatic research, design practitioners, and care providers as they seek safe, comfortable and inviting outdoor spaces for aging adults.
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Affiliation(s)
- Daniel J Vecellio
- Climate Science Lab, Department of Geography, Texas A&M University, College Station, TX, USA.
| | - Eric K Bardenhagen
- Department of Plant and Soil Sciences, University of Delaware, Newark, DE, USA; Center for Health Systems & Design, Texas A&M University, College Station, TX, USA
| | - Ben Lerman
- Department of Biological Sciences, Hunter College of the City University of New York, New York, NY, USA
| | - Robert D Brown
- Department of Landscape Architecture and Urban Planning, Texas A&M University, College Station, TX, USA; Center for Health Systems & Design, Texas A&M University, College Station, TX, USA
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11
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Jay O, Capon A, Berry P, Broderick C, de Dear R, Havenith G, Honda Y, Kovats RS, Ma W, Malik A, Morris NB, Nybo L, Seneviratne SI, Vanos J, Ebi KL. Reducing the health effects of hot weather and heat extremes: from personal cooling strategies to green cities. Lancet 2021; 398:709-724. [PMID: 34419206 DOI: 10.1016/s0140-6736(21)01209-5] [Citation(s) in RCA: 125] [Impact Index Per Article: 41.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/10/2020] [Revised: 12/19/2020] [Accepted: 05/20/2021] [Indexed: 01/01/2023]
Abstract
Heat extremes (ie, heatwaves) already have a serious impact on human health, with ageing, poverty, and chronic illnesses as aggravating factors. As the global community seeks to contend with even hotter weather in the future as a consequence of global climate change, there is a pressing need to better understand the most effective prevention and response measures that can be implemented, particularly in low-resource settings. In this Series paper, we describe how a future reliance on air conditioning is unsustainable and further marginalises the communities most vulnerable to the heat. We then show that a more holistic understanding of the thermal environment at the landscape and urban, building, and individual scales supports the identification of numerous sustainable opportunities to keep people cooler. We summarise the benefits (eg, effectiveness) and limitations of each identified cooling strategy, and recommend optimal interventions for settings such as aged care homes, slums, workplaces, mass gatherings, refugee camps, and playing sport. The integration of this information into well communicated heat action plans with robust surveillance and monitoring is essential for reducing the adverse health consequences of current and future extreme heat.
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Affiliation(s)
- Ollie Jay
- Thermal Ergonomics Laboratory, The University of Sydney, Sydney, NSW, Australia; Sydney School of Health Sciences, The University of Sydney, Sydney, NSW, Australia; Sydney School of Public Health, The University of Sydney, Sydney, NSW, Australia; Faculty of Medicine and Health, Charles Perkins Centre, The University of Sydney, Sydney, NSW, Australia.
| | - Anthony Capon
- Sydney School of Public Health, The University of Sydney, Sydney, NSW, Australia; Monash Sustainable Development Institute, Monash University, Melbourne, VIC, Australia
| | - Peter Berry
- Faculty of Environment, University of Waterloo, ON, Canada
| | - Carolyn Broderick
- School of Medical Sciences, UNSW Medicine, Sydney, UNSW, Australia; The Children's Hospital at Westmead, Sydney, NSW, Australia
| | - Richard de Dear
- Indoor Environmental Quality Laboratory, School of Architecture, Design, and Planning, The University of Sydney, Sydney, NSW, Australia
| | - George Havenith
- Environmental Ergonomics Research Centre, Loughborough University, Loughborough, UK
| | - Yasushi Honda
- Faculty of Health and Sport Sciences, University of Tsukuba, Tsukuba, Japan
| | - R Sari Kovats
- NIHR Health Protection Research Unit in Environmental Change and Health, London School of Hygiene and Tropical Medicine, London, UK
| | - Wei Ma
- School of Public Health, Shandong University, Jinan, China; Climate Change and Health Center, Shandong University, Jinan, China
| | - Arunima Malik
- School of Physics, Faculty of Science, ISA, The University of Sydney, Sydney, NSW, Australia; Discipline of Accounting, Business School, The University of Sydney, Sydney, NSW, Australia
| | - Nathan B Morris
- Thermal Ergonomics Laboratory, The University of Sydney, Sydney, NSW, Australia; Department of Nutrition, Exercise, and Sports, University of Copenhagen, Copenhagen, Denmark
| | - Lars Nybo
- Department of Nutrition, Exercise, and Sports, University of Copenhagen, Copenhagen, Denmark
| | - Sonia I Seneviratne
- Institute for Atmospheric and Climate Science, ETH Zurich, Zurich, Switzerland
| | - Jennifer Vanos
- School of Sustainability, Arizona State University, AZ, USA
| | - Kristie L Ebi
- Center for Health and the Global Environment, University of Washington, WA, USA
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12
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Ebi KL, Capon A, Berry P, Broderick C, de Dear R, Havenith G, Honda Y, Kovats RS, Ma W, Malik A, Morris NB, Nybo L, Seneviratne SI, Vanos J, Jay O. Hot weather and heat extremes: health risks. Lancet 2021; 398:698-708. [PMID: 34419205 DOI: 10.1016/s0140-6736(21)01208-3] [Citation(s) in RCA: 318] [Impact Index Per Article: 106.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/01/2020] [Revised: 12/15/2020] [Accepted: 05/20/2021] [Indexed: 01/18/2023]
Abstract
Hot ambient conditions and associated heat stress can increase mortality and morbidity, as well as increase adverse pregnancy outcomes and negatively affect mental health. High heat stress can also reduce physical work capacity and motor-cognitive performances, with consequences for productivity, and increase the risk of occupational health problems. Almost half of the global population and more than 1 billion workers are exposed to high heat episodes and about a third of all exposed workers have negative health effects. However, excess deaths and many heat-related health risks are preventable, with appropriate heat action plans involving behavioural strategies and biophysical solutions. Extreme heat events are becoming permanent features of summer seasons worldwide, causing many excess deaths. Heat-related morbidity and mortality are projected to increase further as climate change progresses, with greater risk associated with higher degrees of global warming. Particularly in tropical regions, increased warming might mean that physiological limits related to heat tolerance (survival) will be reached regularly and more often in coming decades. Climate change is interacting with other trends, such as population growth and ageing, urbanisation, and socioeconomic development, that can either exacerbate or ameliorate heat-related hazards. Urban temperatures are further enhanced by anthropogenic heat from vehicular transport and heat waste from buildings. Although there is some evidence of adaptation to increasing temperatures in high-income countries, projections of a hotter future suggest that without investment in research and risk management actions, heat-related morbidity and mortality are likely to increase.
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Affiliation(s)
- Kristie L Ebi
- Center for Health and the Global Environment, University of Washington, Seattle, WA, USA.
| | - Anthony Capon
- Monash Sustainable Development Institute, Monash University, Melbourne, VIC, Australia; Sydney School of Public Health, Sydney, NSW, Australia
| | - Peter Berry
- Faculty of Environment, University of Waterloo, Waterloo, ON, Canada
| | - Carolyn Broderick
- School of Medical Sciences, UNSW Sydney, NSW, Australia; The Children's Hospital at Westmead, Sydney, NSW, Australia
| | - Richard de Dear
- Indoor Environmental Quality Laboratory, School of Architecture, Design, and Planning, Sydney, NSW, Australia; The University of Sydney, Sydney, NSW, Australia
| | - George Havenith
- Environmental Ergonomics Research Centre, School of Design and Creative Arts, Loughborough University, Loughborough, UK
| | - Yasushi Honda
- Faculty of Health and Sport Sciences, University of Tsukuba, Tsukuba, Japan
| | - R Sari Kovats
- NIHR Health Protection Research Unit in Environmental Change and Health, London School of Hygiene & Tropical Medicine, London, UK
| | - Wei Ma
- School of Public Health and Climate Change and Health Center, Shandong University, Jinan, China
| | - Arunima Malik
- Discipline of Accounting, Business School, Sydney, NSW, Australia; School of Physics, Faculty of Science, ISA, Sydney, NSW, Australia
| | - Nathan B Morris
- Thermal Ergonomics Laboratory, Sydney, NSW, Australia; Department of Nutrition, Exercise, and Sports, University of Copenhagen, Copenhagen, Denmark
| | - Lars Nybo
- Department of Nutrition, Exercise, and Sports, University of Copenhagen, Copenhagen, Denmark
| | - Sonia I Seneviratne
- Institute for Atmospheric and Climate Science, ETH Zurich, Zurich, Switzerland
| | - Jennifer Vanos
- School of Sustainability, Arizona State University, Tempe, AZ, USA
| | - Ollie Jay
- Thermal Ergonomics Laboratory, Sydney, NSW, Australia; Sydney School of Health Sciences, Sydney, NSW, Australia; Sydney School of Public Health, Sydney, NSW, Australia; Faculty of Medicine and Health, Charles Perkins Centre, Sydney, NSW, Australia
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13
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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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14
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Ravanelli N, Gendron P, Gagnon D. Revisiting the evaluation of central versus peripheral thermoregulatory control in humans. Am J Physiol Regul Integr Comp Physiol 2021; 321:R91-R99. [PMID: 34075801 DOI: 10.1152/ajpregu.00321.2020] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Human thermoregulatory control is often evaluated through the relationship between thermoeffector output and core or mean body temperature. In addition to providing a general indication of whether a variable of interest alters thermoregulatory control, this relationship is often used to determine how this alteration may occur. This latter interpretation relies upon two parameters of the thermoeffector output-body temperature relationship: the onset threshold and thermosensitivity. Traditionally, changes in the onset threshold and thermosensitivity are interpreted as "central" or "peripheral" modulation of thermoregulatory control, respectively. This mini-review revisits the origins of the thermoeffector output-body temperature relationship and its use to interpret "central" or "peripheral" modulation of thermoregulatory control. Against this background, we discuss the strengths and weaknesses of this approach and highlight that "central" thermoregulatory control reflects the neural control of body temperature whereas "peripheral" thermoregulatory control reflects properties specific to the thermoeffector organs. We highlight studies that employed more direct approaches to investigate the neural control of body temperature and peripheral properties of thermoeffector organs. We conclude by encouraging future investigations interested in studying thermoregulatory control to more directly investigate the component of the thermoeffector loop under investigation.heat; human; skin blood flow; sweat; thermoregulatory.
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Affiliation(s)
| | - Philippe Gendron
- Département des Sciences de l'Activité Physique, Université du Québec à Trois-Rivières, Trois-Rivières, Quebec, Canada.,Montreal Heart Institute, Montreal, Quebec, Canada
| | - Daniel Gagnon
- Montreal Heart Institute, Montreal, Quebec, Canada.,School of Kinesiology and Exercise Science, Faculty of Medicine, Université de Montréal, Montreal, Quebec, Canada
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15
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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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16
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Temperature regulation during exercise in the heat: Insights for the aging athlete. J Sci Med Sport 2020; 24:739-746. [PMID: 33358656 DOI: 10.1016/j.jsams.2020.12.007] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2020] [Revised: 11/30/2020] [Accepted: 12/13/2020] [Indexed: 12/16/2022]
Abstract
OBJECTIVE The purpose of this review is to evaluate the currently-available literature regarding the impact of both primary aging and age-related fitness on thermoregulatory function during exercise in the heat. In so doing, we aim to (1) characterize the influence of fitness in mitigating age-related declines in thermoregulation, (2) address the limitations of prior experimental approaches for investigating age-related thermoregulatory impairments, (3) examine to what extent aerobic fitness can be maintained in the aging athlete, and (4) begin to address the specific environmental conditions in which age-related impairments in thermoregulatory function may place highly active older adults at increased risk for heat-related illness and injury and/or limited performance. DESIGN Mini-review. METHODS Review and synthesis of available information. RESULTS The earth's climate is warming, accompanied by a consequently greater frequency and severity of extreme heat events. At the same time, lifespan is increasing and people of all ages are staying increasingly active. Age-related impairments in thermoregulatory function are well-documented, leading to increased heat-related health risks and reduced exercise/athletic performance for older adults in hot environmental conditions. High aerobic fitness improves body temperature regulation during exercise via augmented sweating and improved cardiovascular function, including cardiac output and skin blood flow, in humans of all ages. CONCLUSIONS The masters athlete is better suited for exercise/heat-stress compared to his or her less fit peers. However, while age and thermoregulation in general has been studied extensively, research on the most fit older adults, including highly competitive athletes, is generally lacking.
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17
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Greaney JL, Stanhewicz AE, Wolf ST, Kenney WL. Thermoregulatory reflex control of cutaneous vasodilation in healthy aging. Temperature (Austin) 2020; 8:176-187. [PMID: 33997116 DOI: 10.1080/23328940.2020.1832950] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022] Open
Abstract
Reflex cutaneous vasodilation during heating is attenuated in healthy human aging secondary to blunted increases in efferent skin sympathetic nervous system activity (SSNA) and reductions in end-organ sensitivity. Whether age-related alterations in the mean body temperature ( T - b) threshold for increasing SSNA and/or the sensitivity of responses are evident with aging have not been examined. We tested the hypotheses that the Tb threshold for SSNA and cutaneous vascular conductance (CVC) would be increased, but the sensitivity would be reduced, with aging. Reflex vasodilation was induced in 13 young (23 ± 3 y) and 13 older (67 ± 7 y) adults using a water-perfused suit to systematically increase mean skin and esophageal temperatures. SSNA (peroneal microneurography) and red cell flux (laser Doppler flowmetry) in the innervated dermatome were continuously measured. SSNA was normalized to baseline; CVC was normalized as a percentage of maximal CVC. Baseline T - b was lower in older adults (36.0 ± 0.4°C vs 36.4 ± 0.3°C; p = 0.005). During passive heating, the ∆ T - b thresholds for increasing SSNA and CVC were greater (1.3 ± 0.4°C vs 0.9 ± 0.3°C; p = 0.007 and 1.3 ± 0.4°C vs 0.8 ± 0.3°C; p = 0.002, respectively) in older adults. The slope of the relation between both SSNA (0.31 ± 0.23 vs 0.13 ± 0.10 V⋅s⋅°C -1; p = 0.01) and CVC (87.5 ± 50.1 vs 32.4 ± 18.1%max⋅°C-1; p = 0.002) vs T - b was lower in older adults. The relative T - b threshold for activation of SSNA and the initiation of reflex cutaneous vasodilation is higher in older adults, and once activated, the sensitivity of both responses is diminished, supporting the concept that the efferent component of the thermoregulatory reflex arc is impaired in healthy aging. Abbreviations: CI: confidence interval; CVC: cutaneous vascular conductance; SSNA: skin sympathetic nervous system activity; T - b: mean body temperature; Tes: esophageal temperature; T - sk: mean skin temperature.
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Affiliation(s)
- Jody L Greaney
- Noll Laboratory, Department of Kinesiology, The Pennsylvania State University, University Park, PA, USA.,Department of Kinesiology, The University of Texas at Arlington, Arlington, TX, USA
| | - Anna E Stanhewicz
- Noll Laboratory, Department of Kinesiology, The Pennsylvania State University, University Park, PA, USA.,Department of Health and Human Physiology, The University of Iowa, Iowa City, IA, USA
| | - S Tony Wolf
- Noll Laboratory, Department of Kinesiology, The Pennsylvania State University, University Park, PA, USA
| | - W Larry Kenney
- Noll Laboratory, Department of Kinesiology, The Pennsylvania State University, University Park, PA, USA
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18
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Plagg B, Zerbe S. How does the environment affect human ageing? An interdisciplinary review. JOURNAL OF GERONTOLOGY AND GERIATRICS 2020. [DOI: 10.36150/2499-6564-420] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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19
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Body mapping of regional sweat distribution in young and older males. Eur J Appl Physiol 2020; 121:109-125. [PMID: 32990756 PMCID: PMC7815578 DOI: 10.1007/s00421-020-04503-5] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2020] [Accepted: 09/12/2020] [Indexed: 11/04/2022]
Abstract
Purpose Given the pressing impact of global warming and its detrimental effect on the health of older populations, understanding age-related changes in thermoregulatory function is essential. Age differences in regional sweat distribution have been observed previously, but given the typically small measurement areas assessed, the development of whole body sweat maps for older individuals is required. Therefore, this study investigated age-related differences in regional sweat distribution in a hot environment (32 °C/50%RH) in young and older adults, using a body mapping approach. Methods Technical absorbent pads were applied to the skin of 14 young (age 24 ± 2 years) and 14 older (68 ± 5 years) males to measure regional sweat rate (RSR) at rest (30 min) and during exercise (30 min), at a fixed heat production (200 W m−2). Gastrointestinal (Tgi) and skin temperature (Tsk), heart rate, thermal sensation, and thermal comfort were also measured. Results Whole body sweat maps showed that despite equal heat production, healthy older males had significantly lower gross sweat loss (GSL) than the young and significantly lower RSR at almost all body regions at rest and at the hands, legs, ankles, and feet during exercise. The lower sweat loss in the older group coincided with a greater increase in Tgi and a consistently higher Tsk at the legs, despite subjectively feeling slightly cooler than younger individuals. Conclusion These findings support the evidence of age-related deterioration in both autonomic and subjective responses in the heat and highlight the lower extremities as the most affected body region. Electronic supplementary material The online version of this article (10.1007/s00421-020-04503-5) contains supplementary material, which is available to authorized users.
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20
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Luetkemeier MJ, Allen DR, Huang M, Pizzey FK, Parupia IM, Wilson TE, Davis SL. Skin tattooing impairs sweating during passive whole body heating. J Appl Physiol (1985) 2020; 129:1033-1038. [PMID: 32881627 DOI: 10.1152/japplphysiol.00427.2019] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
Tattooing of the skin involves repeated needle insertions to deposit ink into the dermal layer of the skin, potentially damaging eccrine sweat glands and the cutaneous vasculature. This study tested the hypothesis that reflex increases in sweat rate (SR) and cutaneous vasodilation are blunted in tattooed skin (TAT) compared with adjacent healthy skin (CON) during a passive whole body heat stress (WBH). Ten individuals (5 males and 5 females) with a sufficient area of tattooed skin participated in the study. Intestinal temperature (Tint), skin temperature (Tskin), skin blood flow (laser Doppler flux; LDF), and SR were continuously measured during normothermic baseline (34°C water perfusing a tube-lined suit) and WBH (increased Tint 1.0°C via 48°C water perfusing suit). SR throughout WBH was lower for TAT compared with CON (P = 0.033). Accumulated sweating responses during WBH (area under curve) were attenuated in TAT relative to CON (23.1 ± 12.9, 26.9 ± 14.5 mg/cm2, P = 0.043). Sweating threshold, expressed as the onset of sweating in time or Tint from the initiation of WBH, was not different between TAT and CON. Tattooing impeded the ability to obtain LDF measurements. These data suggest that tattooing functionally damages secretion mechanisms, affecting the reflex capacity of the gland to produce sweat, but does not appear to affect neural signaling to initiate sweating. Decreased sweating could impact heat dissipation especially when tattooing covers a higher percentage of body surface area and could be considered a potential long-term clinical side effect of tattooing.NEW & NOTEWORTHY This study is the first to assess the reflex control of sweating in tattooed skin. The novel findings are twofold. First, attenuated increases in sweat rate were observed in tattooed skin compared with adjacent healthy non-tattooed skin in response to a moderate increase (1.0°C) in internal temperature during a passive whole body heat stress. Second, reduced sweating in tattooed skin is likely related to functional damage to the secretory mechanisms of eccrine sweat glands, rendering it less responsive to cholinergic stimulation.
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Affiliation(s)
| | - Dustin R Allen
- Applied Physiology and Wellness, Southern Methodist University, Dallas, Texas.,Health Sciences, Boston University, Boston, Massachusetts
| | - Mu Huang
- Applied Physiology and Wellness, Southern Methodist University, Dallas, Texas.,Applied Clinical Research, University of Texas Southwestern Medical Center, Dallas, Texas
| | - Faith K Pizzey
- Applied Physiology and Wellness, Southern Methodist University, Dallas, Texas
| | - Iqra M Parupia
- Applied Physiology and Wellness, Southern Methodist University, Dallas, Texas
| | - Thad E Wilson
- Department of Physiology, University of Kentucky College of Medicine, Lexington, Kentucky
| | - Scott L Davis
- Applied Physiology and Wellness, Southern Methodist University, Dallas, Texas.,Department of Neurology and Neurotherapeutics, University of Texas Southwestern Medical Center, Dallas, Texas
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21
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Ad libitum water consumption off-sets the thermal and cardiovascular strain exacerbated by dehydration during a 3-h simulated heatwave. Eur J Appl Physiol 2019; 120:391-399. [DOI: 10.1007/s00421-019-04283-7] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2019] [Accepted: 12/02/2019] [Indexed: 12/14/2022]
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22
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Skin sympathetic nerve activity and ventricular rate control during atrial fibrillation. Heart Rhythm 2019; 17:544-552. [PMID: 31756526 DOI: 10.1016/j.hrthm.2019.11.017] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/30/2019] [Indexed: 10/25/2022]
Abstract
BACKGROUND The relationship between the ventricular rate (VR) during atrial fibrillation (AF) and skin sympathetic nerve activity (SKNA) remains unclear. OBJECTIVE The purpose of this study was to test the hypothesis that SKNA bursts accelerate VR during AF. METHODS We simultaneously recorded electrocardiogram and SKNA in 8 patients (median age 66.0 years [interquartile range {IQR} 59.0-77.0 years]; 4 men [50%]) with 30 paroxysmal AF episodes (all >10-minute long) and 12 patients (73.0 years [IQR 60.5-80.0 years]; 6 men [50%]) with persistent AF. The average amplitude of SKNA (aSKNA [μV]) during AF was analyzed in 1-minute windows and binned, showing 2 Gaussian distributions. We used the mean + 3SD of the first Gaussian distribution as the threshold that separates burst from baseline (nonburst) SKNA. All 1-minute aSKNA values above the threshold were detected, and the area between aSKNA and baseline of every 1 minute was calculated and added as burst area. RESULTS VR was higher during SKNA bursts than during the nonburst period (103 beats/min [IQR 83-113 beats/min] vs 88 beats/min [IQR 76-101 beats/min], respectively; P = .003). In the highest quartile of the burst area during persistent AF, the scatterplot of maximal aSKNA and VR during each SKNA burst shows higher aSKNA and VR. The overall estimate of the correlation between maximal VR and aSKNA during bursts show a positive correlation in the highest quartile of the burst area (0.64; 95% confidence interval 0.54-0.74; P < .0001). CONCLUSION SKNA bursts are associated with VR acceleration. These SKNA bursts may be new therapeutic targets for rate control during AF.
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Fujii N, McGarr GW, Sigal RJ, Boulay P, Nishiyasu T, Kenny GP. Ageing augments nicotinic and adenosine triphosphate-induced, but not muscarinic, cutaneous vasodilatation in women. Exp Physiol 2019; 104:1801-1807. [PMID: 31602716 DOI: 10.1113/ep088144] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2019] [Accepted: 10/08/2019] [Indexed: 12/22/2022]
Abstract
NEW FINDINGS What is the central question of this study? Does ageing augment muscarinic, nicotinic and/or ATP-mediated cutaneous vasodilatation in women? What is the main finding and its importance? Ageing augments nicotinic and ATP-induced, but not muscarinic, cutaneous vasodilatation in women. This will stimulate future studies assessing the pathophysiological significance of the augmented microvascular responsiveness in older women compared to their young counterparts. ABSTRACT We previously reported that ageing attenuates adenosine triphosphate (ATP)-induced, but not muscarinic and nicotinic, cutaneous vasodilatation in men, and that ageing may augment cutaneous vascular responses in women. In the present study, we evaluated the hypothesis that ageing augments muscarinic, nicotinic and/or ATP-mediated cutaneous vasodilatation in healthy women. In 11 young (23 ± 5 years) and 11 older (60 ± 8 years) women, cutaneous vascular conductance was evaluated at three forearm skin sites that were perfused with (1) methacholine (muscarinic receptor agonist, 5 doses: 0.0125, 0.25, 5, 100, 2000 mm), (2) nicotine (nicotinic receptor agonist, 5 doses: 1.2, 3.6, 11, 33, 100 mm), or (3) ATP (purinergic receptor agonist, 5 doses: 0.03, 0.3, 3, 30, 300 mm). Each agonist was administered for 25 min per dose. Methacholine-induced increases in cutaneous vascular conductance were not different between groups at all doses (all P > 0.05). However, a nicotine-induced elevation in cutaneous vascular conductance at the lowest concentration (1.2 mm) was greater in older vs. young women (43 ± 15 vs. 26 ± 10%max, P = 0.04). ATP-induced increases in cutaneous vascular conductance at moderate and high doses (3 and 30 mm) were also greater in older relative to young women (3 mm, 44 ± 11 vs. 28 ± 10%max, P = 0.02; 30 mm, 83 ± 14 vs. 64 ± 17%max, P = 0.05). Therefore, ageing augments nicotinic and ATP-induced, but not muscarinic, cutaneous vasodilatation in women.
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Affiliation(s)
- Naoto Fujii
- Human and Environmental Physiology Research Unit, University of Ottawa, Ottawa, Ontario, Canada.,Faculty of Health and Sport Sciences, University of Tsukuba, Tsukuba, Japan
| | - Gregory W McGarr
- Human and Environmental Physiology Research Unit, University of Ottawa, Ottawa, Ontario, Canada
| | - 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.,Clinical Epidemiology Program, Ottawa Hospital Research Institute, 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, Japan
| | - 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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Brennan M, O’Keeffe ST, Mulkerrin EC. Dehydration and renal failure in older persons during heatwaves-predictable, hard to identify but preventable? Age Ageing 2019; 48:615-618. [PMID: 31268494 DOI: 10.1093/ageing/afz080] [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: 03/27/2019] [Revised: 04/04/2019] [Accepted: 06/06/2019] [Indexed: 11/14/2022] Open
Abstract
Extremes of temperature are likely to increase in frequency associated with climate change. Older patients are particularly vulnerable to the effects of heat with excess mortality well documented in this population. Age-associated neurohormonal changes particularly affecting the renin angiotensin aldosterone system (RAAS), alterations in thermoregulatory mechanisms, changes in renal function and body composition render older persons vulnerable to dehydration, renal failure, heat stroke and increased mortality. Barriers to diagnosis and recognition of dehydration and renal failure include the absence of reliable clinical signs and cost-effective diagnostic tools. Regularly used medications also impact on physiological responses to excess heat as well as interfering with the recognition and management of dehydration during heat waves. In view of the above, anticipatory measures should be instituted ideally prior to the onset of heat waves to minimise morbidity and mortality for older people during periods of excess heat.
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Affiliation(s)
- Michelle Brennan
- Department of Geriatric Medicine, University Hospital Galway, Galway Ireland
| | - Shaun T O’Keeffe
- Department of Geriatric Medicine, University Hospital Galway, Galway Ireland
| | - Eamon C Mulkerrin
- Department of Geriatric Medicine, University Hospital Galway, Galway Ireland
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25
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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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26
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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: 242] [Impact Index Per Article: 48.4] [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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27
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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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28
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Ota A, Takeda R, Imai D, Naghavi N, Kawai E, Saho K, Morita E, Suzuki Y, Yokoyama H, Miyagawa T, Okazaki K. The effects of aging on the distribution of cerebral blood flow with postural changes and mild hyperthermia. Eur J Appl Physiol 2019; 119:1261-1272. [DOI: 10.1007/s00421-019-04118-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2018] [Accepted: 03/01/2019] [Indexed: 11/24/2022]
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29
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Fujii N, McGarr GW, Nishiyasu T, Sigal RJ, Boulay P, Kenny GP. Ageing attenuates muscarinic‐mediated sweating differently in men and women with no effect on nicotinic‐mediated sweating. Exp Dermatol 2019; 28:968-971. [DOI: 10.1111/exd.13878] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2018] [Revised: 11/03/2018] [Accepted: 01/01/2019] [Indexed: 01/29/2023]
Affiliation(s)
- Naoto Fujii
- Faculty of Health and Sport SciencesUniversity of Tsukuba Tsukuba Japan
- Human and Environmental Physiology Research UnitUniversity of Ottawa Ottawa Ontario Canada
| | - Gregory W. McGarr
- Human and Environmental Physiology Research UnitUniversity of Ottawa Ottawa Ontario Canada
| | - Takeshi Nishiyasu
- Faculty of Health and Sport SciencesUniversity of Tsukuba Tsukuba Japan
| | - Ronald J. Sigal
- Human and Environmental Physiology Research UnitUniversity of Ottawa Ottawa Ontario Canada
- Departments of MedicineCardiac Sciences and Community Health SciencesFaculties of Medicine and KinesiologyUniversity of Calgary Calgary Alberta Canada
- Clinical Epidemiology ProgramOttawa Hospital Research Institute Ottawa Ontario Canada
| | - Pierre Boulay
- Faculty of Physical Activity SciencesUniversity of Sherbrooke Sherbrooke Quebec Canada
| | - Glen P. Kenny
- Human and Environmental Physiology Research UnitUniversity of Ottawa Ottawa Ontario Canada
- Clinical Epidemiology ProgramOttawa Hospital Research Institute Ottawa Ontario Canada
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30
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Fujii N, Nishiyasu T, Sigal RJ, Boulay P, McGarr GW, Kenny GP. Aging attenuates adenosine triphosphate-induced, but not muscarinic and nicotinic, cutaneous vasodilation in men. Microcirculation 2018; 25:e12462. [PMID: 29846993 DOI: 10.1111/micc.12462] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2018] [Revised: 05/13/2018] [Accepted: 05/28/2018] [Indexed: 12/22/2022]
Abstract
OBJECTIVE We evaluated the hypothesis that aging attenuates muscarinic, nicotinic, and ATP-related cutaneous vasodilation. METHODS In 11 young (24 ± 4 years) and 11 older males (61 ± 8 years), CVC was assessed at 3 forearm skin sites that were infused with either: (i) methacholine (muscarinic receptor agonist, 5 doses: 0.0125, 0.25, 5, 100, 2000 mmol/L), (ii) nicotine (nicotinic receptor agonist, 5 doses: 1.2, 3.6, 11, 33, 100 mmol/L), or (iii) ATP (purinergic receptor agonist, 5 doses: 0.03, 0.3, 3, 30, 300 mmol/L). Each agonist was administered for 25 minutes per dose. RESULTS We showed that CVC at all doses of methacholine did not differ between groups. Similarly, no between-group differences in CVC were observed during nicotine administration at all doses administered. By contrast, while no differences in CVC were measured during the administration of ATP at low (0.03 and 0.3 mmol/L) or high (300 mmol/L) concentrations, CVC was reduced in the older relative to the young males at moderate concentrations of ATP (3 mmol/L: 23 ± 6 vs 40 ± 13%max, 30 mmol/L: 62 ± 11 vs 83 ± 8%max, both P ≤ .05). CONCLUSIONS We show that aging attenuates ATP-induced, but not muscarinic or nicotinic, cutaneous vasodilation in men.
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Affiliation(s)
- Naoto Fujii
- Human and Environmental Physiology Research Unit, University of Ottawa, Ottawa, ON, Canada.,Faculty of Health and Sport Sciences, University of Tsukuba, Tsukuba, Japan
| | - Takeshi Nishiyasu
- Faculty of Health and Sport Sciences, University of Tsukuba, Tsukuba, Japan
| | - Ronald J Sigal
- Human and Environmental Physiology Research Unit, University of Ottawa, Ottawa, ON, Canada.,Department of Medicine, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada.,Clinical Epidemiology Program, Ottawa Hospital Research Institute, Ottawa, ON, Canada
| | - Pierre Boulay
- Faculty of Physical Activity Sciences, University of Sherbrooke, Sherbrooke, QC, Canada
| | - Gregory W McGarr
- Human and Environmental Physiology Research Unit, University of Ottawa, Ottawa, ON, Canada
| | - Glen P Kenny
- Human and Environmental Physiology Research Unit, University of Ottawa, Ottawa, ON, Canada.,Clinical Epidemiology Program, Ottawa Hospital Research Institute, Ottawa, ON, Canada
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31
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Maley MJ, Costello JT, Borg DN, Bach AJE, Hunt AP, Stewart IB. An Overt Chemical Protective Garment Reduces Thermal Strain Compared with a Covert Garment in Warm-Wet but Not Hot-Dry Environments. Front Physiol 2017; 8:913. [PMID: 29170644 PMCID: PMC5684487 DOI: 10.3389/fphys.2017.00913] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2017] [Accepted: 10/27/2017] [Indexed: 11/23/2022] Open
Abstract
Objectives: A commercial chemical, biological, radiological and nuclear (CBRN) protective covert garment has recently been developed with the aim of reducing thermal strain. A covert CBRN protective layer can be worn under other clothing, with equipment added for full chemical protection when needed. However, it is unknown whether the covert garment offers any alleviation to thermal strain during work compared with a traditional overt ensemble. Therefore, the aim of this study was to compare thermal strain and work tolerance times during work in an overt and covert ensemble offering the same level of CBRN protection. Methods: Eleven male participants wore an overt (OVERT) or covert (COVERT) CBRN ensemble and walked (4 km·h−1, 1% grade) for a maximum of 120 min in either a wet bulb globe temperature [WBGT] of 21, 30, or 37°C (Neutral, WarmWet and HotDry, respectively). The trials were ceased if the participants' gastrointestinal temperature reached 39°C, heart rate reached 90% of maximum, walking time reached 120 min or due to self-termination. Results: All participants completed 120 min of walking in Neutral. Work tolerance time was greater in OVERT compared with COVERT in WarmWet (P < 0.001, 116.5[9.9] vs. 88.9[12.2] min, respectively), though this order was reversed in HotDry (P = 0.003, 37.3[5.3] vs. 48.4[4.6] min, respectively). The rate of change in mean body temperature and mean skin temperature was greater in COVERT (0.025[0.004] and 0.045[0.010]°C·min−1, respectively) compared with OVERT (0.014[0.004] and 0.027[0.007]°C·min−1, respectively) in WarmWet (P < 0.001 and P = 0.028, respectively). However, the rate of change in mean body temperature and mean skin temperature was greater in OVERT (0.068[0.010] and 0.170[0.026]°C·min−1, respectively) compared with COVERT (0.059[0.004] and 0.120[0.017]°C·min−1, respectively) in HotDry (P = 0.002 and P < 0.001, respectively). Thermal sensation, thermal comfort, and ratings of perceived exertion did not differ between garments at trial cessation (P > 0.05). Conclusion: Those dressed in OVERT experienced lower thermal strain and longer work tolerance times compared with COVERT in a warm-wet environment. However, COVERT may be an optimal choice in a hot-dry environment. These findings have practical implications for those making decisions on the choice of CBRN ensemble to be used during work.
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Affiliation(s)
- Matthew J Maley
- Institute of Health and Biomedical Innovation, School of Exercise and Nutrition Sciences, Queensland University of Technology, Brisbane, QLD, Australia
| | - Joseph T Costello
- Institute of Health and Biomedical Innovation, School of Exercise and Nutrition Sciences, Queensland University of Technology, Brisbane, QLD, Australia.,Extreme Environments Laboratory, Department of Sport and Exercise Science, University of Portsmouth, Portsmouth, United Kingdom
| | - David N Borg
- Institute of Health and Biomedical Innovation, School of Exercise and Nutrition Sciences, Queensland University of Technology, Brisbane, QLD, Australia
| | - Aaron J E Bach
- Institute of Health and Biomedical Innovation, School of Exercise and Nutrition Sciences, Queensland University of Technology, Brisbane, QLD, Australia
| | - Andrew P Hunt
- Institute of Health and Biomedical Innovation, School of Exercise and Nutrition Sciences, Queensland University of Technology, Brisbane, QLD, Australia
| | - Ian B Stewart
- Institute of Health and Biomedical Innovation, School of Exercise and Nutrition Sciences, Queensland University of Technology, Brisbane, QLD, Australia
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32
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Schlader ZJ, Sackett JR, Sarker S, Johnson BD. Orderly recruitment of thermoeffectors in resting humans. Am J Physiol Regul Integr Comp Physiol 2017; 314:R171-R180. [PMID: 29021192 DOI: 10.1152/ajpregu.00324.2017] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The recruitment of thermoeffectors, including thermoregulatory behavior, relative to changes in body temperature has not been quantified in humans. We tested the hypothesis that changes in skin blood flow, behavior, and sweating or metabolic rate are initiated with increasing changes in mean skin temperature (Tskin) in resting humans. While wearing a water-perfused suit, 12 healthy young adults underwent heat (Heat) and cold stress (Cold) that induced gradual changes in Tskin. Subjects controlled the temperature of their dorsal neck to their perceived thermal comfort. Thus neck skin temperature provided an index of thermoregulatory behavior. Neck skin temperature (Tskin), core temperature (Tcore), metabolic rate, sweat rate, and nonglabrous skin blood flow were measured continually. Data were analyzed using segmental regression analysis, providing an index of thermoeffector activation relative to changes in Tskin. In Heat, increases in skin blood flow were observed with the smallest elevations in Tskin ( P < 0.01). Thermal behavior was initiated with an increase in Tskin of 2.4 ± 1.3°C (mean ± SD, P = 0.04), while sweating was observed with further elevations in Tskin (3.4 ± 0.5°C, P = 0.04), which coincided with increases in Tcore ( P = 0.98). In Cold, reductions in skin blood flow occurred with the smallest decrease in Tskin ( P < 0.01). Thermal behavior was initiated with a Tskin decrease of 1.5 ± 1.3°C, while metabolic rate ( P = 0.10) and Tcore ( P = 0.76) did not change throughout. These data indicate that autonomic and behavioral thermoeffectors are recruited in coordination with one another and likely in an orderly manner relative to the comparative physiological cost.
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Affiliation(s)
- Zachary J Schlader
- Center for Research and Education in Special Environments, Department of Exercise and Nutrition Sciences, University at Buffalo , Buffalo, New York
| | - James R Sackett
- Center for Research and Education in Special Environments, Department of Exercise and Nutrition Sciences, University at Buffalo , Buffalo, New York
| | - Suman Sarker
- Center for Research and Education in Special Environments, Department of Exercise and Nutrition Sciences, University at Buffalo , Buffalo, New York
| | - Blair D Johnson
- Center for Research and Education in Special Environments, Department of Exercise and Nutrition Sciences, University at Buffalo , Buffalo, New York
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Brazaitis M, Paulauskas H, Eimantas N, Obelieniene D, Baranauskiene N, Skurvydas A. Heat transfer and loss by whole-body hyperthermia during severe lower-body heating are impaired in healthy older men. Exp Gerontol 2017; 96:12-18. [DOI: 10.1016/j.exger.2017.05.018] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2017] [Revised: 05/04/2017] [Accepted: 05/19/2017] [Indexed: 11/25/2022]
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34
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Greaney JL, Kenney WL. Measuring and quantifying skin sympathetic nervous system activity in humans. J Neurophysiol 2017; 118:2181-2193. [PMID: 28701539 DOI: 10.1152/jn.00283.2017] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2017] [Revised: 07/10/2017] [Accepted: 07/10/2017] [Indexed: 01/23/2023] Open
Abstract
Development of the technique of microneurography has substantially increased our understanding of the function of the sympathetic nervous system (SNS) in health and in disease. The ability to directly record signals from peripheral autonomic nerves in conscious humans allows for qualitative and quantitative characterization of SNS responses to specific stimuli and over time. Furthermore, distinct neural outflow to muscle (MSNA) and skin (SSNA) can be delineated. However, there are limitations and caveats to the use of microneurography, measurement criteria, and signal analysis and interpretation. MSNA recordings have a longer history and are considered relatively more straightforward from a measurement and analysis perspective. This brief review provides an overview of the development of the technique as used to measure SSNA. The focus is on the utility of measuring sympathetic activity directed to the skin, the unique issues related to analyzing and quantifying multiunit SSNA, and the challenges related to its interpretation.
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Affiliation(s)
- Jody L Greaney
- Noll Laboratory, Department of Kinesiology, The Pennsylvania State University, University Park, Pennsylvania
| | - W Larry Kenney
- Noll Laboratory, Department of Kinesiology, The Pennsylvania State University, University Park, Pennsylvania
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35
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Stanhewicz AE, Greaney JL, Alexander LM, Kenney WL. Folic acid supplementation increases cutaneous vasodilator sensitivity to sympathetic nerve activity in older adults. Am J Physiol Regul Integr Comp Physiol 2017; 312:R681-R688. [PMID: 28228418 DOI: 10.1152/ajpregu.00493.2016] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2016] [Revised: 02/16/2017] [Accepted: 02/16/2017] [Indexed: 11/22/2022]
Abstract
During heat stress, blunted increases in skin sympathetic nervous system activity (SSNA) and reductions in end-organ vascular responsiveness contribute to the age-related reduction in reflex cutaneous vasodilation. In older adults, folic acid supplementation improves the cutaneous vascular conductance (CVC) response to passive heating; however, the influence of folic acid supplementation on SSNA:CVC transduction is unknown. Fourteen older adults (66 ± 1 yr, 8 male/6 female) ingested folic acid (5 mg/day) or placebo for 6 wk in a randomized, double-blind, crossover design. In protocol 1, esophageal temperature (Tes) was increased by 1.0°C (water-perfused suit) while SSNA (peroneal microneurography) and red cell flux in the innervated dermatome (laser Doppler flowmetry; dorsum of the foot) were continuously measured. In protocol 2, two intradermal microdialysis fibers were placed in the skin of the lateral calf for graded infusions of acetylcholine (ACh; 10-10 to 10-1 M) with and without nitric oxide synthase (NOS) blockade (20 mM nitro-l-arginine methyl ester). Folic acid improved reflex vasodilation (46 ± 4% vs. 31 ± 3% CVCmax for placebo; P < 0.001) without affecting the increase in SSNA (Δ506 ± 104% vs. Δ415 ± 73% for placebo; NS). Folic acid increased the slope of the SSNA-to-CVC relation (0.08 ± 0.02 vs. 0.05 ± 0.01 for placebo; P < 0.05) and extended the response range. Folic acid augmented ACh-induced vasodilation (83 ± 3% vs. 66 ± 4% CVCmax for placebo; P = 0.002); however, there was no difference between treatments at the NOS-inhibited site (53 ± 4% vs. 52 ± 4% CVCmax for placebo; NS). These data demonstrate that folic acid supplementation enhances reflex vasodilation by increasing the sensitivity of skin arterioles to central sympathetic nerve outflow during hyperthermia in aged human subjects.
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Affiliation(s)
- Anna E Stanhewicz
- Department of Kinesiology, The Pennsylvania State University, University Park, Pennsylvania
| | - Jody L Greaney
- Department of Kinesiology, The Pennsylvania State University, University Park, Pennsylvania
| | - Lacy M Alexander
- Department of Kinesiology, The Pennsylvania State University, University Park, Pennsylvania
| | - W Larry Kenney
- Department of Kinesiology, The Pennsylvania State University, University Park, Pennsylvania
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Amano T, Kai S, Nakajima M, Ichinose-Kuwahara T, Gerrett N, Kondo N, Inoue Y. Sweating responses to isometric hand-grip exercise and forearm muscle metaboreflex in prepubertal children and elderly. Exp Physiol 2016; 102:214-227. [DOI: 10.1113/ep085908] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2016] [Accepted: 11/09/2016] [Indexed: 01/21/2023]
Affiliation(s)
- Tatsuro Amano
- Laboratory for Applied Human Physiology, Graduate School of Human Development and Environment; Kobe University; Kobe Japan
- Laboratory for Exercise and Environmental Physiology, Faculty of Education; Niigata University; Niigata Japan
| | - Seiko Kai
- Laboratory for Human Performance Research; Osaka International University; Osaka Japan
| | - Michi Nakajima
- Laboratory for Human Performance Research; Osaka International University; Osaka Japan
| | | | - Nicola Gerrett
- Laboratory for Applied Human Physiology, Graduate School of Human Development and Environment; Kobe University; Kobe Japan
| | - Narihiko Kondo
- Laboratory for Applied Human Physiology, Graduate School of Human Development and Environment; Kobe University; Kobe Japan
| | - Yoshimitsu Inoue
- Laboratory for Human Performance Research; Osaka International University; Osaka Japan
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Stanhewicz AE, Greaney JL, Alexander LM, Kenney WL. Blunted increases in skin sympathetic nerve activity are related to attenuated reflex vasodilation in aged human skin. J Appl Physiol (1985) 2016; 121:1354-1362. [PMID: 27789772 DOI: 10.1152/japplphysiol.00730.2016] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2016] [Revised: 10/06/2016] [Accepted: 10/21/2016] [Indexed: 11/22/2022] Open
Abstract
Reflex cutaneous vasodilation in response to passive heating is attenuated in human aging. This diminished response is mediated, in part, by age-associated reductions in endothelial function; however, the contribution of altered skin sympathetic nervous system activity (SSNA) is unknown. We hypothesized that 1) healthy older adults would demonstrate blunted SSNA responses to increased core temperature compared with young adults and 2) the decreased SSNA response would be associated with attenuated cutaneous vasodilation. Reflex vasodilation was elicited in 13 young [23 ± 1 (SE) yr] and 13 older (67 ± 2 yr) adults using a water-perfused suit to elevate esophageal temperature by 1.0°C. SSNA (peroneal microneurography) and red cell flux (laser Doppler flowmetry) in the innervated dermatome (the dorsum of foot) were continuously measured. SSNA was normalized to, and expressed as, a percentage of baseline. Cutaneous vascular conductance (CVC) was calculated as flux/mean arterial pressure and expressed as a percentage of maximal CVC (local heating, 43°C). Reflex vasodilation was attenuated in older adults (P < 0.001). During heating, SSNA increased in both groups (P < 0.05); however, the response was significantly blunted in older adults (P = 0.01). The increase in SSNA during heating was linearly related to cutaneous vasodilation in both young (R2 = 0.87 ± 0.02, P < 0.01) and older (R2 = 0.76 ± 0.05, P < 0.01) adults; however, slope of the linear regression between ΔSSNA and ΔCVC was reduced in older compared with young (older: 0.05 ± 0.01 vs. young: 0.08 ± 0.01; P < 0.05). These data demonstrate that age-related impairments in reflex cutaneous vasodilation are mediated, in part, by blunted efferent SSNA during hyperthermia.
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Affiliation(s)
- Anna E Stanhewicz
- Department of Kinesiology, The Pennsylvania State University, University Park, Pennsylvania
| | - Jody L Greaney
- Department of Kinesiology, The Pennsylvania State University, University Park, Pennsylvania
| | - Lacy M Alexander
- Department of Kinesiology, The Pennsylvania State University, University Park, Pennsylvania
| | - W Larry Kenney
- Department of Kinesiology, The Pennsylvania State University, University Park, Pennsylvania
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Fujii N, Notley SR, Minson CT, Kenny GP. Administration of prostacyclin modulates cutaneous blood flow but not sweating in young and older males: roles for nitric oxide and calcium-activated potassium channels. J Physiol 2016; 594:6419-6429. [PMID: 27511105 DOI: 10.1113/jp273174] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2016] [Accepted: 08/09/2016] [Indexed: 01/19/2023] Open
Abstract
KEY POINTS In young adults, cyclooxygenase (COX) contributes to the heat loss responses of cutaneous vasodilatation and sweating, and this may be mediated by prostacyclin-induced activation of nitric oxide synthase (NOS) and calcium-activated potassium (KCa) channels. This prostacyclin-induced response may be diminished in older relative to young adults because ageing is known to attenuate COX-dependent heat loss responses. We observed that, although prostacyclin does not mediate sweating in young and older males, it does modulate cutaneous vasodilatation, although the magnitude of increase is similar between groups. We also found that, although NOS and KCa channels contribute to prostacyclin-induced cutaneous vasodilatation in young males, these contributions are diminished in older males. Our findings provide new insight into the mechanisms governing heat loss responses and suggest that the age-related diminished COX-dependent heat loss responses reported in previous studies may be a result of the reduced COX-derived production of prostanoids (e.g., prostacyclin) rather than the decreased sensitivity of prostanoid receptors. ABSTRACT Cyclooxygenase (COX) contributes to the regulation of cutaneous vasodilatation and sweating; however, the mechanism(s) underpinning this response remain unresolved. We hypothesized that prostacyclin (a COX-derived product) may directly mediate cutaneous vasodilatation and sweating through nitric oxide synthase (NOS) and calcium-activated potassium (KCa) channels in young adults. However, these responses would be diminished in older adults because ageing attenuates COX-dependent cutaneous vasodilatation and sweating. In young (25 ± 4 years) and older (60 ± 6 years) males (nine per group), cutaneous vascular conductance (CVC) and sweat rate were evaluated at four intradermal forearm skin sites: (i) control; (ii) 10 mm NG -nitro-l-arginine (l-NNA), a non-specific NOS inhibitor; (iii) 50 mm tetraethylammonium (TEA), a non-specific KCa channel blocker; and (iv) 10 mm l-NNA + 50 mm TEA. All four sites were coadministered with prostacyclin in an incremental manner (0.04, 0.4, 4, 40 and 400 μm each for 25 min). Prostacyclin-induced increases in CVC were similar between groups (all concentrations, P > 0.05). l-NNA and TEA, as well as their combination, lowered CVC in young males at all prostacyclin concentrations (P ≤ 0.05), with the exception of l-NNA at 0.04 μm (P > 0.05). In older males, CVC during prostacyclin administration was not influenced by l-NNA (all concentrations), TEA (4-400 μm) or their combination (400 μm) (P > 0.05). No effect on sweat rate was observed in either group (all concentrations, P > 0.05). We conclude that, although prostacyclin does not mediate sweating, it modulates cutaneous vasodilatation to a similar extent in young and older males. Furthermore, although NOS and KCa channels contribute to the prostacyclin-induced cutaneous vasodilatation in young males, these contributions are diminished in older males.
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Affiliation(s)
- Naoto Fujii
- Human and Environmental Physiology Research Unit, University of Ottawa, Ottawa, Canada
| | - Sean R Notley
- Centre for Human and Applied Physiology, School of Medicine, University of Wollongong, Wollongong, Australia
| | | | - Glen P Kenny
- Human and Environmental Physiology Research Unit, University of Ottawa, Ottawa, Canada.
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Bain AR, Nybo L, Ainslie PN. Cerebral Vascular Control and Metabolism in Heat Stress. Compr Physiol 2016; 5:1345-80. [PMID: 26140721 DOI: 10.1002/cphy.c140066] [Citation(s) in RCA: 61] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
This review provides an in-depth update on the impact of heat stress on cerebrovascular functioning. The regulation of cerebral temperature, blood flow, and metabolism are discussed. We further provide an overview of vascular permeability, the neurocognitive changes, and the key clinical implications and pathologies known to confound cerebral functioning during hyperthermia. A reduction in cerebral blood flow (CBF), derived primarily from a respiratory-induced alkalosis, underscores the cerebrovascular changes to hyperthermia. Arterial pressures may also become compromised because of reduced peripheral resistance secondary to skin vasodilatation. Therefore, when hyperthermia is combined with conditions that increase cardiovascular strain, for example, orthostasis or dehydration, the inability to preserve cerebral perfusion pressure further reduces CBF. A reduced cerebral perfusion pressure is in turn the primary mechanism for impaired tolerance to orthostatic challenges. Any reduction in CBF attenuates the brain's convective heat loss, while the hyperthermic-induced increase in metabolic rate increases the cerebral heat gain. This paradoxical uncoupling of CBF to metabolism increases brain temperature, and potentiates a condition whereby cerebral oxygenation may be compromised. With levels of experimentally viable passive hyperthermia (up to 39.5-40.0 °C core temperature), the associated reduction in CBF (∼ 30%) and increase in cerebral metabolic demand (∼ 10%) is likely compensated by increases in cerebral oxygen extraction. However, severe increases in whole-body and brain temperature may increase blood-brain barrier permeability, potentially leading to cerebral vasogenic edema. The cerebrovascular challenges associated with hyperthermia are of paramount importance for populations with compromised thermoregulatory control--for example, spinal cord injury, elderly, and those with preexisting cardiovascular diseases.
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Affiliation(s)
- Anthony R Bain
- Centre for Heart Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia, Okanagan Campus, Kelowna, Canada
| | - Lars Nybo
- Department of Nutrition, Exercise and Sport Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Philip N Ainslie
- Centre for Heart Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia, Okanagan Campus, Kelowna, Canada
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40
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Tanei R, Hasegawa Y. Atopic dermatitis in older adults: A viewpoint from geriatric dermatology. Geriatr Gerontol Int 2016; 16 Suppl 1:75-86. [DOI: 10.1111/ggi.12771] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/10/2016] [Indexed: 12/13/2022]
Affiliation(s)
- Ryoji Tanei
- Department of Dermatology; Tokyo Metropolitan Geriatric Hospital and Institute of Gerontology; Itabashi Tokyo Japan
| | - Yasuko Hasegawa
- Department of Geriatric Pathology; Tokyo Metropolitan Geriatric Hospital and Institute of Gerontology; Itabashi Tokyo Japan
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41
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Meade RD, Louie JC, Poirier MP, McGinn R, Fujii N, Kenny GP. Exploring the mechanisms underpinning sweating: the development of a specialized ventilated capsule for use with intradermal microdialysis. Physiol Rep 2016; 4:e12738. [PMID: 27033452 PMCID: PMC4814883 DOI: 10.14814/phy2.12738] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2016] [Accepted: 02/18/2016] [Indexed: 01/26/2023] Open
Abstract
Many studies have aimed to identify the controllers of sweating using ventilated capsules with intradermal microdialysis. It is unclear, however, if the surface area covered by the capsule influences the observed response as a result of differences in the number of sweat glands affected by the infused pharmacological agent relative to the total glands captured by the capsule. We evaluated the area of skin perfused with agents delivered via microdialysis. Thereafter, we developed a specialized sweat capsule (1.1 cm(2)) and compared the sweating response with a classic capsule (2.8 cm(2)). InProtocol 1(n = 6), methacholine was delivered to forearm skin in a dose-dependent manner (1-2000 mmol L(-1)). The area of activated sweat glands was assessed via the modified iodine-paper technique. InProtocol 2(n = 6), the area of inhibited sweat glands induced by ouabain and atropine was assessed during moderate-intensity cycling. Marked variability in the affected skin area was observed (0.9 ± 0.4 to 5.2 ± 1.1 cm(2)). InProtocol 3(n = 6), we compared the attenuation in local sweat rate (LSR) induced by atropine between the new and classic capsule during moderate-intensity cycling. Atropine attenuated sweating as assessed using the new (control: 0.87 ± 0.23 mg min(-1) cm(-2)vs. atropine: 0.54 ± 0.22 mg min(-1) cm(-2);P < 0.01) and classic (control: 0.85 ± 0.33 mg min(-1) cm(-2)vs. atropine: 0.60 ± 0.26 mg min(-1) cm(-2);P = 0.05) capsule designs. Importantly, responses did not differ between capsule designs (P = 0.23). These findings provide critical information regarding the skin surface area perfused by microdialysis and suggest that use of a larger capsule does not alter the mechanistic insight into the sweating response gained when using microdialysis.
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Affiliation(s)
- Robert D Meade
- Human and Environmental Physiology Research Unit, Faculty of Health Sciences, University of Ottawa, Ottawa, Ontario, Canada
| | - Jeffrey C Louie
- Human and Environmental Physiology Research Unit, Faculty of Health Sciences, University of Ottawa, Ottawa, Ontario, Canada
| | - Martin P Poirier
- Human and Environmental Physiology Research Unit, Faculty of Health Sciences, University of Ottawa, Ottawa, Ontario, Canada
| | - Ryan McGinn
- Human and Environmental Physiology Research Unit, Faculty of Health Sciences, University of Ottawa, Ottawa, Ontario, Canada
| | - Naoto Fujii
- Human and Environmental Physiology Research Unit, Faculty of Health Sciences, University of Ottawa, Ottawa, Ontario, Canada
| | - Glen P Kenny
- Human and Environmental Physiology Research Unit, Faculty of Health Sciences, University of Ottawa, Ottawa, Ontario, Canada
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42
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Fujii N, Meade RD, Alexander LM, Akbari P, Foudil-Bey I, Louie JC, Boulay P, Kenny GP. iNOS-dependent sweating and eNOS-dependent cutaneous vasodilation are evident in younger adults, but are diminished in older adults exercising in the heat. J Appl Physiol (1985) 2016; 120:318-27. [PMID: 26586908 PMCID: PMC4740499 DOI: 10.1152/japplphysiol.00714.2015] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2015] [Accepted: 11/16/2015] [Indexed: 12/12/2022] Open
Abstract
Nitric oxide synthase (NOS) contributes to sweating and cutaneous vasodilation during exercise in younger adults. We hypothesized that endothelial NOS (eNOS) and neuronal NOS (nNOS) mediate NOS-dependent sweating, whereas eNOS induces NOS-dependent cutaneous vasodilation in younger adults exercising in the heat. Further, aging may upregulate inducible NOS (iNOS), which may attenuate sweating and cutaneous vasodilator responses. We hypothesized that iNOS inhibition would augment sweating and cutaneous vasodilation in exercising older adults. Physically active younger (n = 12, 23 ± 4 yr) and older (n = 12, 60 ± 6 yr) adults performed two 30-min bouts of cycling at a fixed rate of metabolic heat production (400 W) in the heat (35°C). Sweat rate and cutaneous vascular conductance (CVC) were evaluated at four intradermal microdialysis sites with: 1) lactated Ringer (control), 2) nNOS inhibitor (nNOS-I, NPLA), 3) iNOS inhibitor (iNOS-I, 1400W), or 4) eNOS inhibitor (eNOS-I, LNAA). In younger adults during both exercise bouts, all inhibitors decreased sweating relative to control, albeit a lower sweat rate was observed at iNOS-I compared with eNOS-I and nNOS-I sites (all P < 0.05). CVC at the eNOS-I site was lower than control in younger adults throughout the intermittent exercise protocol (all P < 0.05). In older adults, there were no differences between control and iNOS-I sites for sweating and CVC during both exercise bouts (all P > 0.05). We show that iNOS and eNOS are the main contributors to NOS-dependent sweating and cutaneous vasodilation, respectively, in physically active younger adults exercising in the heat, and that iNOS inhibition does not alter sweating or cutaneous vasodilation in exercising physically active older adults.
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Affiliation(s)
- Naoto Fujii
- Human and Environmental Physiology Research Unit, University of Ottawa, Ottawa, Canada
| | - Robert D Meade
- Human and Environmental Physiology Research Unit, University of Ottawa, Ottawa, Canada
| | - Lacy M Alexander
- Department of Kinesiology, Noll Laboratory, Pennsylvania State University, University Park, Pennsylvania; and
| | - Pegah Akbari
- Human and Environmental Physiology Research Unit, University of Ottawa, Ottawa, Canada
| | - Imane Foudil-Bey
- Human and Environmental Physiology Research Unit, University of Ottawa, Ottawa, Canada
| | - Jeffrey C Louie
- Human and Environmental Physiology Research Unit, University of Ottawa, Ottawa, Canada
| | - Pierre Boulay
- Faculty of Physical Activity Sciences, University of Sherbrooke, Sherbrooke, Canada
| | - Glen P Kenny
- Human and Environmental Physiology Research Unit, University of Ottawa, Ottawa, Canada;
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43
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Smith CJ, Johnson JM. Responses to hyperthermia. Optimizing heat dissipation by convection and evaporation: Neural control of skin blood flow and sweating in humans. Auton Neurosci 2016; 196:25-36. [PMID: 26830064 DOI: 10.1016/j.autneu.2016.01.002] [Citation(s) in RCA: 68] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2015] [Revised: 01/14/2016] [Accepted: 01/19/2016] [Indexed: 01/05/2023]
Abstract
Under normothermic, resting conditions, humans dissipate heat from the body at a rate approximately equal to heat production. Small discrepancies between heat production and heat elimination would, over time, lead to significant changes in heat storage and body temperature. When heat production or environmental temperature is high the challenge of maintaining heat balance is much greater. This matching of heat elimination with heat production is a function of the skin circulation facilitating heat transport to the body surface and sweating, enabling evaporative heat loss. These processes are manifestations of the autonomic control of cutaneous vasomotor and sudomotor functions and form the basis of this review. We focus on these systems in the responses to hyperthermia. In particular, the cutaneous vascular responses to heat stress and the current understanding of the neurovascular mechanisms involved. The available research regarding cutaneous active vasodilation and vasoconstriction is highlighted, with emphasis on active vasodilation as a major responder to heat stress. Involvement of the vasoconstrictor and active vasodilator controls of the skin circulation in the context of heat stress and nonthermoregulatory reflexes (blood pressure, exercise) are also considered. Autonomic involvement in the cutaneous vascular responses to direct heating and cooling of the skin are also discussed. We examine the autonomic control of sweating, including cholinergic and noncholinergic mechanisms, the local control of sweating, thermoregulatory and nonthermoregulatory reflex control and the possible relationship between sudomotor and cutaneous vasodilator function. Finally, we comment on the clinical relevance of these control schemes in conditions of autonomic dysfunction.
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Affiliation(s)
- Caroline J Smith
- Department of Health and Exercise Science, Appalachian State University, Boone, NC 28608-2071, United States
| | - John M Johnson
- Department of Physiology, University of Texas Health Science Center, San Antonio, TX 78229-3901, United States
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44
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Kenney WL, Craighead DH, Alexander LM. Heat waves, aging, and human cardiovascular health. Med Sci Sports Exerc 2015; 46:1891-9. [PMID: 24598696 DOI: 10.1249/mss.0000000000000325] [Citation(s) in RCA: 156] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
This brief review is based on a President's Lecture presented at the Annual Meeting of the American College of Sports Medicine in 2013. The purpose of this review was to assess the effects of climate change and consequent increases in environmental heat stress on the aging cardiovascular system. The earth's average global temperature is slowly but consistently increasing, and along with mean temperature changes come increases in heat wave frequency and severity. Extreme passive thermal stress resulting from prolonged elevations in ambient temperature and prolonged physical activity in hot environments creates a high demand on the left ventricle to pump blood to the skin to dissipate heat. Even healthy aging is accompanied by altered cardiovascular function, which limits the extent to which older individuals can maintain stroke volume, increase cardiac output, and increase skin blood flow when exposed to environmental extremes. In the elderly, the increased cardiovascular demand during heat waves is often fatal because of increased strain on an already compromised left ventricle. Not surprisingly, excess deaths during heat waves 1) occur predominantly in older individuals and 2) are overwhelmingly cardiovascular in origin. Increasing frequency and severity of heat waves coupled with a rapidly growing at-risk population dramatically increase the extent of future untoward health outcomes.
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Affiliation(s)
- W Larry Kenney
- Department of Kinesiology, Pennsylvania State University, University Park, PA
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45
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Stapleton JM, Poirier MP, Flouris AD, Boulay P, Sigal RJ, Malcolm J, Kenny GP. At what level of heat load are age-related impairments in the ability to dissipate heat evident in females? PLoS One 2015; 10:e0119079. [PMID: 25790024 PMCID: PMC4366400 DOI: 10.1371/journal.pone.0119079] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2014] [Accepted: 01/28/2015] [Indexed: 11/19/2022] Open
Abstract
Studies have reported that older females have impaired heat loss responses during work in the heat compared to young females. However, it remains unclear at what level of heat stress these differences occur. Therefore, we examined whole-body heat loss [evaporative (HE) and dry heat loss, via direct calorimetry] and changes in body heat storage (∆Hb, via direct and indirect calorimetry) in 10 young (23±4 years) and 10 older (58±5 years) females matched for body surface area and aerobic fitness (VO2peak) during three 30-min exercise bouts performed at incremental rates of metabolic heat production of 250 (Ex1), 325 (Ex2) and 400 (Ex3) W in the heat (40°C, 15% relative humidity). Exercise bouts were separated by 15 min of recovery. Since dry heat gain was similar between young and older females during exercise (p=0.52) and recovery (p=0.42), differences in whole-body heat loss were solely due to HE. Our results show that older females had a significantly lower HE at the end of Ex2 (young: 383±34 W; older: 343±39 W, p=0.04) and Ex3 (young: 437±36 W; older: 389±29 W, p=0.008), however no difference was measured at the end of Ex1 (p=0.24). Also, the magnitude of difference in the maximal level of HE achieved between the young and older females became greater with increasing heat loads (Ex1=10.2%, Ex2=11.6% and Ex3=12.4%). Furthermore, a significantly greater ∆Hb was measured for all heat loads for the older females (Ex1: 178±44 kJ; Ex2: 151±38 kJ; Ex3: 216±25 kJ, p=0.002) relative to the younger females (Ex1: 127±35 kJ; Ex2: 96±45 kJ; Ex3: 146±46 kJ). In contrast, no differences in HE or ∆Hb were observed during recovery (p>0.05). We show that older habitually active females have an impaired capacity to dissipate heat compared to young females during exercise-induced heat loads of ≥325 W when performed in the heat.
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Affiliation(s)
- Jill M. Stapleton
- Human and Environmental Physiology Research Unit, University of Ottawa, Ottawa, Ontario, Canada
| | - Martin P. Poirier
- Human and Environmental Physiology Research Unit, University of Ottawa, Ottawa, Ontario, Canada
| | - Andreas D. Flouris
- FAME Laboratory, Department of Exercise Science, University of Thessaly, Trikala, Greece
| | - Pierre Boulay
- Faculty of Physical Activity Sciences, University of Sherbrooke, Sherbrooke, Quebec, Canada
| | - Ronald J. Sigal
- Departments of Medicine, Cardiac Sciences and Community Health Sciences, Faculties of Medicine and Kinesiology, University of Calgary, Calgary, Alberta
| | - Janine Malcolm
- The Division of Endocrinology and Metabolism, Ottawa Hospital—Riverside Campus, 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
- * E-mail:
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46
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Stapleton JM, Poirier MP, Flouris AD, Boulay P, Sigal RJ, Malcolm J, Kenny GP. Aging impairs heat loss, but when does it matter? J Appl Physiol (1985) 2014; 118:299-309. [PMID: 25505030 DOI: 10.1152/japplphysiol.00722.2014] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Aging is associated with an attenuated physiological ability to dissipate heat. However, it remains unclear if age-related impairments in heat dissipation only occur above a certain level of heat stress and whether this response is altered by aerobic fitness. Therefore, we examined changes in whole body evaporative heat loss (HE) as determined using whole body direct calorimetry in young (n = 10; 21 ± 1 yr), untrained middle-aged (n = 10; 48 ± 5 yr), and older (n = 10; 65 ± 3 yr) males matched for body surface area. We also studied a group of trained middle-aged males (n = 10; 49 ± 5 yr) matched for body surface area with all groups and for aerobic fitness with the young group. Participants performed intermittent aerobic exercise (30-min exercise bouts separated by 15-min rest) in the heat (40°C and 15% relative humidity) at progressively greater fixed rates of heat production equal to 300 (Ex1), 400 (Ex2), and 500 (Ex3) W. Results showed that HE was significantly lower in middle-aged untrained (Ex2: 426 ± 34; and Ex3: 497 ± 17 W) and older (Ex2: 424 ± 38; and Ex3: 485 ± 44 W) compared with young (Ex2: 472 ± 42; and Ex3: 558 ± 51 W) and middle-aged trained (474 ± 21; Ex3: 552 ± 23 W) males at the end of Ex2 and Ex3 (P < 0.05). No differences among groups were observed during recovery. We conclude that impairments in HE in older and middle-aged untrained males occur at exercise-induced heat loads of ≥400 W when performed in a hot environment. These impairments in untrained middle-aged males can be minimized through regular aerobic exercise training.
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Affiliation(s)
- Jill M Stapleton
- Human and Environmental Physiology Research Unit, University of Ottawa, Ottawa, Canada
| | - Martin P Poirier
- Human and Environmental Physiology Research Unit, University of Ottawa, Ottawa, Canada
| | - Andreas D Flouris
- FAME Laboratory, Department of Exercise Science, University of Thessaly, Trikala, Greece
| | - Pierre Boulay
- Faculty of Physical Education and Sports, University of Sherbrooke, Sherbrooke, Canada
| | - Ronald J Sigal
- Departments of Medicine, Cardiac Sciences and Community Health Sciences, Faculties of Medicine and Kinesiology, University of Calgary, Calgary, Canada; and
| | - Janine Malcolm
- Division of Endocrinology and Metabolism, Ottawa Hospital-Riverside Campus, Ottawa, Canada
| | - Glen P Kenny
- Human and Environmental Physiology Research Unit, University of Ottawa, Ottawa, Canada;
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47
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Vionnet J, Calero-Romero I, Heim A, Rotaru C, Engelberger RP, Dischl B, Noël B, Liaudet L, Waeber B, Feihl F. No Major Impact of Skin Aging on the Response of Skin Blood Flow to a Submaximal Local Thermal Stimulus. Microcirculation 2014; 21:730-7. [DOI: 10.1111/micc.12154] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2013] [Revised: 06/20/2014] [Accepted: 06/25/2014] [Indexed: 12/23/2022]
Affiliation(s)
- Julien Vionnet
- Division de Physiopathologie Clinique; Centre Hospitalier Universitaire Vaudois and University of Lausanne; Lausanne Switzerland
| | - Irene Calero-Romero
- Division de Physiopathologie Clinique; Centre Hospitalier Universitaire Vaudois and University of Lausanne; Lausanne Switzerland
| | - Abigaël Heim
- Division de Physiopathologie Clinique; Centre Hospitalier Universitaire Vaudois and University of Lausanne; Lausanne Switzerland
| | - Corina Rotaru
- Division de Physiopathologie Clinique; Centre Hospitalier Universitaire Vaudois and University of Lausanne; Lausanne Switzerland
| | - Rolf Peter Engelberger
- Division de Physiopathologie Clinique; Centre Hospitalier Universitaire Vaudois and University of Lausanne; Lausanne Switzerland
| | - Benoît Dischl
- Division de Physiopathologie Clinique; Centre Hospitalier Universitaire Vaudois and University of Lausanne; Lausanne Switzerland
| | - Bernard Noël
- Service de Dermatologie et Vénéréologie; Centre Hospitalier Universitaire Vaudois and University of Lausanne; Lausanne Switzerland
| | - Lucas Liaudet
- Service de Médecine Intensive de l'Adulte; Centre Hospitalier Universitaire Vaudois and University of Lausanne; Lausanne Switzerland
| | - Bernard Waeber
- Division de Physiopathologie Clinique; Centre Hospitalier Universitaire Vaudois and University of Lausanne; Lausanne Switzerland
| | - François Feihl
- Division de Physiopathologie Clinique; Centre Hospitalier Universitaire Vaudois and University of Lausanne; Lausanne Switzerland
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48
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Sandberg K, Verbalis JG, Yosten GLC, Samson WK. Sex and basic science. A Title IX position. Am J Physiol Regul Integr Comp Physiol 2014; 307:R361-5. [PMID: 24944252 PMCID: PMC5504397 DOI: 10.1152/ajpregu.00251.2014] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Affiliation(s)
- Kathryn Sandberg
- Center for the Study of Sex Differences in Health, Aging and Disease and Department of Medicine, Georgetown University, Washington, DC; and
| | - Joseph G Verbalis
- Center for the Study of Sex Differences in Health, Aging and Disease and Department of Medicine, Georgetown University, Washington, DC; and
| | - Gina L C Yosten
- Department of Pharmacological and Physiological Science, Saint Louis University, Saint Louis, Missouri
| | - Willis K Samson
- Department of Pharmacological and Physiological Science, Saint Louis University, Saint Louis, Missouri
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Stapleton JM, Fujii N, McGinn R, McDonald K, Kenny GP. Age-related differences in postsynaptic increases in sweating and skin blood flow postexercise. Physiol Rep 2014; 2:e12078. [PMID: 25347861 PMCID: PMC4187563 DOI: 10.14814/phy2.12078] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2014] [Revised: 06/03/2014] [Accepted: 06/10/2014] [Indexed: 11/24/2022] Open
Abstract
The influence of peripheral factors on the control of heat loss responses (i.e., sweating and skin blood flow) in the postexercise period remains unknown in young and older adults. Therefore, in eight young (22 ± 3 years) and eight older (65 ± 3 years) males, we examined dose-dependent responses to the administration of acetylcholine (ACh) and methacholine (MCh) for sweating (ventilated capsule), as well as to ACh and sodium nitroprusside (SNP) for cutaneous vascular conductance (CVC, laser-Doppler flowmetry, % of max). In order to assess if peripheral factors are involved in the modulation of thermoeffector activity postexercise, pharmacological agonists were perfused via intradermal microdialysis on two separate days: (1) at rest ( DOSE: ) and (2) following a 30-min bout of exercise ( EX+: DOSE: ). No differences in sweat rate between the DOSE and Ex+DOSE conditions at either ACh or MCh were observed for the young (ACh: P = 0.992 and MCh: P = 0.710) or older (ACh: P = 0.775 and MCh: P = 0.738) adults. Similarly, CVC was not different between the DOSE and Ex+DOSE conditions for the young (ACh: P = 0.123 and SNP: P = 0.893) or older (ACh: P = 0.113 and SNP: P = 0.068) adults. Older adults had a lower sweating response for both the DOSE (ACh: P = 0.049 and MCh: P = 0.006) and Ex+DOSE (ACh: P = 0.050 and MCh: P = 0.029) conditions compared to their younger counterparts. These findings suggest that peripheral factors do not modulate postexercise sweating and skin blood flow in both young and older adults. Additionally, sweat gland function is impaired in older adults, albeit the impairments were not exacerbated during postexercise recovery.
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Affiliation(s)
- Jill M. Stapleton
- Human and Environmental Physiology Research Unit, University of Ottawa, Ottawa, Ontario, Canada
| | - Naoto Fujii
- Human and Environmental Physiology Research Unit, University of Ottawa, Ottawa, Ontario, Canada
| | - Ryan McGinn
- Human and Environmental Physiology Research Unit, University of Ottawa, Ottawa, Ontario, Canada
| | - Katherine McDonald
- 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
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Struhal W, Mišmaš A, Kirchmayr M, Bartl S, Javor A, Vosko MR, Ransmayr G. Onset of sweating depends on the type of reflex syncope. Auton Neurosci 2014; 184:73-6. [PMID: 25009131 DOI: 10.1016/j.autneu.2014.06.002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2014] [Revised: 05/28/2014] [Accepted: 06/07/2014] [Indexed: 11/26/2022]
Abstract
Reflex syncope is classified based on the efferent autonomic system as vasodepressant type, cardioinhibitory type and mixed type. We employed quantitative sweat testing to assess differences in sudomotor sympathetic activity in relation to the type of reflex syncope. In cardioinhibitory type sweating started in 7/9 patients after and in vasodepressor type in 11/12 patients before syncope. In mixed type sweating in 20 patients started before and in 10 after syncope. The onset of sweating correlated significantly with the onset of syncope symptoms. These results possibly reflect different onsets of emotional sweating.
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Affiliation(s)
- Walter Struhal
- Autonomic Unit, Department for Neurology and Psychiatry, General Hospital of the City of Linz, Krankenhausstr. 9, A-4020 Linz, Austria.
| | - Antonija Mišmaš
- Autonomic Unit, Department for Neurology and Psychiatry, General Hospital of the City of Linz, Krankenhausstr. 9, A-4020 Linz, Austria.
| | - Matthias Kirchmayr
- Autonomic Unit, Department for Neurology and Psychiatry, General Hospital of the City of Linz, Krankenhausstr. 9, A-4020 Linz, Austria.
| | - Sigrid Bartl
- Autonomic Unit, Department for Neurology and Psychiatry, General Hospital of the City of Linz, Krankenhausstr. 9, A-4020 Linz, Austria.
| | - Andrija Javor
- Autonomic Unit, Department for Neurology and Psychiatry, General Hospital of the City of Linz, Krankenhausstr. 9, A-4020 Linz, Austria.
| | - Milan R Vosko
- Autonomic Unit, Department for Neurology and Psychiatry, General Hospital of the City of Linz, Krankenhausstr. 9, A-4020 Linz, Austria.
| | - Gerhard Ransmayr
- Autonomic Unit, Department for Neurology and Psychiatry, General Hospital of the City of Linz, Krankenhausstr. 9, A-4020 Linz, Austria.
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