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Blum MF, Feng Y, Tuholske CP, Kim B, McAdams DeMarco MA, Astor BC, Grams ME. Extreme Humid-Heat Exposure and Mortality Among Patients Receiving Dialysis. Am J Kidney Dis 2024:S0272-6386(24)00808-4. [PMID: 38876272 DOI: 10.1053/j.ajkd.2024.04.010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2023] [Revised: 03/29/2024] [Accepted: 04/08/2024] [Indexed: 06/16/2024]
Abstract
RATIONALE & OBJECTIVE Exposure to extreme heat events has been linked to increased morbidity and mortality in the general population. Patients receiving maintenance dialysis may be vulnerable to greater risks from these events, but this is not well understood. We sought to characterize the association of extreme heat events and the risk of death among patients receiving dialysis in the United States. STUDY DESIGN Retrospective cohort study. SETTING & PARTICIPANTS Data from the United States Renal Data System were used to identify adults living in US urban settlements prone to extreme heat who initiated maintenance dialysis between 1997 and 2016. EXPOSURE An extreme heat event was defined as a time-updated heat index (a humid-heat metric) exceeding 40.6°C for ≥2 days or 46.1°C for ≥1 day. OUTCOME Death. ANALYTICAL APPROACH Cox proportional hazards regression to estimate the elevation in risk of death during a humid-heat event adjusted for age, sex, year of dialysis initiation, dialysis modality, poverty level, and climate region. Interactions between humid-heat and these same factors were explored. RESULTS Among 945,251 adults in 245 urban settlements, the mean age was 63 years and 44% were female. During a median follow-up of 3.6 years, 498,049 adults were exposed to at least one of 7,154 extreme humid-heat events, and 500,025 deaths occurred. In adjusted models, there was an increased risk of death (hazard ratio 1.18; 95% confidence interval 1.15-1.20) during extreme humid-heat exposure. Relative mortality risk was higher among patients living in the Southeast (P<0.001) compared with the Southwest. LIMITATIONS Possibility of exposure misclassification, did not account for land use and air pollution co-exposures. CONCLUSIONS This study suggests that patients receiving dialysis face an increased risk of death during extreme humid-heat exposure.
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Affiliation(s)
- Matthew F Blum
- Department of Medicine, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin.
| | - Yijing Feng
- Department of Epidemiology, Harvard T.H. Chan School of Public Health, Boston, Massachusetts
| | - Cascade P Tuholske
- Department of Earth Sciences, Montana State University, Bozeman, Montana; Geospatial Core Facility, Montana State University, Bozeman, Montana
| | - Byoungjun Kim
- Department of Surgery, New York University Grossman School of Medicine, New York, New York
| | - Mara A McAdams DeMarco
- Department of Surgery, New York University Grossman School of Medicine, New York, New York
| | - Brad C Astor
- Department of Medicine, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin; Department of Population Health Sciences, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin
| | - Morgan E Grams
- Department of Medicine, New York University Grossman School of Medicine, New York, New York
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Shaban M, Amer FGM, Shaban MM. The impact of nursing sustainable prevention program on heat strain among agricultural elderly workers in the context of climate change. Geriatr Nurs 2024; 58:215-224. [PMID: 38838403 DOI: 10.1016/j.gerinurse.2024.05.021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2024] [Revised: 05/13/2024] [Accepted: 05/22/2024] [Indexed: 06/07/2024]
Abstract
BACKGROUND This study assesses a geriatric nursing-led sustainable heat prevention program for elderly agricultural workers. It targets those aged 60 and above, addressing the heightened risk of heat strain in the era of climate change. METHODS A community-based quasi-experimental design involved 120 elderly agricultural workers, divided into intervention and control groups. The program, spanning three months, included education on hydration, rest, protective clothing, and recognition of heat-related illnesses. RESULTS The intervention led by geriatric nursing professionals showed significant improvements in heat strain metrics. The Heat Strain Score Index (HSSI) and the Observational-Perceptual Heat Strain Risk Assessment (OPHSRA) Index indicated increased safety levels and reduced risk categories among participants. CONCLUSIONS The study demonstrates the effectiveness of a geriatric nursing-led, tailored prevention program in reducing heat strain among elderly agricultural workers. It highlights the crucial role of nursing in adapting healthcare practices to the challenges posed by climate change. TRIAL REGISTRATION ClinicalTrials.gov, ID NCT06192069 retrospectively registered.
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Goulet N, Tetzlaff EJ, McCormick JJ, King KE, Janetos KMT, Sigal RJ, Boulay P, Kenny GP. Greater hyperthermia in men with type 2 diabetes does not lead to higher serum levels of cellular stress biomarkers following exercise-heat stress. Appl Physiol Nutr Metab 2024; 49:874-879. [PMID: 38507777 DOI: 10.1139/apnm-2023-0599] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/22/2024]
Abstract
Type 2 diabetes (T2D) is associated with worsening age-related impairments in heat loss, causing higher core temperature during exercise. We evaluated whether these thermoregulatory impairments occur with altered serum protein responses to heat stress by measuring cytoprotection, inflammation, and tissue damage biomarkers in middle-aged-to-older men (50-74 years) with (n = 16) and without (n = 14) T2D following exercise in 40°C. There were no changes in irisin, klotho, HSP70, sCD14, TNF-α, and IL-6, whereas NGAL (+539 pg/mL, p = 0.002) and iFABP (+250 pg/mL, p < 0.001) increased similarly across groups. These similar response patterns occurred despite elevated core temperature in individuals with T2D, suggesting greater heat vulnerability.
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Affiliation(s)
- Nicholas Goulet
- Human and Environmental Physiology Research Unit, School of Human Kinetics, Faculty of Health Sciences, University of Ottawa, Ottawa, ON, Canada
- Behavioural and Metabolic Research Unit, School of Human Kinetics, Faculty of Health Sciences, University of Ottawa, Ottawa, ON, Canada
| | - Emily J Tetzlaff
- Human and Environmental Physiology Research Unit, School of Human Kinetics, Faculty of Health Sciences, University of Ottawa, Ottawa, ON, Canada
| | - James J McCormick
- Human and Environmental Physiology Research Unit, School of Human Kinetics, Faculty of Health Sciences, University of Ottawa, Ottawa, ON, Canada
| | - Kelli E King
- Human and Environmental Physiology Research Unit, School of Human Kinetics, Faculty of Health Sciences, University of Ottawa, Ottawa, ON, Canada
| | - Kristina-Marie T Janetos
- Human and Environmental Physiology Research Unit, School of Human Kinetics, Faculty of Health Sciences, University of Ottawa, Ottawa, ON, Canada
| | - Ronald J Sigal
- Human and Environmental Physiology Research Unit, School of Human Kinetics, Faculty of Health Sciences, University of Ottawa, Ottawa, ON, Canada
- Departments of Medicine, Cardiac Sciences, and Community Health Sciences, Cumming School of Medicine, Faculties of Medicine and Kinesiology, 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
| | - Glen P Kenny
- Human and Environmental Physiology Research Unit, School of Human Kinetics, Faculty of Health Sciences, University of Ottawa, Ottawa, ON, Canada
- Clinical Epidemiology Program, Ottawa Hospital Research Institute, Ottawa, ON, Canada
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O'Connor FK, Meade RD, Notley SR, Ioannou LG, Flouris AD, Kenny GP. Agreement between measured and self-reported physiological strain in males and females during simulated occupational heat stress. Am J Ind Med 2024; 67:466-473. [PMID: 38493300 DOI: 10.1002/ajim.23580] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2023] [Revised: 01/26/2024] [Accepted: 02/23/2024] [Indexed: 03/18/2024]
Abstract
RATIONALE Monitoring physiological strain is recommended to safeguard workers during heat exposure, but is logistically challenging. The perceptual strain index (PeSI) is a subjective estimate thought to reflect the physiological strain index (PSI) that requires no physiological monitoring. However, sex is known to influence perceptions of heat stress, potentially limiting the utility of the PeSI. OBJECTIVES The objective of this study was to assess whether sex modifies the relationship between PeSI and PSI. METHODS Thirty-four adults (15 females) walked on a treadmill (moderate intensity; ~200 W/m2) for 180 min or until termination (volitional fatigue, rectal temperature ≥39.5°C) in 16°C, 24°C, 28°C, and 32°C wet-bulb globe temperatures. Rectal temperature and heart rate were recorded to calculate PSI (0-10 scale). Rating of perceived exertion and thermal sensation were recorded to calculate PeSI (0-10 scale). Relationships between PSI and PeSI were evaluated via linear mixed models. Mean bias (95% limits of agreement [LoA]) between PSI and PeSI was assessed via Bland-Altman analysis. Mean absolute error between measures was calculated by summing absolute errors between the PeSI and the PSI and dividing by the sample size. FINDINGS PSI increased with PeSI (p < 0.01) but the slope of this relation was not different between males and females (p = 0.83). Mean bias between PSI and PeSI was small (-0.4 points), but the 95% LoA (-3.5 to 2.7 points) and mean absolute error were wide (1.3 points). IMPACT Our findings indicate that sex does not appreciably impact the agreement between the PeSI and PSI during simulated occupational heat stress. The PeSI is not a suitable surrogate for the PSI in either male or female workers.
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Affiliation(s)
- Fergus K O'Connor
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, Ontario, Canada
| | - Robert D Meade
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, Ontario, Canada
| | - Sean R Notley
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, Ontario, Canada
| | - Leonidas G Ioannou
- Department of Automatics, Biocybernetics and Robotics, Jožef Stefan Institute, Ljubljana, Slovenia
| | - Andreas D Flouris
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, Ontario, Canada
- FAME Laboratory, Department of Physical Education and Sport Science, University of Thessaly, Karies, Trikala, Greece
| | - Glen P Kenny
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, Ontario, Canada
- Clinical Epidemiology Program, Ottawa Hospital Research Institute, Ottawa, Ontario, Canada
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De Barros JA, Macartney MJ, Notley SR, Meade RD, Kenny GP. The utility of heart rate and heart rate variability to identify limits of tolerance to moderate-intensity work in the heat: a secondary analysis. Appl Physiol Nutr Metab 2024; 49:539-546. [PMID: 38170965 DOI: 10.1139/apnm-2023-0466] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2024]
Abstract
We investigated the utility of heart rate (HR) and heart rate variability (HRV) for identifying individuals who may terminate work early due to excessive heat strain. Forty-eight men and women (median = 36 years; Q1 = 20 years; Q3 = 54 years) attempted 180 min of moderate-intensity work at a fixed metabolic rate (∼200 W/m2; ∼3.5 METs) in a hot environment (wet-bulb globe temperature: 32 °C). Receiver operating characteristics (ROC) curves were used to identify the ability of indices of HR (absolute HR, percentage of maximum HR, percentage of HR reserve) and HRV (root-mean-square of successive differences (RMSSD), high-frequency power, and detrended fluctuation analysis component alpha 1 (DFA α1)) to discriminate between participants who completed the 180 min work bout or terminated prematurely. Participants who terminated work prematurely (n = 26) exhibited higher HR and percentage of HR measures, as well as reduced RMSSD and DFA α1 after the first hour of work compared to participants who completed the bout. The discriminative utility of HR and HRV indices was strongest within the first hour of work, with percentage of HR reserve demonstrating excellent discriminative power (ROC area under curve (AUC) of 0.8). Stratifying participants by age and sex improved ROC AUC point estimates for most indices, particularly in female participants. The study provides preliminary evidence supporting the use of noninvasive cardiac monitoring for predicting work tolerance in healthy individuals exposed to occupational heat stress. HR and percentage of HR reserve were suggested to discriminate work termination most effectively. Further investigations are warranted to explore the influence of individual factors and refine the discriminative thresholds for early identification of excessive occupational heat strain.
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Affiliation(s)
- Jordan A De Barros
- School of Graduate Medicine, University of Wollongong, Wollongong, NSW, Australia
| | - Michael J Macartney
- School of Graduate Medicine, University of Wollongong, Wollongong, NSW, Australia
| | - Sean R Notley
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, ON, Canada
- Department of Defence, Defence Science and Technology Group, Melbourne, VIC 3207, Australia
| | - Robert D Meade
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, ON, Canada
| | - Glen P Kenny
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, ON, Canada
- Clinical Epidemiology Program, Ottawa Hospital Research Institute, Ottawa, ON, Canada
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Lee BJ, Flood TR, Galan-Lopez N, McCormick JJ, King KE, Fujii N, Kenny GP. Changes in surrogate markers of intestinal epithelial injury and microbial translocation in young and older men during prolonged occupational heat stress in temperate and hot conditions. Eur J Appl Physiol 2024; 124:1049-1062. [PMID: 37815618 DOI: 10.1007/s00421-023-05329-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2023] [Accepted: 09/16/2023] [Indexed: 10/11/2023]
Abstract
PURPOSE Exertional heat stress can cause damage to the intestinal epithelium and disrupt gastrointestinal barrier integrity, leading to microbial translocation (MT) linked to the development of heat stroke. This study aimed to assess age-related differences in markers of intestinal epithelial injury and MT following non-heat stress and high-heat stress exercise in healthy young and older men. METHODS Markers of intestinal epithelial injury (intestinal fatty acid-binding protein-'IFABP') and MT (soluble cluster of differentiation 14-'sCD14'; and lipopolysaccharide-binding protein-'LBP') were assessed in healthy young (18-30 y, n = 13) and older (50-70 y) men (n = 12). Blood samples were collected before, after 180 min of moderate-intensity (metabolic rate: 200 W/m2) walking and following 60 min recovery in either a non-heat stress [temperate: 21.9 °C, 35% relative humidity (RH)] or high-heat stress (hot: 41.4 °C, 35% RH) environment. RESULTS There were no differences in IFABP and sCD14 between the young and older groups in the temperate condition, while LBP was greater in the older group (+ 0.66 ug/mL; + 0.08 to + 1.24 ug/mL). In the hot condition, the older group experienced greater increases in IFABP compared to the young group (+ 712 pg/mL/hr; + 269 to + 1154 pg/mL/hr). However, there were no clear between-group differences for sCD14 (+ 0.24 ug/mL/hr, - 0.22 to + 0.70 ug/mL/hr) or LBP (+ 0.86 ug/mL/hr, - 0.73 to + 2.46 ug/mL/hr). CONCLUSION While older men may experience greater intestinal epithelial injury following exercise in the heat; this did not lead to a greater magnitude of microbial translocation relative to their younger counterparts.
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Affiliation(s)
- Ben J Lee
- Occupational and Environmental Physiology Group, Centre for Sport, Exercise, and Life Sciences, Coventry University, Coventry, UK
| | - Tessa R Flood
- Institute of Sport, Manchester Metropolitan University, Manchester, UK
| | - Natalia Galan-Lopez
- Occupational and Environmental Physiology Group, Centre for Sport, Exercise, and Life Sciences, Coventry University, Coventry, UK
- School of Sport, Exercise and Health Sciences, Loughborough University, Loughborough, UK
| | - James J McCormick
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, 125 University Ave., Room 367, Montpetit Hall, Ottawa, ON, K1N 6N5, Canada
| | - Kelli E King
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, 125 University Ave., Room 367, Montpetit Hall, Ottawa, ON, K1N 6N5, Canada
| | - Naoto Fujii
- Health and Sport Sciences, University of Tsukuba, Tsukuba, Japan
| | - Glen P Kenny
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, 125 University Ave., Room 367, Montpetit Hall, Ottawa, ON, K1N 6N5, Canada.
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Bachraty JP, Qiao J, Powers ES, Vandermark LW, Pryor JL, Pryor RR. Plateau in Core Temperature during Shorter but Not Longer Work/Rest Cycles in Heat. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2024; 21:371. [PMID: 38541370 PMCID: PMC10970706 DOI: 10.3390/ijerph21030371] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/29/2024] [Revised: 03/12/2024] [Accepted: 03/18/2024] [Indexed: 04/09/2024]
Abstract
This study compared physiological responses to two work/rest cycles of a 2:1 work-to-rest ratio in a hot environment. In a randomized crossover design, fourteen participants completed 120 min of walking and rest in the heat (36.3 ± 0.6 °C, 30.2 ± 4.0% relative humidity). Work/rest cycles were (1) 40 min work/20 min rest [40/20], or (2) 20 min work/10 min rest [20/10], both completing identical work. Core temperature (Tc), skin temperature (Tsk), heart rate (HR), nude body mass, and perception of work were collected. Comparisons were made between trials at equal durations of work using three-way mixed model ANOVA. Tc plateaued in [20/10] during the second hour of work (p = 0.93), while Tc increased in [40/20] (p < 0.01). There was no difference in maximum Tc ([40/20]: 38.08 ± 0.35 °C, [20/10]: 37.99 ± 0.27 °C, p = 0.22) or end-of-work Tsk ([40/20]: 36.1 ± 0.8 °C, [20/10]: 36.0 ± 0.7 °C, p = 0.45). End-of-work HR was greater in [40/20] (145 ± 25 b·min-1) compared to [20/10] (141 ± 27 b·min-1, p = 0.04). Shorter work/rest cycles caused a plateau in Tc while longer work/rest cycles resulted in a continued increase in Tc throughout the work, indicating that either work structure could be used during shorter work tasks, while work greater than 2 h in duration may benefit from shorter work/rest cycles to mitigate hyperthermia.
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Affiliation(s)
| | | | | | | | | | - Riana R. Pryor
- Center for Research and Education in Special Environments, Department of Exercise and Nutrition Sciences, University at Buffalo, Buffalo, NY 14214, USA (J.Q.); (E.S.P.)
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Bach AJE, Cunningham SJK, Morris NR, Xu Z, Rutherford S, Binnewies S, Meade RD. Experimental research in environmentally induced hyperthermic older persons: A systematic quantitative literature review mapping the available evidence. Temperature (Austin) 2024; 11:4-26. [PMID: 38567267 PMCID: PMC7615797 DOI: 10.1080/23328940.2023.2242062] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2023] [Accepted: 07/21/2023] [Indexed: 04/04/2024] Open
Abstract
The heat-related health burden is expected to persist and worsen in the coming years due to an aging global population and climate change. Defining the breadth and depth of our understanding of age-related changes in thermoregulation can identify underlying causes and strategies to protect vulnerable individuals from heat. We conducted the first systematic quantitative literature review to provide context to the historical experimental research of healthy older adults - compared to younger adults or unhealthy age matched cases - during exogenous heat strain, focusing on factors that influence thermoregulatory function (e.g. co-morbidities). We identified 4,455 articles, with 147 meeting eligibility criteria. Most studies were conducted in the US (39%), Canada (29%), or Japan (12%), with 71% of the 3,411 participants being male. About 71% of the studies compared younger and older adults, while 34% compared two groups of older adults with and without factors influencing thermoregulation. Key factors included age combined with another factor (23%), underlying biological mechanisms (18%), age independently (15%), influencing health conditions (15%), adaptation potential (12%), environmental conditions (9%), and therapeutic/pharmacological interventions (7%). Our results suggest that controlled experimental research should focus on the age-related changes in thermoregulation in the very old, females, those with overlooked chronic heat-sensitive health conditions (e.g. pulmonary, renal, mental disorders), the impact of multimorbidity, prolonged and cumulative effects of extreme heat, evidence-based policy of control measures (e.g. personal cooling strategies), pharmaceutical interactions, and interventions stimulating protective physiological adaptation. These controlled studies will inform the directions and use of limited resources in ecologically valid fieldwork studies.
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Affiliation(s)
- Aaron J. E. Bach
- School of Medicine and Dentistry, Griffith University, Gold Coast, QLD, Australia
- Cities Research Institute, Griffith University, Gold Coast, QLD, Australia
| | - Sarah J. K. Cunningham
- School of Medicine and Dentistry, Griffith University, Gold Coast, QLD, Australia
- Cities Research Institute, Griffith University, Gold Coast, QLD, Australia
| | - Norman R. Morris
- School of Health Sciences and Social Work, Griffith University, Gold Coast, QLD, Australia
- Metro North Hospital and Health Service, The Prince Charles Hospital. Allied Health Research Collaborative, Brisbane, QLD, Australia
- Menzies Health Institute Queensland, Griffith University, Gold Coast, QLD, Australia
| | - Zhiwei Xu
- School of Medicine and Dentistry, Griffith University, Gold Coast, QLD, Australia
- Cities Research Institute, Griffith University, Gold Coast, QLD, Australia
| | - Shannon Rutherford
- School of Medicine and Dentistry, Griffith University, Gold Coast, QLD, Australia
- Cities Research Institute, Griffith University, Gold Coast, QLD, Australia
| | - Sebastian Binnewies
- School of Information and Communication Technology, Griffith University, Gold Coast, QLD, Australia
| | - Robert D. Meade
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, ON, Canada
- Harvard T.H. Chan School of Public Health, Harvard University, Boston, MA, USA
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Carrillo AE, Akerman AP, Notley SR, Herry CL, Seely AJE, Ruzicka M, Boulay P, Kenny GP. Cardiac autonomic modulation in individuals with controlled and uncomplicated hypertension during exercise-heat stress. Appl Physiol Nutr Metab 2023; 48:863-869. [PMID: 37556854 DOI: 10.1139/apnm-2023-0173] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/11/2023]
Abstract
TAKE-HOME MESSAGE During short bouts of light-to-vigorous exercise in the heat, controlled and uncomplicated hypertension did not significantly modulate HRV in physically active individuals. These findings can be used to refine guidance on use of exercise for hypertension management in the heat.
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Affiliation(s)
- Andres E Carrillo
- Department of Exercise Science, School of Health Sciences, Chatham University, Pittsburgh, PA 15232, USA
| | - Ashley P Akerman
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, ON, Canada
| | - Sean R Notley
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, ON, Canada
| | - Christophe L Herry
- Clinical Epidemiology Program, Ottawa Hospital Research Institute, Ottawa, ON, Canada
| | - Andrew J E Seely
- Clinical Epidemiology Program, Ottawa Hospital Research Institute, Ottawa, ON, Canada
- Division of Thoracic Surgery and Department of Critical Care Medicine, Ottawa Hospital, Ottawa, ON, Canada
| | - Marcel Ruzicka
- Hypertension Program, Division of Nephrology, University of Ottawa, Ottawa, ON, Canada
| | - Pierre Boulay
- Faculté des sciences de l'activité physique, Université de Sherbrooke, Sherbrooke, QC, 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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Wee J, Tan XR, Gunther SH, Ihsan M, Leow MKS, Tan DSY, Eriksson JG, Lee JKW. Effects of Medications on Heat Loss Capacity in Chronic Disease Patients: Health Implications Amidst Global Warming. Pharmacol Rev 2023; 75:1140-1166. [PMID: 37328294 DOI: 10.1124/pharmrev.122.000782] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2022] [Revised: 04/20/2023] [Accepted: 05/31/2023] [Indexed: 06/18/2023] Open
Abstract
Pharmacological agents used to treat or manage diseases can modify the level of heat strain experienced by chronically ill and elderly patients via different mechanistic pathways. Human thermoregulation is a crucial homeostatic process that maintains body temperature within a narrow range during heat stress through dry (i.e., increasing skin blood flow) and evaporative (i.e., sweating) heat loss, as well as active inhibition of thermogenesis, which is crucial to avoid overheating. Medications can independently and synergistically interact with aging and chronic disease to alter homeostatic responses to rising body temperature during heat stress. This review focuses on the physiologic changes, with specific emphasis on thermolytic processes, associated with medication use during heat stress. The review begins by providing readers with a background of the global chronic disease burden. Human thermoregulation and aging effects are then summarized to give an understanding of the unique physiologic changes faced by older adults. The effects of common chronic diseases on temperature regulation are outlined in the main sections. Physiologic impacts of common medications used to treat these diseases are reviewed in detail, with emphasis on the mechanisms by which these medications alter thermolysis during heat stress. The review concludes by providing perspectives on the need to understand the effects of medication use in hot environments, as well as a summary table of all clinical considerations and research needs of the medications included in this review. SIGNIFICANCE STATEMENT: Long-term medications modulate thermoregulatory function, resulting in excess physiological strain and predisposing patients to adverse health outcomes during prolonged exposures to extreme heat during rest and physical work (e.g., exercise). Understanding the medication-specific mechanisms of altered thermoregulation has importance in both clinical and research settings, paving the way for work toward refining current medication prescription recommendations and formulating mitigation strategies for adverse drug effects in the heat in chronically ill patients.
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Affiliation(s)
- Jericho Wee
- Human Potential Translational Research Programme, Yong Loo Lin School of Medicine (J.W., X.R.T., S.H.G., M.I., M.K.S.L., J.G.E., J.K.W.L.), Department of Pharmacy, Faculty of Science, (D.S.-Y.T), Department of Physiology, Yong Loo Lin School of Medicine (J.K.W.L.), Heat Resilience and Performance Centre, Yong Loo Lin School of Medicine (J.K.W.L.), National University of Singapore, Singapore; Health and Social Sciences, Singapore Institute of Technology, Singapore (X.R.T.); Campus for Research Excellence and Technological Enterprise, Singapore (S.H.G., J.K.W.L.); Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore (M.K.S.L.); Duke-National University of Singapore Medical School, Singapore (M.K.S.L.); Department of Endocrinology, Division of Medicine, Tan Tock Seng Hospital, Singapore (M.K.S.L.); Singapore Institute for Clinical Sciences, Agency for Science, Technology and Research, Singapore (M.K.S.L., J.G.E.); Folkhalsan Research Center, Helsinki, Finland (J.G.E.); Department of General Practice and Primary Health Care, University of Helsinki, and Helsinki University Hospital, University of Helsinki, Helsinki, Finland (J.G.E.); and Department of Obstetrics & Gynaecology, Yong Loo Lin School of Medicine, National University of Singapore and National University Health System, Singapore (J.G.E.)
| | - Xiang Ren Tan
- Human Potential Translational Research Programme, Yong Loo Lin School of Medicine (J.W., X.R.T., S.H.G., M.I., M.K.S.L., J.G.E., J.K.W.L.), Department of Pharmacy, Faculty of Science, (D.S.-Y.T), Department of Physiology, Yong Loo Lin School of Medicine (J.K.W.L.), Heat Resilience and Performance Centre, Yong Loo Lin School of Medicine (J.K.W.L.), National University of Singapore, Singapore; Health and Social Sciences, Singapore Institute of Technology, Singapore (X.R.T.); Campus for Research Excellence and Technological Enterprise, Singapore (S.H.G., J.K.W.L.); Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore (M.K.S.L.); Duke-National University of Singapore Medical School, Singapore (M.K.S.L.); Department of Endocrinology, Division of Medicine, Tan Tock Seng Hospital, Singapore (M.K.S.L.); Singapore Institute for Clinical Sciences, Agency for Science, Technology and Research, Singapore (M.K.S.L., J.G.E.); Folkhalsan Research Center, Helsinki, Finland (J.G.E.); Department of General Practice and Primary Health Care, University of Helsinki, and Helsinki University Hospital, University of Helsinki, Helsinki, Finland (J.G.E.); and Department of Obstetrics & Gynaecology, Yong Loo Lin School of Medicine, National University of Singapore and National University Health System, Singapore (J.G.E.)
| | - Samuel H Gunther
- Human Potential Translational Research Programme, Yong Loo Lin School of Medicine (J.W., X.R.T., S.H.G., M.I., M.K.S.L., J.G.E., J.K.W.L.), Department of Pharmacy, Faculty of Science, (D.S.-Y.T), Department of Physiology, Yong Loo Lin School of Medicine (J.K.W.L.), Heat Resilience and Performance Centre, Yong Loo Lin School of Medicine (J.K.W.L.), National University of Singapore, Singapore; Health and Social Sciences, Singapore Institute of Technology, Singapore (X.R.T.); Campus for Research Excellence and Technological Enterprise, Singapore (S.H.G., J.K.W.L.); Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore (M.K.S.L.); Duke-National University of Singapore Medical School, Singapore (M.K.S.L.); Department of Endocrinology, Division of Medicine, Tan Tock Seng Hospital, Singapore (M.K.S.L.); Singapore Institute for Clinical Sciences, Agency for Science, Technology and Research, Singapore (M.K.S.L., J.G.E.); Folkhalsan Research Center, Helsinki, Finland (J.G.E.); Department of General Practice and Primary Health Care, University of Helsinki, and Helsinki University Hospital, University of Helsinki, Helsinki, Finland (J.G.E.); and Department of Obstetrics & Gynaecology, Yong Loo Lin School of Medicine, National University of Singapore and National University Health System, Singapore (J.G.E.)
| | - Mohammed Ihsan
- Human Potential Translational Research Programme, Yong Loo Lin School of Medicine (J.W., X.R.T., S.H.G., M.I., M.K.S.L., J.G.E., J.K.W.L.), Department of Pharmacy, Faculty of Science, (D.S.-Y.T), Department of Physiology, Yong Loo Lin School of Medicine (J.K.W.L.), Heat Resilience and Performance Centre, Yong Loo Lin School of Medicine (J.K.W.L.), National University of Singapore, Singapore; Health and Social Sciences, Singapore Institute of Technology, Singapore (X.R.T.); Campus for Research Excellence and Technological Enterprise, Singapore (S.H.G., J.K.W.L.); Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore (M.K.S.L.); Duke-National University of Singapore Medical School, Singapore (M.K.S.L.); Department of Endocrinology, Division of Medicine, Tan Tock Seng Hospital, Singapore (M.K.S.L.); Singapore Institute for Clinical Sciences, Agency for Science, Technology and Research, Singapore (M.K.S.L., J.G.E.); Folkhalsan Research Center, Helsinki, Finland (J.G.E.); Department of General Practice and Primary Health Care, University of Helsinki, and Helsinki University Hospital, University of Helsinki, Helsinki, Finland (J.G.E.); and Department of Obstetrics & Gynaecology, Yong Loo Lin School of Medicine, National University of Singapore and National University Health System, Singapore (J.G.E.)
| | - Melvin Khee Shing Leow
- Human Potential Translational Research Programme, Yong Loo Lin School of Medicine (J.W., X.R.T., S.H.G., M.I., M.K.S.L., J.G.E., J.K.W.L.), Department of Pharmacy, Faculty of Science, (D.S.-Y.T), Department of Physiology, Yong Loo Lin School of Medicine (J.K.W.L.), Heat Resilience and Performance Centre, Yong Loo Lin School of Medicine (J.K.W.L.), National University of Singapore, Singapore; Health and Social Sciences, Singapore Institute of Technology, Singapore (X.R.T.); Campus for Research Excellence and Technological Enterprise, Singapore (S.H.G., J.K.W.L.); Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore (M.K.S.L.); Duke-National University of Singapore Medical School, Singapore (M.K.S.L.); Department of Endocrinology, Division of Medicine, Tan Tock Seng Hospital, Singapore (M.K.S.L.); Singapore Institute for Clinical Sciences, Agency for Science, Technology and Research, Singapore (M.K.S.L., J.G.E.); Folkhalsan Research Center, Helsinki, Finland (J.G.E.); Department of General Practice and Primary Health Care, University of Helsinki, and Helsinki University Hospital, University of Helsinki, Helsinki, Finland (J.G.E.); and Department of Obstetrics & Gynaecology, Yong Loo Lin School of Medicine, National University of Singapore and National University Health System, Singapore (J.G.E.)
| | - Doreen Su-Yin Tan
- Human Potential Translational Research Programme, Yong Loo Lin School of Medicine (J.W., X.R.T., S.H.G., M.I., M.K.S.L., J.G.E., J.K.W.L.), Department of Pharmacy, Faculty of Science, (D.S.-Y.T), Department of Physiology, Yong Loo Lin School of Medicine (J.K.W.L.), Heat Resilience and Performance Centre, Yong Loo Lin School of Medicine (J.K.W.L.), National University of Singapore, Singapore; Health and Social Sciences, Singapore Institute of Technology, Singapore (X.R.T.); Campus for Research Excellence and Technological Enterprise, Singapore (S.H.G., J.K.W.L.); Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore (M.K.S.L.); Duke-National University of Singapore Medical School, Singapore (M.K.S.L.); Department of Endocrinology, Division of Medicine, Tan Tock Seng Hospital, Singapore (M.K.S.L.); Singapore Institute for Clinical Sciences, Agency for Science, Technology and Research, Singapore (M.K.S.L., J.G.E.); Folkhalsan Research Center, Helsinki, Finland (J.G.E.); Department of General Practice and Primary Health Care, University of Helsinki, and Helsinki University Hospital, University of Helsinki, Helsinki, Finland (J.G.E.); and Department of Obstetrics & Gynaecology, Yong Loo Lin School of Medicine, National University of Singapore and National University Health System, Singapore (J.G.E.)
| | - Johan G Eriksson
- Human Potential Translational Research Programme, Yong Loo Lin School of Medicine (J.W., X.R.T., S.H.G., M.I., M.K.S.L., J.G.E., J.K.W.L.), Department of Pharmacy, Faculty of Science, (D.S.-Y.T), Department of Physiology, Yong Loo Lin School of Medicine (J.K.W.L.), Heat Resilience and Performance Centre, Yong Loo Lin School of Medicine (J.K.W.L.), National University of Singapore, Singapore; Health and Social Sciences, Singapore Institute of Technology, Singapore (X.R.T.); Campus for Research Excellence and Technological Enterprise, Singapore (S.H.G., J.K.W.L.); Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore (M.K.S.L.); Duke-National University of Singapore Medical School, Singapore (M.K.S.L.); Department of Endocrinology, Division of Medicine, Tan Tock Seng Hospital, Singapore (M.K.S.L.); Singapore Institute for Clinical Sciences, Agency for Science, Technology and Research, Singapore (M.K.S.L., J.G.E.); Folkhalsan Research Center, Helsinki, Finland (J.G.E.); Department of General Practice and Primary Health Care, University of Helsinki, and Helsinki University Hospital, University of Helsinki, Helsinki, Finland (J.G.E.); and Department of Obstetrics & Gynaecology, Yong Loo Lin School of Medicine, National University of Singapore and National University Health System, Singapore (J.G.E.)
| | - Jason Kai Wei Lee
- Human Potential Translational Research Programme, Yong Loo Lin School of Medicine (J.W., X.R.T., S.H.G., M.I., M.K.S.L., J.G.E., J.K.W.L.), Department of Pharmacy, Faculty of Science, (D.S.-Y.T), Department of Physiology, Yong Loo Lin School of Medicine (J.K.W.L.), Heat Resilience and Performance Centre, Yong Loo Lin School of Medicine (J.K.W.L.), National University of Singapore, Singapore; Health and Social Sciences, Singapore Institute of Technology, Singapore (X.R.T.); Campus for Research Excellence and Technological Enterprise, Singapore (S.H.G., J.K.W.L.); Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore (M.K.S.L.); Duke-National University of Singapore Medical School, Singapore (M.K.S.L.); Department of Endocrinology, Division of Medicine, Tan Tock Seng Hospital, Singapore (M.K.S.L.); Singapore Institute for Clinical Sciences, Agency for Science, Technology and Research, Singapore (M.K.S.L., J.G.E.); Folkhalsan Research Center, Helsinki, Finland (J.G.E.); Department of General Practice and Primary Health Care, University of Helsinki, and Helsinki University Hospital, University of Helsinki, Helsinki, Finland (J.G.E.); and Department of Obstetrics & Gynaecology, Yong Loo Lin School of Medicine, National University of Singapore and National University Health System, Singapore (J.G.E.)
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11
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Morrissey MC, Langan SP, Brewer GJ, Struder JF, Navarro JS, Nye MN, Casa DJ. Limitations associated with thermoregulation and cardiovascular research assessing laborers performing work in the heat. Am J Ind Med 2023; 66:267-280. [PMID: 36748881 DOI: 10.1002/ajim.23462] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2022] [Revised: 12/13/2022] [Accepted: 01/10/2023] [Indexed: 02/08/2023]
Abstract
PURPOSE To quantify the current literature and limitations associated with research examining thermoregulatory and cardiovascular strain in laborers working in the heat. METHODS PubMed, SCOPUS, and SPORTDiscus were searched for terms related to the cardiovascular system, heat stress, and physical work. Qualifying studies included adult participants (18-65 years old), a labor-intensive environment or exercise protocol simulating a labor environment, a minimum duration of 120 min of physical work, and environmental heat stress (ambient temperature ≥26.0°C and ≥30% relative humidity). Studies included at least one of the following outcomes: pre- and peak physical work, core temperature, heart rate (HR), systolic blood pressure, diastolic blood pressure, HR variability, and rate pressure product. RESULTS Twenty-one out of 1559 potential studies qualified from our search. There was a total of 598 participants (mean = 28 ± 50 participants per study, range = 4-238 participants per study), which included 51 females (8.5%) and 547 males (91.5%). Of the participants, 3.8% had cardiovascular risk factors (diabetes: n = 10; hypertension: n = 13) and 96.2% were characterized as "healthy". Fifty-seven percent of the included studies were performed in a laboratory setting. CONCLUSIONS Studies were predominantly in men (91.5%), laboratory settings (57%), and "healthy" individuals (96.2%). To advance equity in protection against occupational heat stress and better inform future heat safety recommendations to protect all workers, future studies must focus on addressing these limitations. Employers, supervisors, and other safety stakeholders should consider these limitations while implementing current heat safety recommendations.
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Affiliation(s)
| | - Sean P Langan
- Korey Stringer Institute, University of Connecticut, Storrs, Connecticut, USA
| | - Gabrielle J Brewer
- Korey Stringer Institute, University of Connecticut, Storrs, Connecticut, USA
| | - Jeb F Struder
- Korey Stringer Institute, University of Connecticut, Storrs, Connecticut, USA
| | - John S Navarro
- Korey Stringer Institute, University of Connecticut, Storrs, Connecticut, USA
| | - Megan N Nye
- Korey Stringer Institute, University of Connecticut, Storrs, Connecticut, USA
| | - Douglas J Casa
- Korey Stringer Institute, University of Connecticut, Storrs, Connecticut, USA
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12
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Serum klotho concentrations in older men with hypertension or type 2 diabetes during prolonged exercise in temperate and hot conditions. Eur J Appl Physiol 2023:10.1007/s00421-023-05171-x. [PMID: 36929016 DOI: 10.1007/s00421-023-05171-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2022] [Accepted: 02/27/2023] [Indexed: 03/18/2023]
Abstract
PURPOSE Klotho is a cytoprotective protein that increases during acute physiological stressors (e.g., exercise heat stress), although age-related declines in klotho may underlie cellular vulnerability to heat stress. The present study aimed to compare serum klotho in healthy older men and men with type 2 diabetes (T2D) or hypertension (HTN) during prolonged exercise in temperate or hot conditions. METHODS We evaluated serum klotho in 12 healthy older men (mean [SD]; 59 years [4]), 10 men with HTN (60 years [4]), and 9 men with T2D (60 years [5]) before and after 180 min of moderate-intensity (fixed metabolic rate of 200 W/m2; ~ 3.4 METs) exercise and 60 min of recovery in temperate (wet-bulb globe temperature (WBGT) 16 °C) and hot (WBGT 32 °C) environments. Core temperature (rectal), heart rate (HR), and heart rate reserve (HRR) were measured continuously while klotho was measured at the end of baseline, exercise, and recovery. RESULTS Total exercise duration was reduced during the hot condition in older men with HTN and T2D than healthy older men (both p ≤ 0.049), despite similar core temperatures, HR, and HRR. Klotho was higher than rest following exercise in the heat in healthy older men (+ 191 pg/mL [189]; p < 0.001) and responses were greater (p = 0.036) than men with HTN (+ 118 pg/mL [49]; p = 0.030), although klotho did not increase in men with T2D (+ 4 pg/mL [71]; p ≥ 0.638). CONCLUSION Given klotho's role in cytoprotection, older men with HTN and especially T2D may be at increased cellular vulnerability to prolonged exercise or physically demanding exercise in the heat.
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Goulet N, McCormick JJ, King KE, Notley SR, Goldfield GS, Fujii N, Amano T, Kenny GP. Elevations in serum brain-derived neurotrophic factor following occupational heat stress are not influenced by age or common chronic disease. Temperature (Austin) 2023; 10:454-464. [PMID: 38130657 PMCID: PMC10732602 DOI: 10.1080/23328940.2023.2176107] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2022] [Accepted: 01/30/2023] [Indexed: 02/09/2023] Open
Abstract
With global warming, workers are increasingly exposed to strenuous occupations in hot environments. Given age- and disease-associated declines in thermoregulatory function, older workers are at an elevated risk of developing heat-related injuries. Brain-derived neurotrophic factor (BDNF) is thought to confer neuroprotection during acute exercise, however, the influence of environmental heat on BDNF responses during prolonged work remains unclear. Therefore, we evaluated serum BDNF concentrations before and after 180 min of moderate-intensity treadmill walking (200 W/m2) and after 60 min of post-exercise recovery in temperate (wet-bulb globe temperature (WBGT) 16°C) and hot (WBGT 32°C) environments in 13 healthy young men (mean [SD; 22 [3] years), 12 healthy older men (59 [4] years), 10 men with hypertension (HTN) (60 [4] years), and 9 men with type 2 diabetes (T2D) (60 [5] years). In the temperate condition, all but one participant (1 HTN) completed the 180 min of exercise. While exercise tolerance in the heat was lower in older men with HTN (117 min [45]) and T2D (123 min [42]) compared to healthy older men (159 min [31]) (both p ≤ 0.049), similar end-exercise rectal temperatures (38.9°C [0.4]) were observed across groups, paralleled by similar elevations in serum BDNF across groups at end-exercise (+1106 pg/mL [203]) and end-recovery (+938 pg/mL [146]; all p ≤ 0.01) in the heat. No changes in serum BDNF were observed in the temperate condition. Our findings indicate similar BDNF responses in individuals with HTN or T2D compared to their healthy counterparts, despite exhibiting reduced tolerance to heat.
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Affiliation(s)
- Nicholas Goulet
- Human and Environmental Physiology Research Unit, School of Human Kinetics, Faculty of Health Sciences, University of Ottawa, Ontario, Canada, Canada
- Behavioural and Metabolic Research Unit, School of Human Kinetics, Faculty of Health Sciences, University of Ottawa, Ontario, Canada, Canada
| | - James J. McCormick
- Human and Environmental Physiology Research Unit, School of Human Kinetics, Faculty of Health Sciences, University of Ottawa, Ontario, Canada, Canada
| | - Kelli E. King
- Human and Environmental Physiology Research Unit, School of Human Kinetics, Faculty of Health Sciences, University of Ottawa, Ontario, Canada, Canada
| | - Sean R. Notley
- Human and Environmental Physiology Research Unit, School of Human Kinetics, Faculty of Health Sciences, University of Ottawa, Ontario, Canada, Canada
| | - Gary S. Goldfield
- Healthy Active Living and Obesity Research Group, Children’s Hospital of Eastern Ontario Research Institute, Ontario, Canada, Canada
| | - Naoto Fujii
- Faculty of Health and Sport Sciences, University of Tsukuba, Tsukuba, Japan
| | - Tatsuro Amano
- Laboratory for Exercise and Environmental Physiology, Faculty of Education, Niigata University, Niigata, Japan
| | - Glen P. Kenny
- Human and Environmental Physiology Research Unit, School of Human Kinetics, Faculty of Health Sciences, University of Ottawa, Ontario, Canada, Canada
- Clinical Epidemiology Program, Ottawa Hospital Research Institute, Ontario, Canada, Canada
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Tokizawa K. Effects of wetted inner clothing on thermal strain in young and older males while wearing ventilation garments. Front Physiol 2023; 14:1122504. [PMID: 36909241 PMCID: PMC9992724 DOI: 10.3389/fphys.2023.1122504] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2022] [Accepted: 02/13/2023] [Indexed: 02/24/2023] Open
Abstract
The present study examined the effect of wearing a water-soaked inner t-shirt with a ventilation garment on thermal and cardiovascular strain in eight young (26 ± 4 years) and eight older (67 ± 3 years) men undertaking moderate-intensity work (metabolic rate: 200-230 W m-2) in a hot environment (37°C, 50% RH, 2.8 kPa). While intermittent walking in hot conditions for 60 min, as a control (CON), the subject wore a dry inner t-shirt (long-sleeved) without fanning of a ventilation jacket (single-layered cotton, 0.21 clo). On separate days, under a fanned ventilation jacket, the subject wore a dry inner t-shirt (DRY) or an inner t-shirt soaked with 350 mL of tap water (WET). In the young group, increases in rectal temperature from pre-exercise baseline in the WET trial (0.7°C ± 0.2°C) were lower than in the CON (1.3°C ± 0.3°C) and DRY (1.1°C ± 0.2°C) (both p < 0.05) trials during exercise in hot conditions. In the older group, the increases were also attenuated in WET (0.7°C ± 0.4°C) compared with CON (1.3°C ± 0.4°C) and DRY (1.1°C ± 0.4°C) (both p < 0.05) without differences between age groups. Heart rate and whole-body sweat loss were lowest in the WET, followed by DRY, and then CON conditions in both groups (all p < 0.05). These findings demonstrate that wearing a water-soaked inner t-shirt while using a ventilation garment is an effective and practical cooling strategy to mitigate thermal and cardiovascular strains in young and older individuals during moderate-intensity work in hot conditions.
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Affiliation(s)
- Ken Tokizawa
- National Institute of Occupational Safety and Health, Tokyo, Japan
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15
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The serum irisin response to prolonged physical activity in temperate and hot environments in older men with hypertension or type 2 diabetes. J Therm Biol 2022; 110:103344. [PMID: 36462879 DOI: 10.1016/j.jtherbio.2022.103344] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2022] [Revised: 08/29/2022] [Accepted: 09/20/2022] [Indexed: 12/14/2022]
Abstract
Current labor demographics are changing, with the number of older adults increasingly engaged in physically demanding occupations expected to continually rise, which are often performed in the heat. Given an age-related decline in whole-body heat loss, older adults are at an elevated risk of developing heat injuries that may be exacerbated by hypertension (HTN) and type 2 diabetes (T2D). Elevated irisin production may play a role in mitigating the excess oxidative stress and acute inflammation associated with physically demanding work in the heat. However, the effects of HTN and T2D on this response remain unclear. Therefore, we evaluated serum irisin before and after 3-h of moderate intensity exercise (metabolic rate: 200 W/m2) and at the end of 60-min of post-exercise recovery in a temperate (wet-bulb globe temperature (WBGT) 16 °C) and high-heat stress (WBGT 32 °C) environment in 12 healthy older men (mean ± SD; 59 ± 4 years), 10 men with HTN (60 ± 4 years), and 9 men with T2D (60 ± 5 years). Core temperature (Tco) was measured continuously. In the heat, total exercise duration was significantly lower in older men with HTN and T2D (both, p ≤ 0.049). Despite Tco not being different between groups, Tco was higher in the hot compared to the temperate condition for all groups (p < 0.001). Similarly, serum irisin concentrations did not differ between groups under either condition but were elevated relative to the temperate condition during post-exercise and end-recovery in the heat (+93.9 pg/mL SEM 26 and + 70.5 pg/mL SEM 38 respectively; both p ≤ 0.014). Thus, our findings indicate similar irisin responses in HTN and T2D compared to healthy, age-matched controls, despite reduced exercise tolerance during prolonged exercise in the heat. Therefore, older workers with HTN and T2D may exhibit greater cellular stress during prolonged exercise in the heat, underlying greater vulnerability to heat-induced cellular injury.
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Cramer MN, Gagnon D, Laitano O, Crandall CG. Human temperature regulation under heat stress in health, disease, and injury. Physiol Rev 2022; 102:1907-1989. [PMID: 35679471 PMCID: PMC9394784 DOI: 10.1152/physrev.00047.2021] [Citation(s) in RCA: 57] [Impact Index Per Article: 28.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2021] [Revised: 05/10/2022] [Accepted: 05/28/2022] [Indexed: 12/30/2022] Open
Abstract
The human body constantly exchanges heat with the environment. Temperature regulation is a homeostatic feedback control system that ensures deep body temperature is maintained within narrow limits despite wide variations in environmental conditions and activity-related elevations in metabolic heat production. Extensive research has been performed to study the physiological regulation of deep body temperature. This review focuses on healthy and disordered human temperature regulation during heat stress. Central to this discussion is the notion that various morphological features, intrinsic factors, diseases, and injuries independently and interactively influence deep body temperature during exercise and/or exposure to hot ambient temperatures. The first sections review fundamental aspects of the human heat stress response, including the biophysical principles governing heat balance and the autonomic control of heat loss thermoeffectors. Next, we discuss the effects of different intrinsic factors (morphology, heat adaptation, biological sex, and age), diseases (neurological, cardiovascular, metabolic, and genetic), and injuries (spinal cord injury, deep burns, and heat stroke), with emphasis on the mechanisms by which these factors enhance or disturb the regulation of deep body temperature during heat stress. We conclude with key unanswered questions in this field of research.
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Affiliation(s)
- Matthew N Cramer
- Defence Research and Development Canada-Toronto Research Centre, Toronto, Ontario, Canada
| | - Daniel Gagnon
- Montreal Heart Institute and School of Kinesiology and Exercise Science, Université de Montréal, Montréal, Quebec, Canada
| | - Orlando Laitano
- Department of Applied Physiology and Kinesiology, University of Florida, Gainesville, Florida
| | - Craig G Crandall
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas and University of Texas Southwestern Medical Center, Dallas, Texas
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Koch M, Matzke I, Huhn S, Gunga HC, Maggioni MA, Munga S, Obor D, Sié A, Boudo V, Bunker A, Dambach P, Bärnighausen T, Barteit S. Wearables for Measuring Health Effects of Climate Change–Induced Weather Extremes: Scoping Review. JMIR Mhealth Uhealth 2022; 10:e39532. [PMID: 36083624 PMCID: PMC9508665 DOI: 10.2196/39532] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2022] [Revised: 07/20/2022] [Accepted: 07/26/2022] [Indexed: 11/13/2022] Open
Abstract
Background
Although climate change is one of the biggest global health threats, individual-level and short-term data on direct exposure and health impacts are still scarce. Wearable electronic devices (wearables) present a potential solution to this research gap. Wearables have become widely accepted in various areas of health research for ecological momentary assessment, and some studies have used wearables in the field of climate change and health. However, these studies vary in study design, demographics, and outcome variables, and existing research has not been mapped.
Objective
In this review, we aimed to map existing research on wearables used to detect direct health impacts and individual exposure during climate change–induced weather extremes, such as heat waves or wildfires.
Methods
We conducted a scoping review according to the PRISMA-ScR (Preferred Reporting Items for Systematic Reviews and Meta-Analyses extension for Scoping Reviews) framework and systematically searched 6 databases (PubMed [MEDLINE], IEEE Xplore, CINAHL [EBSCOhost], WoS, Scopus, Ovid [MEDLINE], and Google Scholar). The search yielded 1871 results. Abstracts and full texts were screened by 2 reviewers (MK and IM) independently using the inclusion and exclusion criteria. The inclusion criteria comprised studies published since 2010 that used off-the-shelf wearables that were neither invasive nor obtrusive to the user in the setting of climate change–related weather extremes. Data were charted using a structured form, and the study outcomes were narratively synthesized.
Results
The review included 55,284 study participants using wearables in 53 studies. Most studies were conducted in upper–middle-income and high-income countries (50/53, 94%) in urban environments (25/53, 47%) or in a climatic chamber (19/53, 36%) and assessed the health effects of heat exposure (52/53, 98%). The majority reported adverse health effects of heat exposure on sleep, physical activity, and heart rate. The remaining studies assessed occupational heat stress or compared individual- and area-level heat exposure. In total, 26% (14/53) of studies determined that all examined wearables were valid and reliable for measuring health parameters during heat exposure when compared with standard methods.
Conclusions
Wearables have been used successfully in large-scale research to measure the health implications of climate change–related weather extremes. More research is needed in low-income countries and vulnerable populations with pre-existing conditions. In addition, further research could focus on the health impacts of other climate change–related conditions and the effectiveness of adaptation measures at the individual level to such weather extremes.
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Affiliation(s)
- Mara Koch
- Heidelberg Institute of Global Health, Faculty of Medicine and University Hospital, Heidelberg University, Heidelberg, Germany
| | - Ina Matzke
- Heidelberg Institute of Global Health, Faculty of Medicine and University Hospital, Heidelberg University, Heidelberg, Germany
| | - Sophie Huhn
- Heidelberg Institute of Global Health, Faculty of Medicine and University Hospital, Heidelberg University, Heidelberg, Germany
| | - Hanns-Christian Gunga
- Charité - Universitätsmedizin Berlin, Institute of Physiology, Center for Space Medicine and Extreme Environment Berlin, Berlin, Germany
| | - Martina Anna Maggioni
- Charité - Universitätsmedizin Berlin, Institute of Physiology, Center for Space Medicine and Extreme Environment Berlin, Berlin, Germany
- Department of Biomedical Sciences for Health, Università degli Studi di Milano, Milan, Italy
| | | | - David Obor
- Kenya Medical Research Institute, Kisumu, Kenya
| | - Ali Sié
- Heidelberg Institute of Global Health, Faculty of Medicine and University Hospital, Heidelberg University, Heidelberg, Germany
- Centre de Recherche en Santé, Nouna, Burkina Faso
| | | | - Aditi Bunker
- Heidelberg Institute of Global Health, Faculty of Medicine and University Hospital, Heidelberg University, Heidelberg, Germany
- Center for Climate, Health, and the Global Environment, Harvard T.H. Chan School of Public Health, Boston, MA, United States
| | - Peter Dambach
- Heidelberg Institute of Global Health, Faculty of Medicine and University Hospital, Heidelberg University, Heidelberg, Germany
| | - Till Bärnighausen
- Heidelberg Institute of Global Health, Faculty of Medicine and University Hospital, Heidelberg University, Heidelberg, Germany
- Department of Global Health and Population, Harvard T.H. Chan School of Public Health, Boston, MA, United States
- Africa Health Research Institute, KwaZulu-Natal, South Africa
| | - Sandra Barteit
- Heidelberg Institute of Global Health, Faculty of Medicine and University Hospital, Heidelberg University, Heidelberg, Germany
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18
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Fujii N, Meade RD, Schmidt MD, King KE, Boulay P, Ruzicka M, Amano T, Kenny GP. The effect of acute intradermal administration of ascorbate on heat loss responses in older adults with uncomplicated controlled hypertension. Exp Physiol 2022; 107:834-843. [PMID: 35596934 DOI: 10.1113/ep090422] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2022] [Accepted: 05/16/2022] [Indexed: 11/08/2022]
Abstract
NEW FINDINGS What is the central question of this study? Does acute intradermal administration of the antioxidant ascorbate augment local forearm cutaneous vasodilatation and sweating via nitric oxide synthase (NOS)-dependent mechanisms during exercise-heat stress in older adults with uncomplicated controlled hypertension? What is the main finding and its importance? Relative to control site, ascorbate had no effect on forearm cutaneous vascular conductance (CVC) and sweat rate, although CVC was reduced with NOS-inhibition in older adults with hypertension. We showed that acute local administration of ascorbate to forearm skin does not modulate heat loss responses during exercise-heat stress in older adults with hypertension. ABSTRACT Nitric oxide synthase (NOS) contributes to the heat loss responses of cutaneous vasodilatation and sweating during exercise. However, the contribution of NOS may be attenuated in individuals with uncomplicated, controlled hypertension due to elevated oxidative stress, which can reduce NO bioavailability. We evaluated the hypothesis that the acute local intradermal administration of the antioxidant ascorbate would enhance cutaneous vasodilatation and sweating via NOS-dependent mechanisms during an exercise-heat stress in adults with hypertension. Habitually active adults who were normotensive (n = 14, 7 females, 62 ± 4 years) or had uncomplicated, controlled hypertension (n = 13, 6 females, 62 ± 5 years) performed 30-min of moderate-intensity (50% of their pre-determine peak oxygen uptake) semi-recumbent cycling in the heat (35°C, 20% relative humidity). Cutaneous vascular conductance and sweat rate were assessed at four forearm skin sites continuously perfused with either: 1) lactated Ringer (Control), 2) 10 mM antioxidant ascorbate, 3) 10 mM L-NAME, a non-selective NOS inhibitor, or 4) a combination of ascorbate and L-NAME. Relative to Control, no effect of ascorbate was observed on cutaneous vascular conductance or sweating in either group (P = 0.619). However, L-NAME reduced cutaneous vascular conductance relative to Control in both groups (P ≤ 0.038). No effect of any treatment on sweating was observed (P ≥ 0.306). Thus, acute local administration of ascorbate to forearm skin does not enhance the activation of heat loss responses of cutaneous vasodilatation and sweating in older adults, and those with hypertension during an exercise-heat stress (236/250 words) This article is protected by copyright. All rights reserved.
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Affiliation(s)
- Naoto Fujii
- Faculty of Health and Sport Sciences, University of Tsukuba, Tsukuba City, Japan
| | - Robert D Meade
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, Canada
| | - Madison D Schmidt
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, Canada
| | - Kelli E King
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, Canada
| | - Pierre Boulay
- Faculty of Physical Activity Sciences, University of Sherbrooke, Sherbrooke, Canada
| | - Marcel Ruzicka
- Division of Nephrology, Department of Medicine, University of Ottawa, Ottawa, Canada
| | - Tatsuro Amano
- Laboratory for Exercise and Environmental Physiology, Faculty of Education, Niigata University, Niigata, Japan
| | - Glen P Kenny
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, Canada.,Clinical Epidemiology Program, Ottawa Hospital Research Institute, Ottawa, Canada
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19
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Ioannou LG, Foster J, Morris NB, Piil JF, Havenith G, Mekjavic IB, Kenny GP, Nybo L, Flouris AD. Occupational heat strain in outdoor workers: A comprehensive review and meta-analysis. Temperature (Austin) 2022; 9:67-102. [PMID: 35655665 PMCID: PMC9154804 DOI: 10.1080/23328940.2022.2030634] [Citation(s) in RCA: 26] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2021] [Revised: 01/11/2022] [Accepted: 01/13/2022] [Indexed: 12/29/2022] Open
Abstract
The present comprehensive review (i) summarizes the current knowledge on the impacts of occupational heat stress on outdoor workers, (ii) provides a historical background on this issue, (iii) presents a meta-analysis of published data, (iv) explores inter-individual and intra-individual factors, (v) discusses the available heat mitigation strategies, (vi) estimates physical work capacity, labour productivity, and metabolic rate for the year 2030, and (vii) provides an overview of existing policy and legal frameworks on occupational heat exposure. Meta-analytic findings from 38 field studies that involved monitoring 2,409 outdoor workers across 41 jobs in 21 countries suggest that occupational heat stress increases the core (r = 0.44) and skin (r = 0.44) temperatures, as well as the heart rate (r = 0.38) and urine specific gravity (r = 0.13) of outdoor workers (all p < 0.05). Moreover, it diminishes the capacity of outdoor workers for manual labour (r = -0.82; p < 0.001) and is responsible for more than two thirds of the reduction in their metabolic rate. Importantly, our analysis shows that physical work capacity is projected to be highly affected by the ongoing anthropogenic global warming. Nevertheless, the metabolic rate and, therefore, labour productivity are projected to remain at levels higher than the workers' physical work capacity, indicating that people will continue to work more intensely than they should to meet their financial obligations for food and shelter. In this respect, complementary measures targeting self-pacing, hydration, work-rest regimes, ventilated garments, and mechanization can be adopted to protect outdoor workers.
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Affiliation(s)
- Leonidas G. Ioannou
- FAME Laboratory, Department of Physical Education and Sport Science, University of Thessaly, Trikala, Greece
| | - Josh Foster
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas and University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Nathan B. Morris
- Department of Human Physiology & Nutrition, University of Colorado, Springs, Colorado, USA
| | - Jacob F. Piil
- Department of Nutrition, Exercise and Sports, August Krogh Building, University of Copenhagen, Copenhagen, Denmark
| | - George Havenith
- Environmental Ergonomics Research Centre, Loughborough Design School, Loughborough University, Loughborough, UK
| | - Igor B. Mekjavic
- Department of Automation, Biocybernetics and Robotics, Jozef Stefan Institute, Ljubljana, Slovenia
| | - Glen P. Kenny
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, Ontario, Canada
| | - Lars Nybo
- Department of Nutrition, Exercise and Sports, August Krogh Building, University of Copenhagen, Copenhagen, Denmark
| | - Andreas D. Flouris
- FAME Laboratory, Department of Physical Education and Sport Science, University of Thessaly, Trikala, Greece
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, Ontario, Canada
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20
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De Barros JA, Macartney MJ, Peoples GE, Notley SR, Herry CL, Kenny GP. Effects of sex and wet-bulb globe temperature on heart rate variability during prolonged moderate-intensity exercise: A secondary analysis. Appl Physiol Nutr Metab 2022; 47:725-736. [PMID: 35290752 DOI: 10.1139/apnm-2022-0004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Sex-differences in heart rate (HR) and heart rate variability (HRV), a surrogate of cardiac autonomic modulation, are evident during rest and exercise in young healthy individuals. However, it remains unclear whether sex impacts HRV during prolonged exercise at differing levels of environmental heat stress. Therefore, we completed a secondary analysis upon the effects of sex and wet-bulb globe temperature (WBGT) on HR and HRV during prolonged exercise. To achieve this, HR and HRV were assessed in non-endurance-trained and non-heat-acclimatized healthy men (n=19) and women (n=15) aged 18-45 years during 180-min treadmill walking at a moderate metabolic rate (200 W/m2: equivalent to ~35% peak aerobic power) in 16, 24, 28, and 32°C WBGT. In the final 5 min prior to exercise termination, HR was observed to be higher in women relative to men in all but the 32°C WBGT. Although no sex-differences were observed for the HRV metric of root-mean-square of successive differences, high frequency power was higher in women relative to men across WBGT conditions. These findings indicate that, in healthy non-heat-acclimatized individuals, women respond to prolonged exercise-heat stress with a greater increase in HR despite cardiac vagal autonomic modulation remaining equal or increasing compared to men. Novelty points. • Prior to exercise termination, females respond with a greater increase in heart rate under all wet-bulb globe temperatures except the hottest (32°C). • Sex influenced heart rate variability (HRV) metrics during all wet-bulb globe temperatures, but results were mixed. • Further characterisation of HRV sex differences remains an important area of research.
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Affiliation(s)
| | - Michael J Macartney
- University of Wollongong, 8691, Wollongong, Australia.,University of New South Wales, 7800, Sydney, New South Wales, Australia;
| | - Gregory E Peoples
- University of Wollongong, 8691, School of Medicine, Wollongong, New South Wales, Australia;
| | - Sean R Notley
- University of Ottawa, Faculty of Health Sciences, Ottawa, Ontario, Canada;
| | - Christophe L Herry
- Ottawa Hospital Research Institute, 10055, Clinical Epidemiology, Ottawa, Ontario, Canada;
| | - Glen P Kenny
- University of Ottawa, 6363, Ottawa, Canada, K1N 6N5.,Ottawa Hospital Research Institute, 10055, Ottawa, Canada, K1Y 4E9;
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21
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Notley SR, Akerman AP, Friesen BJ, Poirier MP, McCourt E, Flouris A, Kenny GP. Heat tolerance and the validity of occupational heat exposure limits in women during moderate-intensity work. Appl Physiol Nutr Metab 2022; 47:711-724. [PMID: 35259026 DOI: 10.1139/apnm-2022-0003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
To mitigate excessive rises in core temperature (>1°C) in non heat-acclimatized workers, the American Conference of Governmental Industrial Hygienists (ACGIH) provide heat stress limits (Action Limit Values; ALV), defined by the wet-bulb globe temperature (WBGT) and a worker's metabolic rate. However, since these limits are based on data from men, their suitability for women remains unclear. We therefore assessed core temperature and heart rate in men (n=19; body surface area-to-mass ratio: 250 (SD 17) cm2/kg) and women (n=15; body surface area-to-mass ratio: 268 (SD 24) cm2/kg) aged 18-45 years during 180-min walking at a moderate metabolic rate (200 W/m2) in WBGTs below (16 and 24°C) and above (28 and 32°C) ACGIH ALV. Sex did not significantly influence (i) rises in core temperature, irrespective of WBGT, (ii) the proportion of participants with rises in core temperature >1°C in environments below ACGIH limits, and (iii) work duration before rises in core temperature exceeded 1°C or volitional termination in environments above ACGIH limits. Although further studies are needed, these findings indicate that for the purpose of mitigating rises in core temperature exceeding recommended limits (>1°C), ACGIH guidelines have comparable effectiveness in non heat-acclimatized men and women when working at a moderate metabolic rate. Novelty points • Sex did not appreciably influence thermal strain nor the proportion of participants with core temperatures exceeding recommended limits. • Sex did not significantly influence tolerance to uncompensable heat stress • Despite originating from data obtained in only men, current occupational heat stress guidance offered comparable effectiveness in men and women.
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Affiliation(s)
| | | | - Brian J Friesen
- University of Ottawa, Human Kinetics, Ottawa, Ontario, Canada;
| | - Martin P Poirier
- University of Ottawa, School of Human Kinetics, Faculty of Health Sciences, Ottawa, Ontario, Canada;
| | | | - Andreas Flouris
- FAME Laboratory, Institute of Human Performance and Rehabilitation, Centre for Research and Technology Thessaly, Trikala, Thessaly, Greece.,Department of Research and Technology Development, Biomnic Ltd., Trikala, Thessaly, Greece;
| | - Glen P Kenny
- University of Ottawa, 6363, Ottawa, Canada, K1N 6N5.,Ottawa Hospital Research Institute, 10055, Ottawa, Canada, K1Y 4E9;
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22
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King KE, McCormick JJ, Notley SR, Fujii N, Kenny GP. Serum klotho concentrations in young and older men during prolonged exercise in temperate and hot conditions. Curr Aging Sci 2022; 15:180-185. [PMID: 35249521 DOI: 10.2174/1874609815666220304200939] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2021] [Revised: 01/07/2022] [Accepted: 12/14/2022] [Indexed: 11/22/2022]
Abstract
BACKGROUND The protein klotho protects cellular function during various physiological stressors, such as exercise, however it is unknown how the age-related decline in klotho production affects responses during exercise, especially in the heat. OBJECTIVE Our objective was to determine the effect of exercise in temperate and hot environmental conditions on serum klotho concentrations in young and older men. METHODS 12 young (mean ± SD: 22 ± 3 years) and 12 older (59 ± 4 years) men performed 180 minutes of moderate-intensity treadmill walking (metabolic rate: 200 W/m2) in a temperate [wet-bulb globe temperature (WBGT) 16°C, achieved with 21.9°C, 35% relative humidity (RH)] and hot (WBGT 32°C, achieved with 41.4°C, 35% RH) environment. Serum klotho was assessed before and after exercise, as well as 60-min post-exercise recovery in the respective environments. RESULTS Absolute klotho concentrations were greater in young versus older men during all measured time points in the temperate (p = 0.032), but not the hot condition (p = 0.064). In the hot condition, the change in serum klotho from baseline was significantly higher after exercise in the heat (mean ± SEM: +251 ± 73 pg/mL) than the temperate (+75 ± 57 pg/mL) environment in both groups (p = 0.026). However, this elevation was not maintained during recovery. CONCLUSION We showed that prolonged exercise in a temperate environment does not elicit a klotho response in either group. In contrast, despite lower resting klotho levels, the older men showed a similar exercise-induced increase in serum klotho response as their younger counterparts.
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Affiliation(s)
- Kelli E King
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, Canada
| | - James J McCormick
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, Canada
| | - Sean R Notley
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, Canada
| | - Naoto Fujii
- Faculty of Health and Sport Sciences, University of Tsukuba, Japan
| | - Glen P Kenny
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, Canada
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23
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The impact of age, type 2 diabetes and hypertension on heart rate variability during rest and exercise at increasing levels of heat stress. Eur J Appl Physiol 2022; 122:1249-1259. [PMID: 35239038 DOI: 10.1007/s00421-022-04916-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2021] [Accepted: 02/16/2022] [Indexed: 11/03/2022]
Abstract
PURPOSE In older adults with type 2 diabetes (T2D) and hypertension (HTN), cardiac autonomic modulation is markedly attenuated during exercise-heat stress. However, the extent to which this impairment is evident under increasing levels of heat stress remains unknown. METHODS We examined heart rate variability (HRV), a surrogate of cardiac autonomic modulation, during incremental exercise-heat stress exposures in young (20-30 years) and middle-aged-to-older individuals (50-70 years) without and with T2D and HTN. Thirteen young and healthy (Young, n = 13) and 37 older men without (Older, n = 14) and with HTN (n = 13) or T2D (n = 10) performed 180-min treadmill walking at a fixed metabolic rate (~ 200 W/m2; ~ 3.5 METs) in a differing wet-bulb globe temperature (WBGT; 16 °C, 24 °C, 28 °C, and 32 °C). Electrocardiogram (ECG) and core temperature measurements were recorded throughout. Data were analysed using 5-min averaged epochs following 60-min exercise, which represented the last common timepoint across groups and conditions. RESULTS Ageing did not significantly reduce HRV during increasing exercise-heat stress (all p > 0.050). However, T2D and HTN modified HRV during exercise-heat stress such that Detrended Fluctuation Analysis (DFA) α1 (p = 0.012) and the cardiac sympathetic index (p = 0.037) were decreased compared to Older in all except the warmest WBGT condition (32 °C). CONCLUSION Our unique observations indicate that, relative to their younger counterparts, HRV in healthy older individuals is not perturbed during exercise heat-stress. However, relative to their age-matched healthy counterparts, HRV is reduced during exercise-heat stress in individuals with age-associated chronic conditions, indicative of cardiac autonomic dysfunction.
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24
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Exercise in the heat induces similar elevations in serum irisin in young and older men despite lower resting irisin concentrations in older adults. J Therm Biol 2022; 104:103189. [DOI: 10.1016/j.jtherbio.2022.103189] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2021] [Revised: 12/13/2021] [Accepted: 01/13/2022] [Indexed: 01/02/2023]
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25
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Notley SR, Akerman AP, Kenny GP. Initial stay times for uncompensable occupational heat stress in young and older men: a preliminary assessment. Appl Physiol Nutr Metab 2021; 47:1-4. [PMID: 34710340 DOI: 10.1139/apnm-2021-0550] [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
During uncompensable occupational heat stress, heat-mitigation controls are required to prevent core temperature exceeding recommended limits (≥38 °C). However, the initial stay time before employing controls remained unknown. We estimated these times for moderate-intensity work at 26, 28, 30, and 32 °C wet-bulb globe temperatures (WBGT) in 50 young (18-30 years) and older (50-70 years), non-heat acclimatized men. Initial stay time was 111 min at 26 °C WBGT and declined exponentially to 44 min at 32 °C WBGT. Novelty: We provide estimates of the moderate-intensity work duration before heat-mitigation is required in wet-bulb globe temperatures between 26-32 °C for young and older, non-heat acclimatized men.
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Affiliation(s)
- Sean R Notley
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, Ontario, Canada
| | - Ashley P Akerman
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, Ontario, Canada
| | - Glen P Kenny
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, Ontario, Canada
- Clinical Epidemiology Program, Ottawa Hospital Research Institute, Ottawa, Ontario, Canada
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