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Kirby NV, Meade RD, Poirier MP, Notley SR, Sigal RJ, Boulay P, Kenny GP. Exercise intensity- and body region-specific differences in sweating in middle-aged-to-older men with and without type 2 diabetes. Am J Physiol Regul Integr Comp Physiol 2024. [PMID: 38682241 DOI: 10.1152/ajpregu.00037.2024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2024] [Accepted: 04/20/2024] [Indexed: 05/01/2024]
Abstract
Type 2 diabetes is associated with reduced whole-body sweating during exercise-heat stress. However, it is unclear if this impairment is related to exercise intensity and whether it occurs uniformly across body regions. We evaluated whole-body (direct calorimetry) and local (ventilated-capsule technique; chest, back, forearm, thigh) sweat rates in physically active men with type 2 diabetes (T2D; aged 59 (7) years; V̇O2peak 32.3 (7.6) mL·kg-1·min-1; n=26; HbA1c 5.1-9.1%) and without diabetes (Control; aged 61 (5) years; V̇O2peak 37.5 (5.4) mL·kg-1·min-1; n=26) during light (~40%V̇O2peak), moderate (~50%V̇O2peak), and vigorous (~65%V̇O2peak) intensity exercise (elicited by fixing metabolic heat production at ~150, 200, 250 W·m-2, respectively) in 40°C, ~17% relative humidity. Whole-body sweating was ~11% (T2D-Control mean difference [95% confidence interval]: -37 [-63, -12] g·m-2·h-1) and ~13% (-50 [-76, -25] g·m-2·h-1) lower in the T2D compared to the Control group during moderate- and vigorous- (p≤0.001), but not light-intensity exercise (-21 [-47, 4] g·m-2·h-1; p=0.128). Consequently, the diabetes-related reductions in whole-body sweat rate were 2.3 [1.6, 3.1] times greater during vigorous relative to light exercise (p<0.001). Further, these diabetes-related impairments in local sweating were region-specific during vigorous-intensity exercise (group × region interaction: p=0.024), such that the diabetes-related reduction in local sweat rate at the trunk (chest, back) was 2.4 [1.2, 3.7] times greater than that at the limbs (thigh, arm). In summary, when assessed under hot, dry conditions, diabetes-related impairments in sweating are exercise intensity-dependent and greater at the trunk compared to the limbs.
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Affiliation(s)
- Nathalie V Kirby
- School of Human Kinetics, University of Ottawa, Ottawa, ON, Canada
| | - Robert D Meade
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, ON, Canada
| | - Martin P Poirier
- 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
| | - Ronald J Sigal
- Departments of Medicine, University of Calgary, Calgary, AB, Canada
| | - Pierre Boulay
- Faculty of Physical Activity Sciences, University of Sherbrooke, Sherbrooke, QC, Canada
| | - Glen P Kenny
- School of Human Kinetics, University of Ottawa, Ottawa, ON, Canada
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Poirier MP, Blacklock R, Cao M, Théoret D, Frei L, Gagnon P. Technical-tactical behavior analysis of general duty police officers during non-compliant suspect apprehensions: A novel approach to establish minimum force requirements. Work 2024; 77:1341-1357. [PMID: 38552129 DOI: 10.3233/wor-230307] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/06/2024] Open
Abstract
BACKGROUND While effective apprehensions of non-compliant suspects are central to public safety, the minimal force needed to transition a suspect from standing to the ground, vital for apprehension success, has not been established. OBJECTIVE To examine the technical-tactical behaviors of general duty police officers during simulated apprehensions and quantify the minimum force required to destabilize non-compliant suspects. METHODS Task simulations conducted with 91 officers were analyzed to identify common grappling movements, strikes, control tactics, and changes in body posture. A separate assessment of 55 male officers aimed to determine the minimum force required for destabilization in five body regions (wrist, forearm, shoulder, mid-chest, and mid-back). Data are presented as mean±standard deviation. RESULTS On average, apprehensions took 7.3±3.2 seconds. While all officers used grappling movements (100%) and the majority employed control tactics (75%), strikes were seldom used (4%). Apprehensions typically began with a two-handed pull (97%; Contact Phase), 55% then attempted an arm bar takedown, followed by a two-handed cross-body pull (68%; Transition/Control Phase), and a two-handed push to the ground (19%; Ground Phase). All officers began in the upright posture, with most shifting to squat (75%), kneel (58%), or bent (45%) postures to complete the apprehension. The minimum force required to disrupt balance differed across body regions (wrist: 54±12 kg; forearm: 49±12 kg; shoulder: 42±10 kg; mid-chest: 44±11 kg; mid-back: 30±7 kg, all P < 0.05), except between the shoulder and chest (P = 0.19). CONCLUSION These findings provide insights that can enhance the design and accuracy of future apprehension evaluations and inform the optimization of law enforcement physical employment standards.
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Affiliation(s)
- Martin P Poirier
- Human Performance Research and Development, Directorate of Fitness, Canadian Forces Morale and Welfare Services, Ottawa, ON, Canada
| | - Rachel Blacklock
- Human Performance Research and Development, Directorate of Fitness, Canadian Forces Morale and Welfare Services, Ottawa, ON, Canada
| | - Michael Cao
- Human Performance Research and Development, Directorate of Fitness, Canadian Forces Morale and Welfare Services, Ottawa, ON, Canada
| | - Daniel Théoret
- Human Performance Research and Development, Directorate of Fitness, Canadian Forces Morale and Welfare Services, Ottawa, ON, Canada
| | - Leslie Frei
- Royal Canadian Mounted Police, Ottawa, ON, Canada
| | - Patrick Gagnon
- Human Performance Research and Development, Directorate of Fitness, Canadian Forces Morale and Welfare Services, Ottawa, ON, Canada
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Kirby NV, Meade RD, Poirier MP, Sigal RJ, Boulay P, Kenny GP. Association between haemoglobin A 1c and whole-body heat loss during exercise-heat stress in physically active men with type 2 diabetes. Exp Physiol 2023; 108:338-343. [PMID: 36724895 PMCID: PMC10103889 DOI: 10.1113/ep090915] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2022] [Accepted: 11/30/2022] [Indexed: 02/03/2023]
Abstract
NEW FINDINGS What is the central question of this study? Is the impairment in heat dissipation during exercise observed in men with type 2 diabetes related to glycaemic control (indexed by glycated haemoglobin; haemoglobin A1c )? What is the main finding and its importance? No association was found between haemoglobin A1c (range: 5.1-9.1%) and whole-body heat loss in men with type 2 diabetes during exercise in the heat. However, individuals with elevated haemoglobin A1c exhibited higher body core temperature and heart rate responses. Thus, while haemoglobin A1c is not associated with heat loss per se, it may still have important implications for physiological strain during exercise. ABSTRACT Type 2 diabetes is associated with a reduced capacity to dissipate heat. It is unknown whether this impairment is related to glycaemic control (indexed by glycated haemoglobin; haemoglobin A1c ) is unknown. We evaluated the association between haemoglobin A1c and whole-body heat loss (via direct calorimetry), body core temperature, and heart rate in 26 physically active men with type 2 diabetes (43-73 years; HbA1c 5.1-9.1%) during exercise at increasing rates of metabolic heat production (∼150, 200, 250 W m-2 ) in the heat (40°C, ∼17% relative humidity). Haemoglobin A1c was not associated with whole-body heat loss (P = 0.617), nor the increase in core temperature from pre-exercise (P = 0.347). However, absolute core temperature and heart rate were elevated ∼0.2°C (P = 0.014) and ∼6 beats min-1 (P = 0.049), respectively, with every percentage point increase in haemoglobin A1c . Thus, while haemoglobin A1c does not appear to modify diabetes-related reductions in capacity for heat dissipation, it may still have important implications for physiological strain during exercise-heat stress.
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Affiliation(s)
- Nathalie V. Kirby
- 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 UniversityBostonMAUSA
| | - Martin P. Poirier
- Human and Environmental Physiology Research UnitSchool of Human KineticsUniversity of OttawaOttawaOntarioCanada
- Human Performance Research and DevelopmentCanadian Forces Morale and Welfare ServicesOttawaOntarioCanada
| | - Ronald J. Sigal
- Human and Environmental Physiology Research UnitSchool of Human KineticsUniversity of OttawaOttawaOntarioCanada
- Departments of MedicineCardiac Sciences, and Community Health SciencesCumming School of MedicineFaculties of Medicine and KinesiologyUniversity of CalgaryCalgaryAlbertaCanada
- Clinical Epidemiology ProgramOttawa Hospital Research InstituteOttawaOntarioCanada
| | - Pierre Boulay
- Faculty of Physical Activity SciencesUniversity of SherbrookeSherbrookeQuebecCanada
| | - Glen P. Kenny
- Human and Environmental Physiology Research UnitSchool of Human KineticsUniversity of OttawaOttawaOntarioCanada
- Clinical Epidemiology ProgramOttawa Hospital Research InstituteOttawaOntarioCanada
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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] [What about the content of this article? (0)] [Affiliation(s)] [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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Chassé É, Théoret D, Poirier MP, Lalonde F. Physiological Demands of Basic Fire Management Tasks in Members of the Canadian Armed Forces: A Pilot Study. Mil Med 2021; 188:e942-e948. [PMID: 34652444 DOI: 10.1093/milmed/usab421] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2021] [Revised: 09/22/2021] [Accepted: 09/28/2021] [Indexed: 11/14/2022] Open
Abstract
INTRODUCTION Members of the Canadian Armed Forces (CAF) are required to meet the minimum standards of the Fitness for Operational Requirements of CAF Employment (FORCE) job-based simulation test (JBST) and must possess the capacity to perform other common essential tasks. One of those tasks is to perform basic fire management tasks during fire emergencies to mitigate damage and reduce the risk of injuries and/or death until professional firefighters arrive at the scene. To date however, the physiological demands of common firefighting tasks have mostly been performed on professional firefighters, thus rendering the transferability of the demands to the general military population unclear. This pilot study aimed to quantify, for the first time, the physiological demands of basic fire management tasks in the military, to determine if they are reflected in the FORCE JBST minimum standard. We hypothesized that the physiological demands of basic fire management tasks within the CAF are below the physiological demands of the FORCE JBST minimum standard, and as such, be lower than the demands of professional firefighting. MATERIALS AND METHODS To achieve this, 21 CAF members (8 females; 13 males; mean [SD] age: 33 [10] years; height: 174.5 [10.5] cm; weight: 85.4 [22.1] kg, estimated maximal oxygen uptake [$\dot V$O2peak]: 44.4 (7.4) mL kg-1 min-1) participated in a realistic, but physically demanding, JBST developed by CAF professional firefighting subject matter experts. The actions included lifting, carrying, and manipulating a 13-kg powder fire extinguisher and connecting, coupling, and dragging a 38-mm fire hose over 30 m. The rate of oxygen uptake ($\dot V$O2), heart rate, and percentage of heart rate reserve were measured continuously during two task simulation trials, which were interspersed by a recovery period. Rating of perceived exertion (6-no exertion; 20-maximal exertion) was measured upon completion of both task simulations. Peak $\dot V$O2 ($\dot V$O2peak) was estimated based on the results of the FORCE JBST. RESULTS The mean (SD) duration of both task simulation trials was 3:39 (0:19) min:s, whereas the rest period in between both trials was 62 (19) minutes. The mean O2 was 21.1 (4.7) mL kg-1 min-1 across trials, which represented 52.1 (12.2) %$\dot V$O2peak and ∼81% of the FORCE JBST. This was paralleled by a mean heart rate of 136 (18) beats min-1, mean percentage of heart rate reserve of 61.2 (10.8), and mean rating of perceived exertion of 11 ± 2. Other physical components of the JBST consisted of lifting, carrying, and manipulating a 13-kg load for ∼59 seconds, which represents 65% of the load of the FORCE JBST. The external resistance of the fire hose drag portion increased up to 316 N, translating to a total of 6205 N over 30 m, which represents 96% of the drag force measured during the FORCE JBST. CONCLUSIONS Our findings demonstrate that the physiological demands of basic fire management tasks in the CAF are of moderate intensity, which are reflected in the CAF physical fitness standard. As such, CAF members who achieve the minimum standard on the FORCE JBST are deemed capable of physically performing basic fire management tasks during fire emergencies.
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Affiliation(s)
- Étienne Chassé
- Human Performance Research and Development, Ottawa, ON K1J 1J8, Canada
| | - Daniel Théoret
- Human Performance Research and Development, Ottawa, ON K1J 1J8, Canada
| | - Martin P Poirier
- Human Performance Research and Development, Ottawa, ON K1J 1J8, Canada
| | - François Lalonde
- Department of Exercise Sciences, Faculty of Science, University of Quebec in Montréal (UQAM), Montréal, QC H2X 1Y4, Canada
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Notley SR, Akerman AP, Friesen BJ, Poirier MP, Sigal RJ, Flouris AD, Boulay P, McCourt E, Ruzicka M, Kenny GP. Heat Tolerance and Occupational Heat Exposure Limits in Older Men with and without Type 2 Diabetes or Hypertension. Med Sci Sports Exerc 2021; 53:2196-2206. [PMID: 33988544 DOI: 10.1249/mss.0000000000002698] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
PURPOSE To mitigate rises in core temperature >1°C, the American Conference of Governmental Industrial Hygienists (ACGIH) recommends upper limits for heat stress (Action Limit Values; ALV), defined by wet-bulb globe temperature (WBGT) and a worker's metabolic rate. However, these limits are based on data from young men and are assumed to be suitable for all workers, irrespective of age or health status. We therefore explored the impact of aging, type 2 diabetes (T2D), and hypertension (HTN), on tolerance to prolonged, moderate-intensity work above and below these limits. METHODS Core temperature and heart rate were assessed in healthy, non-heat acclimatized young (18-30 y, n=13) and older (50-70 y) men (n=14), and non-heat acclimatized older men with T2D (n=10) or HTN (n=13) during moderate-intensity (metabolic rate: 200 W/m2) walking for 180 min (or until termination) in environments above (28 and 32°C WBGT) and below (16 and 24°C WBGT) the ALV for continuous work at this intensity (25°C WBGT). RESULTS Work tolerance in the 32°C WBGT was shorter in men with T2D (median [IQR]; 109 [91, 173] min; p=0.041) and HTN (109 [91, 173] min; p=0.010) compared to healthy older men (180 [133, 180] min). However, aging, T2D, and HTN did not significantly influence (i) core temperature or heart rate reserve, irrespective of WBGT, (ii) the probability that core temperature exceeded recommended limits (>1°C) under the ALV, and (iii) work duration before core temperature exceeded recommended limits (>1°C) above the ALV. CONCLUSION These findings demonstrate that T2D and HTN attenuate tolerance to uncompensable heat stress (32°C WBGT); however, these chronic diseases do not significantly impact thermal and cardiovascular strain, or the validity of ACIGH recommendations during moderate-intensity work.
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Affiliation(s)
- Sean R Notley
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, Canada Departments of Medicine, Cardiac Sciences and Community Health Sciences Faculties of Medicine and Kinesiology, University of Calgary, Canada Clinical Epidemiology Program, Ottawa Hospital Research Institute, Ottawa, Canada FAME Laboratory, Department of Exercise Science, University of Thessaly, Greece Faculté des sciences de l'activité physique, Université de Sherbrooke, Sherbrooke, Québec, Canada Hypertension Program, Division of Nephrology, University of Ottawa, Ottawa, Canada
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Fujii N, McGarr GW, Notley SR, Boulay P, Sigal RJ, Amano T, Nishiyasu T, Poirier MP, Kenny GP. Effects of short-term heat acclimation on whole-body heat exchange and local nitric oxide synthase- and cyclooxygenase-dependent heat loss responses in exercising older men. Exp Physiol 2020; 106:450-462. [PMID: 33347660 DOI: 10.1113/ep089025] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2020] [Accepted: 12/04/2020] [Indexed: 11/08/2022]
Abstract
NEW FINDINGS What is the central question of this study? Does short-term heat acclimation enhance whole-body evaporative heat loss and augment nitric oxide synthase (NOS)-dependent cutaneous vasodilatation and NOS- and cyclooxygenase (COX)-dependent sweating, in exercising older men? What is the main finding and its importance? Our preliminary data (n = 8) demonstrated that short-term heat acclimation improved whole-body evaporative heat loss, but it did not influence the effects of NOS and/or COX inhibition on cutaneous vasodilatation or sweating in older men during an exercise-heat stress. These outcomes might imply that although short-term heat acclimation enhances heat dissipation in older men, it does not modulate NOS- and COX-dependent control of cutaneous vasodilatation or sweating on the forearm. ABSTRACT Ageing is associated with decrements in whole-body heat loss (evaporative + dry heat exchange), which might stem from alterations in nitric oxide synthase (NOS)- and cyclooxygenase (COX)-dependent cutaneous vasodilatation and sweating. We evaluated whether short-term heat acclimation would (i) enhance whole-body heat loss primarily by increasing evaporative heat loss, and (ii) augment NOS-dependent cutaneous vasodilatation and NOS- and COX-dependent sweating, in exercising older men. Eight older men [mean (SD) age, 59 (8) years] completed a calorimetry and microdialysis trial before and after 7 days of exercise-heat acclimation. For the calorimetry trials, whole-body evaporative and dry heat exchange were assessed using direct calorimetry during 30 min bouts of cycling at light, moderate and vigorous metabolic heat productions (150, 200 and 250 W/m2 , respectively) in dry heat (40°C, 20% relative humidity). For the microdialysis trials, local cutaneous vascular conductance and sweat rate were assessed during 60 min exercise in the heat (35°C, 20% relative humidity) at four dorsal forearm skin sites treated with lactated Ringer solution (control), NOS inhibitor, COX inhibitor or combined NOS and COX inhibitors, via microdialysis. Evaporative heat loss during moderate (P = 0.036) and vigorous (P = 0.021) exercise increased after acclimation. Inhibition of NOS alone reduced cutaneous vascular conductance to a similar extent before and after acclimation (P < 0.040), whereas separate and combined NOS and COX inhibition had no significant effects on sweating relative to the control site (P = 0.745). Our preliminary results might suggest that short-term heat acclimation improves evaporative heat loss, but does not significantly modulate the contributions of NOS or COX to cutaneous vasodilatation or sweating on the forearm in older men during an exercise-heat stress.
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Affiliation(s)
- Naoto Fujii
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, Ontario, Canada.,Faculty of Health and Sport Sciences, University of Tsukuba, Tsukuba, Japan
| | - Gregory W McGarr
- 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
| | - Pierre Boulay
- Faculty of Physical Activity Sciences, University of Sherbrooke, Sherbrooke, Québec, Canada
| | - Ronald J Sigal
- Human and Environmental Physiology Research Unit, School of Human Kinetics, 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
| | - Tatsuro Amano
- Department of Health and Sports, Niigata University of Health and Welfare, Niigata, Japan
| | - Takeshi Nishiyasu
- Faculty of Health and Sport Sciences, University of Tsukuba, Tsukuba, Japan
| | - Martin P Poirier
- 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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Notley SR, Meade RD, Akerman AP, Poirier MP, Boulay P, Sigal RJ, Flouris AD, Kenny GP. Evidence for age‐related differences in heat acclimatisation responsiveness. Exp Physiol 2020; 105:1491-1499. [DOI: 10.1113/ep088728] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2020] [Accepted: 06/23/2020] [Indexed: 12/12/2022]
Affiliation(s)
- Sean R. Notley
- Human and Environmental Physiology Research UnitSchool of Human KineticsFaculty of Health SciencesUniversity of Ottawa Ottawa Canada
| | - Robert D. Meade
- Human and Environmental Physiology Research UnitSchool of Human KineticsFaculty of Health SciencesUniversity of Ottawa Ottawa Canada
| | - Ashley P. Akerman
- Human and Environmental Physiology Research UnitSchool of Human KineticsFaculty of Health SciencesUniversity of Ottawa Ottawa Canada
| | - Martin P. Poirier
- Human and Environmental Physiology Research UnitSchool of Human KineticsFaculty of Health SciencesUniversity of Ottawa Ottawa Canada
| | - Pierre Boulay
- Faculté des sciences de l'activité physiqueUniversité de Sherbrooke Sherbrooke Canada
| | - Ronald J. Sigal
- Human and Environmental Physiology Research UnitSchool of Human KineticsFaculty of Health SciencesUniversity of Ottawa Ottawa Canada
- Departments of MedicineCardiac Sciences and Community Health Sciences Faculties of Medicine and KinesiologyUniversity of Calgary Calgary Canada
- Clinical Epidemiology ProgramOttawa Hospital Research Institute Ottawa Canada
| | - Andreas D. Flouris
- FAME LaboratoryDepartment of Exercise ScienceUniversity of Thessaly Trikala Greece
| | - Glen P. Kenny
- Human and Environmental Physiology Research UnitSchool of Human KineticsFaculty of Health SciencesUniversity of Ottawa Ottawa Canada
- Clinical Epidemiology ProgramOttawa Hospital Research Institute Ottawa Canada
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Poirier MP, Notley SR, Boulay P, Sigal RJ, Friesen BJ, Malcolm J, Flouris AD, Kenny GP. Type 2 diabetes does not exacerbate body heat storage in older adults during brief, extreme passive heat exposure. Temperature (Austin) 2020; 7:263-269. [PMID: 33123619 DOI: 10.1080/23328940.2020.1736760] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Aging exacerbates hyperthermia and cardiovascular strain during passive heat exposure, but it remains unclear whether those effects worsen in older adults with type 2 diabetes (T2D). We examined these responses in unacclimatized, physically active, older individuals with (n = 13, mean ± SD age: 60 ± 8 years, HbA1c: 7.0 ± 1.0%) and without (Control, n = 30, 62 ± 6 years) well-controlled T2D during a brief, 3-h passive exposure to extreme heat (44°C, 30% relative humidity). Metabolic heat production, dry heat gain, total heat gain (metabolic heat production + dry heat gain), evaporative heat loss, body heat storage (summation of heat gain/loss), rectal and mean skin temperatures as well as heart rate were measured continuously. No between-group differences were observed for metabolic heat production (T2D vs. Control; 53 ± 5 vs. 55 ± 7 W/m2), dry heat gain (48 ± 9 vs. 47 ± 11 W/m2), total heat gain (101 ± 10 vs. 102 ± 14 W/m2) and evaporative heat loss (83 ± 10 vs. 85 ± 12 W/m2) over the 3 h (all P > 0.05). Consequently, the changes in body heat storage (380 ± 93 vs. 358 ± 172 kJ, P = 0.67) were similar between groups. Moreover, no between-group differences in rectal and mean skin temperatures or heart rate were measured. We conclude that unacclimatized, physically active, older adults with well-controlled T2D do not experience greater hyperthermia and cardiovascular strain compared to their healthy counterparts while resting in extreme heat for a brief, 3-h period.
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Affiliation(s)
- Martin P Poirier
- Human and Environmental Physiology Research Unit, School of Human Kinetics, Faculty of Health Sciences, University of Ottawa, Ottawa, Canada
| | - Sean R Notley
- Human and Environmental Physiology Research Unit, School of Human Kinetics, Faculty of Health Sciences, University of Ottawa, Ottawa, Canada
| | - Pierre Boulay
- Faculté des Sciences de l'activité Physique, Université de Sherbrooke, Sherbrooke, Canada
| | - Ronald J Sigal
- Human and Environmental Physiology Research Unit, School of Human Kinetics, Faculty of Health Sciences, University of Ottawa, Ottawa, Canada.,Departments of Medicine, Cardiac Sciences and Community Health Sciences, Faculties of Medicine and Kinesiology, University of Calgary, Division of Endocrinology and Metabolism, RRDTC, Calgary, Canada.,Clinical Epidemiology Program, Ottawa Hospital Research Institute, Ottawa, Canada
| | - Brian J Friesen
- Human and Environmental Physiology Research Unit, School of Human Kinetics, Faculty of Health Sciences, University of Ottawa, Ottawa, Canada
| | - Janine Malcolm
- Division of Endocrinology and Metabolism, Department of Medicine, University of Ottawa, Ottawa, Canada
| | - Andreas D Flouris
- FAME Laboratory, Department of Exercise Science, University of Thessaly, Trikala, Greece
| | - Glen P Kenny
- Human and Environmental Physiology Research Unit, School of Human Kinetics, Faculty of Health Sciences, University of Ottawa, Ottawa, Canada.,Clinical Epidemiology Program, Ottawa Hospital Research Institute, Ottawa, Canada
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Abstract
This physiology study assesses whole-body heat loss in physically active middle-aged and older men with vs without type 2 diabetes after aerobic cycling to evaluate whether type 2 diabetes impairs heat loss and by what mechanism.
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Affiliation(s)
- Sean R. Notley
- 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
| | - Ronald J. Sigal
- Department of Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Andrew D’Souza
- Human and Environmental Physiology Research Unit, University of Ottawa, Ottawa, Ontario, Canada
| | | | - Naoto Fujii
- 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, Ontario, Canada
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11
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Notley SR, Poirier MP, Yardley JE, Sigal RJ, Kenny GP. Impaired whole-body heat loss in type 1 diabetes during exercise in the heat: a cause for concern? Diabetologia 2019; 62:1087-1089. [PMID: 30941449 DOI: 10.1007/s00125-019-4858-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/30/2019] [Accepted: 03/11/2019] [Indexed: 01/09/2023]
Affiliation(s)
- Sean R Notley
- Human and Environmental Physiology Research Unit, School of Human Kinetics, 125 University, Room 367, Montpetit Hall, University of Ottawa, Ottawa, ON, K1N 6N5, Canada
| | - Martin P Poirier
- Human and Environmental Physiology Research Unit, School of Human Kinetics, 125 University, Room 367, Montpetit Hall, University of Ottawa, Ottawa, ON, K1N 6N5, Canada
| | - Jane E Yardley
- Augustana Faculty, University of Alberta, Camrose, AB, Canada
- Alberta Diabetes Institute, Edmonton, AB, Canada
| | - Ronald J Sigal
- Human and Environmental Physiology Research Unit, School of Human Kinetics, 125 University, Room 367, Montpetit Hall, University of Ottawa, Ottawa, ON, K1N 6N5, Canada
- Department of Medicine, University of Calgary, Calgary, AB, Canada
- Department of Community Health Sciences, University of Calgary, Calgary, AB, Canada
- Department of Cardiac Sciences, 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, 125 University, Room 367, Montpetit Hall, University of Ottawa, Ottawa, ON, K1N 6N5, Canada.
- Clinical Epidemiology Program, Ottawa Hospital Research Institute, Ottawa, ON, Canada.
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12
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Notley SR, Lamarche DT, Poirier MP, Flouris AD, Kenny GP. A Preliminary Analysis of the Inter‐Individual Determinants of Whole‐Body Heat Exchange in 100 Young Men and Women during Exercise in the Heat. FASEB J 2019. [DOI: 10.1096/fasebj.2019.33.1_supplement.842.8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Sean R. Notley
- Human and Environmental Physiology Research UnitSchool of Human Kinetics, University of OttawaOttawaONCanada
| | - Dallon T. Lamarche
- Human and Environmental Physiology Research UnitSchool of Human Kinetics, University of OttawaOttawaONCanada
| | - Martin P. Poirier
- Human and Environmental Physiology Research UnitSchool of Human Kinetics, University of OttawaOttawaONCanada
| | - Andreas D. Flouris
- Human and Environmental Physiology Research UnitSchool of Human Kinetics, University of OttawaOttawaONCanada
- FAME LaboratoryDepartment of Exercise ScienceUniversity of ThessalyTrikalaGreece
| | - Glen P. Kenny
- Human and Environmental Physiology Research UnitSchool of Human Kinetics, University of OttawaOttawaONCanada
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13
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Notley SR, Dervis S, Poirier MP, Kenny GP. Menstrual cycle phase does not modulate whole body heat loss during exercise in hot, dry conditions. J Appl Physiol (1985) 2018; 126:286-293. [PMID: 30496713 DOI: 10.1152/japplphysiol.00735.2018] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Menstrual cycle phase has long been thought to modulate thermoregulatory function. However, information pertaining to the effects of menstrual phase on time-dependent changes in whole body dry and evaporative heat exchange during exercise-induced heat stress and the specific heat load at which menstrual phase modulates whole body heat loss remained unavailable. We therefore used direct calorimetry to continuously assess whole body dry and evaporative exchange in 12 habitually active, non-endurance-trained, eumenorrheic women [21 ± 3 (SD) yr] within the early-follicular, late-follicular, and midluteal menstrual phases during three 30-min bouts of cycling at increasing fixed exercise intensities of 40% (Low), 55% (Moderate), and 70% (High) peak oxygen uptake, each followed by a 15-min recovery, in hot, dry conditions (40°C, 15% relative humidity). This model elicited equivalent rates of metabolic heat production among menstrual phases ( P = 0.80) of ~250 (Low), ~340 (Moderate), and ~430 W (High). However, dry and evaporative heat exchange and the resulting changes in net heat loss (dry ± evaporative heat exchange) were similar among phases (all P > 0.05), with net heat loss averaging 216 ± 43 (Low), 287 ± 63 (Moderate), and 331 ± 75 W (High) across phases. Accordingly, cumulative body heat storage (summation of heat production and loss) across all exercise bouts was similar among phases ( P = 0.55), averaging 464 ± 122 kJ. For some time, menstrual cycle phase has been thought to modulate heat dissipation; however, we show that menstrual cycle phase does not influence the contribution of whole body dry and evaporative heat exchange or the resulting changes in net heat loss or body heat storage, irrespective of the heat load. NEW & NOTEWORTHY Menstrual phase has long been thought to modulate thermoregulatory function in eumenorrheic women during exercise-induced heat stress. Contrary to that perception, we show that when assessed in young, non-endurance-trained women within the early-follicular, late-follicular, and midluteal phases during three incremental exercise-induced heat loads in hot, dry conditions, menstrual phase does not modify whole body dry and evaporative heat exchange or the resulting changes in body heat storage, regardless of the heat load employed.
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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
| | - Sheila Dervis
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa , Ottawa, Ontario , Canada
| | - Martin P Poirier
- 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
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14
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D'Souza AW, Notley SR, Brown EK, Poirier MP, Kenny GP. The Hexoskin physiological monitoring shirt does not impair whole-body heat loss during exercise in hot-dry conditions. Appl Physiol Nutr Metab 2018; 44:332-335. [PMID: 30336069 DOI: 10.1139/apnm-2018-0370] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Using direct calorimetry, we determined if the Hexoskin shirt (Carré Technologies Inc., Que., Canada), a wearable device for monitoring physiological strain, would compromise whole-body heat loss and exacerbate body heat storage during moderate-intensity activity in hot-dry conditions. The shirt did not impair heat dissipation and resulted in similar body heat storage when worn alone relative to a semi-nude condition (214 vs. 211 kJ) or when worn underneath a work uniform compared with a cotton undershirt (307 vs. 318 kJ).
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Affiliation(s)
- Andrew W D'Souza
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, ON K1N 6N5, Canada.,Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, ON K1N 6N5, Canada
| | - Sean R Notley
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, ON K1N 6N5, Canada.,Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, ON K1N 6N5, Canada
| | - Erin K Brown
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, ON K1N 6N5, Canada.,Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, ON K1N 6N5, Canada
| | - Martin P Poirier
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, ON K1N 6N5, Canada.,Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, ON K1N 6N5, Canada
| | - Glen P Kenny
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, ON K1N 6N5, Canada
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15
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Lamarche DT, Notley SR, Poirier MP, Kenny GP. Self-reported physical activity level does not alter whole-body total heat loss independently of aerobic fitness in young adults during exercise in the heat. Appl Physiol Nutr Metab 2018; 44:99-102. [PMID: 30063161 DOI: 10.1139/apnm-2018-0211] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We evaluated whether self-reported physical activity (PA) level modulates whole-body total heat loss (WB-THL) as assessed using direct calorimetry in 10 young adults (aged 22 ± 3 years) matched for rate of peak oxygen consumption (an index for aerobic fitness), but of low and high self-reported PA, during 3 incremental cycling bouts (∼39%, 52%, and 64% peak oxygen consumption) in the heat (40 °C). We showed that level of self-reported PA does not appear to influence WB-THL independently of peak oxygen consumption.
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Affiliation(s)
- Dallon T Lamarche
- Human and Environmental Physiological Research Unit, Faculty of Health Sciences, University of Ottawa, Ottawa, ON K1N 6N5, Canada.,Human and Environmental Physiological Research Unit, Faculty of Health Sciences, University of Ottawa, Ottawa, ON K1N 6N5, Canada
| | - Sean R Notley
- Human and Environmental Physiological Research Unit, Faculty of Health Sciences, University of Ottawa, Ottawa, ON K1N 6N5, Canada.,Human and Environmental Physiological Research Unit, Faculty of Health Sciences, University of Ottawa, Ottawa, ON K1N 6N5, Canada
| | - Martin P Poirier
- Human and Environmental Physiological Research Unit, Faculty of Health Sciences, University of Ottawa, Ottawa, ON K1N 6N5, Canada.,Human and Environmental Physiological Research Unit, Faculty of Health Sciences, University of Ottawa, Ottawa, ON K1N 6N5, Canada
| | - Glen P Kenny
- Human and Environmental Physiological Research Unit, Faculty of Health Sciences, University of Ottawa, Ottawa, ON K1N 6N5, Canada
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16
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Poirier MP, Notley SR, Gagnon D, McGinn RR, Friesen BJ, Flouris AD, Kenny GP. Defining Acceptable Cold‐Water Immersion Times for the Treatment of Exertional Hyperthermia When Rectal Temperature Measurements are not Available. FASEB J 2018. [DOI: 10.1096/fasebj.2018.32.1_supplement.859.4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Martin P. Poirier
- Human and Environmental Physiology Research UnitSchool of Human KineticsUniversity of OttawaOttawaONCanada
| | - Sean R. Notley
- Human and Environmental Physiology Research UnitSchool of Human KineticsUniversity of OttawaOttawaONCanada
| | - Daniel Gagnon
- Département de Pharmacologie Et Physiologie, Faculté de MédecineUniversité de MontréalMontréalQCCanada
- Cardiovascular Prevention and Rehabilitation CentreMontreal Heart InstituteMontréalQCCanada
| | | | - Brian J. Friesen
- Human and Environmental Physiology Research UnitSchool of Human KineticsUniversity of OttawaOttawaONCanada
| | - Andreas D. Flouris
- FAME LaboratoryDepartment of Exercise ScienceUniversity of ThessalyTrikalaGreece
| | - Glen P. Kenny
- Human and Environmental Physiology Research UnitSchool of Human KineticsUniversity of OttawaOttawaONCanada
- Clinical Epidemiology ProgramOttawa Hospital Research InstituteOttawaONCanada
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17
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Poirier MP, Notley SR, Flouris AD, Kenny GP. Physical characteristics cannot be used to predict cooling time using cold-water immersion as a treatment for exertional hyperthermia. Appl Physiol Nutr Metab 2018. [PMID: 29529383 DOI: 10.1139/apnm-2017-0619] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We examined if physical characteristics could be used to predict cooling time during cold water immersion (CWI, 2 °C) following exertional hyperthermia (rectal temperature ≥39.5 °C) in a physically heterogeneous group of men and women (n = 62). Lean body mass was the only significant predictor of cooling time following CWI (R2 = 0.137; P < 0.001); however, that prediction did not provide the precision (mean residual square error: 3.18 ± 2.28 min) required to act as a safe alternative to rectal temperature measurements.
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Affiliation(s)
- Martin P Poirier
- a Human and Environmental Physiological Research Unit, Faculty of Health Sciences, University of Ottawa, Ottawa, ON K1N 6N5, Canada
| | - Sean R Notley
- a Human and Environmental Physiological Research Unit, Faculty of Health Sciences, University of Ottawa, Ottawa, ON K1N 6N5, Canada
| | - Andreas D Flouris
- b FAME Laboratory, Department of Exercise Science, University of Thessaly, Trikala, 42100, Greece
| | - Glen P Kenny
- c Human and Environmental Physiological Research Unit, Faculty of Health Sciences, University of Ottawa, Ottawa, ON K1N 6N5, Canada.,d Human and Environmental Physiological Research Unit, Faculty of Health Sciences, University of Ottawa, Ottawa, ON K1N 6N5, Canada.,e Clinical Epidemiology Program, Ottawa Hospital Research Institute, Ottawa, ON K1Y 4E9, Canada
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18
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Lamarche DT, Notley SR, Poirier MP, Kenny GP. Fitness-related differences in the rate of whole-body total heat loss in exercising young healthy women are heat-load dependent. Exp Physiol 2018; 103:312-317. [DOI: 10.1113/ep086752] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2017] [Accepted: 12/13/2017] [Indexed: 11/08/2022]
Affiliation(s)
- Dallon T. Lamarche
- 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
| | - Martin P. Poirier
- 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
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19
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Friesen BJ, Poirier MP, Lamarche DT, D'Souza AW, Kim JH, Notley SR, Kenny GP. Postexercise whole-body sweating increases during muscle metaboreceptor activation in young men. Appl Physiol Nutr Metab 2018; 43:423-426. [PMID: 29316406 DOI: 10.1139/apnm-2017-0675] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We assessed the effect of metaboreceptor activation on whole-body evaporative heat loss (WB-EHL) in 12 men (aged 24 ± 4 years) in the early-to-late stages of a 60-min exercise recovery in the heat. Metaboreceptor activation induced by 1-min isometric-handgrip (IHG) exercise followed by 5-min forearm ischemia to trap metabolites increased WB-EHL by 25%-31% and 26%-34% during the ischemic period relative to IHG-only and control (natural recovery only), respectively, throughout recovery. We show that metaboreceptor activation enhances WB-EHL in recovery.
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Affiliation(s)
- Brian J Friesen
- a Human and Environmental Physiological Research Unit, Faculty of Health Sciences, University of Ottawa, Ottawa, ON K1N 6N5, Canada
| | - Martin P Poirier
- a Human and Environmental Physiological Research Unit, Faculty of Health Sciences, University of Ottawa, Ottawa, ON K1N 6N5, Canada
| | - Dallon T Lamarche
- a Human and Environmental Physiological Research Unit, Faculty of Health Sciences, University of Ottawa, Ottawa, ON K1N 6N5, Canada
| | - Andrew W D'Souza
- a Human and Environmental Physiological Research Unit, Faculty of Health Sciences, University of Ottawa, Ottawa, ON K1N 6N5, Canada
| | - Jung-Hyun Kim
- b Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health, Pittsburgh, PA, USA
| | - Sean R Notley
- a Human and Environmental Physiological Research Unit, Faculty of Health Sciences, University of Ottawa, Ottawa, ON K1N 6N5, Canada
| | - Glen P Kenny
- a Human and Environmental Physiological Research Unit, Faculty of Health Sciences, University of Ottawa, Ottawa, ON K1N 6N5, Canada
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20
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Meade RD, Fujii N, Poirier MP, Boulay P, Sigal RJ, Kenny GP. Oxidative stress does not influence local sweat rate during high-intensity exercise. Exp Physiol 2017; 103:172-178. [PMID: 29152797 DOI: 10.1113/ep086746] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2017] [Accepted: 11/14/2017] [Indexed: 01/13/2023]
Abstract
NEW FINDINGS What is the central question of this study? We evaluated whether oxidative stress attenuates the contribution of nitric oxide to sweating during high-intensity exercise. What is the main finding and its importance? In contrast to our previous report of an oxidative stress-mediated reduction in nitric oxide-dependent cutaneous vasodilatation in this cohort during intense exercise, we demonstrated no influence of local ascorbate administration on the sweating response during moderate- (∼51% peak oxygen uptake) or high-intensity exercise (∼72% peak oxygen uptake). These new findings provide important mechanistic insight into how exercise-induced oxidative stress impacts sudomotor activity. Nitric oxide (NO)-dependent sweating is diminished during high- but not moderate-intensity exercise. We evaluated whether this impairment stems from increased oxidative stress during high-intensity exercise. On two separate days, 11 young (24 ± 4 years) men cycled in the heat (35°C) at a moderate [500 W; 52 ± 6% peak oxygen uptake (V̇O2 peak )] or high (700 W; 71 ± 5% V̇O2 peak ) rate of metabolic heat production. Each session included two 30 min exercise bouts separated by a 20 min recovery period. Local sweat rate was monitored at four forearm skin sites continuously perfused via intradermal microdialysis with the following: (i) lactated Ringer solution (Control); (ii) 10 mm ascorbate (Ascorbate; non-selective antioxidant); (iii) 10 mm NG -nitro-l-arginine methyl ester (l-NAME; NO synthase inhibitor); or (iv) 10 mm ascorbate plus 10 mm l-NAME (Ascorbate + l-NAME). During moderate exercise, sweat rate was attenuated at the l-NAME and Ascorbate + l-NAME sites (both ∼1.0 mg min-1 cm-2 ; all P < 0.05) but not at the Ascorbate site (∼1.1 mg min-1 cm-2 ; both P ≥ 0.28) in comparison to the Control site (∼1.1 mg min-1 cm-2 ). However, no differences were observed between treatment sites (∼1.4 mg min-1 cm-2 ; P = 0.75) during high-intensity exercise. We conclude that diminished NO-dependent sweating during intense exercise occurs independent of oxidative stress.
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Affiliation(s)
- Robert D Meade
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, Ontario, Canada
| | - Naoto Fujii
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, Ontario, Canada.,Faculty of Health and Sport Sciences, University of Tsukuba, Tsukuba City, Japan
| | - Martin P Poirier
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, Ontario, Canada
| | - Pierre Boulay
- Faculty of Physical Activity Sciences, University of Sherbrooke, Sherbrooke, Quebec, Canada
| | - Ronald J Sigal
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, Ontario, Canada.,Departments of Medicine, Cardiac Sciences and Community Health Sciences, University of Calgary, Calgary, Alberta, Canada.,Clinical Epidemiology Program, Ottawa Hospital Research Institute, Ottawa, Ontario, Canada
| | - Glen P Kenny
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, Ontario, Canada.,Clinical Epidemiology Program, Ottawa Hospital Research Institute, Ottawa, Ontario, Canada
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21
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Flouris AD, McGinn R, Poirier MP, Louie JC, Ioannou LG, Tsoutsoubi L, Sigal RJ, Boulay P, Hardcastle SG, Kenny GP. Screening criteria for increased susceptibility to heat stress during work or leisure in hot environments in healthy individuals aged 31-70 years. Temperature (Austin) 2017; 5:86-99. [PMID: 29687046 PMCID: PMC5902215 DOI: 10.1080/23328940.2017.1381800] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2017] [Revised: 09/15/2017] [Accepted: 09/15/2017] [Indexed: 10/18/2022] Open
Abstract
Population aging and global warming generate important public health risks, as older adults have increased susceptibility to heat stress (SHS). We defined and validated sex-specific screening criteria for SHS during work and leisure activities in hot environments in individuals aged 31-70 years using age, anthropometry, and cardiorespiratory fitness. A total of 123 males and 44 females [44 ± 14 years; 22.9 ± 7.4% body fat; 40.3 ± 8.6 peak oxygen uptake (mlO2/kg/min)] participated, separated into the Analysis (n = 111) and Validation (n = 56) groups. Within these groups, participants were categorized into YOUNG (19-30 years; n = 47) and OLDER (31-70 years; n = 120). All participants performed exercise in the heat inside a direct calorimeter. Screening criteria for OLDER participants were defined from the Analysis group and were cross-validated in the Validation group. Results showed that 30% of OLDER individuals in the Analysis group were screened as SHS positive. A total of 274 statistically valid (p < 0.05) criteria were identified suggesting that OLDER participants were at risk for SHS when demonstrating two or more of the following (males/females): age ≥ 53.0/55.8 years; body mass index ≥29.5/25.7 kg/m2; body fat percentage ≥ 28.8/34.9; body surface area ≤2.0/1.7 m2; peak oxygen uptake ≤48.3/41.4 mlO2/kg fat free mass/min. In the Validation group, McNemar χ2 comparisons confirmed acceptable validity for the developed criteria. We conclude that the developed criteria can effectively screen individuals 31-70 years who are at risk for SHS during work and leisure activities in hot environments and can provide simple and effective means to mitigate the public health risks caused by heat exposure.
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Affiliation(s)
- Andreas D. Flouris
- FAME Laboratory, Department of Exercise Science, University of Thessaly, Trikala, Greece
- Human and Environmental Physiological Research Unit, School of Human Kinetics, Faculty of Health Sciences, University of Ottawa, Ontario, Canada
| | - Ryan McGinn
- Human and Environmental Physiological Research Unit, School of Human Kinetics, Faculty of Health Sciences, University of Ottawa, Ontario, Canada
| | - Martin P. Poirier
- Human and Environmental Physiological Research Unit, School of Human Kinetics, Faculty of Health Sciences, University of Ottawa, Ontario, Canada
| | - Jeffrey C. Louie
- Human and Environmental Physiological Research Unit, School of Human Kinetics, Faculty of Health Sciences, University of Ottawa, Ontario, Canada
| | - Leonidas G. Ioannou
- FAME Laboratory, Department of Exercise Science, University of Thessaly, Trikala, Greece
| | - Lydia Tsoutsoubi
- FAME Laboratory, Department of Exercise Science, University of Thessaly, Trikala, Greece
| | - Ronald J. Sigal
- Human and Environmental Physiological Research Unit, School of Human Kinetics, Faculty of Health Sciences, University of Ottawa, Ontario, Canada
- Departments of Medicine, Cardiac Sciences, and Community Health Sciences, Faculties of Medicine and Kinesiology, University of Calgary, Calgary, Canada
- Clinical Epidemiology Program, Ottawa Hospital Research Institute, Ottawa, Canada
| | - Pierre Boulay
- Faculty of Physical Activity Sciences, Department of Human Kinetics, University of Sherbrooke, Sherbrooke, Canada
| | | | - Glen P. Kenny
- Human and Environmental Physiological Research Unit, School of Human Kinetics, Faculty of Health Sciences, University of Ottawa, Ontario, Canada
- Clinical Epidemiology Program, Ottawa Hospital Research Institute, Ottawa, Canada
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22
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Lamarche DT, Notley SR, Louie JC, Poirier MP, Kenny GP. Fitness-related differences in the rate of whole-body evaporative heat loss in exercising men are heat-load dependent. Exp Physiol 2017; 103:101-110. [DOI: 10.1113/ep086637] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2017] [Accepted: 10/11/2017] [Indexed: 11/08/2022]
Affiliation(s)
- Dallon T. Lamarche
- 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
| | - Jeffrey C. Louie
- Human and Environmental Physiology Research Unit, School of Human Kinetics; University of Ottawa; Ottawa Ontario Canada
| | - Martin P. Poirier
- 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
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23
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McGinn R, Poirier MP, Louie JC, Sigal RJ, Boulay P, Flouris AD, Kenny GP. Increasing age is a major risk factor for susceptibility to heat stress during physical activity. Appl Physiol Nutr Metab 2017; 42:1232-1235. [DOI: 10.1139/apnm-2017-0322] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We evaluated the extent to which age, cardiorespiratory fitness, and body fat can independently determine whole-body heat loss (WBHL) in 87 otherwise healthy adults. We show that increasing age is a major predictor for decreasing WBHL in otherwise healthy adults (aged 20–70 years), accounting for 40% of the variation in the largest study to date. While greater body fat also had a minor detrimental impact on WBHL, there was no significant role for cardiorespiratory fitness.
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Affiliation(s)
- Ryan McGinn
- Human and Environmental Physiological Research Unit, Faculty of Health Sciences, University of Ottawa; Faculty of Medicine, University of Ottawa, Ottawa, ON K1N 6N5, Canada
| | - Martin P. Poirier
- Human and Environmental Physiological Research Unit, Faculty of Health Sciences, University of Ottawa, Ottawa, ON K1N 6N5, Canada
| | - Jeffrey C. Louie
- Human and Environmental Physiological Research Unit, Faculty of Health Sciences, University of Ottawa, Ottawa, ON K1N 6N5, Canada
| | - Ronald J. Sigal
- Departments of Medicine, Cardiac Sciences, and Community Health Sciences, Faculties of Medicine and Kinesiology, University of Calgary, Calgary, AB T2N 1N4, Canada
- Human and Environmental Physiological Research Unit, Faculty of Health Sciences, University of Ottawa, Ottawa, ON K1N 6N5, Canada
| | - Pierre Boulay
- Faculty of Human Kinetics, University of Sherbrooke, Sherbrooke, QC J1K 0A5, Canada
| | - Andreas D. Flouris
- FAME Laboratory, Department of Exercise Science, University of Thessaly, Trikala 382 21, Greece
| | - Glen P. Kenny
- Human and Environmental Physiological Research Unit, Faculty of Health Sciences, University of Ottawa, Ottawa, ON K1N 6N5, Canada
- Clinical Epidemiology Program, Ottawa Hospital Research Institute, Ottawa, ON K1N 6N5, Canada
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Dervis S, Poirier MP, Boulay P, Sigal RJ, Malcolm J, Fujii N, Kenny GP. Does the Exercise-Induced Heat Load Influence Whole-Body Heat Loss in Type 1 Diabetes? Med Sci Sports Exerc 2017. [DOI: 10.1249/01.mss.0000516861.96340.87] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Lamarche DT, Louie JC, Notley SR, Poirier MP, Kenny GP. Aerobic Fitness Modulates Whole-body Heat Loss in Young Adult Females during Exercise in the Heat. Med Sci Sports Exerc 2017. [DOI: 10.1249/01.mss.0000518117.32671.71] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Friesen BJ, Poirier MP, Lamarche DT, D’Souza AW, Kim JH, Kenny GP. Postexercise Activation of Muscle Metaboreceptors Modulates Whole-Body Evaporative Heat Loss. Med Sci Sports Exerc 2017. [DOI: 10.1249/01.mss.0000518116.25047.ad] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Poirier MP, Dervis S, Boulay P, Sigal RJ, Malcolm J, Kenny GP. Are Type 2 Diabetes-Related Impairments in Heat Dissipation Heat Load Dependent? Med Sci Sports Exerc 2017. [DOI: 10.1249/01.mss.0000516862.96340.5c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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D’Souza AW, Meade RD, Krishen L, Poirier MP, Kenny GP. A Case Report. Med Sci Sports Exerc 2017. [DOI: 10.1249/01.mss.0000517116.62984.3d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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McGinn R, Poirier MP, Kenny GP. Using heat as a therapeutic tool for the aging vascular tree. Am J Physiol Heart Circ Physiol 2017; 312:H806-H807. [PMID: 28159811 DOI: 10.1152/ajpheart.00827.2016] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/16/2016] [Revised: 01/16/2017] [Accepted: 01/31/2017] [Indexed: 11/22/2022]
Affiliation(s)
- Ryan McGinn
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, Ontario, Canada; and.,Faculty of Medicine, University of Ottawa, Ottawa, Ontario, Canada
| | - Martin P Poirier
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, Ontario, Canada; and
| | - Glen P Kenny
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, Ontario, Canada; and
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Kenny GP, Poirier MP, Metsios GS, Boulay P, Dervis S, Friesen BJ, Malcolm J, Sigal RJ, Seely AJE, Flouris AD. Hyperthermia and cardiovascular strain during an extreme heat exposure in young versus older adults. Temperature (Austin) 2017; 4:79-88. [PMID: 28349096 PMCID: PMC5356213 DOI: 10.1080/23328940.2016.1230171] [Citation(s) in RCA: 52] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2016] [Revised: 08/21/2016] [Accepted: 08/25/2016] [Indexed: 11/21/2022] Open
Abstract
We examined whether older individuals experience greater levels of hyperthermia and cardiovascular strain during an extreme heat exposure compared to young adults. During a 3-hour extreme heat exposure (44°C, 30% relative humidity), we compared body heat storage, core temperature (rectal, visceral) and cardiovascular (heart rate, cardiac output, mean arterial pressure, limb blood flow) responses of young adults (n = 30, 19-28 years) against those of older adults (n = 30, 55-73 years). Direct calorimetry measured whole-body evaporative and dry heat exchange. Body heat storage was calculated as the temporal summation of heat production (indirect calorimetry) and whole-body heat loss (direct calorimetry) over the exposure period. While both groups gained a similar amount of heat in the first hour, the older adults showed an attenuated increase in evaporative heat loss (p < 0.033) in the first 30-min. Thereafter, the older adults were unable to compensate for a greater rate of heat gain (11 ± 1 ; p < 0.05) with a corresponding increase in evaporative heat loss. Older adults stored more heat (358 ± 173 kJ) relative to their younger (202 ± 92 kJ; p < 0.001) counterparts at the end of the exposure leading to greater elevations in rectal (p = 0.043) and visceral (p = 0.05) temperatures, albeit not clinically significant (rise < 0.5°C). Older adults experienced a reduction in calf blood flow (p < 0.01) with heat stress, yet no differences in cardiac output, blood pressure or heart rate. We conclude, in healthy habitually active individuals, despite no clinically observable cardiovascular or temperature changes, older adults experience greater heat gain and decreased limb perfusion in response to 3-hour heat exposure.
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Affiliation(s)
- Glen P. Kenny
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, Canada
- Clinical Epidemiology Program, The Ottawa Hospital Research Institute, Ottawa, Canada
- CONTACT Glen P. Kenny, PhD 125 University Private, Room 367, Montpetit Hall, Ottawa, Ontario K1N 6N5, Canada
| | - Martin P. Poirier
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, Canada
| | - George S. Metsios
- Institute of Sport, Faculty of Education Health and Wellbeing, University of Wolverhampton, Walsall, UK
| | - Pierre Boulay
- Faculty of Physical Activity Sciences, University of Sherbrooke, Sherbrooke, Canada
| | - Sheila Dervis
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, Canada
| | - Brian J. Friesen
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, Canada
| | - Janine Malcolm
- Clinical Epidemiology Program, The Ottawa Hospital Research Institute, Ottawa, Canada
| | - Ronald J. Sigal
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, Canada
- Clinical Epidemiology Program, The Ottawa Hospital Research Institute, Ottawa, Canada
- Departments of Medicine, Cardiac Sciences and Community Health Sciences, Faculties of Medicine and Kinesiology, University of Calgary, Calgary, Canada
| | - Andrew J. E. Seely
- Divisions of Thoracic Surgery and Critical Care Medicine, Ottawa Hospital Research Institute, University of Ottawa, Ottawa, Canada
| | - Andreas D. Flouris
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, Canada
- FAME Laboratory, Department of Exercise Science, University of Thessaly, Trikala, Greece
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Carrillo AE, Flouris AD, Herry CL, Poirier MP, Boulay P, Dervis S, Friesen BJ, Malcolm J, Sigal RJ, Seely AJE, Kenny GP. Heart rate variability during high heat stress: a comparison between young and older adults with and without Type 2 diabetes. Am J Physiol Regul Integr Comp Physiol 2016; 311:R669-R675. [PMID: 27511279 DOI: 10.1152/ajpregu.00176.2016] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2016] [Accepted: 08/08/2016] [Indexed: 11/22/2022]
Abstract
We examined whether older individuals with and without Type 2 diabetes (T2D) experience differences in heart rate variability (HRV) during a 3-h exposure to high heat stress compared with young adults. Young (Young; n = 22; 23 ± 3 yr) and older individuals with (T2D; n = 11; 59 ± 9 yr) and without (Older; n = 25; 63 ± 5 yr) T2D were exposed to heat stress (44°C, 30% relative humidity) for 3 h. Fifty-five HRV measures were assessed for 15 min at baseline and at minutes 82.5-97.5 (Mid) and minutes 165-180 (End) during heat stress. When compared with Young, a similar number of HRV indices were significantly different (P < 0.05) in Older (Baseline: 35; Mid: 29; End: 32) and T2D (Baseline: 31; Mid: 30; End: 27). In contrast, the number of HRV indices significantly different (P < 0.05) between Older and T2D were far fewer (Baseline: 13, Mid: 1, End: 3). Within-group analyses demonstrated a greater change in the Young group's HRV during heat stress compared with Older and T2D; the number of significantly different (P < 0.05) HRV indices between baseline and End were 42, 29, and 20, for Young, Older, and T2D, respectively. Analysis of specific HRV domains suggest that the Young group experienced greater sympathetic activity during heat stress compared with Older and T2D. In conclusion, when compared with young, older individuals with and without T2D demonstrate low HRV at baseline and less change in HRV (including an attenuated sympathetic response) during 3 h high heat stress, potentially contributing to impaired thermoregulatory function.
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Affiliation(s)
- Andres E Carrillo
- FAME Laboratory, Department of Exercise Science, University of Thessaly, Trikala, Greece.,Department of Exercise Science, Chatham University, Pittsburgh, Pennsylvania
| | - Andreas D Flouris
- FAME Laboratory, Department of Exercise Science, University of Thessaly, Trikala, Greece.,Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, Ontario, Canada
| | - Christophe L Herry
- Clinical Epidemiology Program, The Ottawa Hospital Research Institute, Ottawa, Ontario, Canada
| | - Martin P Poirier
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, Ontario, Canada
| | - Pierre Boulay
- Faculty of Physical Activity Sciences, University of Sherbrooke, Sherbrooke, Quebec, Canada
| | - Sheila Dervis
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, Ontario, Canada
| | - Brian J Friesen
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, Ontario, Canada
| | - Janine Malcolm
- Clinical Epidemiology Program, The Ottawa Hospital Research Institute, Ottawa, Ontario, Canada
| | - Ronald J Sigal
- Clinical Epidemiology Program, The Ottawa Hospital Research Institute, Ottawa, Ontario, Canada.,Departments of Medicine, Cardiac Sciences, and Community Health Sciences, Faculties of Medicine and Kinesiology, University of Calgary, Calgary, Alberta, Canada; and
| | - Andrew J E Seely
- Thoracic Surgery and Critical Care Medicine, Ottawa Hospital Research Institute, University of 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, The Ottawa Hospital Research Institute, Ottawa, Ontario, Canada
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Poirier MP, Gagnon D, Kenny GP. Local versus whole-body sweating adaptations following 14 days of traditional heat acclimation. Appl Physiol Nutr Metab 2016; 41:816-24. [DOI: 10.1139/apnm-2015-0698] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
The purpose of this study was to examine if local changes in sweat rate following 14 days of heat acclimation reflect those that occur at the whole-body level. Both prior to and following a 14-day traditional heat acclimation protocol, 10 males exercised in the heat (35 °C, ∼20% relative humidity) at increasing rates of heat production equal to 300 (Ex1), 350 (Ex2), and 400 (Ex3) W·m−2. A 10-min recovery period followed Ex1, while a 20-min recovery period separated Ex2 and Ex3. The exercise protocol was performed in a direct calorimeter to measure whole-body sweat rate and, on a separate day, in a thermal chamber to measure local sweat rate (LSR), sweat gland activation (SGA), and sweat gland output (SGO) on the upper back, chest, and mid-anterior forearm. Post-acclimation, whole-body sweat rate was greater during each exercise bout (Ex1: 14.3 ± 0.9; Ex2: 17.3 ± 1.2; Ex3: 19.4 ± 1.3 g·min−1, all p ≤ 0.05) relative to pre-acclimation (Ex1: 13.1 ± 0.6; Ex2: 15.4 ± 0.8; Ex3: 16.5 ± 1.3 g·min−1). In contrast, only LSR on the forearm increased with acclimation, and this increase was only observed during Ex2 (Post: 1.32 ± 0.33 vs. Pre: 1.06 ± 0.22 mg·min−1·cm−2, p = 0.03) and Ex3 (Post: 1.47 ± 0.41 vs. Pre: 1.17 ± 0.23 mg·min−1·cm−2, p = 0.05). The greater forearm LSR post-acclimation was due to an increase in SGO, as no changes in SGA were observed. Overall, these data demonstrate marked regional variability in the effect of heat acclimation on LSR, such that not all local measurements of sweat rate reflect the improvements observed at the whole-body level.
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Affiliation(s)
- Martin P. Poirier
- School of Human Kinetics, Faculty of Health Sciences, University of Ottawa, Ottawa, ON K1N 6N5, Canada
| | - Daniel Gagnon
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital of Dallas and University of Texas Southwestern Medical Center, Dallas, TX 75231, USA
| | - Glen P. Kenny
- School of Human Kinetics, Faculty of Health Sciences, University of Ottawa, Ottawa, ON K1N 6N5, Canada
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Friesen BJ, Lauzon MA, Blondin DP, Haman F, Poirier MP, Kenny GP. Does the Rate of Heat Storage Define Exercise Intensity Level During Self-paced Exercise at a Fixed Rating of Perceived Exertion? Med Sci Sports Exerc 2016. [DOI: 10.1249/01.mss.0000487423.76265.37] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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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; 4:4/6/e12738. [PMID: 27033452 PMCID: PMC4814883 DOI: 10.14814/phy2.12738] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [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 cm2) and compared the sweating response with a classic capsule (2.8 cm2). In Protocol 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. In Protocol 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 cm2). In Protocol 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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Lamarche DT, Meade RD, McGinn R, Poirier MP, Friesen BJ, Kenny GP. Temperature of Ingested Water during Exercise Does Not Affect Body Heat Storage. Med Sci Sports Exerc 2016; 47:1272-80. [PMID: 25259541 DOI: 10.1249/mss.0000000000000533] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
PURPOSE The objective of this study was to examine the effect of ingested water temperature on heat balance during exercise as assessed by direct calorimetry. METHODS Ten healthy males (25 ± 4 yr) cycled at 50% V˙O2peak (equivalent rate of metabolic heat production (M-W) of 523 ± 84 W) for 75 min under thermocomfortable conditions (25°C, 25% relative humidity) while consuming either hot (50°C) or cold (1.5°C) water. Four 3.2 mL·kg⁻¹ boluses of hot or cold water were consumed 5 min before and at 15, 30, and 45 min after the onset of exercise. Total heat loss (HL = evaporative heat loss (HE) ± dry heat exchange (HD)) and M-W were measured by direct and indirect calorimetry, respectively. Change in body heat content (ΔHb) was calculated as the temporal summation of M-W and HL and adjusted for changes in heat transfer from the ingested fluid (Hfluid). RESULTS The absolute difference for HL (209 ± 81 kJ) was similar to the absolute difference of Hfluid (204 ± 36 kJ) between conditions (P = 0.785). Furthermore, the difference in HL was primarily explained by the corresponding changes in HE (hot: 1538 ± 393 kJ; cold: 1358 ± 330 kJ) because HD was found to be similar between conditions (P = 0.220). Consequently, no difference in ΔHb was observed between the hot (364 ± 152 kJ) and cold (363 ± 134 kJ) conditions (P = 0.971) during exercise. CONCLUSION We show that ingestion of hot water elicits a greater HL relative to cold water ingestion during exercise. However, this response was only compensated for the heat of the ingested fluid as evidenced by similar ΔHb between conditions. Therefore, our findings indicate that relative to cold water ingestion, consuming hot water does not provide a thermoregulatory advantage. Both hot and cold water ingestion results in the same amount of heat stored during prolonged moderate-intensity exercise.
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Affiliation(s)
- Dallon T Lamarche
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, Ontario, CANADA
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Abstract
We assessed the physical demands associated with electrical utilities work in North America and how they influence the level of thermal and cardiovascular strain experienced. Three common job categories were monitored as they are normally performed in thirty-two electrical utility workers: (i) Ground Work (n = 11), (ii) Bucket Work (n = 9), and (iii) Manual Pole Work (n = 12). Video analysis was performed to determine the proportion of the work monitoring period (duration: 187 ± 104 min) spent at different levels of physical effort (i.e., rest as well as light, moderate and heavy effort). Core and skin temperatures as well as heart rate were measured continuously. On average, workers spent 35.9 ± 15.9, 36.8 ± 17.8, 24.7 ± 12.8, and 2.6 ± 3.3% of the work period at rest and performing work classified as light, moderate, and heavy physical effort, respectively. Moreover, a greater proportion of the work period was spent performing heavy work in Ground Work (1.6 ± 1.4%) relative to Bucket Work (0.0 ± 0.0%; P<0.01) and in Manual Pole Climbing (5.5 ± 3.6%) in comparison to both other work job (both P≤0.03). Furthermore, the proportion of time spent during work classified as heavy physical effort was positively correlated to the mean (r = 0.51, P<0.01) and peak (r = 0.42, P = 0.02) core temperatures achieved during the work period as well as the mean heart rate response (presented as a percentage of heart rate reserve; r = 0.40, P = 0.03). Finally, mean and peak core temperatures and mean heart rate responses increased from the first to the second half of the work shift; however, no differences in the proportion of the work spent at the different intensity classifications were observed. We show that Manual Pole Work is associated with greater levels of physical effort compared to Ground or Bucket Work. Moreover, we suggest that the proportion of time spent performing work classified as heavy physical exertion is related to the level of thermal and cardiovascular strain experienced and that workers may not be employing self-pacing as a strategy to manage their level of physiological strain.
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Affiliation(s)
- Robert D Meade
- a Human and Environmental Physiology Research Unit, School of Human Kinetics , University of Ottawa , Ottawa , ON , Canada
| | - Martin Lauzon
- a Human and Environmental Physiology Research Unit, School of Human Kinetics , University of Ottawa , Ottawa , ON , Canada
| | - Martin P Poirier
- a Human and Environmental Physiology Research Unit, School of Human Kinetics , University of Ottawa , Ottawa , ON , Canada
| | - Andreas D Flouris
- a Human and Environmental Physiology Research Unit, School of Human Kinetics , University of Ottawa , Ottawa , ON , Canada
- b FAME Laboratory, Department of Exercise Science , University of Thessaly , Trikala , Greece
| | - Glen P Kenny
- a Human and Environmental Physiology Research Unit, School of Human Kinetics , University of Ottawa , Ottawa , ON , Canada
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Abstract
PURPOSE We examined the effect of differences in body surface area-to-lean body mass ratio (AD/LBM) on core temperature cooling rates during cold water immersion (CWI, 2°C) and temperate water immersion (TWI, 26°C) after exercise-induced hyperthermia. METHODS Twenty male participants were divided into two groups: high (315.6 ± 7.9 cm·kg, n = 10) and low (275.6 ± 8.6 cm·kg, n = 10) AD/LBM. On two separate occasions, participants ran on a treadmill in the heat (40.0°C, 20% relative humidity) wearing an impermeable rain suit until rectal temperature reached 40.0°C. After exercise, participants were immersed up to the nipples (arms remained out of the water) in either a CWI (2°C) or a TWI (26°C) circulated water bath until rectal temperature returned to 37.5°C. RESULTS Overall rectal cooling rates were significantly different between experimental groups (high vs low AD/LBM, P = 0.005) and between immersion conditions (CWI vs TWI, P < 0.001). Individuals with a high AD/LBM had an approximately 1.7-fold greater overall rectal cooling rate relative to those with low AD/LBM during both CWI (high: 0.27°C·min ± 0.10°C·min vs low: 0.16°C·min ± 0.10°C·min) and TWI (high: 0.10°C·min ± 0.05°C·min vs low: 0.06°C·min ± 0.02°C·min). Further, the overall rectal cooling rates during CWI were approximately 2.7-fold greater than during TWI for both the high (CWI: 0.27°C·min ± 0.10°C·min vs TWI: 0.10°C·min ± 0.05°C·min) and the low (CWI: 0.16°C·min ± 0.10°C·min vs TWI: 0.06°C·min ± 0.02°C·min) AD/LBM groups. CONCLUSION We show that individuals with a low AD/LBM have a reduced rectal cooling rate and take longer to cool than those with a high AD/LBM during both CWI and TWI. However, CWI provides the most effective cooling treatment irrespective of physical differences.
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Affiliation(s)
- Brian J Friesen
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, ON, CANADA
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Lamarche DT, Meade RD, McGinn R, Poirier MP, Friesen BJ, Kenny GP. Response. Med Sci Sports Exerc 2015; 47:1318. [PMID: 25978350 DOI: 10.1249/mss.0000000000000639] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Affiliation(s)
- Dallon T Lamarche
- Human and Environmental Physiology Research Unit School of Human Kinetics, University of Ottawa Ottawa, ON, CANADA
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Friesen BJ, Poirier MP, Gagnon D, McGinn R, Kenny GP. The Influence of Physical Characteristics in the Treatment of Exertional Hyperthermia by Cold Water Immersion. Med Sci Sports Exerc 2015. [DOI: 10.1249/01.mss.0000477699.78133.d8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Meade RD, Lauzon M, Poirier MP, Flouris AD, Kenny GP. An Evaluation of the Physiological Strain Experienced by North American Electrical Utility Workers. Med Sci Sports Exerc 2015. [DOI: 10.1249/01.mss.0000478966.93951.b8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Kenny GP, Flouris AD, Dervis S, Friesen BJ, Sigal RJ, Malcolm J, Poirier MP. Older Adults Experience Greater Levels of Thermal and Cardiovascular Strain During Extreme Heat Exposures. Med Sci Sports Exerc 2015. [DOI: 10.1249/01.mss.0000477799.65084.9a] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Poirier MP, Friesen BJ, McGinn R, Meade RD, Hardcastle SG, Flouris AD, Kenny GP. Does Fire And Arc-resistant Clothing Influence Whole-body Heat Dissipation During Work In The Heat? Med Sci Sports Exerc 2015. [DOI: 10.1249/01.mss.0000477801.42213.e5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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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] [What about the content of this article? (0)] [Affiliation(s)] [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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Meade RD, Lauzon M, Poirier MP, Flouris AD, Kenny GP. An Evaluation of the Physiological Strain Experienced by Electrical Utility Workers in North America. J Occup Environ Hyg 2015; 12:708-720. [PMID: 26011148 DOI: 10.1080/15459624.2015.1043054] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The purpose of this study was to assess the physiological strain experienced by North American electrical utility workers during the performance of their normal work duties in heat stressed conditions. Three common job categories were monitored as they are normally performed in 32 electrical utility workers: (i) Ground Work (n = 11); (ii) Bucket Work (n = 9); and (iii) Manual Pole Work (n = 12). Worker hydration status (urine specific gravity (USG)) was measured prior to and following the work monitoring period (duration: 187 ± 104 min). Core and skin temperatures as well as heart rate were measured continuously. Physiological Strain Index (PSI) was calculated from the measurements of core temperature and heart rate. Prior to the start of the work shift, 38% of workers were euhydrated (USG < 1.020; n = 12) whereas the majority of workers were dehydrated (USG > 1.020; prevalence: 75%; p < 0.01) following work. The overall mean and peak core temperatures for all monitored workers were 37.9 ± 0.3 °C and 38.3 ± 0.5 °C, respectively. When responses were compared between job categories, greater mean and peak increases in core temperature were observed in Manual Pole Work relative to the other job categories (both p < 0.04). In fact, six workers performing Manual Pole Work achieved core temperatures in excess of 38.5 °C, while only one other worker surpassed this threshold in Bucket Work. The high levels of thermal strain were paralleled by elevated mean and peak heart rate and PSI responses, which were greater in Manual Pole Work in comparison to the other job categories (all p ≤ 0.05). Furthermore, two workers performing Manual Pole Work achieved severely elevated core temperatures reaching or exceeding 39.5 °C along with prolonged periods of near maximal heart rate responses (i.e., >90% of heart rate reserve). We report elevated levels of thermal and cardiovascular strain in electrical utility workers during work in the heat and potentially dangerous levels of hyperthermia during particularly strenuous work.
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Affiliation(s)
- Robert D Meade
- a Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa , Ottawa , Ontario , Canada
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Poirier MP, Meade RD, McGinn R, Friesen BJ, Hardcastle SG, Flouris AD, Kenny GP. The Influence of Arc-Flash and Fire-Resistant Clothing on Thermoregulation during Exercise in the Heat. J Occup Environ Hyg 2015; 12:654-667. [PMID: 25898230 DOI: 10.1080/15459624.2015.1029615] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
We evaluated the effect of arc-flash and fire-resistant (AFR) clothing ensembles (CE) on whole-body heat dissipation during work in the heat. On 10 occasions, 7 males performed four 15-min cycling bouts at a fixed rate of metabolic heat production (400 W) in the heat (35°C), each separated by 15-min of recovery. Whole-body heat loss and metabolic heat production were measured by direct and indirect calorimetry, respectively. Body heat storage was calculated as the temporal summation of heat production and heat loss. Responses were compared in a semi-nude state and while wearing two CE styles: (1) single-piece (coveralls) and (2) two-piece (workpant + long-sleeve shirt). For group 1, there was one non-AFR single-piece CE (CE1STD) and three single-piece CE with AFR properties (CE2AFR, CE3AFR, CE4AFR). For group 2, there was one non-AFR two-piece CE (CE5STD) and four two-piece CE with AFR properties (CE6AFR, CE7AFR, CE8AFR, CE9AFR). The workpants for CE6AFR were not AFR-rated, while a cotton undershirt was also worn for conditions CE8AFR and CE9AFR and for all single-piece CE. Heat storage for all conditions (CE1STD: 328 ± 55, CE2AFR: 335 ± 87, CE3AFR: 309 ± 95, CE4AFR: 403 ± 104, CE5STD: 253 ± 78, CE6AFR: 268 ± 89, CE7AFR: 302 ± 70, CE8AFR: 360 ± 36, CE9AFR: 381 ± 99 kJ) was greater than the semi-nude state (160 ± 124 kJ) (all p ≤ 0.05). No differences were measured between single-piece uniforms (p = 0.273). Among the two-piece uniforms, heat storage was greater for CE8AFR and CE9AFR relative to CE5STD and CE6AFR (all p ≤ 0.05), but not CE7AFR (both p > 0.05). Differences between clothing styles were measured such that greater heat storage was observed in both CE1STD and CE2-4AFR relative to CE5STD. Further, heat storage was greater in CE2AFR and CE4AFR relative to CE6AFR, while it was greater in CE4AFR compared to CE7AFR. Body heat storage during work in the heat was not influenced by the use of AFR fabrics in the single- or two-piece uniforms albeit less heat was stored in the two-piece uniforms when no undershirt was worn. However, heat storage was comparable between clothing styles when an undershirt was worn with the two-piece uniform.
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Affiliation(s)
- Martin P Poirier
- a Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa , Ottawa , Ontario , Canada
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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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Poirier MP, Friesen BJ, Hardcastle SG, Kenny GP. Local Sweat Rates do not Accurately Represent Whole-Body Evaporative Heat Loss following 14-day Dry-Heat Acclimation. Med Sci Sports Exerc 2014. [DOI: 10.1249/01.mss.0000494119.59966.28] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Friesen BJ, Poirier MP, Hardcastle SG, Kenny GP. The Influence of Fire and Arc-Resistant Clothing on Heat Dissipation During Work in the Heat. Med Sci Sports Exerc 2014. [DOI: 10.1249/01.mss.0000496299.80492.e0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Abstract
OBJECTIVE The objective was to determine whether 2 days of oral dexamethasone (DEX) is more effective than 5 days of oral prednisone/prednisolone (PRED) in improving symptoms and preventing relapse in children with acute asthma. STUDY DESIGN This was a prospective randomized trial of children (2 to 18 years old) who presented to the emergency department with acute asthma. PRED 2 mg/kg, maximum 60 mg (odd days) or DEX 0.6 mg/kg, maximum 16 mg (even days) was used. At discharge children in the PRED group were prescribed 4 daily doses (1 mg/kg/d, maximum 60 mg); children in the DEX group received a prepackaged dose (0.6 mg/kg, maximum 16 mg) to take the next day. The primary outcome was relapse within 10 days. RESULTS When DEX was compared with PRED, relapse rates (7.4% of 272 vs 6.9% of 261), hospitalization rates from the emergency department (11% vs 12%) or after relapse (20% vs 17%), and symptom persistence at 10 days (22% vs 21%) were similar. In the PRED group more children were excluded for vomiting in the emergency department (3% vs 0.3%; P =.008), more parents were noncompliant (4% vs. 0.4%; P =.004), and more children missed > or =2 days of school (19.5% vs. 13.2%; P =.05). CONCLUSION In children with acute asthma, 2 doses of dexamethasone provide similar efficacy with improved compliance and fewer side effects than 5 doses of prednisone.
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Affiliation(s)
- F Qureshi
- Department of Pediatrics and the Division of Pediatric Emergency Medicine, Children's Hospital of The Kings Daughters and Eastern Virginia Medical School, Norfolk, Virginia 23507, USA
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Abstract
Concussion is the most common head injury occurring in sports participation. Concussions range from a brief period of neural dysfunction to a prolonged period of unconsciousness with retrograde amnesia. It is imperative that the pediatric emergency medicine specialist be familiar with the proper initial assessment of the child or adolescent athlete who has sustained a sports-related concussion, the latest grading scales of concussions, and the current recommendations for returning the athlete to competition. A systematic approach to the athlete who has suffered a concussion will minimize the risk of further injury or mortality.
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Affiliation(s)
- M P Poirier
- Division of Emergency Medicine, Children's Hospital of The King's Daughters, Eastern Virginia Medical School, Norfolk, Virginia 23507, USA
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