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Leicht AS, Flouris AD, Kaltsatou A, Seely AJ, Herry CL, Wright Beatty HE, Kenny GP. Age alters cardiac autonomic modulations during and following exercise-induced heat stress in females. Temperature (Austin) 2018; 5:184-196. [PMID: 30377635 DOI: 10.1080/23328940.2018.1432918] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2017] [Revised: 01/26/2018] [Accepted: 02/07/2018] [Indexed: 12/19/2022] Open
Abstract
The aim of this study was to examine the effect of natural ageing on heart rate variability during and following exercise-induced heat stress in females. Eleven young (∼24 years) and 13 older (∼51 years), habitually active females completed an experimental session consisting of baseline rest, moderate intensity intermittent exercise (four 15-min bouts separated by 15-min recovery) and 1-hour of final recovery in a hot and dry (35°C, 20% relative humidity) environment. Respiratory and heart rate recordings were continuously logged with 10-min periods analysed at the end of: baseline rest; each of the exercise and recovery bouts; and during the 1-hour final recovery period. Comparisons over time during exercise and recovery, and between groups were conducted via two-way repeated-measures ANCOVAs with rest values as the covariate. During baseline rest, older females exhibited lower heart rate variability compared to young females with similar levels of respiration and most (∼71-79%) heart rate variability measures during repeated exercise and recovery. However, older females exhibited heart rate variability metrics suggestive of greater parasympathetic modulation (greater long axis of Poincare plot, cardiac vagal index; lower low-high frequency ratio) during repeated exercise with lower indices during the latter stage of prolonged recovery (less very low frequency component, Largest Lyapunov Exponent; greater cardiac sympathetic index). The current study documented several unique, age-dependent differences in heart rate variability, independent of respiration, during and following exercise-induced heat stress for females that may assist in the detection of normal heat-induced adaptations as well as individuals vulnerable to heat stress.
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Affiliation(s)
- Anthony S Leicht
- Sport and Exercise Science, James Cook University, Townsville, Australia
| | - Andreas D Flouris
- FAME Laboratory, Department of Exercise Science, University of Thessaly, Trikala, Greece
| | - Antonia Kaltsatou
- FAME Laboratory, Department of Exercise Science, University of Thessaly, Trikala, Greece
| | - Andrew J Seely
- Divisions of Thoracic Surgery and Critical Care Medicine, Ottawa Hospital Research Institute, University of Ottawa, Ottawa, Ontario, Canada
| | - Christophe L Herry
- Dynamical Analysis Lab, Clinical Epidemiology Program, Ottawa Hospital Research Institute, Ontario, Canada
| | | | - Glen P Kenny
- Human and Environmental Physiology Research Unit, University of Ottawa, Ontario, Canada
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52
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Di Giulio C. Ageing of the carotid body. J Physiol 2018; 596:3021-3027. [PMID: 29319194 DOI: 10.1113/jp275300] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2017] [Accepted: 01/05/2018] [Indexed: 02/03/2023] Open
Abstract
The ageing process is characterized by a decline in several physiological functions resulting in a reduced capability to maintain homeostasis. The lowered homeostatic capacity seems to involve the carotid body (CB), whose role is to modulate ventilation and tissue oxygen supply. It thus plays a prime role in all ageing processes. Ageing causes marked changes in CB morphology. In older animals, it is enlarged and shows a concomitant decrease in the percentage of chemoreceptor tissue, as well as a proliferation of type II cells. The carotid glomitis is present with aggregates of lymphocytes and fibrosis of the lobules. Type I cells are dehydrated, with a profound vacuolization, a shrinking nucleus, and lipofuscin accumulation. With increased age, human CB shows a reduction in the number and volume of mitochondria, fewer synaptic junctions between glomi, along with a reduction in CB content of neurotransmitters, leading to a sort of 'physiological denervation'. Ageing could be interpreted as a cumulative result of oxidative damage to cells, which derives from aerobic metabolism. Moreover, metabolic rate is tightly correlated with life duration; thus a loss in mitochondrial function is one of the prime factors affecting CB ageing processes. The age-related reduction in synaptic junctions might be a self-protective mechanism through which cells buffer themselves against an accumulation of reactive oxygen species. The correlation between hypoxia and the life duration of CB cells remains an open question until how and why cells sense oxygen is understood.
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Affiliation(s)
- Camillo Di Giulio
- Department of Neurosciences Imaging and Clinical Sciences, "G. d'Annunzio" University of Chieti-Pescara, Italy
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54
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Schoffelen PFM, Plasqui G. Classical experiments in whole-body metabolism: open-circuit respirometry-diluted flow chamber, hood, or facemask systems. Eur J Appl Physiol 2018; 118:33-49. [PMID: 29080000 PMCID: PMC5754424 DOI: 10.1007/s00421-017-3735-5] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2017] [Accepted: 09/30/2017] [Indexed: 11/25/2022]
Abstract
For over two centuries, scientists have measured gas exchange in animals and humans and linked this to energy expenditure of the body. The aim of this review is to provide a comprehensive overview of open-circuit diluted flow indirect calorimetry and to help researchers to make the optimal choice for a certain system and its application. A historical perspective shows that 'open circuit diluted flow' is a technique first used in the 19th century and applicable today for room calorimeters, ventilated hood systems, and facemasks. Room calorimeters are a classic example of an open-circuit diluted flow system. The broadly applied ventilated hood calorimeters follow the same principle and can be classified as a derivative of these room calorimeters. The basic principle is that the subject breathes freely in a passing airflow that is fully captured and analyzed. Oxygen and CO2 concentrations are measured in inlet ambient air and captured outlet air. The airflow, which is adapted depending on the application (e.g., rest versus exercise), is measured. For a room indirect calorimeter, the dilution in the large room volume is also taken into account, and this is the most complex application of this type of calorimeter. Validity of the systems can be tested by alcohol burns, gas infusions and by performing repeated measurements on subjects. Using the latter, the smallest CV (%) was found for repeated VO2max tests (1.2%) with an SD of approximately 1 kJ min-1. The smallest SD was found for sleeping metabolic rate (0.11 kJ min-1) with a CV (%) of 2.4%.
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Affiliation(s)
- P F M Schoffelen
- Department of Human Biology and Movement Sciences, NUTRIM School of Nutrition and Translational Research in Metabolism, Maastricht University Medical Centre +, PO Box 616, 6200 MD, Maastricht, The Netherlands
| | - G Plasqui
- Department of Human Biology and Movement Sciences, NUTRIM School of Nutrition and Translational Research in Metabolism, Maastricht University Medical Centre +, PO Box 616, 6200 MD, Maastricht, The Netherlands.
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55
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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] [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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56
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McNeely BD, Meade RD, Fujii N, Seely AJE, Sigal RJ, Kenny GP. Fluid replacement modulates oxidative stress- but not nitric oxide-mediated cutaneous vasodilation and sweating during prolonged exercise in the heat. Am J Physiol Regul Integr Comp Physiol 2017; 313:R730-R739. [PMID: 28931548 PMCID: PMC5814697 DOI: 10.1152/ajpregu.00284.2017] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2017] [Revised: 09/11/2017] [Accepted: 09/11/2017] [Indexed: 01/29/2023]
Abstract
The roles of nitric oxide synthase (NOS), reactive oxygen species (ROS), and angiotensin II type 1 receptor (AT1R) activation in regulating cutaneous vasodilation and sweating during prolonged (≥60 min) exercise are currently unclear. Moreover, it remains to be determined whether fluid replacement (FR) modulates the above thermoeffector responses. To investigate, 11 young men completed 90 min of continuous moderate intensity (46% V̇o2peak) cycling performed at a fixed rate of metabolic heat production of 600 W (No FR condition). On a separate day, participants completed a second session of the same protocol while receiving FR to offset sweat losses (FR condition). Cutaneous vascular conductance (CVC) and local sweat rate (LSR) were measured at four intradermal microdialysis forearm sites perfused with: 1) lactated Ringer (Control); 2) 10 mM NG-nitro-l-arginine methyl ester (l-NAME, NOS inhibition); 3) 10 mM ascorbate (nonselective antioxidant); or 4) 4.34 nM losartan (AT1R inhibition). Relative to Control (71% CVCmax at both time points), CVC with ascorbate (80% and 83% CVCmax) was elevated at 60 and 90 min of exercise during FR (both P < 0.02) but not at any time during No FR (all P > 0.31). In both conditions, CVC was reduced at end exercise with l-NAME (60% CVCmax; both P < 0.02) but was not different relative to Control at the losartan site (76% CVCmax; both P > 0.19). LSR did not differ between sites in either condition (all P > 0.10). We conclude that NOS regulates cutaneous vasodilation, but not sweating, irrespective of FR, and that ROS influence cutaneous vasodilation during prolonged exercise with FR.
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Affiliation(s)
- Brendan D McNeely
- Human and Environmental Physiology Research Unit, University of Ottawa, Ottawa, Canada
| | - Robert D Meade
- Human and Environmental Physiology Research Unit, University of Ottawa, Ottawa, Canada
| | - Naoto Fujii
- Human and Environmental Physiology Research Unit, University of Ottawa, Ottawa, Canada
- Faculty of Health and Sports Science, University of Tsukuba, Tsukuba, Japan
| | - Andrew J E Seely
- Thoracic Surgery and Critical Care Medicine, Ottawa Hospital Research Institute, University of Ottawa, Ontario, Canada
| | - Ronald J Sigal
- Human and Environmental Physiology Research Unit, University of Ottawa, Ottawa, Canada
- Clinical Epidemiology Program, Ottawa Hospital Research Institute, Ottawa, Ontario, Canada; and
- Departments of Medicine, Cardiac Sciences and Community Health Sciences, Faculties of Medicine and Kinesiology University of Calgary, Calgary, Alberta, Canada
| | - Glen P Kenny
- Human and Environmental Physiology Research Unit, University of Ottawa, Ottawa, Canada;
- Clinical Epidemiology Program, Ottawa Hospital Research Institute, Ottawa, Ontario, Canada; and
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57
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NOTLEY SEANR, POIRIER MARTINP, HARDCASTLE STEPHENG, FLOURIS ANDREASD, BOULAY PIERRE, SIGAL RONALDJ, KENNY GLENP. Aging Impairs Whole-Body Heat Loss in Women under Both Dry and Humid Heat Stress. Med Sci Sports Exerc 2017; 49:2324-2332. [DOI: 10.1249/mss.0000000000001342] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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58
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Piil JF, Lundbye-Jensen J, Trangmar SJ, Nybo L. Performance in complex motor tasks deteriorates in hyperthermic humans. Temperature (Austin) 2017; 4:420-428. [PMID: 29435481 PMCID: PMC5800368 DOI: 10.1080/23328940.2017.1368877] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2017] [Revised: 08/11/2017] [Accepted: 08/11/2017] [Indexed: 10/25/2022] Open
Abstract
Heat stress, leading to elevations in whole-body temperature, has a marked impact on both physical performance and cognition in ecological settings. Lab experiments confirm this for physically demanding activities, whereas observations are inconsistent for tasks involving cognitive processing of information or decision-making prior to responding. We hypothesized that divergences could relate to task complexity and developed a protocol consisting of 1) simple motor task [TARGET_pinch], 2) complex motor task [Visuo-motor tracking], 3) simple math task [MATH_type], 4) combined motor-math task [MATH_pinch]. Furthermore, visuo-motor tracking performance was assessed both in a separate- and a multipart protocol (complex motor tasks alternating with the three other tasks). Following familiarization, each of the 10 male subjects completed separate and multipart protocols in randomized order in the heat (40°C) or control condition (20°C) with testing at baseline (seated rest) and similar seated position, following exercise-induced hyperthermia (core temperature ∼ 39.5°C in the heat and 38.2°C in control condition). All task scores were unaffected by control exercise or passive heat exposure, but visuo-motor tracking performance was reduced by 10.7 ± 6.5% following exercise-induced hyperthermia when integrated in the multipart protocol and 4.4 ± 5.7% when tested separately (both P < 0.05). TARGET_pinch precision declined by 2.6 ± 1.3% (P < 0.05), while no significant changes were observed for the math tasks. These results indicate that heat per se has little impact on simple motor or cognitive test performance, but complex motor performance is impaired by hyperthermia and especially so when multiple tasks are combined.
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Affiliation(s)
- Jacob F Piil
- Department of Nutrition, Exercise and Sports, August Krogh Building, University of Copenhagen, Copenhagen, Denmark
| | - Jesper Lundbye-Jensen
- Department of Nutrition, Exercise and Sports, August Krogh Building, University of Copenhagen, Copenhagen, Denmark
| | - Steven J Trangmar
- Department of Life Sciences, University of Roehampton, London, United Kingdom
| | - Lars Nybo
- Department of Nutrition, Exercise and Sports, August Krogh Building, University of Copenhagen, Copenhagen, Denmark
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59
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Fujii N, McNeely BD, Nishiyasu T, Kenny GP. Intradermal administration of atrial natriuretic peptide has no effect on sweating and cutaneous vasodilator responses in young male adults. Temperature (Austin) 2017; 4:406-413. [PMID: 29435479 DOI: 10.1080/23328940.2017.1356433] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2017] [Revised: 07/07/2017] [Accepted: 07/07/2017] [Indexed: 01/27/2023] Open
Abstract
Atrial natriuretic peptide (ANP) increases during exercise in the heat wherein heat loss responses of sweating and cutaneous vasodilatation are activated. Hence ANP might be involved in the regulation of sweating and cutaneous vasodilatation. However, whether ANP directly mediates sweating and cutaneous vasodilatation needs to be clarified. Also, muscarinic receptor activation induces sweating and cutaneous vasodilatation, however, it remains to be determined whether ANP modulates these responses. In this study, in 11 young males (25 ± 5 years), cutaneous vascular conductance and sweat rate were assessed at intradermal microdialysis sites that were continuously perfused with either lactated Ringer (Control) or 3 different concentrations of ANP (0.1, 1, 10 µM). All 4 sites were co-administrated with methacholine, a muscarinic receptor agonist, in a dose-dependent fashion (0.0125, 0.25, 5, 100, and 2000 mM, 25 min for each). ANP at all concentrations did not increase sweat rate and cutaneous vascular conductance as compared with pre-ANP infusion values (all P > 0.05). Methacholine increased both sweat rate and cutaneous vascular conductance (all P ≤ 0.05). However, the responses were unaffected by co-administration of ANP relative to methacholine only, even as assessed in context of the methacholine concentration required to elicit 50% of the maximal response (EC50) (all P > 0.05). We show that exogenous ANP administration intradermally does not directly modulate sweating and cutaneous vasodilatation under room temperature conditions in resting young adults. Further, there is no effect of ANP on muscarinic sweating and cutaneous vasodilatation.
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Affiliation(s)
- Naoto Fujii
- Human and Environmental Physiology Research Unit, University of Ottawa, Ottawa, Canada.,Institute of Health and Sport Sciences, University of Tsukuba, Tsukuba City, Japan
| | - Brendan D McNeely
- Human and Environmental Physiology Research Unit, University of Ottawa, Ottawa, Canada
| | - Takeshi Nishiyasu
- Institute of Health and Sport Sciences, University of Tsukuba, Tsukuba City, Japan
| | - Glen P Kenny
- Human and Environmental Physiology Research Unit, University of Ottawa, Ottawa, Canada
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60
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Fujii N, Meade RD, Akbari P, Louie JC, Alexander LM, Boulay P, Sigal RJ, Kenny GP. No effect of ascorbate on cutaneous vasodilation and sweating in older men and those with type 2 diabetes exercising in the heat. Physiol Rep 2017; 5:e13238. [PMID: 28400505 PMCID: PMC5392524 DOI: 10.14814/phy2.13238] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2017] [Accepted: 03/11/2017] [Indexed: 12/23/2022] Open
Abstract
Aging and chronic disease such as type 2 diabetes (T2D) are associated with impairments in the body's ability to dissipate heat. To reduce the risk of heat-related injuries in these heat vulnerable individuals, it is necessary to identify interventions that can attenuate this impairment. We evaluated the hypothesis that intradermal administration of ascorbate improves cutaneous vasodilation and sweating in older adults via nitric oxide synthase (NOS)-dependent mechanisms during exercise in the heat and whether these improvements, if any, are greater in individuals with T2D. Older males with (n = 12, 61 ± 9 years) and without (n = 12, 64 ± 7 years) T2D performed two 30-min bouts of cycling at a fixed rate of metabolic heat production of 500 W (~70% peak oxygen uptake) in the heat (35°C); each followed by a 20- and 40-min recovery, respectively. Cutaneous vascular conductance (CVC) and sweat rate were measured at four intradermal microdialysis sites treated with either (1) lactated Ringer (Control), (2) 10 mmol/L ascorbate (an antioxidant), (3) 10 mmol/L L-NAME (non-selective NOS inhibitor), or (4) a combination of ascorbate + L-NAME. In both groups, ascorbate did not modulate CVC or sweating during exercise relative to Control (all P > 0.05). In comparison to Control, L-NAME alone or combined with ascorbate attenuated CVC during exercise (all P ≤ 0.05) but had no influence on sweating (all P > 0.05). We show that in both healthy and T2D older adults, intradermal administration of ascorbate does not improve cutaneous vasodilation and sweating during exercise in the heat. However, NOS plays an important role in mediating cutaneous vasodilation.
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Affiliation(s)
- Naoto Fujii
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, Ontario, Canada
- Institute of Health and Sport Sciences, University of Tsukuba, Tsukuba City, Japan
| | - Robert D Meade
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, Ontario, Canada
| | - Pegah Akbari
- 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
| | - Lacy M Alexander
- Department of Kinesiology, Noll Laboratory, Pennsylvania State University, University Park, Pennsylvania
| | - Pierre Boulay
- Faculty of Physical Activity Sciences, University of Sherbrooke, Sherbrooke, Canada
| | - Ronald J Sigal
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, Ontario, Canada
- Departments of Medicine, Cardiac Sciences and Community Health Sciences, Faculties of Medicine and Kinesiology, University of Calgary, Calgary, Alberta, Canada
- Clinical Epidemiology Program, Ottawa Hospital Research Institute, Ottawa, Ontario, Canada
| | - Glen P Kenny
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, Ontario, Canada
- Clinical Epidemiology Program, Ottawa Hospital Research Institute, Ottawa, Ontario, Canada
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61
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Pallubinsky H, Schellen L, Kingma BRM, Dautzenberg B, van Baak MA, van Marken Lichtenbelt WD. Thermophysiological adaptations to passive mild heat acclimation. Temperature (Austin) 2017; 4:176-186. [PMID: 28680933 PMCID: PMC5489020 DOI: 10.1080/23328940.2017.1303562] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2017] [Revised: 03/03/2017] [Accepted: 03/03/2017] [Indexed: 01/09/2023] Open
Abstract
Passive mild heat acclimation (PMHA) reflects realistic temperature challenges encountered in everyday life. Active heat acclimation, combining heat exposure and exercise, influences several important thermophysiological parameters; for example, it decreases core temperature and enhances heat exchange via the skin. However, it is unclear whether PMHA elicits comparable adaptations. Therefore, this study investigated the effect of PMHA on thermophysiological parameters. Participants were exposed to slightly increased temperatures (∼33°C/22% RH) for 6 h/d over 7 consecutive days. To study physiologic responses before and after PMHA, participants underwent a temperature ramp (UP), where ambient temperature increased from a thermoneutral value (28.8 ± 0.3°C) to 37.5 ± 0.6°C. During UP, core and skin temperature, water loss, cardiovascular parameters, skin blood flow and energy expenditure were measured. Three intervals were selected to compare data before and after PMHA: baseline (minutes 30–55: 28.44 ± 0.21°C), T1 (minutes 105–115: 33.29 ± 0.4°C) and T2 (minutes 130–140: 35.68 ± 0.61°C). After 7 d of PMHA, core (T1: −0.13 ± 0.13°C, P = 0.011; T2: −0.14 ± 0.15°C, P = 0.026) and proximal skin temperature (T1: −0.22 ± 0.29°C, P = 0.029) were lower during UP, whereas distal skin temperature was higher in a thermoneutral state (baseline: +0.74 ± 0.77°C, P = 0.009) and during UP (T1: +0.49 ± 0.76°C, P = .057 (not significant), T2:+0.51 ± 0.63°C, P = .022). Moreover, water loss was reduced (−30.5 ± 33.3 ml, P = 0.012) and both systolic (−7.7 ± 7.7 mmHg, P = 0.015) and diastolic (−4.4 ± 4.8 mmHg, P = 0.001) blood pressures were lowered in a thermoneutral state. During UP, only systolic blood pressure was decreased (T2: −6.1 ± 4.4 mmHg, P = 0.003). Skin blood flow was significantly decreased at T1 (−28.35 ± 38.96%, P = 0.037), yet energy expenditure remained unchanged. In conclusion, despite the mild heat stimulus, we show that PMHA induces distinct thermophysiological adaptations leading to increased resilience to heat.
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Affiliation(s)
- H Pallubinsky
- Department of Human Biology and Movement Sciences, NUTRIM, Maastricht University, the Netherlands
| | - L Schellen
- Department of Human Biology and Movement Sciences, NUTRIM, Maastricht University, the Netherlands.,School of Built Environment and Infrastructure, Avans University of Applied Sciences, the Netherlands
| | - B R M Kingma
- Department of Human Biology and Movement Sciences, NUTRIM, Maastricht University, the Netherlands
| | - B Dautzenberg
- Department of Human Biology and Movement Sciences, NUTRIM, Maastricht University, the Netherlands
| | - M A van Baak
- Department of Human Biology and Movement Sciences, NUTRIM, Maastricht University, the Netherlands
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62
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Faulkner SH, Jackson S, Fatania G, Leicht CA. The effect of passive heating on heat shock protein 70 and interleukin-6: A possible treatment tool for metabolic diseases? Temperature (Austin) 2017; 4:292-304. [PMID: 28944271 DOI: 10.1080/23328940.2017.1288688] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2016] [Revised: 01/23/2017] [Accepted: 01/25/2017] [Indexed: 12/11/2022] Open
Abstract
Increasing physical activity remains the most widely publicized way of improving health and wellbeing. However, in populations that benefit most from exercise (EX), adherence is often poor and alternatives to EX are important to bring about health improvements. Recent work suggests a role for passive heating (PH) and heat shock proteins (HSP) in improving cardio-metabolic health. The aim of this study was to investigate the expression of HSP70 and interleukin-6 in response to either EX or PH and the subsequent effect on glucose control. Fourteen males volunteered and were categorized lean (BMI 23.5 ± 2.2 kg·m-2) or overweight (29.2 ± 2.7 kg·m-2) and completed 60 minutes of either moderate cycling at a fixed rate of metabolic heat production (EX) or warm water immersion in 40°C water (PH). Extracellular HSP70 increased from baseline in both conditions with no differences between PH (0.98 ± 1.1 ng·mL-1) or EX (0.84 ± 1.0 ng·mL-1, p = 0.814). IL-6 increased following both conditions with a two-fold increase after PH and four-fold after EX. Energy expenditure increased by 61.0 ± 14.4 kcal·h-1 (79%) after PH. Peak glucose concentration after a meal immediately following PH was reduced when compared with EX (6.3 ± 1.4 mmol·L-1 versus 6.8 ± 1.2 mmol·L-1; p < 0.05). There was no difference in 24-hour glucose area under the curve (AUC) between conditions. These data indicate the potential for thermal therapy as an alternative treatment and management strategy for those at risk of developing metabolic disease where adherence, or ability to EX, may be compromised.
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Affiliation(s)
- S H Faulkner
- National Centre for Sports and Exercise Medicine, School of Sport Exercise and Health Sciences, Loughborough University, Loughborough, Leicestershire, United Kingdom
| | - S Jackson
- National Centre for Sports and Exercise Medicine, School of Sport Exercise and Health Sciences, Loughborough University, Loughborough, Leicestershire, United Kingdom
| | - G Fatania
- National Centre for Sports and Exercise Medicine, School of Sport Exercise and Health Sciences, Loughborough University, Loughborough, Leicestershire, United Kingdom
| | - C A Leicht
- National Centre for Sports and Exercise Medicine, School of Sport Exercise and Health Sciences, Loughborough University, Loughborough, Leicestershire, United Kingdom
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63
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Abstract
In the aftermath of the Paris Agreement, there is a crucial need for scientists in both thermal physiology and climate change research to develop the integrated approaches necessary to evaluate the health, economic, technological, social, and cultural impacts of 1.5°C warming. Our aim was to explore the fidelity of remote temperature measurements for quantitatively identifying the continuous redistribution of heat within both the Earth and the human body. Not accounting for the regional distribution of warming and heat storage patterns can undermine the results of thermal physiology and climate change research. These concepts are discussed herein using two parallel examples: the so-called slowdown of the Earth's surface temperature warming in the period 1998-2013; and the controversial results in thermal physiology, arising from relying heavily on core temperature measurements. In total, the concept of heat is of major importance for the integrity of systems, such as the Earth and human body. At present, our understanding about the interplay of key factors modulating the heat distribution on the surface of the Earth and in the human body remains incomplete. Identifying and accounting for the interconnections among these factors will be instrumental in improving the accuracy of both climate models and health guidelines.
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Affiliation(s)
- Andreas D Flouris
- FAME Laboratory, Department of Exercise Science, University of Thessaly, Trikala, Greece; Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, ON, Canada
| | - Glen P Kenny
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, ON, Canada
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64
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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] [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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