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Halperin I, Vigotsky AD. An Integrated Perspective of Effort and Perception of Effort. Sports Med 2024; 54:2019-2032. [PMID: 38909350 PMCID: PMC11329614 DOI: 10.1007/s40279-024-02055-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/22/2024] [Indexed: 06/24/2024]
Abstract
Effort and the perception of effort (PE) have been extensively studied across disciplines, resulting in multiple definitions. These inconsistencies block scientific progress by impeding effective communication between and within fields. Here, we present an integrated perspective of effort and PE that is applicable to both physical and cognitive activities. We define effort as the energy utilized to perform an action. This definition can be applied to biological entities performing various voluntary or involuntary activities, irrespective of whether the effort contributes to goal achievement. Then, we define PE as the instantaneous experience of utilizing energy to perform an action. This definition builds on that of effort without conflating it with other subjective experiences. We explore the nature of effort and PE as constructs and variables and highlight key considerations in their measurement. Our integrated perspective aims to facilitate a deeper understanding of these constructs, refine research methodologies, and promote interdisciplinary collaborations.
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Affiliation(s)
- Israel Halperin
- Department of Health Promotion, School of Public Health, Faculty of Medical & Health Sciences, Tel-Aviv University, Tel-Aviv, Israel.
- Sylvan Adams Sports Institute, Tel Aviv University, Tel-Aviv, Israel.
| | - Andrew D Vigotsky
- Departments of Biomedical Engineering and Statistics, Northwestern University, Evanston, IL, USA
- Department of Neuroscience, Northwestern University, Chicago, IL, USA
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Topham TH, Smallcombe JW, Brown HA, Clark B, Woodward AP, Telford RD, Jay O, Périard JD. Biological sex does not independently influence core temperature change and sweating of children exercising in uncompensable heat stress. J Appl Physiol (1985) 2024; 136:1440-1449. [PMID: 38660730 DOI: 10.1152/japplphysiol.00877.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2023] [Revised: 04/03/2024] [Accepted: 04/21/2024] [Indexed: 04/26/2024] Open
Abstract
The purpose of this study was to investigate the influence of biological sex, independent of differences in aerobic fitness and body fatness, on the change in gastrointestinal temperature (ΔTgi) and whole body sweat rate (WBSR) of children exercising under uncompensable heat stress. Seventeen boys (means ± SD; 13.7 ± 1.3 yr) and 18 girls (13.7 ± 1.4 yr) walked for 45 min at a fixed rate of metabolic heat production per kg body mass (8 W·kg-1) in 40°C and 30% relative humidity. Sex and peak oxygen consumption (V̇o2peak) were entered into a Bayesian hierarchical general additive model (HGAM) for Tgi. Sex, V̇o2peak, and the evaporative requirement for heat balance (Ereq) were entered into a Bayesian hierarchical linear regression for WBSR. For 26 (12 M and 14 F) of the 35 children with measured body composition, body fat percentage was entered in a separate HGAM and hierarchical linear regression for Tgi and WBSR, respectively. Conditional on sex-specific mean V̇o2peak, ΔTgi was 1.00°C [90% credible intervals (Crl): 0.84, 1.16] for boys and 1.17°C [1.01, 1.33] for girls, with a difference of 0.17°C [-0.39, 0.06]. When sex differences in V̇o2peak were accounted for, the difference in ΔTgi between boys and girls was 0.01°C [-0.25, 0.22]. The difference in WBSR between boys and girls was 0.03 L·h-1 [-0.02, 0.07], when isolated from differences in Ereq. The difference in ΔTgi between boys and girls was -0.10°C [-0.38, 0.17] when sex differences in body fat (%) were accounted for. Biological sex did not independently influence the ΔTgi and WBSR of children exercising under uncompensable heat stress.NEW & NOTEWORTHY Limited studies have investigated the thermoregulatory responses of boys and girls exercising under uncompensable heat stress. Boys and girls often differ in physiological characteristics other than biological sex, such as aerobic fitness and body fat percentage, which may confound interpretations. We investigated the influence of biological sex on exercise thermoregulation in children, independent of differences in aerobic fitness and body fatness.
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Affiliation(s)
- Thomas H Topham
- Research Institute for Sport and Exercise (UCRISE), University of Canberra, Bruce, Australian Capital Territory, Australia
| | - James W Smallcombe
- Faculty of Medicine and Health, Heat and Health Research Incubator, The University of Sydney, Sydney, New South Wales, Australia
| | - Harry A Brown
- Research Institute for Sport and Exercise (UCRISE), University of Canberra, Bruce, Australian Capital Territory, Australia
| | - Brad Clark
- Research Institute for Sport and Exercise (UCRISE), University of Canberra, Bruce, Australian Capital Territory, Australia
| | - Andrew P Woodward
- Faculty of Health, University of Canberra, Bruce, Australian Capital Territory, Australia
| | - Richard D Telford
- Research Institute for Sport and Exercise (UCRISE), University of Canberra, Bruce, Australian Capital Territory, Australia
| | - Ollie Jay
- Faculty of Medicine and Health, Heat and Health Research Incubator, The University of Sydney, Sydney, New South Wales, Australia
| | - Julien D Périard
- Research Institute for Sport and Exercise (UCRISE), University of Canberra, Bruce, Australian Capital Territory, Australia
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Topham TH, Smallcombe JW, Brown HA, Clark B, Woodward AP, Telford RD, Jay O, Périard JD. Influence of Biological Sex and Fitness on Core Temperature Change and Sweating in Children Exercising in Warm Conditions. Med Sci Sports Exerc 2024; 56:697-705. [PMID: 38051094 DOI: 10.1249/mss.0000000000003347] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/07/2023]
Abstract
PURPOSE This study aimed to investigate the associations of biological sex and aerobic fitness (i.e., V̇O 2peak ) on the change in gastrointestinal temperature (∆ Tgi ) and whole-body sweat rate (WBSR) of children exercising in warm conditions. METHODS Thirty-eight children (17 boys, mean ± SD = 13.7 ± 1.2 yr; 21 girls, 13.6 ± 1.8 yr) walked for 45 min at a fixed rate of metabolic heat production (8 W·kg -1 ) in 30°C and 40% relative humidity. Biological sex and relative V̇O 2peak were entered as predictors into a Bayesian hierarchical generalized additive model for Tgi . For a subsample of 13 girls with measured body composition, body fat percent was entered into a separate hierarchical generalized additive model for Tgi . Sex, V̇O 2peak , and the evaporative requirement for heat balance ( Ereq ) were entered into a Bayesian hierarchical linear regression for WBSR. RESULTS The mean ∆ Tgi for boys was 0.71°C (90% credible interval = 0.60-0.82) and for girls 0.78°C (0.68-0.88). A predicted 20 mL·kg -1 ·min -1 higher V̇O 2peak resulted in a 0.19°C (-0.03 to 0.43) and 0.24°C (0.07-0.40) lower ∆ Tgi in boys and girls, respectively. A predicted ~13% lower body fat in the subsample of girls resulted in a 0.15°C (-0.12 to 0.45) lower ∆ Tgi . When Ereq was standardized to the grand mean, the difference in WBSR between boys and girls was -0.00 L·h -1 (-0.06 to 0.06), and a 20-mL·kg -1 ·min -1 higher predicted V̇O 2peak resulted in a mean difference in WBSR of -0.07 L·h -1 (-0.15 to 0.00). CONCLUSIONS Biological sex did not independently influence ∆ Tgi and WBSR in children. However, a higher predicted V̇O 2peak resulted in a lower ∆ Tgi of children, which was not associated with a greater WBSR, but may be related to differences in body fat percent between high and low fitness individuals.
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Affiliation(s)
- Thomas H Topham
- Research Institute for Sport and Exercise (UCRISE), University of Canberra, Bruce, ACT, AUSTRALIA
| | - James W Smallcombe
- The University of Sydney, Heat and Health Research Incubator, Faculty of Medicine and Health, Sydney, NSW, AUSTRALIA
| | - Harry A Brown
- Research Institute for Sport and Exercise (UCRISE), University of Canberra, Bruce, ACT, AUSTRALIA
| | - Brad Clark
- Research Institute for Sport and Exercise (UCRISE), University of Canberra, Bruce, ACT, AUSTRALIA
| | | | - Richard D Telford
- Research Institute for Sport and Exercise (UCRISE), University of Canberra, Bruce, ACT, AUSTRALIA
| | - Ollie Jay
- The University of Sydney, Heat and Health Research Incubator, Faculty of Medicine and Health, Sydney, NSW, AUSTRALIA
| | - Julien D Périard
- Research Institute for Sport and Exercise (UCRISE), University of Canberra, Bruce, ACT, AUSTRALIA
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Cramer MN, Gagnon D, Laitano O, Crandall CG. Human temperature regulation under heat stress in health, disease, and injury. Physiol Rev 2022; 102:1907-1989. [PMID: 35679471 PMCID: PMC9394784 DOI: 10.1152/physrev.00047.2021] [Citation(s) in RCA: 65] [Impact Index Per Article: 32.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2021] [Revised: 05/10/2022] [Accepted: 05/28/2022] [Indexed: 12/30/2022] Open
Abstract
The human body constantly exchanges heat with the environment. Temperature regulation is a homeostatic feedback control system that ensures deep body temperature is maintained within narrow limits despite wide variations in environmental conditions and activity-related elevations in metabolic heat production. Extensive research has been performed to study the physiological regulation of deep body temperature. This review focuses on healthy and disordered human temperature regulation during heat stress. Central to this discussion is the notion that various morphological features, intrinsic factors, diseases, and injuries independently and interactively influence deep body temperature during exercise and/or exposure to hot ambient temperatures. The first sections review fundamental aspects of the human heat stress response, including the biophysical principles governing heat balance and the autonomic control of heat loss thermoeffectors. Next, we discuss the effects of different intrinsic factors (morphology, heat adaptation, biological sex, and age), diseases (neurological, cardiovascular, metabolic, and genetic), and injuries (spinal cord injury, deep burns, and heat stroke), with emphasis on the mechanisms by which these factors enhance or disturb the regulation of deep body temperature during heat stress. We conclude with key unanswered questions in this field of research.
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Affiliation(s)
- Matthew N Cramer
- Defence Research and Development Canada-Toronto Research Centre, Toronto, Ontario, Canada
| | - Daniel Gagnon
- Montreal Heart Institute and School of Kinesiology and Exercise Science, Université de Montréal, Montréal, Quebec, Canada
| | - Orlando Laitano
- Department of Applied Physiology and Kinesiology, University of Florida, Gainesville, Florida
| | - Craig G Crandall
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas and University of Texas Southwestern Medical Center, Dallas, Texas
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Topham TH, Smallcombe JW, Clark B, Brown HA, Telford RD, Jay O, Periard JD. The influence of sex and biological maturation on the sudomotor response to exercise-heat stress: Are girls disadvantaged? Am J Physiol Regul Integr Comp Physiol 2022; 323:R161-R168. [PMID: 35670483 DOI: 10.1152/ajpregu.00328.2021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Both adult females and children have been reported to have a lower sweating capacity and thus reduced evaporative heat loss potential which may increase their susceptibility to exertional hyperthermia in the heat. Compared to males, females have a lower maximal sweat rate and thus a theoretically lower maximum skin wettedness, due to a lower sweat output per gland. Similarly, children have been suggested to be disadvantaged in high ambient temperatures due to a lower sweat production and therefore reduced evaporative capacity, despite modifications of heat transfer due to physical attributes and possible evaporative efficiency. The reported reductions in sudomotor activity of females and children suggests a lower sweating capacity in girls. However, due to the complexities of isolating sex and maturation from the confounding effects of morphological differences (e.g., body surface area-to-mass ratio) and metabolic heat production, limited evidence exists supporting whether children and, more specifically, girls are at a thermoregulatory disadvantage. Furthermore, a limited number of child-adult comparison studies involve females and very few studies have directly compared regional and whole-body sudomotor activity between boys and girls. This mini review highlights the exercise-induced sudomotor response of females and children, summarises previous research investigating the sudomotor response to exercise in girls and suggests important areas for further research.
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Affiliation(s)
- Thomas H Topham
- Research Institute for Sport and Exercise, University of Canberra, Bruce, Australia
| | - James W Smallcombe
- The University of Sydney, Heat and Health Research Incubator, Faculty of Medicine and Health, Sydney, New South Wales, Australia
| | - Brad Clark
- Research Institute for Sport and Exercise, University of Canberra, Bruce, Australia
| | - Harry A Brown
- Research Institute for Sport and Exercise, University of Canberra, Bruce, Australia
| | - Richard D Telford
- Research Institute for Sport and Exercise, University of Canberra, Bruce, Australia
| | - Ollie Jay
- The University of Sydney, Heat and Health Research Incubator, Faculty of Medicine and Health, Sydney, New South Wales, Australia
| | - Julien D Periard
- Research Institute for Sport and Exercise, University of Canberra, Bruce, Australia
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Amano T, Asami T, Ichinose-Kuwahara T, Okushima D, Ueda H, Kondo N, Inoue Y. Influence of exercise intensity and regional differences in the sudomotor recruitment pattern in exercising prepubertal boys and young men. Physiol Behav 2022; 243:113642. [PMID: 34762900 DOI: 10.1016/j.physbeh.2021.113642] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2021] [Revised: 11/05/2021] [Accepted: 11/05/2021] [Indexed: 10/19/2022]
Abstract
We investigated the influence of exercise intensities and regional differences in the sudomotor recruitment pattern in boys. Six prepubertal boys (age 11 ± 1 yr) cycled at light, moderate, and high exercise intensity (35%, 50%, and 65% VO2max) for 30 min in a temperate condition (28 °C, 40% relative humidity). Local sweat rate (ventilated capsule) and number of activated sweat glands (starch-iodine technique) at five body sites were assessed and sweat gland output was calculated. Responses in boys were compared with those in nine young men (23 ± 1 yr) tested under identical conditions. The forehead, chest, back, and forearm, but not thigh, sweat rate increased from light to moderate and at high intensities in boys (all p ≤ 0.005) but not from moderate to high (all p ≥ 0.071). The sweat rate on the forehead was relatively higher (p ≤ 0.045) and thigh was lower (p ≤ 0.050) than other sites in boys at moderate and high intensities. Exercise intensity-dependent sweating was associated with activating more sweat glands but not increasing glandular output in boys. The sweat rate in boys was attenuated versus men heterogeneously across body sites concurrent to low glandular outputs (all p ≤ 0.027). We conclude that exercise intensity modulates the sweat rate in boys by changing the number of activated sweat glands heterogeneously among skin sites. Age-related differences in the sudomotor pattern are evident at higher exercise intensities. Development of glandular output per gland occurring from boys to young men may play a key role in modulating sweat rate with respect to exercise intensity and regional differences.
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Affiliation(s)
- Tatsuro Amano
- Laboratory for Exercise and Environmental Physiology, Faculty of Education, Niigata University, Niigata, Japan
| | - Takako Asami
- Laboratory for Human Performance Research, Osaka International University, Moriguchi, Osaka, Japan
| | - Tomoko Ichinose-Kuwahara
- Laboratory for Human Performance Research, Osaka International University, Moriguchi, Osaka, Japan
| | - Dai Okushima
- Laboratory for Human Performance Research, Osaka International University, Moriguchi, Osaka, Japan
| | - Hiroyuki Ueda
- Department of Nurse, Osaka Shin-ai College, Tsurumi-ku, Osaka, Japan
| | - Narihiko Kondo
- Laboratory for Applied Human Physiology, Graduate School of Human Development and Environment, Kobe University, Kobe, Japan
| | - Yoshimitsu Inoue
- Laboratory for Human Performance Research, Osaka International University, Moriguchi, Osaka, Japan.
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Okamoto Y, Amano T. Effects of sex and menstrual cycle on sweating during isometric handgrip exercise and postexercise forearm occlusion. Exp Physiol 2021; 106:1508-1523. [PMID: 33899281 DOI: 10.1113/ep089464] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2021] [Accepted: 04/20/2021] [Indexed: 11/08/2022]
Abstract
NEW FINDINGS What is the central question of this study? Do sex and menstrual cycle modulate sweating during isometric handgrip exercise and muscle metaboreceptor stimulation? What is the main finding and its importance? Sex modulates sweating during isometric handgrip exercise, as indicated by the lower sweat output per gland in women than in men, but not during muscle metaboreceptor stimulation. Sweat output per gland during isometric handgrip exercise and muscle metaboreceptor stimulation were lower in the mid-luteal phase than in the early follicular phase in women. Cholinergic sweat gland sensitivity might explain, in part, the individual variation of the response. Our results provide new insights regarding sex- and menstrual cycle-related modulation of the sweating response. ABSTRACT We investigated whether sex and menstrual cycle could modulate sweating during isometric handgrip (IH) exercise and muscle metaboreceptor stimulation. Twelve young, healthy women in the early follicular (EF) and mid-luteal (ML) phases and 14 men underwent two experimental sessions consisting of a 1.5 min IH exercise at 25 and 50% of maximal voluntary contraction (MVC) in a hot environment (35°C, relative humidity 50%) followed by 2 min forearm occlusion to stimulate muscle metaboreceptors. Sweat rates, the number of activated sweat glands and the sweat output per gland (SGO) on the forearm and chest were assessed. Pilocarpine-induced sweating was also assessed via transdermal iontophoresis to compare the responses with those of IH exercise and muscle metaboreceptor stimulation, based on correlation analysis. Sweat rates on the forearm and chest during IH exercise and muscle metaboreceptor stimulation did not differ between men and women in either menstrual cycle phase (all P ≥ 0.144). However, women in both phases showed lower SGO on the forearm and/or chest compared with men during IH exercise at 50% of MVC, with no differences in muscle metaboreceptor stimulation. Women in the ML phase had a lower forearm sweat rate during IH exercise at 50% of MVC (P = 0.015) and SGO during exercise and muscle metaboreceptor stimulation (main effect, both P ≤ 0.003) compared with those in the EF phase. Overall, sweat rate and SGO during IH exercise and muscle metaboreceptor stimulation were correlated with pilocarpine-induced responses (all P ≤ 0.064, r ≥ 0.303). We showed that sex and menstrual cycle modulate sudomotor activity during IH exercise and/or muscle metaboreceptor stimulation. Cholinergic sweat gland sensitivity might explain, in part, the individual variation of the response.
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Affiliation(s)
- Yumi Okamoto
- Laboratory for Exercise and Environmental Physiology, Faculty of Education, Niigata University, Niigata, Japan
| | - Tatsuro Amano
- Laboratory for Exercise and Environmental Physiology, Faculty of Education, Niigata University, Niigata, Japan
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Périard JD, Eijsvogels TMH, Daanen HAM. Exercise under heat stress: thermoregulation, hydration, performance implications, and mitigation strategies. Physiol Rev 2021; 101:1873-1979. [PMID: 33829868 DOI: 10.1152/physrev.00038.2020] [Citation(s) in RCA: 148] [Impact Index Per Article: 49.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
A rise in body core temperature and loss of body water via sweating are natural consequences of prolonged exercise in the heat. This review provides a comprehensive and integrative overview of how the human body responds to exercise under heat stress and the countermeasures that can be adopted to enhance aerobic performance under such environmental conditions. The fundamental concepts and physiological processes associated with thermoregulation and fluid balance are initially described, followed by a summary of methods to determine thermal strain and hydration status. An outline is provided on how exercise-heat stress disrupts these homeostatic processes, leading to hyperthermia, hypohydration, sodium disturbances, and in some cases exertional heat illness. The impact of heat stress on human performance is also examined, including the underlying physiological mechanisms that mediate the impairment of exercise performance. Similarly, the influence of hydration status on performance in the heat and how systemic and peripheral hemodynamic adjustments contribute to fatigue development is elucidated. This review also discusses strategies to mitigate the effects of hyperthermia and hypohydration on exercise performance in the heat by examining the benefits of heat acclimation, cooling strategies, and hyperhydration. Finally, contemporary controversies are summarized and future research directions are provided.
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Affiliation(s)
- Julien D Périard
- University of Canberra Research Institute for Sport and Exercise, Bruce, Australia
| | - Thijs M H Eijsvogels
- Department of Physiology, Radboud Institute for Health Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Hein A M Daanen
- Department of Human Movement Sciences, Faculty of Behavioural and Movement Sciences, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands
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9
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D'Souza AW, Notley SR, Kenny GP. The Relation between Age and Sex on Whole-Body Heat Loss during Exercise-Heat Stress. Med Sci Sports Exerc 2021; 52:2242-2249. [PMID: 32496737 DOI: 10.1249/mss.0000000000002373] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
INTRODUCTION Increasing age is associated with decrements in sweat rate that compromise whole-body total heat loss (evaporative + dry heat exchange) in both men and women during moderate-to-vigorous exercise in dry heat. Similarly, young women also display reductions in sweating (that lower evaporative heat loss) relative to young men in such conditions. Nevertheless, it remained unclear whether these effects act synergistically to exacerbate the age-related decline in whole-body total heat loss in women relative to men. We therefore assessed the interrelation between age and sex on whole-body total heat loss during light, moderate, and vigorous exercise in dry heat. METHODS To achieve this, we used direct and indirect calorimetry to assess whole-body total heat loss and metabolic heat production (respectively) in 46 men and 34 women age between 18 and 70 yr. Participants performed three, 30-min bouts of cycling at metabolic heat productions of 150 (light), 200 (moderate), and 250 (vigorous) W·m, each separated by 15-min recovery in dry heat (40°C, ~15% relative humidity). RESULTS Whole-body total heat loss was ~5% lower in women relative to men during moderate and vigorous exercise (both, P < 0.01), irrespective of age. Total heat loss declined with age during moderate and vigorous exercise in both men and women (all, P < 0.050), although the rate of that decline (~4% per decade) was similar between men and women across all exercise bouts (all, P > 0.050). CONCLUSIONS We show that, when assessed in dry heat, whole-body total heat loss is lower in women relative to men, irrespective of age. Furthermore, total heat loss declines with increasing age in both men and women during moderate-to-vigorous exercise, albeit the rate of that decline is not appreciably modified by sex.
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Affiliation(s)
- Andrew W D'Souza
- Human and Environmental Physiology Research Unit, University of Ottawa, Ottawa, CANADA
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10
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Sotiridis A, Debevec T, Ciuha U, McDonnell AC, Mlinar T, Royal JT, Mekjavic IB. Aerobic but not thermoregulatory gains following a 10-day moderate-intensity training protocol are fitness level dependent: A cross-adaptation perspective. Physiol Rep 2021; 8:e14355. [PMID: 32061183 PMCID: PMC7023889 DOI: 10.14814/phy2.14355] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2019] [Accepted: 10/28/2019] [Indexed: 11/24/2022] Open
Abstract
Moderate‐intensity exercise sessions are incorporated into heat‐acclimation and hypoxic‐training protocols to improve performance in hot and hypoxic environments, respectively. Consequently, a training effect might contribute to aerobic performance gains, at least in less fit participants. To explore the interaction between fitness level and a training stimulus commonly applied during acclimation protocols, we recruited 10 young males of a higher (more fit‐MF, peak aerobic power [VO2peak]: 57.9 [6.2] ml·kg−1·min−1) and 10 of a lower (less fit‐LF, VO2peak: 41.7 [5.0] ml·kg−1·min−1) fitness level. They underwent 10 daily exercise sessions (60 min@50% peak power output [Wpeak]) in thermoneutral conditions. The participants performed exercise testing on a cycle ergometer before and after the training period in normoxic (NOR), hypoxic (13.5% FiO2; HYP), and hot (35°C, 50% RH; HE) conditions in a randomized and counterbalanced order. Each test consisted of two stages; a steady‐state exercise (30 min@40% NOR Wpeak to evaluate thermoregulatory function) followed by incremental exercise to exhaustion. VO2peak increased by 9.2 (8.5)% (p = .024) and 10.2 (15.4)% (p = .037) only in the LF group in NOR and HE, respectively. Wpeak increases were correlated with baseline values in NOR (r = −.58, p = .010) and HYP (r = −.52, p = .018). MF individuals improved gross mechanical efficiency in HYP. Peak sweat rate increased in both groups in HE, whereas MF participants activated the forehead sweating response at lower rectal temperatures post‐training. In conclusion, an increase in VO2peak but not mechanical efficiency seems probable in LF males after a 10‐day moderate‐exercise training protocol.
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Affiliation(s)
- Alexandros Sotiridis
- Department of Automation, Biocybernetics and Robotics, Jozef Stefan Institute, Ljubljana, Slovenia
| | - Tadej Debevec
- Department of Automation, Biocybernetics and Robotics, Jozef Stefan Institute, Ljubljana, Slovenia.,Faculty of Sports, University of Ljubljana, Ljubljana, Slovenia
| | - Urša Ciuha
- Department of Automation, Biocybernetics and Robotics, Jozef Stefan Institute, Ljubljana, Slovenia
| | - Adam C McDonnell
- Department of Automation, Biocybernetics and Robotics, Jozef Stefan Institute, Ljubljana, Slovenia
| | - Tinkara Mlinar
- Department of Automation, Biocybernetics and Robotics, Jozef Stefan Institute, Ljubljana, Slovenia.,Jozef Stefan International Postgraduate School, Ljubljana, Slovenia
| | - Joshua T Royal
- Department of Automation, Biocybernetics and Robotics, Jozef Stefan Institute, Ljubljana, Slovenia.,Jozef Stefan International Postgraduate School, Ljubljana, Slovenia
| | - Igor B Mekjavic
- Department of Automation, Biocybernetics and Robotics, Jozef Stefan Institute, Ljubljana, Slovenia
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11
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Amano T, Fujii N, Kenny GP, Okamoto Y, Inoue Y, Kondo N. Effects of L-type voltage-gated Ca 2+ channel blockade on cholinergic and thermal sweating in habitually trained and untrained men. Am J Physiol Regul Integr Comp Physiol 2020; 319:R584-R591. [PMID: 32966123 DOI: 10.1152/ajpregu.00167.2020] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
We evaluated the hypothesis that the activation of L-type voltage-gated Ca2+ channels contributes to exercise training-induced augmentation in cholinergic sweating. On separate days, 10 habitually trained and 10 untrained men participated in two experimental protocols. Prior to each protocol, we administered 1% verapamil (Verapamil, L-type voltage-gated Ca2+ channel blocker) and saline (Control) at forearm skin sites on both arms via transdermal iontophoresis. In protocol 1, we administered low (0.001%) and high (1%) doses of pilocarpine at both the verapamil-treated and verapamil-untreated forearm sites. In protocol 2, participants were passively heated by immersing their limbs in hot water (43°C) until rectal temperature increased by 1.0°C above baseline resting levels. Sweat rate at all forearm sites was continuously measured throughout both protocols. Pilocarpine-induced sweating in Control was higher in trained than in untrained men for both the concentrations of pilocarpine (both P ≤ 0.001). Pilocarpine-induced sweating at the low-dose site was attenuated at the Verapamil versus the Control site in both the groups (both P ≤ 0.004), albeit the reduction was greater in trained as compared with in untrained men (P = 0.005). The verapamil-mediated reduction in sweating remained intact at the high-dose pilocarpine site in the untrained men (P = 0.004) but not the trained men (P = 0.180). Sweating did not differ between Control and Verapamil sites with increases in rectal temperature in both groups (interaction, P = 0.571). We show that activation of L-type voltage-gated Ca2+ channels modulates sweat production in habitually trained men induced by a low dose of pilocarpine. However, no effect on sweating was observed during passive heating in either group.
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Affiliation(s)
- Tatsuro Amano
- Laboratory for Exercise and Environmental Physiology, Faculty of Education, Niigata University, Niigata, Japan
| | - 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, Canada
| | - Yumi Okamoto
- Laboratory for Exercise and Environmental Physiology, Faculty of Education, Niigata University, Niigata, Japan
| | - Yoshimitsu Inoue
- Laboratory for Human Performance Research, Osaka International University, Osaka, Japan
| | - Narihiko Kondo
- Laboratory for Applied Human Physiology, Graduate School of Human Development and Environment, Kobe University, Kobe, Japan
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12
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Notley SR, D'Souza AW, Meade RD, Richards BJ, Kenny GP. Whole-body heat exchange in women during constant- and variable-intensity work in the heat. Eur J Appl Physiol 2020; 120:2665-2675. [PMID: 32902693 DOI: 10.1007/s00421-020-04486-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2020] [Accepted: 08/27/2020] [Indexed: 10/23/2022]
Abstract
PURPOSE Time-weighted averaging is used in occupational heat stress guidelines to estimate the metabolic demands of variable-intensity work. However, compared to constant-intensity work of the same time-weighted average metabolic rate, variable-intensity work may cause decrements in total heat loss (dry + evaporative heat loss) that exacerbate heat storage in women. We therefore used direct calorimetry to assess whole-body total heat loss and heat storage (metabolic heat production minus total heat loss) in women and men during constant- and variable-intensity work of equal average intensity. METHODS Ten women [mean (SD); 31 (11) years] and fourteen men [30 (8) years] completed two trials involving 90-min of constant- and variable-intensity work (cycling) eliciting an average metabolic heat production of ~ 200 W/m2 in dry-heat (40 °C, ~ 15% relative humidity). External work was fixed at ~ 40 W/m2 for constant-intensity work, and alternated between ~ 15 and ~ 60 W/m2 (5-min each) for variable-intensity work. RESULTS When expressed as a time-weighted average over each work period, total heat loss did not differ between men and women (mean difference [95% CI]; 4 W/m2 [- 11, 20]; p = 0.572) or between constant- and variable-intensity work (1 W/m2 [- 3, 5]; p = 0.642). Consequently, heat storage did not differ significantly between men and women (- 4 W/m2 [- 17, 8]; p = 0.468) or between constant- and variable-intensity work (0 W/m2 [- 3, 3]; p = 0.834). CONCLUSION Neither whole-body heat loss nor heat storage was modulated by the partitioning of work intensity, indicating that time-weighted averaging is appropriate for estimating metabolic demand to assess occupational heat stress in women.
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Affiliation(s)
- Sean R Notley
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, 125 University Private, Room 367 Montpetit Hall, Ottawa, ON, K1N 6N5, Canada
| | - Andrew W D'Souza
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, 125 University Private, Room 367 Montpetit Hall, Ottawa, ON, K1N 6N5, Canada
| | - Robert D Meade
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, 125 University Private, Room 367 Montpetit Hall, Ottawa, ON, K1N 6N5, Canada
| | - Brodie J Richards
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, 125 University Private, Room 367 Montpetit Hall, Ottawa, ON, K1N 6N5, Canada
| | - Glen P Kenny
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, 125 University Private, Room 367 Montpetit Hall, Ottawa, ON, K1N 6N5, Canada.
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13
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Notley SR, Meade RD, Kenny GP. Effect of aerobic fitness on the relation between age and whole‐body heat exchange during exercise‐heat stress: a retrospective analysis. Exp Physiol 2020; 105:1550-1560. [DOI: 10.1113/ep088783] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2020] [Accepted: 06/30/2020] [Indexed: 01/24/2023]
Affiliation(s)
- Sean R. Notley
- Human and Environmental Physiology Research UnitSchool of Human KineticsUniversity of Ottawa Ottawa Canada
| | - Robert D. Meade
- Human and Environmental Physiology Research UnitSchool of Human KineticsUniversity of Ottawa Ottawa Canada
| | - Glen P. Kenny
- Human and Environmental Physiology Research UnitSchool of Human KineticsUniversity of Ottawa Ottawa Canada
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14
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Effects of Casein Hydrolysate Ingestion on Thermoregulatory Responses in Healthy Adults during Exercise in Heated Conditions: A Randomized Crossover Trial. Nutrients 2020; 12:nu12030867. [PMID: 32213899 PMCID: PMC7146450 DOI: 10.3390/nu12030867] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2020] [Revised: 03/19/2020] [Accepted: 03/22/2020] [Indexed: 11/17/2022] Open
Abstract
Food ingestion has been shown to affect thermoregulation during exercise, while the impact of protein degradant consumption remains unclear. We investigated the effects of casein hydrolysate ingestion on thermoregulatory responses during exercise in the heat. In a randomized, placebo-controlled, double-blind, crossover trial, five men and five women consumed either 5 g of casein hydrolysate or placebo. Thirty minutes after ingestion, participants cycled at 60% VO2max until voluntary exhaustion wearing a hot-water (43 °C) circulation suit. Exercise time to exhaustion, body core temperature, forearm sweat rate, and forearm cutaneous vascular conductance did not differ different between the conditions. However, chest sweat rate and mean skin temperature increased upon casein hydrolysate ingestion compared with placebo during exercise. Increased chest sweat rate upon casein hydrolysate ingestion was associated with elevated sudomotor sensitivity to increasing body core temperature, but not the temperature threshold for initiating sweating. A positive correlation was found between chest sweat rate and plasma total amino acid concentration during exercise. These results suggest that casein hydrolysate ingestion enhances sweating heterogeneously by increasing peripheral sensitivity of the chest's sweating mechanism and elevating skin temperature during exercise in the heat. However, the physiological link between plasma amino acid concentration and sweat rate remains unclear.
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15
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Ravanelli N, Gagnon D, Imbeault P, Jay O. A retrospective analysis to determine if exercise training-induced thermoregulatory adaptations are mediated by increased fitness or heat acclimation. Exp Physiol 2020; 106:282-289. [PMID: 32118324 DOI: 10.1113/ep088385] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2019] [Accepted: 02/28/2020] [Indexed: 11/08/2022]
Abstract
NEW FINDINGS What is the central question of this study? Are fitness-related improvements in thermoregulatory responses during uncompensable heat stress mediated by aerobic capacity V ̇ O 2 max or is it the partial heat acclimation associated with training? What is the main finding and its importance? During uncompensable heat stress, individuals with high and low V ̇ O 2 max displayed similar sweating and core temperature responses whereas exercise training in previously untrained individuals resulted in a greater sweat rate and a smaller rise in core temperature. These observations suggest that it is training, not V ̇ O 2 max per se, that mediates thermoregulatory improvements during uncompensable heat stress. ABSTRACT It remains unclear whether aerobic fitness, as defined by the maximum rate of oxygen consumption V ̇ O 2 max , independently improves heat dissipation in uncompensable environments, or whether the thermoregulatory adaptations associated with heat acclimation are due to repeated bouts of exercise-induced heat stress during regular aerobic training. The present analysis sought to determine if V ̇ O 2 max independently influences thermoregulatory sweating, maximum skin wettedness (ωmax ) and the change in rectal temperature (ΔTre ) during 60 min of exercise in an uncompensable environment (37.0 ± 0.8°C, 4.0 ± 0.2 kPa, 64 ± 3% relative humidity) at a fixed rate of heat production per unit mass (6 W kg-1 ). Retrospective analyses were performed on 22 participants (3 groups), aerobically unfit (UF; n = 7; V ̇ O 2 max : 41.7 ± 9.4 ml kg-1 min-1 ), aerobically fit (F; n = 7; V ̇ O 2 max : 55.6 ± 4.3 ml kg-1 min-1 ; P < 0.01) and aerobically unfit (n = 8) individuals, before (pre; V ̇ O 2 max : 45.8 ± 11.6 ml kg-1 min-1 ) and after (post; V ̇ O 2 max : 52.0 ± 11.1 ml kg-1 min-1 ; P < 0.001) an 8-week training intervention. ωmax was similar between UF (0.74 ± 0.09) and F (0.78 ± 0.08, P = 0.22). However, ωmax was greater post- (0.84 ± 0.08) compared to pre- (0.72 ± 0.06, P = 0.02) training. During exercise, mean local sweat rate (forearm and upper-back) was greater post- (1.24 ± 0.20 mg cm-2 min-1 ) compared to pre- (1.04 ± 0.25 mg cm-2 min-1 , P < 0.01) training, but similar between UF (0.94 ± 0.31 mg cm-2 min-1 , P = 0.90) and F (1.02 ± 0.30 mg cm-2 min-1 ). The ΔTre at 60 min of exercise was greater pre- (1.13 ± 0.16°C, P < 0.01) compared to post- (0.96 ± 0.14°C) training, but similar between UF (0.85 ± 0.29°C, P = 0.22) and F (0.95 ± 0.22°C). Taken together, aerobic training, not V ̇ O 2 max per se, confers an increased ωmax , greater sweat rate, and smaller rise in core temperature during uncompensable heat stress in fit individuals.
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Affiliation(s)
- Nicholas Ravanelli
- Cardiovascular Prevention and Rehabilitation Centre and Research Centre, Montreal Heart Institute, Montreal, QC, Canada.,Département de pharmacologie et physiologie, Université de Montréal, Montreal, QC, Canada
| | - Daniel Gagnon
- Cardiovascular Prevention and Rehabilitation Centre and Research Centre, Montreal Heart Institute, Montreal, QC, Canada.,Département de pharmacologie et physiologie, Université de Montréal, Montreal, QC, Canada
| | - Pascal Imbeault
- School of Human Kinetics, University of Ottawa, 200 Lees Ave, Ottawa, Canada
| | - Ollie Jay
- Thermal Ergonomics Laboratory, Faculty of Health Sciences, University of Sydney, Sydney, NSW, Australia.,Charles Perkins Centre, University of Sydney, Sydney, NSW, Australia
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16
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Notley SR, Flouris AD, Kenny GP. Occupational heat stress management: Does one size fit all? Am J Ind Med 2019; 62:1017-1023. [PMID: 30791115 DOI: 10.1002/ajim.22961] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2018] [Revised: 02/21/2019] [Accepted: 03/04/2019] [Indexed: 01/20/2023]
Abstract
Heat stress is a deadly occupational hazard that is projected to increase in severity with global warming. While upper limits for heat stress designed to protect all workers have been recommended by occupational safety institutes for some time, heat stress continues to compromise health and productivity. In our view, this is largely explained by the inability of existing guidelines to consider the inter-individual (age, sex, disease, others) and intra-individual (medication use, fitness, hydration, others) factors that cause extensive variability in physiological tolerance to a given heat stress. In conditions that do not exceed the recommended limits, this 'one size fits all' approach to heat stress management can lead to reductions in productivity in more heat-tolerant workers, while compromising safety in less heat-tolerant workers who may develop heat-related illness, even in temperate conditions. Herein, we discuss future directions in occupational heat stress management that consider this individual variability.
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Affiliation(s)
- Sean R. Notley
- Human and Environmental Physiology Research UnitSchool of Human Kinetics, University of Ottawa OttawaCanada
| | - Andreas D. Flouris
- Human and Environmental Physiology Research UnitSchool of Human Kinetics, University of Ottawa OttawaCanada
- FAME LaboratoryDepartment of Exercise Science, University of Thessaly TrikalaGreece
| | - Glen P. Kenny
- Human and Environmental Physiology Research UnitSchool of Human Kinetics, University of Ottawa OttawaCanada
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17
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Notley SR, Lamarche DT, Meade RD, Flouris AD, Kenny GP. Revisiting the influence of individual factors on heat exchange during exercise in dry heat using direct calorimetry. Exp Physiol 2019; 104:1038-1050. [DOI: 10.1113/ep087666] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2019] [Accepted: 04/17/2019] [Indexed: 11/08/2022]
Affiliation(s)
- Sean R. Notley
- Human and Environmental Physiology Research UnitSchool of Human KineticsUniversity of Ottawa Ottawa ON Canada
| | - Dallon T. Lamarche
- Human and Environmental Physiology Research UnitSchool of Human KineticsUniversity of Ottawa Ottawa ON Canada
| | - Robert D. Meade
- Human and Environmental Physiology Research UnitSchool of Human KineticsUniversity of Ottawa Ottawa ON Canada
| | - Andreas D. Flouris
- Human and Environmental Physiology Research UnitSchool of Human KineticsUniversity of Ottawa Ottawa ON Canada
- FAME LaboratoryDepartment of Exercise ScienceUniversity of Thessaly Trikala Greece
| | - Glen P. Kenny
- Human and Environmental Physiology Research UnitSchool of Human KineticsUniversity of Ottawa Ottawa ON Canada
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18
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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) 2019; 126:286-293. [PMID: 30496713 PMCID: PMC6397413 DOI: 10.1152/japplphysiol.00735.2018] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2018] [Revised: 11/26/2018] [Accepted: 11/26/2018] [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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19
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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] [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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