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Brychta RJ, McGehee S, Huang S, Leitner BP, Duckworth CJ, Fletcher LA, Kim K, Cassimatis TM, Israni NS, Lea HJ, Lentz TN, Pierce AE, Jiang A, LaMunion SR, Thomas RJ, Ishihara A, Courville AB, Yang SB, Reitman ML, Cypess AM, Chen KY. The thermoneutral zone in women takes an "arctic" shift compared to men. Proc Natl Acad Sci U S A 2024; 121:e2311116121. [PMID: 38683977 PMCID: PMC11087792 DOI: 10.1073/pnas.2311116121] [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: 06/30/2023] [Accepted: 03/05/2024] [Indexed: 05/02/2024] Open
Abstract
Conventionally, women are perceived to feel colder than men, but controlled comparisons are sparse. We measured the response of healthy, lean, young women and men to a range of ambient temperatures typical of the daily environment (17 to 31 °C). The Scholander model of thermoregulation defines the lower critical temperature as threshold of the thermoneutral zone, below which additional heat production is required to defend core body temperature. This parameter can be used to characterize the thermoregulatory phenotypes of endotherms on a spectrum from "arctic" to "tropical." We found that women had a cooler lower critical temperature (mean ± SD: 21.9 ± 1.3 °C vs. 22.9 ± 1.2 °C, P = 0.047), resembling an "arctic" shift compared to men. The more arctic profile of women was predominantly driven by higher insulation associated with more body fat compared to men, countering the lower basal metabolic rate associated with their smaller body size, which typically favors a "tropical" shift. We did not detect sex-based differences in secondary measures of thermoregulation including brown adipose tissue glucose uptake, muscle electrical activity, skin temperatures, cold-induced thermogenesis, or self-reported thermal comfort. In conclusion, the principal contributors to individual differences in human thermoregulation are physical attributes, including body size and composition, which may be partly mediated by sex.
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Affiliation(s)
- Robert J. Brychta
- Diabetes, Endocrinology, and Obesity Branch, National Institute of Diabetes and Digestive and Kidney Diseases, NIH, Bethesda, MD20892
| | - Suzanne McGehee
- Diabetes, Endocrinology, and Obesity Branch, National Institute of Diabetes and Digestive and Kidney Diseases, NIH, Bethesda, MD20892
| | - Shan Huang
- Diabetes, Endocrinology, and Obesity Branch, National Institute of Diabetes and Digestive and Kidney Diseases, NIH, Bethesda, MD20892
| | - Brooks P. Leitner
- Diabetes, Endocrinology, and Obesity Branch, National Institute of Diabetes and Digestive and Kidney Diseases, NIH, Bethesda, MD20892
| | - Courtney J. Duckworth
- Diabetes, Endocrinology, and Obesity Branch, National Institute of Diabetes and Digestive and Kidney Diseases, NIH, Bethesda, MD20892
| | - Laura A. Fletcher
- Diabetes, Endocrinology, and Obesity Branch, National Institute of Diabetes and Digestive and Kidney Diseases, NIH, Bethesda, MD20892
| | - Katherine Kim
- Diabetes, Endocrinology, and Obesity Branch, National Institute of Diabetes and Digestive and Kidney Diseases, NIH, Bethesda, MD20892
| | - Thomas M. Cassimatis
- Diabetes, Endocrinology, and Obesity Branch, National Institute of Diabetes and Digestive and Kidney Diseases, NIH, Bethesda, MD20892
| | - Nikita S. Israni
- Diabetes, Endocrinology, and Obesity Branch, National Institute of Diabetes and Digestive and Kidney Diseases, NIH, Bethesda, MD20892
| | - Hannah J. Lea
- Diabetes, Endocrinology, and Obesity Branch, National Institute of Diabetes and Digestive and Kidney Diseases, NIH, Bethesda, MD20892
| | - Taylor N. Lentz
- Diabetes, Endocrinology, and Obesity Branch, National Institute of Diabetes and Digestive and Kidney Diseases, NIH, Bethesda, MD20892
| | - Anne E. Pierce
- Diabetes, Endocrinology, and Obesity Branch, National Institute of Diabetes and Digestive and Kidney Diseases, NIH, Bethesda, MD20892
| | - Alex Jiang
- Diabetes, Endocrinology, and Obesity Branch, National Institute of Diabetes and Digestive and Kidney Diseases, NIH, Bethesda, MD20892
| | - Samuel R. LaMunion
- Diabetes, Endocrinology, and Obesity Branch, National Institute of Diabetes and Digestive and Kidney Diseases, NIH, Bethesda, MD20892
| | - Reed J. Thomas
- Diabetes, Endocrinology, and Obesity Branch, National Institute of Diabetes and Digestive and Kidney Diseases, NIH, Bethesda, MD20892
| | - Asuka Ishihara
- Diabetes, Endocrinology, and Obesity Branch, National Institute of Diabetes and Digestive and Kidney Diseases, NIH, Bethesda, MD20892
| | - Amber B. Courville
- Diabetes, Endocrinology, and Obesity Branch, National Institute of Diabetes and Digestive and Kidney Diseases, NIH, Bethesda, MD20892
| | - Shanna B. Yang
- Nutrition Department, Hatfield Clinical Research Center, NIH, Bethesda, MD20892
| | - Marc L. Reitman
- Diabetes, Endocrinology, and Obesity Branch, National Institute of Diabetes and Digestive and Kidney Diseases, NIH, Bethesda, MD20892
| | - Aaron M. Cypess
- Diabetes, Endocrinology, and Obesity Branch, National Institute of Diabetes and Digestive and Kidney Diseases, NIH, Bethesda, MD20892
| | - Kong Y. Chen
- Diabetes, Endocrinology, and Obesity Branch, National Institute of Diabetes and Digestive and Kidney Diseases, NIH, Bethesda, MD20892
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Ocobock C. Human cold adaptation: An unfinished agenda v2.0. Am J Hum Biol 2024; 36:e23937. [PMID: 37345289 DOI: 10.1002/ajhb.23937] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2023] [Revised: 05/29/2023] [Accepted: 05/30/2023] [Indexed: 06/23/2023] Open
Abstract
BACKGROUND Research on human extreme cold climate adaptations has benefitted from a recent resurgence since Ted Steegmann laid out his Human Cold Adaptation Agenda in 2007. Human biologists have drastically expanded our knowledge in this area during the last 15 years, but we still have a great deal more work to do to fulfill the cold climate adaptation agenda. METHODS Here, I follow Steegmann's example by providing a review of cold climate adaptations and setting forth a new, expanded agenda. RESULTS I review the foundational work on cold climate adaptations including classic Bergmann, Allen, and Thomson rules as well as early work assessing metabolic differences among Indigenous cold climate populations. From there, I discuss some of the groundbreaking work currently taking place on cold climate adaptations such as brown adipose tissue (a heat generating organ), physical activity levels, metabolic rates, and behavioral/cultural mechanisms. Finally, I present a path forward for future research with a focus on some of the basic extreme cold adaptations as well as how human biologists should approach the effects of climate change on human health and well-being, particularly within a cold climate context. CONCLUSION The Arctic has felt the dramatic effects of climate change sooner and more acutely than other parts of the world, making it an ideal location for studying both cold climate adaptations and climate change resilience. Human biologists have a great deal to contribute to the conversation on not only adaptations to extreme cold, but also the ways in which climate change is being embodied by cold climate populations.
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Affiliation(s)
- Cara Ocobock
- Department of Anthropology, University of Notre Dame, Notre Dame, Indiana, USA
- Department of Gender Studies, University of Notre Dame, Notre Dame, Indiana, USA
- Eck Institute for Global Health, Institute for Educational Initiatives, University of Notre Dame, Notre Dame, Indiana, USA
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Coertjens M, Coertjens PC, Tartaruga MP, Gorski T, Lima-Silva AE, Carminatti LJ, Beyer PO, de Almeida APV, Geremia JM, Peyré-Tartaruga LA, Kruel LFM. Energetic responses of head-out water immersion at different temperatures during post-exercise recovery and its consequence on anaerobic mechanical power. Eur J Appl Physiol 2023; 123:2813-2831. [PMID: 37393218 DOI: 10.1007/s00421-023-05265-6] [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: 01/31/2023] [Accepted: 06/20/2023] [Indexed: 07/03/2023]
Abstract
PURPOSE While exercise recovery may be beneficial from a physiological point of view, it may be detrimental to subsequent anaerobic performance. To investigate the energetic responses of water immersion at different temperatures during post-exercise recovery and its consequences on subsequent anaerobic performance, a randomized and controlled crossover experimental design was performed with 21 trained cyclists. METHOD Participants were assigned to receive three passive recovery strategies during 10 min after a Wingate Anaerobic Test (WAnT): control (CON: non-immersed condition), cold water immersion (CWI: 20 ℃), and hot water immersion (HWI: 40 ℃). Blood lactate, cardiorespiratory, and mechanical outcomes were measured during the WAnT and its recovery. Time constant (τ), asymptotic value, and area under the curve (AUC) were quantified for each physiologic parameter during recovery. After that, a second WAnT test and 10-min recovery were realized in the same session. RESULTS Regardless the water immersion temperature, water immersion increased [Formula: see text] (+ 18%), asymptote ([Formula: see text]+ 16%, [Formula: see text] + 13%, [Formula: see text] + 17%, HR + 16%) and AUC ([Formula: see text]+ 27%, [Formula: see text] + 18%, [Formula: see text] + 20%, HR + 25%), while decreased [Formula: see text] (- 33%). There was no influence of water immersion on blood lactate parameters. HWI improved the mean power output during the second WAnT (2.2%), while the CWI decreased 2.4% (P < 0.01). CONCLUSION Independent of temperature, water immersion enhanced aerobic energy recovery without modifying blood lactate recovery. However, subsequent anaerobic performance was increased only during HWI and decreased during CWI. Despite higher than in other studies, 20 °C effectively triggered physiological and performance responses. Water immersion-induced physiological changes did not predict subsequent anaerobic performance.
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Affiliation(s)
- Marcelo Coertjens
- School of Physiotherapy, Universidade Federal do Delta do Parnaíba, Av. São Sebastião, 2819, Parnaíba, PI, CEP: 64202-020, Brazil.
- Postgraduate Program in Biomedical Sciences, Universidade Federal do Delta do Parnaíba, Parnaíba, PI, Brazil.
- Exercise Research Laboratory, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil.
| | - Patricia Chaves Coertjens
- School of Physiotherapy, Universidade Federal do Delta do Parnaíba, Av. São Sebastião, 2819, Parnaíba, PI, CEP: 64202-020, Brazil
| | - Marcus Peikriszwili Tartaruga
- Laboratory of Biomechanics and Energetics of the Human Movement, Universidade Estadual do Centro-Oeste do Paraná, Guarapuava, PR, Brazil
- Postgraduate Program in Physical Education, Universidade Federal do Paraná, Curitiba, PR, Brazil
| | - Tatiane Gorski
- Laboratory of Exercise and Health, ETH Zürich-Swiss Federal Institute of Technology, Zurich, Switzerland
| | - Adriano Eduardo Lima-Silva
- Postgraduate Program in Physical Education, Universidade Federal do Paraná, Curitiba, PR, Brazil
- The Human Performance Research Group, Universidade Tecnológica Federal do Paraná, Curitiba, PR, Brazil
| | - Lorival José Carminatti
- Morpho-Functional Research Laboratory, Universidade do Estado de Santa Catarina, Florianópolis, SC, Brazil
| | - Paulo Otto Beyer
- Laboratory of Steam and Refrigeration, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil
| | | | - Jeam Marcel Geremia
- Exercise Research Laboratory, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil
- Postgraduate Program in Human Movement Sciences, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil
| | - Leonardo Alexandre Peyré-Tartaruga
- Exercise Research Laboratory, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil
- Postgraduate Program in Human Movement Sciences, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil
| | - Luiz Fernando Martins Kruel
- Exercise Research Laboratory, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil
- Postgraduate Program in Human Movement Sciences, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil
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Niclou A, Sarma M, Levy S, Ocobock C. To the extreme! How biological anthropology can inform exercise physiology in extreme environments. Comp Biochem Physiol A Mol Integr Physiol 2023; 284:111476. [PMID: 37423419 DOI: 10.1016/j.cbpa.2023.111476] [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: 01/29/2023] [Revised: 07/03/2023] [Accepted: 07/04/2023] [Indexed: 07/11/2023]
Abstract
The fields of biological anthropology and exercise physiology are closely related and can provide mutually beneficial insights into human performance. These fields often use similar methods and are both interested in how humans function, perform, and respond in extreme environments. However, these two fields have different perspectives, ask different questions, and work within different theoretical frameworks and timescales. Biological anthropologists and exercise physiologists can greatly benefit from working together when examining human adaptation, acclimatization, and athletic performance in the extremes of heat, cold, and high-altitude. Here we review the adaptations and acclimatizations in these three different extreme environments. We then examine how this work has informed and built upon exercise physiology research on human performance. Finally, we present an agenda for moving forward, hopefully, with these two fields working more closely together to produce innovative research that improves our holistic understanding of human performance capacities informed by evolutionary theory, modern human acclimatization, and the desire to produce immediate and direct benefits.
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Affiliation(s)
- Alexandra Niclou
- Pennington Biomedical Research Center, Baton Rouge, LA, United States of America. https://twitter.com/fiat_luxandra
| | - Mallika Sarma
- Human Space Flight Lab, Johns Hopkins School of Medicine, Baltimore, MD, United States of America. https://twitter.com/skyy_mal
| | - Stephanie Levy
- Department of Anthropology, CUNY Hunter College, New York, NY, United States of America; New York Consortium in Evolutionary Primatology, New York, NY, United States of America. https://twitter.com/slevyscience
| | - Cara Ocobock
- University of Notre Dame Department of Anthropology, Notre Dame, IN, United States of America; Eck Institute for Global Health, Institute for Educational Initiatives, University of Notre Dame, United States of America.
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5
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Greenfield AM, Alba BK, Giersch GEW, Seeley AD. Sex differences in thermal sensitivity and perception: Implications for behavioral and autonomic thermoregulation. Physiol Behav 2023; 263:114126. [PMID: 36787810 DOI: 10.1016/j.physbeh.2023.114126] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2022] [Revised: 01/20/2023] [Accepted: 02/10/2023] [Indexed: 02/16/2023]
Abstract
Temperature sensitive receptors in the skin and deep body enable the detection of the external and internal environment, including the perception of thermal stimuli. Changes in heat balance require autonomic (e.g., sweating) and behavioral (e.g., seeking shade) thermoeffector initiation to maintain thermal homeostasis. Sex differences in body morphology can largely, but not entirely, account for divergent responses in thermoeffector and perceptual responses to environmental stress between men and women. Thus, it has been suggested that innate differences in thermosensation may exist between men and women. Our goal in this review is to summarize the existing literature that investigates localized and whole-body cold and heat exposure pertaining to sex differences in thermal sensitivity and perception, and the interplay between autonomic and behavioral thermoeffector responses. Overall, it appears that local differences in thermal sensitivity and perception are minimized, yet still apparent, when morphological characteristics are well-controlled. Sex differences in the early vasomotor response to environmental stress and subsequent changes in blood flow likely contribute to the heightened thermal awareness observed in women. However, the contribution of thermoreceptors to observed sex differences in thermal perception and thermoeffector function is unclear, as human studies investigating these questions have not been performed.
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Affiliation(s)
- Andrew M Greenfield
- Thermal and Mountain Medicine Division, US Army Research Institute of Environmental Medicine, Natick, MA, United States of America; Oak Ridge Institute for Science and Education, Belcamp, MD, United States of America.
| | - Billie K Alba
- Thermal and Mountain Medicine Division, US Army Research Institute of Environmental Medicine, Natick, MA, United States of America
| | - Gabrielle E W Giersch
- Thermal and Mountain Medicine Division, US Army Research Institute of Environmental Medicine, Natick, MA, United States of America
| | - Afton D Seeley
- Thermal and Mountain Medicine Division, US Army Research Institute of Environmental Medicine, Natick, MA, United States of America
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Xu X, Rioux TP, Castellani MP. Three dimensional models of human thermoregulation: A review. J Therm Biol 2023; 112:103491. [PMID: 36796931 DOI: 10.1016/j.jtherbio.2023.103491] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2023] [Revised: 01/27/2023] [Accepted: 02/02/2023] [Indexed: 02/05/2023]
Abstract
Numerous human thermoregulatory models have been developed and widely used in various applications such as aerospace, medicine, public health, and physiology research. This paper is a review of three dimensional (3D) models for human thermoregulation. This review begins with a short introduction of thermoregulatory model development followed by key principles for mathematical description of human thermoregulation systems. Different representations of 3D human bodies are discussed with respect to their detail and prediction capability. The human body was divided into fifteen layered cylinders in early 3D models (cylinder model). Recent 3D models have utilized medical image datasets to develop geometrically correct human models (realistic geometry model). The finite element method is mostly used to solve the governing equations and get numerical solutions. The realistic geometry models provide a high degree of anatomical realism and predict whole-body thermoregulatory responses at high resolution and at organ and tissue levels. Thus, 3D models extend to a wide range of applications where temperature distribution is critical, such as hypothermia/hyperthermia therapy and physiology research. The development of thermoregulatory models will continue with the growth in computational power, advancement in numerical methods and simulation software, advances in modern imaging techniques, and progress in the basic science of thermal physiology.
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Affiliation(s)
- Xiaojiang Xu
- Thermal and Mountain Medicine Division, U.S. Army Research Institute of Environmental Medicine, USA.
| | - Timothy P Rioux
- Thermal and Mountain Medicine Division, U.S. Army Research Institute of Environmental Medicine, USA
| | - Michael P Castellani
- Thermal and Mountain Medicine Division, U.S. Army Research Institute of Environmental Medicine, USA; Oak Ridge Institute for Science and Education (ORISE), USA
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Castellani MP, Rioux TP, Castellani JW, Potter AW, Notley SR, Xu X. Finite element model of female thermoregulation with geometry based on medical images. J Therm Biol 2023; 113:103477. [PMID: 37055108 DOI: 10.1016/j.jtherbio.2023.103477] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2022] [Revised: 01/04/2023] [Accepted: 01/05/2023] [Indexed: 01/09/2023]
Abstract
INTRODUCTION this study describes the development of a female finite element thermoregulatory model (FETM) METHOD: the female body model was developed from medical image datasets of a median U.S. female and was constructed to be anatomically correct. The body model preserves the geometric shapes of 13 organs and tissues, including skin, muscles, fat, bones, heart, lungs, brain, bladder, intestines, stomach, kidneys, liver, and eyes. Heat balance within the body is described by the bio-heat transfer equation. Heat exchange at the skin surface includes conduction, convection, radiation, and sweat evaporation. Vasodilation, vasoconstriction, sweating, and shivering are controlled by afferent and efferent signals to and from the skin and hypothalamus. RESULTS the model was validated with measured physiological data during exercise and rest in thermoneutral, hot, and cold conditions. Validations show the model predicted the core temperature (rectal and tympanic temperatures) and mean skin temperatures with acceptable accuracy (within 0.5 °C and 1.6 °C, respectively) CONCLUSION: this female FETM predicted high spatial resolution temperature distribution across the female body, which provides quantitative insights into human thermoregulatory responses in females to non-uniform and transient environmental exposure.
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Affiliation(s)
- Michael P Castellani
- Oak Ridge Institute for Science and Education (ORISE), USA; Thermal and Mountain Medicine Division, U.S. Army Research Institute of Environmental Medicine, USA.
| | - Timothy P Rioux
- Thermal and Mountain Medicine Division, U.S. Army Research Institute of Environmental Medicine, USA
| | - John W Castellani
- Thermal and Mountain Medicine Division, U.S. Army Research Institute of Environmental Medicine, USA
| | - Adam W Potter
- Thermal and Mountain Medicine Division, U.S. Army Research Institute of Environmental Medicine, USA
| | | | - Xiaojiang Xu
- Thermal and Mountain Medicine Division, U.S. Army Research Institute of Environmental Medicine, USA.
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Eimonte M, Eimantas N, Baranauskiene N, Solianik R, Brazaitis M. Kinetics of lipid indicators in response to short- and long-duration whole-body, cold-water immersion. Cryobiology 2022; 109:62-71. [PMID: 36150503 DOI: 10.1016/j.cryobiol.2022.09.003] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2022] [Revised: 09/08/2022] [Accepted: 09/15/2022] [Indexed: 01/16/2023]
Abstract
Cold exposure-induced secretion of stress hormones activates cold-defense responses and mobilizes substrates for increased energy demands to fuel thermogenesis. However, it is unclear whether acute cold exposure-induced stress hormone response kinetics affect circulating lipid parameter kinetics. Therefore, we aimed to investigate the 2-day kinetics of stress hormones (i.e., cortisol, epinephrine, and norepinephrine) and the lipid profile (i.e., total cholesterol [TC], high-density lipoprotein [HDL] cholesterol, low-density lipoprotein [LDL] cholesterol, and triglycerides) in response to whole-body long- (intermittent 170 min; 170-CWI) or short-duration (10 min; 10-CWI) cold-water immersion (CWI; 14 °C water) in 17 healthy, young, adult men. Both CWI trials induced a marked release of the stress hormones, epinephrine, and norepinephrine, with higher concentrations detected after 170-CWI (p < 0.05) and a disrupted diurnal peak of cortisol lasting for a few hours. 170-CWI increased triglyceride levels from immediately after until 2 h after CWI, thereafter the concentration decreased at 4 h, 6 h, 1 day and 2 days after CWI (p < 0.05). Furthermore, the HDL-cholesterol level increased immediately after and at 6 h after 170-CWI (p < 0.05), while TC and LDL-cholesterol levels were not altered within 2 days. Lipid parameters were not affected within the 2 days after 10-CWI. Although both CWIs decreased deep body temperature and increased stress hormone levels for a few hours, only long-duration CWI induced changes in the circulating lipid profile within 2 days after CWI. This should be considered when discussing therapeutic protocols to improve circulating lipid profiles and ameliorate diseases associated with such profiles.
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Affiliation(s)
- Milda Eimonte
- Institute of Sport Science and Innovations, Lithuanian Sports University, Kaunas, Lithuania.
| | - Nerijus Eimantas
- Institute of Sport Science and Innovations, Lithuanian Sports University, Kaunas, Lithuania
| | - Neringa Baranauskiene
- Institute of Sport Science and Innovations, Lithuanian Sports University, Kaunas, Lithuania
| | - Rima Solianik
- Institute of Sport Science and Innovations, Lithuanian Sports University, Kaunas, Lithuania
| | - Marius Brazaitis
- Institute of Sport Science and Innovations, Lithuanian Sports University, Kaunas, Lithuania.
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Koenig FS, Miller KC, O'Connor P, Amaria N. Body Anthropometrics and Rectal Temperature Cooling Rates in Women With Hyperthermia. J Athl Train 2022; 57:464-469. [PMID: 35230443 PMCID: PMC9205556 DOI: 10.4085/1062-6050-225-20] [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: 11/09/2022]
Abstract
CONTEXT Cold-water immersion (CWI) is the best treatment for exertional heat stroke (EHS), and rectal temperature (Trec) cooling rates may differ between sexes. Previous authors have suggested body surface area (BSA) to lean body mass (LBM) ratio is the largest factor affecting CWI Trec cooling rates in men with hyperthermia; this has never been confirmed in women with hyperthermia. OBJECTIVE To examine whether the BSA:LBM ratio and other anthropometrics affect Trec cooling rates in women with hyperthermia. DESIGN Cross-sectional study. SETTING Laboratory. PATIENTS OR OTHER PARTICIPANTS Sixteen women were placed in either a low BSA:LBM ratio (LOW; n = 8; age = 22 ± 1 years, height = 166.8 ± 6.0 cm, mass = 64.1 ± 4.5 kg, BSA:LBM ratio = 3.759 ± 0.214 m2/kg·102) or high BSA:LBM ratio group (HIGH; n = 8; age = 22 ± 2 years, height = 162.7 ± 8.9 cm, mass = 65.8 ± 12.7 kg, BSA:LBM ratio = 4.161 ± 0.232 m2/kg·102). INTERVENTION(S) On day 1, we measured physical characteristics using dual-energy x-ray absorptiometry, and participants completed a maximal oxygen consumption test. On day 2, participants walked at 4.8 km/h for 3 minutes and then ran at 80% of their predetermined maximal oxygen consumption for 2 minutes in the heat (temperature = ~40°C, relative humidity = 40%). This sequence was repeated until Trec reached 39.5°C. Then, they completed CWI (temperature = ~10°C) until Trec was 38°C. MAIN OUTCOME MEASURE(S) Rectal temperature and CWI cooling rates. RESULTS Groups had different BSA:LBM ratios (P = .001), body fat percentages (LOW: 25.7% ± 5.0%; HIGH: 33.7% ± 6.3%; P = .007), and LBM (LOW: 45.8 ± 3.0 kg; HIGH: 41.0 ± 5.1 kg; P = .02) but not different BSA (LOW: 1.72 ± 0.08 m2; HIGH: 1.70 ± 0.16 m2; P = .40) or BMI (LOW: 23.1 ± 2.1; HIGH: 24.9 ± 4.7; P = .17). Despite differences in several physical characteristics, Trec cooling rates were excellent but comparable (LOW: 0.26°C/min ± 0.09°C/min; HIGH: 0.27°C/min ± 0.07°C/min; P = .39). The BSA:LBM ratio (r = 0.14, P = .59), body fat percentage (r = 0.29, P = .28), LBM (r = -0.10, P = .70), BSA (r = -0.01, P = .97), and BMI (r = 0.37, P = .16) were not correlated with Trec cooling rates. CONCLUSIONS Body anthropometrics did not affect CWI Trec cooling rates in women with hyperthermia. Clinicians need not worry about anthropometric characteristics slowing the treatment of severe hyperthermia in women using CWI.
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Affiliation(s)
- Fallon S Koenig
- *School of Health Sciences, Central Michigan University, Mount Pleasant
| | - Kevin C Miller
- †School of Rehabilitation and Medical Sciences, Central Michigan University, Mount Pleasant
| | - Paul O'Connor
- *School of Health Sciences, Central Michigan University, Mount Pleasant
| | - Noshir Amaria
- ‡College of Medicine, Central Michigan University, Mount Pleasant
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Ocobock C, Niclou A. Commentary—fat but fit…and cold? Potential evolutionary and environmental drivers of metabolically healthy obesity. Evol Med Public Health 2022; 10:400-408. [PMID: 36071988 PMCID: PMC9447378 DOI: 10.1093/emph/eoac030] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2022] [Accepted: 08/04/2022] [Indexed: 11/29/2022] Open
Abstract
As global obesity rates continue to rise, it is important to understand the origin, role and range of human variation of body mass index (BMI) in assessing health and healthcare. A growing body of evidence suggests that BMI is a poor indicator of health across populations, and that there may be a metabolically healthy obese phenotype. Here, we review the reasons why BMI is an inadequate tool for assessing cardiometabolic health. We then suggest that cold climate adaptations may also render BMI an uninformative metric. Underlying evolutionary and environmental drivers may allow for heat conserving larger body sizes without necessarily increasing metabolic health risks. However, there may also be a potential mismatch between modern obesogenic environments and adaptations to cold climates, highlighting the need to further investigate the potential for metabolically healthy obese phenotypes among circumpolar and other populations as well as the broader meaning for metabolic health.
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Affiliation(s)
- Cara Ocobock
- Department of Anthropology, University of Notre Dame , Notre Dame, IN, USA
- Eck Institute for Global Health, Institute for Educational Initiatives, University of Notre Dame , Notre Dame, IN, USA
| | - Alexandra Niclou
- Department of Anthropology, University of Notre Dame , Notre Dame, IN, USA
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Greenfield AM, Charkoudian N, Alba BK. Influences of ovarian hormones on physiological responses to cold in women. Temperature (Austin) 2021; 9:23-45. [DOI: 10.1080/23328940.2021.1953688] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Affiliation(s)
- Andrew Martin Greenfield
- Thermal & Mountain Medicine Division, US Army Research Institute of Environmental Medicine, Natick, MA, USA
- Oak Ridge Institute of Science and Education, Belcamp, MD, USA
| | - Nisha Charkoudian
- Thermal & Mountain Medicine Division, US Army Research Institute of Environmental Medicine, Natick, MA, USA
| | - Billie Katherine Alba
- Thermal & Mountain Medicine Division, US Army Research Institute of Environmental Medicine, Natick, MA, USA
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12
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Ocobock C, Soppela P, Turunen M, Stenbäck V, Herzig KH, Rimbach R, Pontzer H. Reindeer herders from subarctic Finland exhibit high total energy expenditure and low energy intake during the autumn herd roundup. Am J Hum Biol 2021; 34:e23676. [PMID: 34520587 DOI: 10.1002/ajhb.23676] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2021] [Revised: 08/26/2021] [Accepted: 08/27/2021] [Indexed: 12/31/2022] Open
Abstract
OBJECTIVE High levels of total energy expenditure (TEE, kcal/day) have been documented among numerous human populations such as tropical climate horticulturalists and high-altitude agriculturalists. However, less work has been conducted among highly physically active cold climate populations. METHODS In October 2018, TEE was measured using the doubly labeled water (TEEDLW , N = 10) and flex-heart rate methods (TEEHR , N = 24) for 6-14 days among reindeer herders (20-62 years) in northern Finland during an especially physically demanding, but not seasonally representative, period of the year for herders-the annual reindeer herd roundup. Self-reported dietary intake was also collected during TEE measurement periods. TEE was then compared to that of hunter gatherer, farming, and market economies. RESULTS During the herd roundup, herders expended a mean of 4183 ± 949 kcal/day as measured by the DLW method, which was not significantly different from TEEHR . Mean caloric intake was 1718 ± 709 kcal/day, and was significantly lower than TEEDLW and TEEHR (p < .001). Herder TEEDLW was significantly higher than that of hunter gatherer (p = .0014) and market (p < .0014) economy populations; however, herder TEEDLW was not different from that of farming populations (p = .91). CONCLUSION High TEE and low caloric intake among herders reflect the extreme demands placed on herders during the annual herd round up. Although TEEDLW was similar between cold climate herders and hot climate farming populations, there are likely differences in how that TEE is comprised, reflecting the local ecologies of these populations.
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Affiliation(s)
- Cara Ocobock
- Department of Anthropology, University of Notre Dame, Notre Dame, Indiana, USA.,Eck Institute for Global Health, Institute for Educational Initiatives, University of Notre Dame, Notre Dame, Indiana, USA
| | - Päivi Soppela
- University of Lapland, Arctic Centre, Rovaniemi, Finland
| | - Minna Turunen
- University of Lapland, Arctic Centre, Rovaniemi, Finland
| | - Ville Stenbäck
- Research Unit of Biomedicine, Medical Research Center, Faculty of Medicine, University of Oulu and Oulu University Hospital, Oulu, Finland.,Biocenter Oulu, Oulu, Finland
| | - Karl-Heinz Herzig
- Research Unit of Biomedicine, Medical Research Center, Faculty of Medicine, University of Oulu and Oulu University Hospital, Oulu, Finland.,Institute of Pediatrics, Department of Gastroenterology and Metabolism, Poznan University of Medical Sciences, Poznan, Poland
| | - Rebecca Rimbach
- Department of Evolutionary Anthropology, Duke University, Durham, North Carolina, USA.,School of Animal, Plant & Environmental Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Herman Pontzer
- Department of Evolutionary Anthropology, Duke University, Durham, North Carolina, USA.,Duke Global Health Institute, Duke University, Durham, North Carolina, USA
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13
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Ocobock C, Lacy S, Niclou A. Between a rock and a cold place: Neanderthal biocultural cold adaptations. Evol Anthropol 2021; 30:262-279. [PMID: 33797824 DOI: 10.1002/evan.21894] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2020] [Revised: 07/16/2020] [Accepted: 03/14/2021] [Indexed: 12/15/2022]
Abstract
A large body of work focuses on the unique aspects of Neanderthal anatomy, inferred physiology, and behavior to test the assumption that Neanderthals were hyper-adapted to living in cold environments. This research has expanded over the years to include previously unexplored and potentially adaptive features such as brown adipose tissue and fire-usage. Here we review the current state of knowledge of Neanderthal cold adaptations along morphological, physiological, and behavioral lines. While highlighting foundational as well as recent work, we also emphasize key areas for future research. Despite thriving in a variety of climates, it is well-accepted that Neanderthals appear to be the most cold-adapted of known fossil hominin groups; however, there are still many unknowns. There is a great deal yet to be uncovered about the nature and manifestation of Neanderthal adaptation and how the synergy of biology and culture helped buffer them against extreme and variable environments.
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Affiliation(s)
- Cara Ocobock
- Department of Anthropology, University of Notre Dame, South Bend, Indiana, USA.,Eck Institute for Global Health, Institute for Educational Initiatives, University of Notre Dame, South Bend, Indiana, USA
| | - Sarah Lacy
- Department of Anthropology, California State University Dominguez Hills, Carson, California, USA
| | - Alexandra Niclou
- Department of Anthropology, University of Notre Dame, South Bend, Indiana, USA
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14
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Ivanova YM, Blondin DP. Examining the benefits of cold exposure as a therapeutic strategy for obesity and type 2 diabetes. J Appl Physiol (1985) 2021; 130:1448-1459. [PMID: 33764169 DOI: 10.1152/japplphysiol.00934.2020] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
The pathogenesis of metabolic diseases such as obesity and type 2 diabetes are characterized by a progressive dysregulation in energy partitioning, often leading to end-organ complications. One emerging approach proposed to target this metabolic dysregulation is the application of mild cold exposure. In healthy individuals, cold exposure can increase energy expenditure and whole body glucose and fatty acid utilization. Repeated exposures can lower fasting glucose and insulin levels and improve dietary fatty acid handling, even in healthy individuals. Despite its apparent therapeutic potential, little is known regarding the effects of cold exposure in populations for which this stimulation could benefit the most. The few studies available have shown that both acute and repeated exposures to the cold can improve insulin sensitivity and reduce fasting glycemia in individuals with type 2 diabetes. However, critical gaps remain in understanding the prolonged effects of repeated cold exposures on glucose regulation and whole body insulin sensitivity in individuals with metabolic syndrome. Much of the metabolic benefits appear to be attributable to the recruitment of shivering skeletal muscles. However, further work is required to determine whether the broader recruitment of skeletal muscles observed during cold exposure can confer metabolic benefits that surpass what has been historically observed from endurance exercise. In addition, although cold exposure offers unique cardiovascular responses for a physiological stimulus that increases energy expenditure, further work is required to determine how acute and repeated cold exposure can impact cardiovascular responses and myocardial function across a broader scope of individuals.
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Affiliation(s)
- Yoanna M Ivanova
- Centre de Recherche du Centre Hospitalier Universitaire de Sherbrooke, Sherbrooke, Québec, Canada.,Department of Pharmacology-Physiology, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Sherbrooke, Québec, Canada
| | - Denis P Blondin
- Centre de Recherche du Centre Hospitalier Universitaire de Sherbrooke, Sherbrooke, Québec, Canada.,Division of Neurology, Department of Medicine, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Sherbrooke, Québec, Canada
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15
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Loss of α-actinin-3 during human evolution provides superior cold resilience and muscle heat generation. Am J Hum Genet 2021; 108:446-457. [PMID: 33600773 PMCID: PMC8008486 DOI: 10.1016/j.ajhg.2021.01.013] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2020] [Accepted: 01/19/2021] [Indexed: 12/12/2022] Open
Abstract
The protein α-actinin-3 expressed in fast-twitch skeletal muscle fiber is absent in 1.5 billion people worldwide due to homozygosity for a nonsense polymorphism in ACTN3 (R577X). The prevalence of the 577X allele increased as modern humans moved to colder climates, suggesting a link between α-actinin-3 deficiency and improved cold tolerance. Here, we show that humans lacking α-actinin-3 (XX) are superior in maintaining core body temperature during cold-water immersion due to changes in skeletal muscle thermogenesis. Muscles of XX individuals displayed a shift toward more slow-twitch isoforms of myosin heavy chain (MyHC) and sarcoplasmic reticulum (SR) proteins, accompanied by altered neuronal muscle activation resulting in increased tone rather than overt shivering. Experiments on Actn3 knockout mice showed no alterations in brown adipose tissue (BAT) properties that could explain the improved cold tolerance in XX individuals. Thus, this study provides a mechanism for the positive selection of the ACTN3 X-allele in cold climates and supports a key thermogenic role of skeletal muscle during cold exposure in humans.
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16
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Polidori G, Elfahem R, Abbes B, Bogard F, Legrand F, Bouchet B, Beaumont F. Preliminary study on the effect of sex on skin cooling response during whole body cryostimulation (-110 °C): Modeling and prediction of exposure durations. Cryobiology 2020; 97:12-19. [PMID: 33130106 DOI: 10.1016/j.cryobiol.2020.10.014] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2020] [Revised: 10/13/2020] [Accepted: 10/22/2020] [Indexed: 10/23/2022]
Abstract
In order to determine the required duration of whole-body exposure to extreme cold (-110 °C) in males and females for achieving the same cold-induced response, a mathematical model of skin cooling kinetics was developed. This modeling is derived from the implementation of a new experimental cryotherapy protocol to obtain continuous skin temperature maps over time. Each 3-min whole-body cryostimulation session was divided into six incremental sessions of 30 s carried out over six consecutive days. Seventeen young, healthy subjects (8 males aged 22.6 ±3.0 years and 9 females aged 23.7 ±4.7 years) agreed to participate in this study. The smallest sex-related difference in temperature was found in the trunk area (2.93 °C after 3 min) while the greatest temperature drop was found in the lower limbs (5.92 °C after 3 min). The largest temperature variation was observed between the trunk and the lower limbs, and peaked at 2.67 °C in males and 6.99 °C in females. For both sexes, skin cooling kinetics showed a strong transient exponential type decrease followed by linear regression behavior. It appeared that for achieving the same cold-induced response, the required duration of cryostimulation is longer for males. For example, a trunk skin cooling of -12 °C could be achieved in 125s for females vs 170s for males (+36% longer); for the lower limbs, the same skin cooling magnitude could be reached after 87s for females vs 140s for males (+62% longer).
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Affiliation(s)
- G Polidori
- Faculty of Exact and Natural Sciences, University of Reims Champagne Ardenne, France
| | - R Elfahem
- Faculty of Exact and Natural Sciences, University of Reims Champagne Ardenne, France
| | - B Abbes
- Faculty of Exact and Natural Sciences, University of Reims Champagne Ardenne, France
| | - F Bogard
- Faculty of Exact and Natural Sciences, University of Reims Champagne Ardenne, France
| | - F Legrand
- C2S, Cognition Health and Society, EA 6291, University of Reims Champagne-Ardenne, France
| | - B Bouchet
- Cryotera, 2 Rue Jules Méline, 51430, Bezannes, France
| | - F Beaumont
- Faculty of Exact and Natural Sciences, University of Reims Champagne Ardenne, France.
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17
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Hattersley J, Wilson AJ, Gifford R, Facer-Childs J, Stoten O, Cobb R, Thake CD, Reynolds RM, Woods D, Imray C. A comparison of the metabolic effects of sustained strenuous activity in polar environments on men and women. Sci Rep 2020; 10:13912. [PMID: 32807833 PMCID: PMC7431584 DOI: 10.1038/s41598-020-70296-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2020] [Accepted: 06/24/2020] [Indexed: 01/05/2023] Open
Abstract
This study investigates differences in pre- to post-expedition energy expenditure, substrate utilisation and body composition, between the all-male Spear17 (SP-17) and all-female Ice Maiden (IM) transantarctic expeditions (IM: N = 6, 61 days, 1700 km; SP-17: N = 5, 67 days, 1750 km). Energy expenditure and substrate utilisation were measured by a standardised 36 h calorimetry protocol; body composition was determined using air displacement plethysmography. Energy balance calculation were used to assess the physical challenge. There was difference in the daily energy expenditure (IM: 4,939 kcal day−1; SP-17: 6,461 kcal day−1, p = 0.004); differences related to physical activity were small, but statistically significant (IM = 2,282 kcal day−1; SP-17 = 3,174 kcal day−1; p = 0.004). Bodyweight loss was modest (IM = 7.8%, SP-17 = 6.5%; p > 0.05) as was fat loss (IM = 30.4%, SP-17 = 40.4%; p > 0.05). Lean tissue weight change was statistically significant (IM = − 2.5%, SP-17 = + 1.0%; p = 0.05). No difference was found in resting or sleeping energy expenditure, normalised to lean tissue weight (p > 0.05); nor in energy expenditure when exercising at 80, 100 and 120 steps min−1, normalised to body weight (p > 0.05). Similarly, no difference was found in the change in normalised substrate utilisation for any of the activities (p > 0.05). Analysis suggested that higher daily energy expenditures for the men in Spear-17 was the result of higher physical demands resulting in a reduced demand for energy to thermoregulate compared to the women in Ice Maiden. The lack of differences between men and women in the change in energy expenditure and substrate utilisation, suggests no sex difference in response to exposure to extreme environments.
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Affiliation(s)
- John Hattersley
- Coventry NIHR CRF Human Metabolic Research Unit, University Hospitals Coventry and Warwickshire NHS Trust, Coventry, CV2 2DX, UK. .,School of Engineering, University of Warwick, Coventry, CV4 7AL, USA. .,Faculty of Health and Life Sciences, Coventry University, Coventry, UK.
| | - Adrian J Wilson
- Coventry NIHR CRF Human Metabolic Research Unit, University Hospitals Coventry and Warwickshire NHS Trust, Coventry, CV2 2DX, UK.,Department of Physics, University of Warwick, Coventry, CV4 7AL, UK
| | - Rob Gifford
- University/British Heart Foundation Centre for Cardiovascular Science, Queen's Medical Research Institute, University of Edinburgh, Edinburgh, UK.,Research and Clinical Innovation, Royal Centre for Defence Medicine, Birmingham, UK
| | - Jamie Facer-Childs
- Institute of Child Health, University College London, London, WC1N 1EH, UK
| | - Oliver Stoten
- Emergency Department, Royal Bournemouth Hospital, Bournemouth, BH7 7DW, UK
| | - Rinn Cobb
- Performance, Nutrition and Dietetic Consulting, pnd consulting.co.uk, Middlesbrough, UK
| | - C Doug Thake
- Faculty of Health and Life Sciences, Coventry University, Coventry, UK
| | - Rebecca M Reynolds
- University/British Heart Foundation Centre for Cardiovascular Science, Queen's Medical Research Institute, University of Edinburgh, Edinburgh, UK
| | - David Woods
- Research and Clinical Innovation, Royal Centre for Defence Medicine, Birmingham, UK.,Research Institute for Sport, Physical Activity and Leisure, Leeds Beckett University, Leeds, UK.,Northumbria and Newcastle NHS Trusts, Wansbeck General and Royal Victoria Infirmary, Newcastle, UK
| | - Chris Imray
- Coventry NIHR CRF Human Metabolic Research Unit, University Hospitals Coventry and Warwickshire NHS Trust, Coventry, CV2 2DX, UK.,Faculty of Health and Life Sciences, Coventry University, Coventry, UK.,Department of Vascular and Renal Transplant Surgery, University Hospitals Coventry and Warwickshire NHS Trust, Coventry, CV2 2DX, UK
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18
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Affiliation(s)
- Cara Ocobock
- Department of Anthropology University Notre Dame Notre Dame IN 46556 USA
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19
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Longman DP, Wells JCK, Stock JT. Human athletic paleobiology; using sport as a model to investigate human evolutionary adaptation. AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY 2020; 171 Suppl 70:42-59. [PMID: 31957878 PMCID: PMC7217212 DOI: 10.1002/ajpa.23992] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/01/2019] [Revised: 10/29/2019] [Accepted: 12/12/2019] [Indexed: 11/11/2022]
Abstract
The use of sport as a conceptual framework offers unprecedented opportunities to improve our understanding of what the body does, shedding new light on our evolutionary trajectory, our capacity for adaptation, and the underlying biological mechanisms. This approach has gained traction over recent years. To date, sport has facilitated exploration not only of the evolutionary history of our species as a whole, but also of human variation and adaptation at the interindividual and intraindividual levels. At the species level, analysis of lower and upper limb biomechanics and energetics with respect to walking, running and throwing have led to significant advances in the understanding of human adaptations relative to other hominins. From an interindividual perspective, investigation of physical activity patterns and endurance running performance is affording greater understanding of evolved constraints of energy expenditure, thermoregulatory energetics, signaling theory, and morphological variation. Furthermore, ultra-endurance challenges provoke functional trade-offs, allowing new ground to be broken in the study of life history trade-offs and human adaptability. Human athletic paleobiology-the recruitment of athletes as study participants and the use of contemporary sports as a model for studying evolutionary theory-has great potential. Here, we draw from examples in the literature to provide a review of how the use of athletes as a model system is enhancing understanding of human evolutionary adaptation.
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Affiliation(s)
- Daniel P. Longman
- School of Sport, Exercise and Health SciencesLoughborough UniversityLoughboroughUK
| | | | - Jay T. Stock
- Department of AnthropologyUniversity of Western OntarioLondonOntarioCanada
- Department of ArchaeologyMax Planck Institute for the Science of Human HistoryJenaGermany
- Department of ArchaeologyUniversity of CambridgeCambridgeUK
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20
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Longman DP, Macintosh Murray A, Roberts R, Oakley S, Wells JC, Stock JT. Ultra-endurance athletic performance suggests that energetics drive human morphological thermal adaptation. EVOLUTIONARY HUMAN SCIENCES 2019; 1:e16. [PMID: 37588394 PMCID: PMC10427320 DOI: 10.1017/ehs.2019.13] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Both extinct and extant hominin populations display morphological features consistent with Bergmann's and Allen's Rules. However, the functional implications of the morphologies described by these ecological laws are poorly understood. We examined this through the lens of endurance running. Previous research concerning endurance running has focused on locomotor energetic economy. We considered a less-studied dimension of functionality, thermoregulation. The performance of male ultra-marathon runners (n = 88) competing in hot and cold environments was analysed with reference to expected thermoregulatory energy costs and the optimal morphologies predicted by Bergmann's and Allen's Rules. Ecogeographical patterning supporting both principles was observed in thermally challenging environments. Finishers of hot-condition events had significantly longer legs than finishers of cold-condition events. Furthermore, hot-condition finishers had significantly longer legs than those failing to complete hot-condition events. A degree of niche-picking was evident; athletes may have tailored their event entry choices in accordance with their previous race experiences. We propose that the interaction between prolonged physical exertion and hot or cold climates may induce powerful selective pressures driving morphological adaptation. The resulting phenotypes reduce thermoregulatory energetic expenditure, allowing diversion of energy to other functional outcomes such as faster running.
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Affiliation(s)
- Daniel P. Longman
- School of Sport, Health and Exercise Sciences, Loughborough University, LoughboroughLE11 3TU, UK
| | | | - Rebecca Roberts
- Department of Archaeology, University of Cambridge, CambridgeCB2 3QG, UK
| | - Saskia Oakley
- Department of Archaeology, University of Cambridge, CambridgeCB2 3QG, UK
| | - Jonathan C.K. Wells
- Childhood Nutrition Research Centre, UCL Institute of Child Health, LondonWC1N 1EH, UK
| | - Jay T. Stock
- Department of Archaeology, University of Cambridge, CambridgeCB2 3QG, UK
- Department of Anthropology, University of Western Ontario, Ontario, Canada
- Department of Archaeology, Max Planck Institute for the Science of Human History, Kahlaische Strasse 10, D-07745Jena, Germany
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21
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Does Gender Affect Rectal Temperature Cooling Rates? A Critically Appraised Topic. J Sport Rehabil 2019; 28:522-525. [DOI: 10.1123/jsr.2018-0081] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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22
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Kaikaew K, van den Beukel JC, Neggers SJCMM, Themmen APN, Visser JA, Grefhorst A. Sex difference in cold perception and shivering onset upon gradual cold exposure. J Therm Biol 2018; 77:137-144. [PMID: 30196892 DOI: 10.1016/j.jtherbio.2018.08.016] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2018] [Revised: 08/21/2018] [Accepted: 08/22/2018] [Indexed: 01/22/2023]
Abstract
To maintain a thermal balance when experiencing cold, humans reduce heat loss and enhance heat production. A potent and rapid mechanism for heat generation is shivering. Research has shown that women prefer a warmer environment and feel less comfortable than men in the same thermal condition. Using the Blanketrol® III, a temperature management device commonly used to study brown adipose tissue activity, we tested whether the experimental temperature (TE) at which men and women start to shiver differs. Twenty male and 23 female volunteers underwent a cooling protocol, starting at 24 °C and gradually decreasing by 1-2 °C every 5 min until an electromyogram detected the shivering or the temperature reached 9 °C. Women started shivering at a higher TE than men (11.3 ± 1.8 °C for women vs 9.6 ± 1.8 °C for men, P = 0.003). In addition, women felt cool, scored by a visual analogue scale, at a higher TE than men (18.3 ± 3.0 °C for women vs 14.6 ± 2.6 °C for men, P < 0.001). This study demonstrates a sex difference in response to cold exposure: women require shivering as a source of heat production earlier than men. This difference could be important and sex should be considered when using cooling protocols in physiological studies.
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Affiliation(s)
- Kasiphak Kaikaew
- Department of Internal Medicine, Erasmus MC, University Medical Center Rotterdam, PO Box 2040, 3000 CA Rotterdam, the Netherlands; Department of Physiology, Faculty of Medicine, Chulalongkorn University, 1873, Rama IV Road, Pathumwan, Bangkok 10330, Thailand
| | - Johanna C van den Beukel
- Department of Internal Medicine, Erasmus MC, University Medical Center Rotterdam, PO Box 2040, 3000 CA Rotterdam, the Netherlands
| | - Sebastian J C M M Neggers
- Department of Internal Medicine, Erasmus MC, University Medical Center Rotterdam, PO Box 2040, 3000 CA Rotterdam, the Netherlands
| | - Axel P N Themmen
- Department of Internal Medicine, Erasmus MC, University Medical Center Rotterdam, PO Box 2040, 3000 CA Rotterdam, the Netherlands
| | - Jenny A Visser
- Department of Internal Medicine, Erasmus MC, University Medical Center Rotterdam, PO Box 2040, 3000 CA Rotterdam, the Netherlands.
| | - Aldo Grefhorst
- Department of Internal Medicine, Erasmus MC, University Medical Center Rotterdam, PO Box 2040, 3000 CA Rotterdam, the Netherlands
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23
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Abstract
Human obesity has a large genetic component, yet has many serious negative consequences. How this state of affairs has evolved has generated wide debate. The thrifty gene hypothesis was the first attempt to explain obesity as a consequence of adaptive responses to an ancient environment that in modern society become disadvantageous. The idea is that genes (or more precisely, alleles) predisposing to obesity may have been selected for by repeated exposure to famines. However, this idea has many flaws: for instance, selection of the supposed magnitude over the duration of human evolution would fix any thrifty alleles (famines kill the old and young, not the obese) and there is no evidence that hunter-gatherer populations become obese between famines. An alternative idea (called thrifty late) is that selection in famines has only happened since the agricultural revolution. However, this is inconsistent with the absence of strong signatures of selection at single nucleotide polymorphisms linked to obesity. In parallel to discussions about the origin of obesity, there has been much debate regarding the regulation of body weight. There are three basic models: the set-point, settling point and dual-intervention point models. Selection might act against low and high levels of adiposity because food unpredictability and the risk of starvation selects against low adiposity whereas the risk of predation selects against high adiposity. Although evidence for the latter is quite strong, evidence for the former is relatively weak. The release from predation ∼2-million years ago is suggested to have led to the upper intervention point drifting in evolutionary time, leading to the modern distribution of obesity: the drifty gene hypothesis. Recent critiques of the dual-intervention point/drifty gene idea are flawed and inconsistent with known aspects of energy balance physiology. Here, I present a new formulation of the dual-intervention point model. This model includes the novel suggestion that food unpredictability and starvation are insignificant factors driving fat storage, and that the main force driving up fat storage is the risk of disease and the need to survive periods of pathogen-induced anorexia. This model shows why two independent intervention points are more likely to evolve than a single set point. The molecular basis of the lower intervention point is likely based around the leptin pathway signalling. Determining the molecular basis of the upper intervention point is a crucial key target for future obesity research. A potential definitive test to separate the different models is also described.
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Affiliation(s)
- John R Speakman
- Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, China .,Institute of Biological and Environmental Sciences, University of Aberdeen, Aberdeen, Scotland, UK
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24
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Abstract
Excised fat tissue has a lower thermal conductivity than excised lean tissue. In theory then subcutaneous fat might serve as a barrier to heat loss and influence thermoregulatory abilities. In some aquatic mammals and animals from severely cold habitats subcutaneous adipose tissue has evolved into a continuous sheet that envelopes the organs and acts as a thermal insulation layer. This layer can comprise more than half of the cross-sectional area of the body. In most mammals however, the distribution of fat is less continuous. It has been suggested that in tropical animals this distribution may in fact allow animals to still store energy while not impeding heat loss. Studies of humans immersed in cool water convincingly demonstrate that obesity in humans also serves an insulation function. Humans with obesity cool less rapidly and have to elevate their metabolism less significantly than lean individuals when immersed in water. Although obesity provides an advantage in cold conditions it conversely impedes heat loss and makes obese people susceptible to heat stress more than lean individuals. In small mammals like mice the role of subcutaneous (or intradermal) fat for providing thermal insulation is less clear. In theory variations in thermoregulatory capacity may allow individuals different capabilities to burn off excess consumption. Hence, thermoregulatory variations may cause obesity differences. Thermoregulatory capacity is related to ambient temperature. Yet, levels of obesity are only weakly related to ambient temperature and this effect disappears when confounding factors like poverty and race are taken into account. Hence we conclude that obesity may have a significant impact on thermoregulatory physiology, but the converse is much less likely.
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25
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Davis JT, Hay MW, Hardin AM, White MD, Lovering AT. Effect of a patent foramen ovale in humans on thermal responses to passive cooling and heating. J Appl Physiol (1985) 2017; 123:1423-1432. [PMID: 28819008 DOI: 10.1152/japplphysiol.01032.2016] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2016] [Revised: 08/11/2017] [Accepted: 08/11/2017] [Indexed: 11/22/2022] Open
Abstract
Humans with a patent foramen ovale (PFO) have a higher esophageal temperature (Tesoph) than humans without a PFO (PFO-). Thus the presence of a PFO might also be associated with differences in thermal responsiveness to passive cooling and heating such as shivering and hyperpnea, respectively. The purpose of this study was to determine whether thermal responses to passive cooling and heating are different between PFO- subjects and subjects with a PFO (PFO+). We hypothesized that compared with PFO- subjects PFO+ subjects would cool down more rapidly and heat up slower and that PFO+ subjects who experienced thermal hyperpnea would have a blunted increase in ventilation. Twenty-seven men (13 PFO+) completed two trials separated by >48 h: 1) 60 min of cold water immersion (19.5 ± 0.9°C) and 2) 30 min of hot water immersion (40.5 ± 0.2°C). PFO+ subjects had a higher Tesoph before and during cold water and hot water immersion (P < 0.05). However, the rate of temperature change was similar between groups for each condition. Within a subset of 18 subjects (8 PFO+) who experienced thermal hyperpnea, PFO+ subjects experienced thermal hyperpnea at a higher absolute Tesoph but with a blunted magnitude compared with PFO- subjects. These data suggest that PFO+ subjects have a higher Tesoph at rest and have blunted thermal hyperpnea during passive heating.NEW & NOTEWORTHY Patent foramen ovale (PFO) is found in ~25-40% of the population. The presence of a PFO appears to be associated with a greater core body temperature and blunted ventilatory responses during passive heating. The reason for this blunted ventilatory response to passive heating is unknown but may suggest differences in thermal sensitivity in PFO+ subjects compared with PFO- subjects.
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Affiliation(s)
- James T Davis
- Department of Kinesiology, Recreation, and Sport, Indiana State University, Terre Haute, Indiana
| | - Madeline W Hay
- Department of Human Physiology, University of Oregon, Eugene, Oregon; and
| | - Alyssa M Hardin
- Department of Human Physiology, University of Oregon, Eugene, Oregon; and
| | - Matthew D White
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, Vancouver, British Columbia, Canada
| | - Andrew T Lovering
- Department of Human Physiology, University of Oregon, Eugene, Oregon; and
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Haman F, Blondin DP. Shivering thermogenesis in humans: Origin, contribution and metabolic requirement. Temperature (Austin) 2017; 4:217-226. [PMID: 28944268 DOI: 10.1080/23328940.2017.1328999] [Citation(s) in RCA: 69] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2017] [Revised: 05/07/2017] [Accepted: 05/08/2017] [Indexed: 01/01/2023] Open
Abstract
As endotherms, humans exposed to a compensable cold environment rely on an increase in thermogenic rate to counteract heat lost to the environment, thereby maintaining a stable core temperature. This review focuses primarily on the most important contributor of heat production in cold-exposed adult humans, shivering skeletal muscles. Specifically, it presents current understanding on (1) the origins of shivering, (2) the contribution of shivering to total heat production and (3) the metabolic requirements of shivering. Although shivering had commonly been measured as a metabolic outcome measure, considerable research is still needed to clearly identify the neuroanatomical structures and circuits that initiate and modulate shivering and drives the shivering patterns (continuous and burst shivering). One thing is clear, the thermogenic rate in humans can be maintained despite significant inter-individual differences in the thermogenic contribution of shivering, the muscles recruited in shivering, the burst shivering rate and the metabolic substrates used to support shivering. It has also become evident that the variability in burst shivering rate between individuals, despite not influencing heat production, does play a key role in orchestrating metabolic fuel selection in the cold. In addition, advances in our understanding of the thermogenic role of brown adipose tissue have been able to explain, at least in part, the large inter-individual differences in the contribution of shivering to total heat production. Whether these differences in the thermogenic role of shivering have any bearing on cold endurance and survival remains to be established. Despite the available research describing the relative thermogenic importance of shivering skeletal muscles in humans, the advancement in our understanding of how shivering is initiated and modulated is needed. Such research is critical to consider strategies to either reduce its role to improve occupational performance or exploit its metabolic potential for clinical purposes.
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Affiliation(s)
- François Haman
- Faculty of Health Sciences, University of Ottawa, Ottawa, Ontario, Canada
| | - Denis P Blondin
- Department of Medicine, Centre de Recherche du Centre Hospitalier Universitaire de Sherbrooke, Université de Sherbrooke, Sherbrooke, Canada
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Brazaitis M, Paulauskas H, Skurvydas A, Budde H, Daniuseviciute L, Eimantas N. Brief Rewarming Blunts Hypothermia-Induced Alterations in Sensation, Motor Drive and Cognition. Front Physiol 2016; 7:592. [PMID: 27990123 PMCID: PMC5133047 DOI: 10.3389/fphys.2016.00592] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2016] [Accepted: 11/15/2016] [Indexed: 12/25/2022] Open
Abstract
Background: It is well known that cold exposure experienced during occupational or recreational activities may adversely affect motor, cognitive performance, and health. Most research has used prolonged passive external rewarming modalities and focused on the direct effects on the kinetics of physiological and psychological responses in hypothermic subjects. However, the brief whole body rewarming effects on physiological and psychological responses in parallel with functional consequences on cognitive and neurophysiological functions have not been investigated. This study explores these effects in 12 healthy young men. Methods: Subjects (20 ± 1 years) participated in 4 randomized trials, which were designed to compare the effects of whole-body brief (5-min) rewarming in 37°C water with rewarming for the same duration in 24°C (air) thermoneutral environment in mildly hypothermic subjects. After each rewarming, indicators of neuromuscular function (reflexes, central activation ratio, electromyography of exercising muscle, and contractile properties of calf muscles) and cognitive function (attention, simple motor speed, and information processing speed) were assessed. Results: Compared to rewarming in thermoneutral environment, after brief rewarming in 37°C water, significantly lower metabolic heat production (MHP) (206 ± 33.4 vs. 121.9 ± 24.3 W·m2, P < 0.01), heart rate (76 ± 16 vs. 60 ± 12 b·min−1, P < 0.01), cold strain (6.4 ± 3.1 vs. 5.3 ± 2.7, P < 0.01), improved thermal comfort and induced cessation of shivering were found. Electrically induced maximum torque amplitudes increased (P100, 102.8 ± 21.3 vs. 109.2 ± 17.5 Nm and PTT100, 83.1 ± 17.1 vs. 92.7 ± 16.0 Nm, P < 0.05), contraction half-relaxation time decreased (599.0 ± 53.8 vs. 589.0 ± 56.3 ms, P < 0.05), and Mmax-wave latency shortened (17.5 ± 2.2 vs. 15.6 ± 2.0 ms, P < 0.05) after 37°C water rewarming. Unlike rewarming in thermoneutral environment, 37°C water rewarming blunted the hypothermia-induced alterations in neural drive transmission (4.3 ± 0.5 vs. 3.4 ± 0.8 mV H-reflex and 4.9 ± 0.2 vs. 4.4 ± 0.4 mV V-wave, P < 0.05), which increased central fatigue during a 2-min maximum load (P < 0.05). Furthermore, only in brief warm water rewarming cerebral alterations were restored to the control level and it was indicated by shortened reaction times (P < 0.05). Conclusions: Brief rewarming in warm water rather than the same duration rewarming in thermoneutral environment blunted the hypothermia-induced alterations for sensation, motor drive, and cognition, despite the fact that rectal and deep muscle temperature remained lowered.
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Affiliation(s)
- Marius Brazaitis
- Institute of Sport Science and Innovations, Lithuanian Sports University Kaunas, Lithuania
| | - Henrikas Paulauskas
- Institute of Sport Science and Innovations, Lithuanian Sports University Kaunas, Lithuania
| | - Albertas Skurvydas
- Institute of Sport Science and Innovations, Lithuanian Sports University Kaunas, Lithuania
| | - Henning Budde
- Institute of Sport Science and Innovations, Lithuanian Sports UniversityKaunas, Lithuania; Faculty of Human Sciences, Medical School HamburgHamburg, Germany; Sports Science Department, Reykjavik UniversityReykjavik, Iceland
| | - Laura Daniuseviciute
- Faculty of Social Sciences, Arts and Humanities, Kaunas University of Technology Kaunas, Lithuania
| | - Nerijus Eimantas
- Institute of Sport Science and Innovations, Lithuanian Sports University Kaunas, Lithuania
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Ocobock C. Human energy expenditure, allocation, and interactions in natural temperate, hot, and cold environments. AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY 2016; 161:667-675. [PMID: 27561011 DOI: 10.1002/ajpa.23071] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/25/2016] [Revised: 07/12/2016] [Accepted: 08/04/2016] [Indexed: 11/10/2022]
Abstract
OBJECTIVE The aim of this research is to analyze how energy is allocated differently in temperate, hot, and cold environments among National Outdoor Leadership School students. METHOD Basal metabolic rate, physical activity, thermoregulation, and the thermic effect of food were estimated to determine the total energy expenditure and energy allocation differences among a group of healthy, highly active adults (N = 59) participating in National Outdoor Leadership School courses in the western United States. Two of these courses took place in both hot and temperate climates (N = 22) and the other two in both temperate and cold climates (N = 28). Data from a pilot study (N = 6) in a temperate climate were also included. Each climate regime lasted for one month. RESULTS Total energy expenditure values were statistically equivalent in temperate and hot climates (p = .97). However, subjects experienced significantly higher total energy expenditures in cold climates (p < .0001), expending an additional ∼1550 kcal day-1 . There is a significant interaction between physical activity and thermoregulation, such that physical activity reduces thermoregulatory costs in cold climates, but increases it in hot climates. CONCLUSIONS Dissection of the energy budget revealed that total energy expenditure is significantly higher in cold climates. This is due to a combination of high levels of physical activity and high thermoregulatory costs. High levels of physical activity may substantially lower the cost of thermoregulation in cold climates, and this interaction should be taken into account when estimating TEE.
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Affiliation(s)
- Cara Ocobock
- Department of Anthropology, University at Albany
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Ciuha U, Mekjavic IB. Regional thermal comfort zone in males and females. Physiol Behav 2016; 161:123-129. [DOI: 10.1016/j.physbeh.2016.04.008] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2015] [Revised: 04/05/2016] [Accepted: 04/06/2016] [Indexed: 11/17/2022]
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Roberts D, Gebhardt DL, Gaskill SE, Roy TC, Sharp MA. Current considerations related to physiological differences between the sexes and physical employment standards. Appl Physiol Nutr Metab 2016; 41:S108-20. [DOI: 10.1139/apnm-2015-0540] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The use of physical employment standards (PES) has helped ensure that workers have the physical attributes necessary to complete their jobs in a safe and efficient manner. However, PES used in the selection processes have not always reflected the critical physical requirements of the job tasks. Women generally have smaller anthropometric stature than men, less muscle mass, and therefore less strength, power, and endurance, particularly in the upper body. Nonetheless, these attributes in themselves are not valid grounds for exclusion from employment in physically demanding occupations. Selection standards based upon size or strength, irrespective of the job requirements, have resulted in the barring of capable women from physically demanding jobs, claims of gender bias, and costly litigations. To ensure all individuals are provided with equal access to employment, accurate characterization of the critical physical requirements of the job is paramount. This paper summarizes the existing research related to disparities between the sexes that contribute to sex differences in job performance in physically demanding occupations including physical and legal factors. Strategies for mitigating these differences in the setting of PES and the meeting of minimum employment standards are discussed. Where available, injury rates for women and men in physically demanding occupations are presented and the etiology considered. Finally, areas for further research are identified.
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Affiliation(s)
- Delia Roberts
- Fellow of the American College of Sports Medicine (FACSM), School of University Arts and Sciences, Selkirk College, 2808 9th Ave., Castlegar, BC VIN 2Z1, Canada
| | - Deborah L. Gebhardt
- Human Performance Systems Inc., 5000 Sunnyside Avenue, Suite 203, Beltsville, MD 20705, USA
| | - Steven E. Gaskill
- Health and Human Performance Department – Exercise Science, The University of Montana, Missoula, MT 59812, USA
| | - Tanja C. Roy
- Epidemiology and Disease Surveillance, US Army Public Health Command, Blackhawk Rd., Aberdeen Proving Ground, MD 21010, USA
| | - Marilyn A. Sharp
- Military Performance Division, US Army Research Institute of Environmental Medicine, 42 General Green Ave., Natick, MA 01760-5007, USA
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Pendergast DR, Moon RE, Krasney JJ, Held HE, Zamparo P. Human Physiology in an Aquatic Environment. Compr Physiol 2015; 5:1705-50. [PMID: 26426465 DOI: 10.1002/cphy.c140018] [Citation(s) in RCA: 99] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Water covers over 70% of the earth, has varying depths and temperatures and contains much of the earth's resources. Head-out water immersion (HOWI) or submersion at various depths (diving) in water of thermoneutral (TN) temperature elicits profound cardiorespiratory, endocrine, and renal responses. The translocation of blood into the thorax and elevation of plasma volume by autotransfusion of fluid from cells to the vascular compartment lead to increased cardiac stroke volume and output and there is a hyperperfusion of some tissues. Pulmonary artery and capillary hydrostatic pressures increase causing a decline in vital capacity with the potential for pulmonary edema. Atrial stretch and increased arterial pressure cause reflex autonomic responses which result in endocrine changes that return plasma volume and arterial pressure to preimmersion levels. Plasma volume is regulated via a reflex diuresis and natriuresis. Hydrostatic pressure also leads to elastic loading of the chest, increasing work of breathing, energy cost, and thus blood flow to respiratory muscles. Decreases in water temperature in HOWI do not affect the cardiac output compared to TN; however, they influence heart rate and the distribution of muscle and fat blood flow. The reduced muscle blood flow results in a reduced maximal oxygen consumption. The properties of water determine the mechanical load and the physiological responses during exercise in water (e.g. swimming and water based activities). Increased hydrostatic pressure caused by submersion does not affect stroke volume; however, progressive bradycardia decreases cardiac output. During submersion, compressed gas must be breathed which introduces the potential for oxygen toxicity, narcosis due to nitrogen, and tissue and vascular gas bubbles during decompression and after may cause pain in joints and the nervous system.
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Affiliation(s)
- David R Pendergast
- Center for Research and Education in Special Environments, University at Buffalo, Buffalo, New York, USA
- Department of Physiology and Biophysics, University at Buffalo, Buffalo, New York, USA
| | - Richard E Moon
- Center for Hyperbaric Medicine and Environmental Physiology, Duke University, Durham, North Carolina, USA
| | - John J Krasney
- Department of Physiology and Biophysics, University at Buffalo, Buffalo, New York, USA
| | - Heather E Held
- Biomedical Hyperbarics Research Laboratory, Molecular Pharmacology and Physiology, College of Medicine, University of South Florida, Tampa, Florida, USA
| | - Paola Zamparo
- Department of Neurological and Movement Sciences, University of Verona, Verona, Italy
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Daanen HAM, Peerbooms M, van den Hurk CJG, van Os B, Levels K, Teunissen LPJ, Breed WPM. Core temperature affects scalp skin temperature during scalp cooling. Int J Dermatol 2015; 54:916-21. [DOI: 10.1111/ijd.12568] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/05/2013] [Revised: 10/25/2013] [Accepted: 11/09/2013] [Indexed: 11/29/2022]
Affiliation(s)
- Hein A. M. Daanen
- Nederlandse Organisatie voor Toegepast Natuurwetenschappelijk Onderzoek (TNO [Dutch Organization for Applied Scientific Research]); Soesterberg The Netherlands
- MOVE Research Institute; Faculty of Human Movement Sciences; VU University Amsterdam; The Netherlands
| | - Mijke Peerbooms
- Department of Research; Integraal Kankercentrum Zuid (Comprehensive Cancer Center South); Eindhoven The Netherlands
| | - Corina J. G. van den Hurk
- Department of Research; Integraal Kankercentrum Zuid (Comprehensive Cancer Center South); Eindhoven The Netherlands
| | - Bernadet van Os
- MOVE Research Institute; Faculty of Human Movement Sciences; VU University Amsterdam; The Netherlands
| | - Koen Levels
- Nederlandse Organisatie voor Toegepast Natuurwetenschappelijk Onderzoek (TNO [Dutch Organization for Applied Scientific Research]); Soesterberg The Netherlands
- MOVE Research Institute; Faculty of Human Movement Sciences; VU University Amsterdam; The Netherlands
| | - Lennart P. J. Teunissen
- Nederlandse Organisatie voor Toegepast Natuurwetenschappelijk Onderzoek (TNO [Dutch Organization for Applied Scientific Research]); Soesterberg The Netherlands
- MOVE Research Institute; Faculty of Human Movement Sciences; VU University Amsterdam; The Netherlands
| | - Wim P. M. Breed
- Department of Research; Integraal Kankercentrum Zuid (Comprehensive Cancer Center South); Eindhoven The Netherlands
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Solianik R, Skurvydas A, Mickevičienė D, Brazaitis M. Intermittent whole-body cold immersion induces similar thermal stress but different motor and cognitive responses between males and females. Cryobiology 2014; 69:323-32. [DOI: 10.1016/j.cryobiol.2014.08.007] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2014] [Revised: 08/20/2014] [Accepted: 08/20/2014] [Indexed: 11/28/2022]
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Roberts LA, Nosaka K, Coombes JS, Peake JM. Cold water immersion enhances recovery of submaximal muscle function after resistance exercise. Am J Physiol Regul Integr Comp Physiol 2014; 307:R998-R1008. [PMID: 25121612 DOI: 10.1152/ajpregu.00180.2014] [Citation(s) in RCA: 72] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We investigated the effect of cold water immersion (CWI) on the recovery of muscle function and physiological responses after high-intensity resistance exercise. Using a randomized, cross-over design, 10 physically active men performed high-intensity resistance exercise followed by one of two recovery interventions: 1) 10 min of CWI at 10°C or 2) 10 min of active recovery (low-intensity cycling). After the recovery interventions, maximal muscle function was assessed after 2 and 4 h by measuring jump height and isometric squat strength. Submaximal muscle function was assessed after 6 h by measuring the average load lifted during 6 sets of 10 squats at 80% of 1 repetition maximum. Intramuscular temperature (1 cm) was also recorded, and venous blood samples were analyzed for markers of metabolism, vasoconstriction, and muscle damage. CWI did not enhance recovery of maximal muscle function. However, during the final three sets of the submaximal muscle function test, participants lifted a greater load (P < 0.05, Cohen's effect size: 1.3, 38%) after CWI compared with active recovery. During CWI, muscle temperature decreased ∼7°C below postexercise values and remained below preexercise values for another 35 min. Venous blood O2 saturation decreased below preexercise values for 1.5 h after CWI. Serum endothelin-1 concentration did not change after CWI, whereas it decreased after active recovery. Plasma myoglobin concentration was lower, whereas plasma IL-6 concentration was higher after CWI compared with active recovery. These results suggest that CWI after resistance exercise allows athletes to complete more work during subsequent training sessions, which could enhance long-term training adaptations.
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Affiliation(s)
- Llion A Roberts
- School of Human Movement Studies, The University of Queensland, Brisbane, Queensland, Australia; Centre of Excellence for Applied Sport Science Research, Queensland Academy of Sport, Brisbane, Queensland, Australia
| | - Kazunori Nosaka
- School of Exercise and Health Sciences, Edith Cowan University, Joondalup, Western Australia, Australia; and
| | - Jeff S Coombes
- School of Human Movement Studies, The University of Queensland, Brisbane, Queensland, Australia
| | - Jonathan M Peake
- Centre of Excellence for Applied Sport Science Research, Queensland Academy of Sport, Brisbane, Queensland, Australia; School of Biomedical Sciences and Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, Queensland, Australia
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Solianik R, Skurvydas A, Vitkauskienė A, Brazaitis M. Gender-specific cold responses induce a similar body-cooling rate but different neuroendocrine and immune responses. Cryobiology 2014; 69:26-33. [DOI: 10.1016/j.cryobiol.2014.04.015] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2013] [Revised: 04/24/2014] [Accepted: 04/24/2014] [Indexed: 12/25/2022]
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Brazaitis M, Eimantas N, Daniuseviciute L, Baranauskiene N, Skrodeniene E, Skurvydas A. Time course of physiological and psychological responses in humans during a 20-day severe-cold-acclimation programme. PLoS One 2014; 9:e94698. [PMID: 24722189 PMCID: PMC3983237 DOI: 10.1371/journal.pone.0094698] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2014] [Accepted: 03/17/2014] [Indexed: 12/21/2022] Open
Abstract
The time course of physiological and psychological markers during cold acclimation (CA) was explored. The experiment included 17 controlled (i.e., until the rectal temperature reached 35.5°C or 170 min had elapsed; for the CA-17 session, the subjects (n = 14) were immersed in water for the same amount of time as that used in the CA-1 session) head-out water immersions at a temperature of 14°C over 20 days. The data obtained in this study suggest that the subjects exhibited a thermoregulatory shift from peripheral-to-central to solely central input thermoregulation, as well as from shivering to non-shivering thermogenesis throughout the CA. In the first six CA sessions, a hypothermic type of acclimation was found; further CA (CA-7 to CA-16) led to a transitional shift to a hypothermic–insulative type of acclimation. Interestingly, when the subjects were immersed in water for the same time as that used in the CA-1 session (CA-17), the CA led to a hypothermic type of acclimation. The presence of a metabolic type of thermogenesis was evident only under thermoneutral conditions. Cold-water immersion decreased the concentration of cold-stress markers, reduced the activity of the innate immune system, suppressed specific immunity to a lesser degree and yielded less discomfort and cold sensation. We found a negative correlation between body mass index and Δ metabolic heat production before and after CA.
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Affiliation(s)
- Marius Brazaitis
- Sports Science and Innovation Institute, Lithuanian Sports University, Kaunas, Lithuania
- * E-mail:
| | - Nerijus Eimantas
- Sports Science and Innovation Institute, Lithuanian Sports University, Kaunas, Lithuania
| | - Laura Daniuseviciute
- Department of Educational Studies, Kaunas University of Technology, Kaunas, Lithuania
| | - Neringa Baranauskiene
- Sports Science and Innovation Institute, Lithuanian Sports University, Kaunas, Lithuania
| | - Erika Skrodeniene
- Department of Laboratory Medicines, Medical Academy, Lithuanian University of Health Science, Kaunas, Lithuania
| | - Albertas Skurvydas
- Sports Science and Innovation Institute, Lithuanian Sports University, Kaunas, Lithuania
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Leonard WR, Levy SB, Tarskaia LA, Klimova TM, Fedorova VI, Baltakhinova ME, Krivoshapkin VG, Snodgrass JJ. Seasonal variation in basal metabolic rates among the Yakut (Sakha) of Northeastern Siberia. Am J Hum Biol 2014; 26:437-45. [PMID: 24644044 DOI: 10.1002/ajhb.22524] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2013] [Revised: 01/25/2014] [Accepted: 01/26/2014] [Indexed: 11/07/2022] Open
Abstract
OBJECTIVES Previous research has shown that indigenous circumpolar populations have elevated basal metabolic rates (BMRs), yet few studies have explored whether metabolic rates increase during the winter. This study addresses this gap by examining seasonal variation in BMR and its associations with thyroid function and lifestyle factors among the Yakut (Sakha) of Siberia. METHODS Anthropometric dimensions, BMR, and thyroid hormone levels (free triiodothyronine [fT3], free thyroxine [fT4], thyroid-stimulating hormone [TSH]) were measured on two occasions (July/August, 2009 and January 2011) on a sample of 94 Yakut (Sakha) adults (35 men, 59 women) from the rural village of Berdygestiakh, Sakha Republic, Russia. RESULTS Seasonal changes in BMR varied by age. Younger Yakut adults (19-49 years) showed significant elevations in winter-time BMR of 6% (P < 0.05), whereas older individuals (≥50 years) showed modest declines (2%; n.s.). Both younger and older Yakut men and women showed increased respiratory quotients during the winter. FT3 and fT4 levels significantly declined during the winter in both younger and older Yakut men and women (P < 0.05). Lifestyle factors were significant predictors of BMR variation, particularly among older men and women. CONCLUSIONS Among the Yakut, increased wintertime BMR was observed among younger but not older adults, whereas all adults showed sharp reductions in free thyroid hormone levels during the winter. Among men, greater participation in subsistence activities was associated with increased BMRs and greater fat oxidation. Among women, variation in food use had the strongest impact on metabolic function.
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Affiliation(s)
- W R Leonard
- Department of Anthropology, Northwestern University, Evanston, Illinois
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Eichenberger E, Knechtle B, Knechtle P, Rüst CA, Rosemann T, Lepers R, Senn O. Sex difference in open-water ultra-swim performance in the longest freshwater lake swim in Europe. J Strength Cond Res 2013; 27:1362-9. [PMID: 22744414 DOI: 10.1519/jsc.0b013e318265a3e9] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
This study examined participation and performance trends in the 26.4-km open-water ultra-swim "Marathon Swim in Lake Zurich," Switzerland. A total of 461 athletes (157 women and 304 men) finished the race between 1987 and 2011. The mean age of the finishers during the studied period was 32.0 ± 6.5 years for men and 30.9 ± 7.2 years for women. The mean age of finishers and the age of winners increased significantly across years for both sexes (p < 0.01). The winner times were significantly lower for men (403 ± 43 minutes) compared with women (452 ± 63 minutes) (p < 0.01). In contrast, the mean swimming time of the finishers did not differ between men (530 ± 39 minutes) and women (567 ± 71 minutes) (p > 0.05). The swimming time performance remained stable (p > 0.05) for both sexes across years. A higher age was associated with an increased risk for not finishing the race (odds ratio = 0.93, p = 0.045). Swim time was negatively associated with water temperature in the top 3 swimmers (ß = -9.87, p = 0.025). These results show that open-water ultra-swimming performance of elite swimmers over 26.4 km in a freshwater lake is affected by age, sex, and water temperature. The sex difference in open-water ultra-swimming performance (approximately 11.5%) remained unchanged these last 25 years. It seems unlikely that elite female swimmers will achieve the same performance of elite male swimmers competing in open-water ultra-swimming in water of approximately 20 °C. Anthropometric and physiological characteristics such as skeletal muscle mass and thermoregulation need additional investigations in female and male open-water ultra-swimmers.
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Affiliation(s)
- Evelyn Eichenberger
- Institute of General Practice and Health Services Research, University of Zurich, Zurich, Switzerland
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Khadrawy YA, AboulEzz HS, Ahmed NA, Mohammed HS. The Anticonvulant Effect of Cooling in Comparison to α-Lipoic Acid: A Neurochemical Study. Neurochem Res 2013; 38:906-15. [DOI: 10.1007/s11064-013-0995-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2012] [Revised: 01/28/2013] [Accepted: 01/31/2013] [Indexed: 11/29/2022]
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41
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Physiological employment standards IV: integration of women in combat units physiological and medical considerations. Eur J Appl Physiol 2012; 113:2673-90. [DOI: 10.1007/s00421-012-2558-7] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2012] [Accepted: 11/22/2012] [Indexed: 12/20/2022]
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TARLOCHAN F, RAMESH S. HEAT TRANSFER MODEL FOR PREDICTING SURVIVAL TIME IN COLD WATER IMMERSION. BIOMEDICAL ENGINEERING-APPLICATIONS BASIS COMMUNICATIONS 2012. [DOI: 10.4015/s1016237205000251] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
In the present paper a heat transfer (HT) model to estimate survival time of individual stranded in cold water such as at sea is proposed. The HT model was derived based on the assumption that the body specific heat capacity and thermal conductance are not time dependent. The solution to the HT model simulates expected survival time as a function of water temperature, metabolism rate, skin, muscle and fat thickness, insulation thermal conductivity and thickness, height and weight of the subject. Although, these predictions must be considered approximate due to the complex nature of the variables involved, the proposed HT model can be employed to determine supplemental body insulation such as personal protective clothing to meet a predefined survival time in any given water temperature. In particular, the results obtained are useful as a decision aid in search and rescue mission in predicting survival time for shipwreck victims at sea.
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Affiliation(s)
- F. TARLOCHAN
- Department of Mechanical Engineering, University Tenaga Nasional, Selangor, Malaysia
| | - S. RAMESH
- Department of Mechanical Engineering, University Tenaga Nasional, Selangor, Malaysia
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Abstract
PURPOSE OF REVIEW The review covers the main aspects of thermoregulation physiology and highlights the implications for therapeutic hypothermia trials. Prevention of shivering and other hypothermia side-effects is of key importance because controlling thermoregulatory responses may be essential for demonstrating neuro-protective properties of hypothermia in several pathologic conditions in which its role is still uncertain, such as in traumatic brain injury and stroke. RECENT FINDINGS Several recommendations and clinical reviews have been produced in the past 2 years about the application and feasibility of therapeutic hypothermia. Many drugs have been tested in healthy volunteers and anaesthetized patients to abolish shivering but the best protocol for managing side-effects has not yet been defined. A possible strategy might be to simultaneously apply physical methods, such as skin warming, and combination drug therapy. Different drug protocols can be applied, depending on the nature of the care setting. SUMMARY During moderate hypothermia treatment, conducted in an intensive care environment, shivering can be treated with sedatives, opioids (meperidine in particular), and α2-agonists, combined with active skin counter-warming. However, new randomized controlled clinical trials in intensive care patients are required to improve our knowledge regarding this treatment.
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Blondin DP, Maneshi A, Imbeault MA, Haman F. Effects of the menstrual cycle on muscle recruitment and oxidative fuel selection during cold exposure. J Appl Physiol (1985) 2011; 111:1014-20. [PMID: 21737827 DOI: 10.1152/japplphysiol.00293.2011] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Differences in core temperature and body heat content, generally observed between the luteal and follicular phase of the menstrual cycle, have been reported to modulate the thermogenic activity of cold-exposed women. However, it is unclear how this change in whole body shivering activity will influence fuel selection. The goal of this study was to quantify the effects of the menstrual cycle on muscle recruitment and oxidative fuel selection during low-intensity shivering. Electromyographic activity of eight large muscles was monitored while carbohydrate, lipid, and protein utilization was simultaneously quantified in the follicular and luteal phases of the menstrual cycle in nonacclimatized women shivering at a low intensity. The onset (∼25 min), intensity (∼15% of maximal voluntary contraction), and pattern (∼6 shivering bursts/min) of the shivering response did not differ between menstrual cycle phases, regardless of differences in core temperature and hormone levels. This resulted in lipids remaining the predominant substrate, contributing 75% of total heat production, independent of menstrual phase. We conclude that hormone fluctuations inherent in the menstrual cycle do not affect mechanisms of substrate utilization in the cold. Whether the large contribution of lipids to total heat production in fuel selection confers a survival advantage remains to be established.
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Affiliation(s)
- Denis P Blondin
- Faculty of Health Sciences, University of Ottawa, and Unité de Recherche sur la Nutrition et le Métabolisme, Institut de Recherche de l'Hôpital Montfort, Hôpital Montfort, Ottawa, Ontario, Canada
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45
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Lemire BB, Gagnon D, Jay O, Kenny GP. Differences between sexes in rectal cooling rates after exercise-induced hyperthermia. Med Sci Sports Exerc 2009; 41:1633-9. [PMID: 19568196 DOI: 10.1249/mss.0b013e31819e010c] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
PURPOSE We evaluated differences between sexes in core cooling rates during cold water immersion after exercise-induced hyperthermia. METHODS Ten male (M) and nine female (F) participants, matched for body surface area-to-mass ratio (AD/M) (F: 268 +/- 19 vs M: 261 +/- 16 cm2 x kg(-1)), were recruited for the study. Participants exercised until rectal temperature reached 39.5 degrees C and were subsequently immersed in a 2.0 degrees C circulated water bath until rectal temperature decreased to 37.5 degrees C. Rectal and mean skin temperatures and the relative rate of nonevaporative heat loss (W x m(-2)) were measured continuously during the immersion period. RESULTS Males were heavier, had a lower body fat percentage, and had a greater amount of lean body mass compared with females (P < or = 0.05). Significant differences were found in the overall cooling rate for rectal temperature (F: 0.22 +/- 0.07 vs M: 0.12 +/- 0.03 degrees C x min(-1), P = 0.001) and in the overall immersion times (F: 10.89 +/- 4.49 vs M: 18.13 +/- 4.47 min, P = 0.003). Mean skin temperature was lower in females compared with that in males during the immersion period (P < 0.001), although there were no differences between sexes in the rate of nonevaporative heat loss (P = 0.180). CONCLUSIONS Although females had a similar AD/M and greater body adiposity, they had approximately 1.7-fold greater rectal cooling rate. Because AD/M and body adiposity do not seem to influence rectal cooling rates in previously hyperthermic individuals, the greater cooling rates in females may be attributed to physical differences in lean body mass.
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Affiliation(s)
- Bruno B Lemire
- Laboratory of Human Bioenergetics and Environmental Physiology, School of Human Kinetics, Faculty of Health Sciences, University of Ottawa, Ottawa, Ontario, Canada
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Mujahid A, Furuse M. Oxidative damage in different tissues of neonatal chicks exposed to low environmental temperature. Comp Biochem Physiol A Mol Integr Physiol 2009; 152:604-8. [DOI: 10.1016/j.cbpa.2009.01.011] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Imbeault P, Dépault I, Haman F. Cold exposure increases adiponectin levels in men. Metabolism 2009; 58:552-9. [PMID: 19303978 DOI: 10.1016/j.metabol.2008.11.017] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/09/2008] [Accepted: 11/04/2008] [Indexed: 11/21/2022]
Abstract
Sympathetic nerve activation is recognized at the adipose tissue level during cold exposure. Adiponectin is a key protein produced by adipose tissue, but its acute modulation remains unknown in humans exposed to cold. The aim of this study were (1) to examine the acute effects of cold exposure on circulating adiponectin and (2) to determine whether the changes are modulated by (a) an acute glucose ingestion as well as (b) a short-term modulation in carbohydrate (CHO) availability. Using a random crossover design, 6 healthy men were exposed to cold for 120 minutes with ingestion of beverages containing low (Control, 0.04 g/min) or high (High, 0.8 g/min) amounts of glucose during the course of the experiment (study 1). In study 2, 6 healthy men were exposed twice to cold for 120 minutes after equicaloric low-CHO diet and exercise and high-CHO diet without exercise. Plasma adiponectin concentrations were quantified before and during cold exposure. In study 1, adiponectin levels did not change during High, whereas a 20% rise was observed during Control (condition x time interaction, P = .06). In study 2, adiponectin levels increased by approximately 70% during cold exposure after both low- and high-CHO diets (effect of time, P < .05). A 120-minute period of cold exposure is accompanied by a significant increase in adiponectin levels in young healthy men. The rise in adiponectin levels observed during shivering is inhibited with glucose ingestion but not after diets varying in CHO content.
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Affiliation(s)
- Pascal Imbeault
- Behavioural and Metabolic Research Unit (Montfort Hospital), School of Human Kinetics, Faculty of Health Sciences, University of Ottawa, Ontario, Canada K1N 6N5.
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Pendergast DR, Lundgren CEG. The underwater environment: cardiopulmonary, thermal, and energetic demands. J Appl Physiol (1985) 2009; 106:276-83. [DOI: 10.1152/japplphysiol.90984.2008] [Citation(s) in RCA: 104] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Water covers over 75% of the earth, has a wide variety of depths and temperatures, and holds a great deal of the earth's resources. The challenges of the underwater environment are underappreciated and more short term compared with those of space travel. Immersion in water alters the cardio-endocrine-renal axis as there is an immediate translocation of blood to the heart and a slower autotransfusion of fluid from the cells to the vascular compartment. Both of these changes result in an increase in stroke volume and cardiac output. The stretch of the atrium and transient increase in blood pressure cause both endocrine and autonomic changes, which in the short term return plasma volume to control levels and decrease total peripheral resistance and thus regulate blood pressure. The reduced sympathetic nerve activity has effects on arteriolar resistance, resulting in hyperperfusion of some tissues, which for specific tissues is time dependent. The increased central blood volume results in increased pulmonary artery pressure and a decline in vital capacity. The effect of increased hydrostatic pressure due to the depth of submersion does not affect stroke volume; however, a bradycardia results in decreased cardiac output, which is further reduced during breath holding. Hydrostatic compression, however, leads to elastic loading of the chest wall and negative pressure breathing. The depth-dependent increased work of breathing leads to augmented respiratory muscle blood flow. The blood flow is increased to all lung zones with some improvement in the ventilation-perfusion relationship. The cardiac-renal responses are time dependent; however, the increased stroke volume and cardiac output are, during head-out immersion, sustained for at least hours. Changes in water temperature do not affect resting cardiac output; however, maximal cardiac output is reduced, as is peripheral blood flow, which results in reduced maximal exercise performance. In the cold, maximal cardiac output is reduced and skin and muscle are vasoconstricted, resulting in a further reduction in exercise capacity.
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O'Brien C, Mahoney C, Tharion WJ, Sils IV, Castellani JW. Dietary tyrosine benefits cognitive and psychomotor performance during body cooling. Physiol Behav 2007; 90:301-7. [PMID: 17078981 DOI: 10.1016/j.physbeh.2006.09.027] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2006] [Revised: 08/22/2006] [Accepted: 09/19/2006] [Indexed: 11/17/2022]
Abstract
Supplemental tyrosine is effective at limiting cold-induced decreases in working memory, presumably by augmenting brain catecholamine levels, since tyrosine is a precursor for catecholamine synthesis. The effectiveness of tyrosine for preventing cold-induced decreases in physical performance has not been examined. This study evaluated the effect of tyrosine supplementation on cognitive, psychomotor, and physical performance following a cold water immersion protocol that lowered body core temperature. Fifteen subjects completed a control trial (CON) in warm (35 degrees C) water and two cold water trials, each spaced a week apart. Subjects ingested an energy bar during each trial; on one cold trial (TYR) the bar contained tyrosine (300 mg/kg body weight), and on the other cold trial (PLB) and on CON the bar contained no tyrosine. Following each water immersion, subjects completed a battery of performance tasks in a cold air (10 degrees C) chamber. Core temperature was lower (p=0.0001) on PLB and TYR (both 35.5+/-0.6 degrees C) than CON (37.1+/-0.3 degrees C). On PLB, performance on a Match-to-Sample task decreased 18% (p=0.02) and marksmanship performance decreased 14% (p=0.002), compared to CON, but there was no difference between TYR and CON. Step test performance decreased by 11% (p=0.0001) on both cold trials, compared to CON. These data support previous findings that dietary tyrosine supplementation is effective for mitigating cold-induced cognitive performance such as working memory, even with reduced core temperature, and extends those findings to include the psychomotor task of marksmanship.
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Affiliation(s)
- Catherine O'Brien
- Thermal and Mountain Medicine Division, U.S. Army Research Institute of Environmental Medicine, Natick, MA 01760, USA
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50
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Hawkins MN, Raven PB, Snell PG, Stray-Gundersen J, Levine BD. American College of Sports Medicine position stand: prevention of cold injuries during exercise. Med Sci Sports Exerc 2007; 39:103-7. [PMID: 17218891 DOI: 10.1249/01.mss.0000241641.75101.64] [Citation(s) in RCA: 189] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
It is the position of the American College of Sports Medicine that exercise can be performed safely in most cold-weather environments without incurring cold-weather injuries. The key to prevention is use of a comprehensive risk management strategy that: a) identifies/assesses the cold hazard; b) identifies/assesses contributing factors for cold-weather injuries; c) develops controls to mitigate cold stress/strain; d) implements controls into formal plans; and e) utilizes administrative oversight to ensure controls are enforced or modified. The American College of Sports Medicine recommends that: 1) coaches/athletes/medical personnel know the signs/symptoms and risk factors for hypothermia, frostbite, and non-freezing cold injuries, identify individuals susceptible to cold injuries, and have the latest up-to-date information about current and future weather conditions before conducting training sessions or competitions; 2) cold-weather clothing be chosen based on each individual's requirements and that standardized clothing ensembles not be mandated for entire groups; 3) the wind-chill temperature index be used to estimate the relative risk of frostbite and that heightened surveillance of exercisers be used at wind-chill temperatures below -27 degrees C (-18 degrees F); and 4) individuals with asthma and cardiovascular disease can exercise in cold environments, but should be monitored closely.
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Affiliation(s)
- Megan N Hawkins
- Institute for Exercise and Environmental Medicine, Presbyterian Hospital of Dallas, 7232 Greenville Avenue, Dallas, TX 75231, USA
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