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Li K, Lin C, Liu G, Wang G, Ma W, Li M, Li Y, Huang B. Stepless IR Chromism in Ti 3 C 2 T x MXene Tuned by Interlayer Water Molecules. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2024; 36:e2308189. [PMID: 38014765 DOI: 10.1002/adma.202308189] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/13/2023] [Revised: 11/12/2023] [Indexed: 11/29/2023]
Abstract
Real-time control over infrared (IR) radiation of objects is highly desired in a variety of areas such as personal thermal regulation and IR camouflage. This requires the dynamic modulation of IR emissivity in a stepless manner over a wide range (>50%), which remains a daunting challenge. Here, an emissivity modulation phenomenon is reported in stacked 2D Ti3 C2 Tx MXene nanosheets, from 12% to 68% as the intercalation/discharging of water molecules within the interlayers. The intercalation of water molecules dynamically changes the electronic properties and the complex permittivity in IR frequencies of Ti3 C2 Tx . This emissivity modulation is a stepless and reversible process without the assistance of any external energy input. Further, intercalating cellulose nanofibers into the Ti3 C2 Tx interlayers makes this dynamic process highly repeatable. Last, a sweat-responsive adaptive textile that can improve thermal comfort of human body under changes in metabolic rates and environmental conditions is demonstrated, showing great potential of this mechanism in passive on-demand radiation modulation.
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Affiliation(s)
- Keqiao Li
- Department of Mechanical and Aerospace Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, 999077, China
| | - Chongjia Lin
- Department of Mechanical and Aerospace Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, 999077, China
| | - Gongze Liu
- Department of Mechanical and Aerospace Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, 999077, China
| | - Guang Wang
- Department of Mechanical and Aerospace Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, 999077, China
| | - Wei Ma
- Department of Mechanical and Aerospace Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, 999077, China
| | - Meng Li
- Department of Mechanical and Aerospace Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, 999077, China
| | - Yang Li
- State Key Laboratory of Fluid Power and Mechatronic Systems, School of Mechanical Engineering, Zhejiang University, Hangzhou, 310027, China
- Key Laboratory of Advanced Manufacturing Technology of Zhejiang Province, School of Mechanical Engineering, Zhejiang University, Hangzhou, 310027, China
| | - Baoling Huang
- Department of Mechanical and Aerospace Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, 999077, China
- The Hong Kong University of Science and Technology, Foshan Research Institute for Smart Manufacturing, Clear Water Bay, Kowloon, Hong Kong, 999077, China
- HKUST Shenzhen-Hong Kong Collaborative Innovation Research Institute, Futian, Shenzhen, 518000, China
- Thrust of Sustainable Energy and Environment, The Hong Kong University of Science and Technology, Guangzhou, 511400, China
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Liu Z, Nie J, Yang F, Zheng Y, Ding L. Influence of shoe upper structure on shoe microclimate and human physiological characteristics during running. Technol Health Care 2024; 32:487-499. [PMID: 38759071 DOI: 10.3233/thc-248043] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/19/2024]
Abstract
BACKGROUND Shoes upper has been shown to affect the shoe microclimate (temperature and humidity). However, the existing data on the correlation between the microclimate inside footwear and the body's physical factors is still quite limited. OBJECTIVE This study examined whether shoes air permeability would influence foot microclimate and spatial characteristics of lower limb and body. METHODS Twelve recreational male habitual runners were instructed to finish an 80 min experimental protocol, wearing two running shoes with different air permeability. RESULTS Participants wearing CLOSED upper structure shoe exhibited higher in-shoe temperature and relative humidity. Although there was no significant difference, shank temperature and metabolism in OPEN upper structure shoes were lower. CONCLUSIONS This indicates that the air permeability of shoes can modify the microclimate of the feet, potentially affecting the lower limb temperature. This study provides relevant information for the design and evaluation of footwear.
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Affiliation(s)
- Zuoliang Liu
- Key Laboratory of Biomechanics and Mechanobiology (Beihang University), Ministry of Education; Beijing Advanced Innovation Center for Biomedical Engineering; School of Biological Science and Medical Engineering, Beihang University, Beijing, China
| | - Jiachen Nie
- Key Laboratory of Biomechanics and Mechanobiology (Beihang University), Ministry of Education; Beijing Advanced Innovation Center for Biomedical Engineering; School of Biological Science and Medical Engineering, Beihang University, Beijing, China
| | - Fan Yang
- Department of Physical Education, China University of Mining and Technology - Beijing, Beijing, China
- Li Ning Sports Science Research Center, Li Ning (China) Sports Goods Company Limited, Beijing, China
| | - Yi Zheng
- Capital University of Physical Education and Sports, Beijing, China
| | - Li Ding
- Key Laboratory of Biomechanics and Mechanobiology (Beihang University), Ministry of Education; Beijing Advanced Innovation Center for Biomedical Engineering; School of Biological Science and Medical Engineering, Beihang University, Beijing, China
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Notley SR, Mitchell D, Taylor NAS. A century of exercise physiology: concepts that ignited the study of human thermoregulation. Part 3: Heat and cold tolerance during exercise. Eur J Appl Physiol 2024; 124:1-145. [PMID: 37796292 DOI: 10.1007/s00421-023-05276-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2023] [Accepted: 07/04/2023] [Indexed: 10/06/2023]
Abstract
In this third installment of our four-part historical series, we evaluate contributions that shaped our understanding of heat and cold stress during occupational and athletic pursuits. Our first topic concerns how we tolerate, and sometimes fail to tolerate, exercise-heat stress. By 1900, physical activity with clothing- and climate-induced evaporative impediments led to an extraordinarily high incidence of heat stroke within the military. Fortunately, deep-body temperatures > 40 °C were not always fatal. Thirty years later, water immersion and patient treatments mimicking sweat evaporation were found to be effective, with the adage of cool first, transport later being adopted. We gradually acquired an understanding of thermoeffector function during heat storage, and learned about challenges to other regulatory mechanisms. In our second topic, we explore cold tolerance and intolerance. By the 1930s, hypothermia was known to reduce cutaneous circulation, particularly at the extremities, conserving body heat. Cold-induced vasodilatation hindered heat conservation, but it was protective. Increased metabolic heat production followed, driven by shivering and non-shivering thermogenesis, even during exercise and work. Physical endurance and shivering could both be compromised by hypoglycaemia. Later, treatments for hypothermia and cold injuries were refined, and the thermal after-drop was explained. In our final topic, we critique the numerous indices developed in attempts to numerically rate hot and cold stresses. The criteria for an effective thermal stress index were established by the 1930s. However, few indices satisfied those requirements, either then or now, and the surviving indices, including the unvalidated Wet-Bulb Globe-Thermometer index, do not fully predict thermal strain.
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Affiliation(s)
- Sean R Notley
- Defence Science and Technology Group, Department of Defence, Melbourne, Australia
- School of Human Kinetics, University of Ottawa, Ottawa, Canada
| | - Duncan Mitchell
- Brain Function Research Group, School of Physiology, University of the Witwatersrand, Johannesburg, South Africa
- School of Human Sciences, University of Western Australia, Crawley, Australia
| | - Nigel A S Taylor
- Research Institute of Human Ecology, College of Human Ecology, Seoul National University, Seoul, Republic of Korea.
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Cheuvront SN, Sollanek KJ, Kenefick RW. Forecasting individual exercise sweat losses from forecast air temperature and energy expenditure. Front Sports Act Living 2023; 5:1277070. [PMID: 38111903 PMCID: PMC10725974 DOI: 10.3389/fspor.2023.1277070] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2023] [Accepted: 11/17/2023] [Indexed: 12/20/2023] Open
Abstract
Introduction Recent success in predicting individual sweat losses from air temperature and energy expenditure measurements suggests a potential for forecasting individual sweat losses for future combinations of environment and exercise. The purpose of this study is to determine the plausibility of accurately forecasting exercise sweat losses from meteorological air temperature forecasts and individual running energy expenditure forecasts. The potential impact on plasma sodium is also estimated when setting drinking rates equal to forecast sweat losses. Materials and methods Individual exercise sweat losses (equated to water needs) and energy expended while running were measured in 33 participants along with air temperature and compared with forecasts of the same. Forecast inputs were used in a web app to forecast exercise sweat losses for comparison with observed values. The bias between forecast and observed exercise sweat losses was used to calculate the potential drinking impact on plasma sodium. Results The concordance correlation coefficient between forecast and observed values was 0.95, 0.96, and 0.91 for air temperature, energy expenditure, and exercise sweat losses, respectively, indicating excellent agreement and no significant differences observed via t-test. Perfect matching of water intake to sweat losses would lower plasma sodium concentrations from 140 to 138 mmol/L; calculations using the 95% limits of agreement for bias showed that drinking according to forecast exercise sweat losses would alter plasma sodium concentrations from 140 to between 136 and 141 mmol/L. Conclusions The outcomes support the strong potential for accurately forecasting exercise sweat losses from commonly available meteorological air temperature forecasts and energy expenditure from forecast running distance.
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Affiliation(s)
| | - Kurt J. Sollanek
- Department of Kinesiology, Sonoma State University, Rohnert Park, CA, United States
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Notley SR, Mitchell D, Taylor NAS. A century of exercise physiology: concepts that ignited the study of human thermoregulation. Part 2: physiological measurements. Eur J Appl Physiol 2023; 123:2587-2685. [PMID: 37796291 DOI: 10.1007/s00421-023-05284-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2023] [Accepted: 07/14/2023] [Indexed: 10/06/2023]
Abstract
In this, the second of four historical reviews on human thermoregulation during exercise, we examine the research techniques developed by our forebears. We emphasise calorimetry and thermometry, and measurements of vasomotor and sudomotor function. Since its first human use (1899), direct calorimetry has provided the foundation for modern respirometric methods for quantifying metabolic rate, and remains the most precise index of whole-body heat exchange and storage. Its alternative, biophysical modelling, relies upon many, often dubious assumptions. Thermometry, used for >300 y to assess deep-body temperatures, provides only an instantaneous snapshot of the thermal status of tissues in contact with any thermometer. Seemingly unbeknownst to some, thermal time delays at some surrogate sites preclude valid measurements during non-steady state conditions. To assess cutaneous blood flow, immersion plethysmography was introduced (1875), followed by strain-gauge plethysmography (1949) and then laser-Doppler velocimetry (1964). Those techniques allow only local flow measurements, which may not reflect whole-body blood flows. Sudomotor function has been estimated from body-mass losses since the 1600s, but using mass losses to assess evaporation rates requires precise measures of non-evaporated sweat, which are rarely obtained. Hygrometric methods provide data for local sweat rates, but not local evaporation rates, and most local sweat rates cannot be extrapolated to reflect whole-body sweating. The objective of these methodological overviews and critiques is to provide a deeper understanding of how modern measurement techniques were developed, their underlying assumptions, and the strengths and weaknesses of the measurements used for humans exercising and working in thermally challenging conditions.
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Affiliation(s)
- Sean R Notley
- Defence Science and Technology Group, Department of Defence, Melbourne, Australia
- School of Human Kinetics, University of Ottawa, Ottawa, Canada
| | - Duncan Mitchell
- Brain Function Research Group, School of Physiology, University of the Witwatersrand, Johannesburg, South Africa
- School of Human Sciences, University of Western Australia, Crawley, Australia
| | - Nigel A S Taylor
- College of Human Ecology, Research Institute of Human Ecology, Seoul National University, Seoul, Republic of Korea.
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Liu C, Liu J, Shao W, Lu J, Gao H. The Considerable Water Evaporation Induced by Human Perspiration and Respiration in Megacities: Quantifying Method and Case Study in Beijing. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2022; 19:ijerph19148638. [PMID: 35886494 PMCID: PMC9324489 DOI: 10.3390/ijerph19148638] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/24/2022] [Revised: 07/13/2022] [Accepted: 07/13/2022] [Indexed: 11/16/2022]
Abstract
The water cycle in urban areas is called the natural-social dualistic water cycle, and it is driven not only by natural forces, but also by human activities. As the drivers of the social water cycle, human perspire continuously, and this is often overlooked as a contributing factor to the water cycle. This paper proposes a method for quantifying the water evaporation induced by human perspiration and respiration in megacities. A calculation based on the sweating prediction model was applied to the city of Beijing to evaluate the evaporation from the human body. The results show that the greatest volume of evaporation produced by human occurs in summer, and the least in spring. The total evaporation produced by human was converted to the evaporation on unit area of the city and reached 5075.2 m3/km2 in the six core districts of Beijing. According to the calculation, the total volume was considerable and reached 14.0 million m3 in 2020, which was equivalent to the annual evapotranspiration from an area of 104.9 km2 of Acer truncatum forest (15 cm diameter at breast height, afforestation density 800 plants/hm2), and even twice the annual total water use in Tartu, Estonia. The results of the study provide a reference for dualistic water cycle research and water cycle flux calculation in urban areas.
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Affiliation(s)
- Chuang Liu
- State Key Laboratory of Simulation and Regulation of Water Cycle in River Basin, China Institute of Water Resources and Hydropower Research, Beijing 100038, China; (C.L.); (W.S.); (J.L.)
| | - Jiahong Liu
- State Key Laboratory of Simulation and Regulation of Water Cycle in River Basin, China Institute of Water Resources and Hydropower Research, Beijing 100038, China; (C.L.); (W.S.); (J.L.)
- Engineering and Technology Research Center for Water Resources and Hydroecology of the Ministry of Water Resources, Beijing 100038, China
- Key Laboratory of River Basin Digital Twinning of Ministry of Water Resources, Beijing 100038, China
- Correspondence: ; Tel.: +86-10-6878-1936
| | - Weiwei Shao
- State Key Laboratory of Simulation and Regulation of Water Cycle in River Basin, China Institute of Water Resources and Hydropower Research, Beijing 100038, China; (C.L.); (W.S.); (J.L.)
| | - Jiahui Lu
- State Key Laboratory of Simulation and Regulation of Water Cycle in River Basin, China Institute of Water Resources and Hydropower Research, Beijing 100038, China; (C.L.); (W.S.); (J.L.)
| | - Han Gao
- College of New Energy and Environment, Jilin University, Changchun 130021, China;
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Szurko A, Kasprzyk-Kucewicz T, Cholewka A, Kazior M, Sieroń K, Stanek A, Morawiec T. Thermovision as a Tool for Athletes to Verify the Symmetry of Work of Individual Muscle Segments. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2022; 19:ijerph19148490. [PMID: 35886342 PMCID: PMC9324238 DOI: 10.3390/ijerph19148490] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/23/2022] [Revised: 07/04/2022] [Accepted: 07/08/2022] [Indexed: 12/31/2022]
Abstract
In the presented research, we characterised the temperature profiles and the degree of preparation for exercise of individual muscle groups of athletes We hypothesise that by means of thermal imaging studies, the effectiveness of the warm-up can be monitored to determine whether the effort of individual muscles is equal and symmetrical, which can help to avoid a potential injury. In the study, thermographic imaging was performed on a group of athletes exercising on a rowing ergometer involving almost 80% of the muscle parts of the human body for intense and symmetrical exercise. Thermovision studies have confirmed, based on the increased temperature of the muscle areas, that the rowing ergometer involves many muscle groups in training. Moreover, based on the shape of the temperature function obtained from individual body regions of interest, it was shown that conventional exercise on a rowing ergometer causes almost symmetrical work of the right and left sides of the body. Obtained temperature changes in most of the studied muscle areas showed minimum temperature reached the beginning of training—mostly phases 1 and 2. During the subsequent phases, the temperature increase was monitored, stopping at resting temperature. Significantly, temperature variations did not exceed 0.5 °C in all post-training phases. Statistical analyses did not show any significant differences in the symmetry of right and left muscle areas corresponding to the muscle location temperature. Thermal imaging may be an innovative wholly non-invasive and safe method, because checking induces adaptation processes, which may become indicators of an athlete’s efficiency. The imaging can be continuously repeated, and automatic comparison of average temperature or temperature difference may provide some clues that protect athletes from overtraining or serious injuries.
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Affiliation(s)
- Agnieszka Szurko
- Faculty of Science and Technology, University of Silesia, 75 Pułku Piechoty 1A, 41-500 Chorzów, Poland; (T.K.-K.); (A.C.); (M.K.)
- Correspondence: ; Tel.: +32-349-75-86
| | - Teresa Kasprzyk-Kucewicz
- Faculty of Science and Technology, University of Silesia, 75 Pułku Piechoty 1A, 41-500 Chorzów, Poland; (T.K.-K.); (A.C.); (M.K.)
| | - Armand Cholewka
- Faculty of Science and Technology, University of Silesia, 75 Pułku Piechoty 1A, 41-500 Chorzów, Poland; (T.K.-K.); (A.C.); (M.K.)
| | - Maksymilian Kazior
- Faculty of Science and Technology, University of Silesia, 75 Pułku Piechoty 1A, 41-500 Chorzów, Poland; (T.K.-K.); (A.C.); (M.K.)
| | - Karolina Sieroń
- Department of Internal Diseases, Oncology, with Department of Gastroenterology, Cardiology, and Angiology, Hospital MSWiA in Katowice, 40-752 Katowice, Poland;
| | - Agata Stanek
- Department and Clinic of Internal Medicine, Angiology and Physical Medicine, Faculty of Medical Sciences in Zabrze, Medical University of Silesia, Batorego 15, 41-902 Bytom, Poland;
| | - Tadeusz Morawiec
- Division of Medicine and Dentistry, Department of Oral Surgery, Medical University of Silesia, Pl. Akademicki 17, 41-902 Bytom, Poland;
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Davis JK, Oikawa SY, Halson S, Stephens J, O'Riordan S, Luhrs K, Sopena B, Baker LB. In-Season Nutrition Strategies and Recovery Modalities to Enhance Recovery for Basketball Players: A Narrative Review. Sports Med 2021; 52:971-993. [PMID: 34905181 PMCID: PMC9023401 DOI: 10.1007/s40279-021-01606-7] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/18/2021] [Indexed: 01/15/2023]
Abstract
Basketball players face multiple challenges to in-season recovery. The purpose of this article is to review the literature on recovery modalities and nutritional strategies for basketball players and practical applications that can be incorporated throughout the season at various levels of competition. Sleep, protein, carbohydrate, and fluids should be the foundational components emphasized throughout the season for home and away games to promote recovery. Travel, whether by air or bus, poses nutritional and sleep challenges, therefore teams should be strategic about packing snacks and fluid options while on the road. Practitioners should also plan for meals at hotels and during air travel for their players. Basketball players should aim for a minimum of 8 h of sleep per night and be encouraged to get extra sleep during congested schedules since back-to back games, high workloads, and travel may negatively influence night-time sleep. Regular sleep monitoring, education, and feedback may aid in optimizing sleep in basketball players. In addition, incorporating consistent training times may be beneficial to reduce bed and wake time variability. Hydrotherapy, compression garments, and massage may also provide an effective recovery modality to incorporate post-competition. Future research, however, is warranted to understand the influence these modalities have on enhancing recovery in basketball players. Overall, a strategic well-rounded approach, encompassing both nutrition and recovery modality strategies, should be carefully considered and implemented with teams to support basketball players' recovery for training and competition throughout the season.
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Affiliation(s)
- Jon K Davis
- Gatorade Sports Science Institute, PepsiCo, Inc., 3800 Gaylord Parkway, Suite 210, Frisco, TX, 75034, USA.
| | - Sara Y Oikawa
- Gatorade Sports Science Institute, PepsiCo, Inc., Bradenton, FL, 34210, USA
| | - Shona Halson
- Institute for Health and Sport (iHeS), Victoria University, Melbourne, Australia.,Department of Physiology, Australian Institute of Sport, Canberra, Australia
| | | | - Shane O'Riordan
- Institute for Health and Sport (iHeS), Victoria University, Melbourne, Australia.,Department of Physiology, Australian Institute of Sport, Canberra, Australia
| | - Kevin Luhrs
- Gatorade Sports Science Institute, PepsiCo, Inc., Bradenton, FL, 34210, USA
| | - Bridget Sopena
- Gatorade Sports Science Institute, PepsiCo, Inc., Barrington, IL, 60010, USA
| | - Lindsay B Baker
- Gatorade Sports Science Institute, PepsiCo, Inc., Barrington, IL, 60010, USA
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Abstract
For thermal physiologists, calorimetry is an important methodological tool to assess human heat balance during heat or cold exposures. A whole body direct calorimeter remains the gold standard instrument for assessing human heat balance; however, this equipment is rarely available to most researchers. A more widely accessible substitute is partitional calorimetry, a method by which all components of the conceptual heat balance equation-metabolic heat production, conduction, radiation, convection, and evaporation-are calculated separately based on fundamental properties of energy exchange. Since partitional calorimetry requires relatively inexpensive equipment (vs. direct calorimetry) and can be used over a wider range of experimental conditions (i.e., different physical activities, laboratory or field settings, clothed or seminude), it allows investigators to address a wide range of problems such as predicting human responses to thermal stress, developing climatic exposure limits and fluid replacement guidelines, estimating clothing properties, evaluating cooling/warming interventions, and identifying potential thermoregulatory dysfunction in unique populations. In this Cores of Reproducibility in Physiology (CORP) review, we summarize the fundamental principles underlying the use of partitional calorimetry, present the various methodological and arithmetic requirements, and provide typical examples of its use. Strategies to minimize estimation error of specific heat balance components, as well as the limitations of the method, are also discussed. The goal of this CORP paper is to present a standardized methodology and thus improve the accuracy and reproducibility of research employing partitional calorimetry.
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Affiliation(s)
- Matthew N Cramer
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas and University of Texas Southwestern Medical Center , Dallas, Texas
| | - Ollie Jay
- Thermal Ergonomics Laboratory, Faculty of Health Sciences, The University of Sydney , Sydney, NSW , Australia.,Charles Perkins Centre, The University of Sydney , Sydney, NSW , Australia
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Turner JM, Marsteller DA, Luxkaranayagam AT, Fletcher JM, Stachenfeld NS. Mild exercise in female subjects impairs complex learning independent of hydration status and emotion. Physiol Behav 2017; 180:113-119. [PMID: 28842190 DOI: 10.1016/j.physbeh.2017.08.013] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2017] [Revised: 08/17/2017] [Accepted: 08/18/2017] [Indexed: 01/27/2023]
Abstract
INTRODUCTION Depending on type, intensity and duration, exercise can have both beneficial and detrimental effects on cognitive function. The impact of exercise on learning and memory is also sensitive to hydration status, so we hypothesized that mild hypohydration induced with exercise, will adversely impact executive and complex memory function tasks and that these changes in cognitive function are independent of changes in emotion. METHODS Using a cross over design, on separate days 11 women exercised on a recumbent bicycle. On day 1, women exercised to 1.5% hypohydration at 34°C, and <10% rh, on day 2, water loss from sweating was replaced by drinking water (euhydration). Pre- and post-euhydration and hypohydration, subjects underwent computer based cognitive tasks (simple, learning, memory, executive function) and visual analog testing to determine emotion. RESULTS Exercise increased Groton Maze Learning Test errors within both conditions: [Pre: 41.5±11.8, Post: 46.8±12.4, and Pre: 41.9±9.2, Post: 46.5±12.9, hypohydrated and euhydrated, respectively, Pre vs Post, ANOVA, time effect, P=0.007], a test of acquisition, storage, and use of new knowledge. None of the measures of emotion were affected by exercise under either hydration condition. CONCLUSIONS A bout of mild aerobic exercise compromised performance on a complex learning and memory task, but this change was unaffected by hydration status or emotion.
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Affiliation(s)
| | | | - Anita T Luxkaranayagam
- The John B. Pierce Laboratory, New Haven, CT, United States; Department of Obstetrics, Gynecology and Reproductive Sciences, Yale School of Medicine, New Haven, CT, United States
| | | | - Nina S Stachenfeld
- The John B. Pierce Laboratory, New Haven, CT, United States; Department of Obstetrics, Gynecology and Reproductive Sciences, Yale School of Medicine, New Haven, CT, United States; Yale School of Public Health, New Haven, CT, United States.
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11
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Direct calorimetry: a brief historical review of its use in the study of human metabolism and thermoregulation. Eur J Appl Physiol 2017; 117:1765-1785. [DOI: 10.1007/s00421-017-3670-5] [Citation(s) in RCA: 49] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2017] [Accepted: 06/21/2017] [Indexed: 01/08/2023]
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12
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Cheuvront SN, Kenefick RW. CORP: Improving the status quo for measuring whole body sweat losses. J Appl Physiol (1985) 2017; 123:632-636. [PMID: 28684591 DOI: 10.1152/japplphysiol.00433.2017] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2017] [Revised: 06/22/2017] [Accepted: 07/05/2017] [Indexed: 11/22/2022] Open
Abstract
The measurement of whole body sweat losses (WBSL) is important to the study of body heat balance, body water balance, establishing guidelines for water and electrolyte consumption, and the study of metabolism and health. In principal, WBSL is measured by an acute change in body mass (ΔBM) in response to a thermoregulatory sweating stimulus. In this Cores of Reproducibility in Physiology (CORP) review, we revisit several basic, but rarely discussed, assumptions important to WBSL research, including the common equivalences: mass = weight = water = sweat. Sources of large potential measurement errors are also discussed, as are best practices for avoiding them. The goal of this CORP review is to ultimately improve the accuracy, reproducibility, and application of WBSL research.
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Affiliation(s)
- Samuel N Cheuvront
- Thermal and Mountain Medicine Division, US Army Research Institute of Environmental Medicine, Natick, Massachusetts
| | - Robert W Kenefick
- Thermal and Mountain Medicine Division, US Army Research Institute of Environmental Medicine, Natick, Massachusetts
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13
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Ainslie PN. Professor Bengt Saltin Symposium - Environmental challenges to human performance. Appl Physiol Nutr Metab 2016; 42:104-107. [PMID: 28006436 DOI: 10.1139/apnm-2016-0319] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
This short review is from a presentation made at the Bengt Saltin Symposium, October 15-17, at the 2015 Canadian Society for Exercise Physiology conference, Hamilton, Canada. The review provides context of the important work of the late Dr. Saltin's contributions to environmental physiology. In addition to well-controlled laboratory experiments to better understand the influence of hypoxia or temperature, or both, Dr. Saltin also led several field expeditions to the North Greenland, Kenya, Himalayas, and the Andes, where he studied several aspects of human adaptation to environment. The 1998 Danish High-Altitude Expedition to the Andes, in particular, resulted in many major contributions to the field of altitude physiology including, but not limited to, mechanisms of reductions in maximal oxygen uptake, the lactate paradox, acclimatization, muscle metabolism, gas exchange, cerebrovascular physiology, etc. Of note, many of these related studies were conducted in both Danish sojourners to altitude and Bolivian altitude natives of Aymara ancestry, thus providing some of the most mechanistic comparisons with high altitude natives to date. A framework of these physiological contributions in terrestrial extremes is provided in this review.
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Affiliation(s)
- Philip N Ainslie
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, Faculty of Health and Social Development, University of British Columbia - Okanagan Campus, 3333 University Way, Kelowna, BC V1V 1V7, Canada.,Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, Faculty of Health and Social Development, University of British Columbia - Okanagan Campus, 3333 University Way, Kelowna, BC V1V 1V7, Canada
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Kritikos H, Poster K, Schwan H. Temperature Profiles in Spheres Due to Electromagnetic Heating. ACTA ACUST UNITED AC 2016. [DOI: 10.1080/16070658.1981.11689256] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Affiliation(s)
- H.N. Kritikos
- Department of Electrical Engineering, University of Pennsylvania
| | - K.R. Poster
- Department of Bioengineering/D2, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - H.P Schwan
- Department of Bioengineering/D2, University of Pennsylvania, Philadelphia, PA 19104, USA
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Priego Quesada JI, Carpes FP, Salvador Palmer R, Pérez-Soriano P, Cibrián Ortiz de Anda RM. Effect of saddle height on skin temperature measured in different days of cycling. SPRINGERPLUS 2016; 5:205. [PMID: 27026901 PMCID: PMC4769707 DOI: 10.1186/s40064-016-1843-z] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/24/2015] [Accepted: 02/15/2016] [Indexed: 11/10/2022]
Abstract
Infrared thermography can be useful to explore the effects of exercise on neuromuscular function. During cycling, it could be used to investigate the effects of saddle height on thermoregulation. The aim of this study was to examine whether different cycling postures, elicited by different knee flexion angles, could influence skin temperature. Furthermore, we also determined whether the reproducibility of thermal measurements in response to cycling differed in the body regions affected or not affected by saddle height. Sixteen cyclists participated in three tests of 45 min of cycling at their individual 50 % peak power output. Each test was performed in a different knee flexion position on the bicycle (20°, 30°, 40° knee flexion when the pedal crank was at 180°). Different knee angles were obtained by changing saddle height. Skin temperatures were determined by infrared thermography before, immediately after and 10 min after the cycling test, in 16 different regions of interest (ROI) in the trunk and lower limbs. Changes in saddle height did not result in changes in skin temperature in the ROI. However, lower knee flexion elicited higher temperature in popliteus after cycling than higher flexion (p = 0.008 and ES = 0.8), and higher knee flexion elicited lower temperature variation in the tibialis anterior than intermediate knee flexion (p = 0.004 and ES = 0.8). Absolute temperatures obtained good and very good intraday reproducibility in the different measurements (ICCs between 0.44 and 0.85), but temperature variations showed lower reproducibility (ICCs between 0.11 and 0.74). Different postures assumed by the cyclist due to different saddle height did not influence temperature measurements. Skin temperature can be measured on different days with good repeatability, but temperature variations can be more sensitive to the effects of an intervention.
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Affiliation(s)
- Jose Ignacio Priego Quesada
- />Research Group in Sport Biomechanics (GIBD), Department of Physical Education and Sports, University of Valencia, Valencia, Spain
- />Biophysics and Medical Physics Group, Department of Physiology, University of Valencia, Avd/Blasco Ibañez 15, 46010 Valencia, Spain
- />Applied Neuromechanics Group, Laboratory of Neuromechanics, Federal University of Pampa, Uruguaiana, RS Brazil
| | - Felipe P. Carpes
- />Applied Neuromechanics Group, Laboratory of Neuromechanics, Federal University of Pampa, Uruguaiana, RS Brazil
| | - Rosario Salvador Palmer
- />Biophysics and Medical Physics Group, Department of Physiology, University of Valencia, Avd/Blasco Ibañez 15, 46010 Valencia, Spain
| | - Pedro Pérez-Soriano
- />Research Group in Sport Biomechanics (GIBD), Department of Physical Education and Sports, University of Valencia, Valencia, Spain
| | - Rosa Mª Cibrián Ortiz de Anda
- />Biophysics and Medical Physics Group, Department of Physiology, University of Valencia, Avd/Blasco Ibañez 15, 46010 Valencia, Spain
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Marshall PWM, Cross R, Lovell R. Passive heating following the prematch warm-up in soccer: examining the time-course of changes in muscle temperature and contractile function. Physiol Rep 2015; 3:3/12/e12635. [PMID: 26634901 PMCID: PMC4760448 DOI: 10.14814/phy2.12635] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
This study examined changes in muscle temperature, electrically evoked muscle contractile properties, and voluntary power before and after a soccer specific active warm-up and subsequent rest period. Ten amateur soccer players performed two experimental sessions that involved performance of a modified FIFA 11+ soccer specific warm-up, followed by a 12.5-min rest period where participants were required to wear either normal clothing or a passive electrical heating garment was applied to the upper thigh muscles. Assessments around the warm-up and cool-down included measures of maximal torque, rate of torque development, muscle temperature (Tm), and electrically evoked measures of quadriceps contractile function. Tm was increased after the warm-up by 3.2 ± 0.7°C (P < 0.001). Voluntary and evoked rates of torque development increased after the warm-up between 20% and 30% (P < 0.05), despite declines in both maximal voluntary torque and voluntary activation (P < 0.05). Application of a passive heating garment in the cool-down period after the warm-up did not effect variables measured. While Tm was reduced by 1.4 ± 0.4°C after the rest period (P < 0.001), this value was still higher than pre warm-up levels. Voluntary and evoked rate of torque development remained elevated from pre warm-up levels at the end of the cool-down (P < 0.05). The soccer specific warm-up elevated muscle temperature by 3.2°C and was associated with concomitant increases of between 20% and 30% in voluntary rate of torque development, which seems explained by elevations in rate-dependent measures of intrinsic muscle contractile function. Application of a passive heating garment did not attenuate declines in muscle temperature during a 12.5-min rest period.
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Affiliation(s)
- Paul W M Marshall
- Human Performance Laboratory, School of Science and Health, Western Sydney University, Sydney, New South Wales, Australia
| | - Rebecca Cross
- Human Performance Laboratory, School of Science and Health, Western Sydney University, Sydney, New South Wales, Australia
| | - Ric Lovell
- Human Performance Laboratory, School of Science and Health, Western Sydney University, Sydney, New South Wales, Australia
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Considerations for the measurement of core, skin and mean body temperatures. J Therm Biol 2014; 46:72-101. [DOI: 10.1016/j.jtherbio.2014.10.006] [Citation(s) in RCA: 228] [Impact Index Per Article: 22.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2014] [Revised: 10/24/2014] [Accepted: 10/27/2014] [Indexed: 11/23/2022]
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Thermally-induced structural changes in an armadillo repeat protein suggest a novel thermosensor mechanism in a molecular chaperone. FEBS Lett 2014; 589:123-30. [PMID: 25436418 DOI: 10.1016/j.febslet.2014.11.034] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2014] [Revised: 11/18/2014] [Accepted: 11/19/2014] [Indexed: 01/12/2023]
Abstract
Molecular chaperones are commonly identified by their ability to suppress heat-induced protein aggregation. The muscle-specific molecular chaperone UNC-45B is known to be involved in myosin folding and is trafficked to the sarcomeres A-band during thermal stress. Here, we identify temperature-dependent structural changes in the UCS chaperone domain of UNC-45B that occur within a physiologically relevant heat-shock range. We show that distinct changes to the armadillo repeat protein topology result in exposure of hydrophobic patches, and increased flexibility of the molecule. These rearrangements suggest the existence of a novel thermosensor within the chaperone domain of UNC-45B. We propose that these changes may function to suppress aggregation under stress by allowing binding to a wide variety of aggregation prone loops on its client.
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Kenny GP, Jay O. Thermometry, calorimetry, and mean body temperature during heat stress. Compr Physiol 2014; 3:1689-719. [PMID: 24265242 DOI: 10.1002/cphy.c130011] [Citation(s) in RCA: 164] [Impact Index Per Article: 16.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Heat balance in humans is maintained at near constant levels through the adjustment of physiological mechanisms that attain a balance between the heat produced within the body and the heat lost to the environment. Heat balance is easily disturbed during changes in metabolic heat production due to physical activity and/or exposure to a warmer environment. Under such conditions, elevations of skin blood flow and sweating occur via a hypothalamic negative feedback loop to maintain an enhanced rate of dry and evaporative heat loss. Body heat storage and changes in core temperature are a direct result of a thermal imbalance between the rate of heat production and the rate of total heat dissipation to the surrounding environment. The derivation of the change in body heat content is of fundamental importance to the physiologist assessing the exposure of the human body to environmental conditions that result in thermal imbalance. It is generally accepted that the concurrent measurement of the total heat generated by the body and the total heat dissipated to the ambient environment is the most accurate means whereby the change in body heat content can be attained. However, in the absence of calorimetric methods, thermometry is often used to estimate the change in body heat content. This review examines heat exchange during challenges to heat balance associated with progressive elevations in environmental heat load and metabolic rate during exercise. Further, we evaluate the physiological responses associated with heat stress and discuss the thermal and nonthermal influences on the body's ability to dissipate heat from a heat balance perspective.
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Affiliation(s)
- Glen P Kenny
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, Canada
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Borisov VV, Lin DC. Temperature fluctuations in the lower limbs of young and elderly individuals during activities of daily living. Exp Gerontol 2014; 57:243-9. [DOI: 10.1016/j.exger.2014.06.005] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2014] [Revised: 05/07/2014] [Accepted: 06/05/2014] [Indexed: 10/25/2022]
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Kenny GP. Muscle temperature and sweating during exercise: a new link? Acta Physiol (Oxf) 2014; 212:11-3. [PMID: 24957481 DOI: 10.1111/apha.12335] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- G. P. Kenny
- Human and Environmental Physiology Research Unit; School of Human Kinetics; University of Ottawa; Ottawa ON Canada
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External muscle heating during warm-up does not provide added performance benefit above external heating in the recovery period alone. Eur J Appl Physiol 2013; 113:2713-21. [PMID: 23974847 DOI: 10.1007/s00421-013-2708-6] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2013] [Accepted: 08/06/2013] [Indexed: 10/26/2022]
Abstract
PURPOSE Having previously shown the use of passive external heating between warm-up completion and sprint cycling to have had a positive effect on muscle temperature (T m) and maximal sprint performance, we sought to determine whether adding passive heating during active warm up was of further benefit. METHODS Ten trained male cyclists completed a standardised 15 min sprint based warm-up on a cycle ergometer, followed by 30 min passive recovery before completing a 30 s maximal sprint test. Warm up was completed either with or without additional external passive heating. During recovery, external passive leg heating was used in both standard warm-up (CONHOT) and heated warm-up (HOTHOT) conditions, for control, a standard tracksuit was worn (CON). RESULTS T m declined exponentially during CON, CONHOT and HOTHOT reduced the exponential decline during recovery. Peak (11.1 %, 1561 ± 258 W and 1542 ± 223 W), relative (10.6 % 21.0 ± 2.2 W kg(-1) and 20.9 ± 1.8 W kg(-1)) and mean (4.1 %, 734 ± 126 W and 729 ± 125 W) power were all improved with CONHOT and HOTHOT, respectively compared to CON (1,397 ± 239 W; 18.9 ± 3.0 W kg(-1) and 701 ± 109 W). There was no additional benefit of HOTHOT on T m or sprint performance compared to CONHOT. CONCLUSION External heating during an active warm up does not provide additional physiological or performance benefit. As noted previously, external heating is capable of reducing the rate of decline in T m after an active warm-up, improving subsequent sprint cycling performance.
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Ely MR, Ely BR, Chinevere TD, Lacher CP, Lukaski HC, Cheuvront SN. Evaluation of the Megaduct sweat collector for mineral analysis. Physiol Meas 2012; 33:385-94. [PMID: 22369987 DOI: 10.1088/0967-3334/33/3/385] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Accurate measurement of sweat mineral loss is important for whole body mineral balance estimates and dietary reference intake formulation. Currently, common localized sweat collection methods such as the pouch and patch techniques may be limited by skin encapsulation and/or hidromeiosis, which may alter sweat mineral concentrations. The design of the newly developed Megaduct sweat collector may avoid these possible limitations. Therefore, the purpose of this study was to evaluate the utility of the Megaduct sweat collector for mineral analysis. Megaduct sweat collectors were affixed to ten volunteers on the final day of a heat acclimation protocol; collection time, sweat volume, and mineral concentrations of calcium, copper, iron, potassium, sodium, and zinc were measured. Megaduct filling required a collection period of 62 ± 3 min due to a small collection surface (22.1 cm(2)). The mineral content of the sweat was 0.3 ± 0.1 mmol L(-1), 1.5 ± 1.5 µmol L(-1), 8.5 ± 2.1 mmol L(-1), 43.2 ± 15.0 mmol L(-1), and 10.1 ± 5.7 µmol L(-1) for Ca, Cu, K, Na, and Zn, respectively. The Megaduct sweat collector appears to avoid skin encapsulation and hidromeiosis, and captures sweat with similar mineral concentrations as reported in the literature for pouches. However, the filling time of the Megaduct (>60 min) may not capture possible changes in sweat mineral concentrations that are documented to occur in as little as 15 to 30 min.
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Affiliation(s)
- M R Ely
- US Army Research Institute of Environmental Medicine, Natick, MA, USA.
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Munguía-Izquierdo D, Santalla A, Legaz-Arrese A. Evaluation of a wearable body monitoring device during treadmill walking and jogging in patients with fibromyalgia syndrome. Arch Phys Med Rehabil 2012; 93:115-22. [PMID: 22200390 DOI: 10.1016/j.apmr.2011.08.021] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2011] [Revised: 07/06/2011] [Accepted: 08/17/2011] [Indexed: 10/14/2022]
Abstract
OBJECTIVE To evaluate the reliability and validity of a body monitoring device against measures obtained from indirect calorimetry (IC) in patients with fibromyalgia syndrome (FMS) during various incremental exercise intensities. DESIGN Cross-sectional reliability and validity study. SETTING Testing was completed in a university exercise physiology laboratory. PARTICIPANTS Women (N=25) with FMS, with a mean age ± SD of 48.6±8.4 years and a median symptom duration of 15 years (25th-75th percentiles, 10-23y), were recruited to the study. INTERVENTIONS Not applicable. MAIN OUTCOME MEASURES Patients walked and jogged on a treadmill at 4 intensities (50m·min(-1), 0% grade [n=25]; 83.3m·min(-1), 0% grade [n=25]; 116.7m·min(-1), 0% grade [n=21]; 116.7m·min(-1), 2.5% grade [n=13]) during 2 measurement conditions, while IC and a multiple-sensor body monitor measured energy expenditure (EE). The differences between the readings (test 1 - test 2) and the SD of the differences, intraclass correlation coefficient (ICC), 95% confidence interval (CI) for the ICC, coefficient of repeatability, intrapatient SD, standard error of mean (SEM), minimal detectable change, Wilcoxon signed-rank test, and Bland-Altman graphs were used to examine reliability. The magnitude of the associations between IC and the body monitoring device, ICC, 95% CI for the ICC, paired t tests, and Bland-Altman graphs were used to examine the validity of the body monitoring device versus the IC. RESULTS Moderate to excellent test-retest reliability was found for the 4 bouts of exercise (ICC=.73-.76). The SEM and minimal detectable change were satisfactory for the 4 bouts of exercise (.54-1.18kcal·min(-1) and 1.51-3.28kcal·min(-1), respectively). The differences mean between test and retest were lower than the SEM for the 4 bouts of exercise, varying from -.17 to .14kcal·min(-1). No significant differences were found between test and retest for any bout. The Bland-Altman plots and the coefficients of repeatability indicated that the differences between repeated tests would lie within 2 SDs in 95% of the cases for the 4 bouts of exercise. Significant associations were found between the body monitoring device and IC measurements of EE for the 4 bouts of exercise (r=.87-.99). The differences for all bouts between the 2 methods were nonsignificant, except for the second bout (P<.001). The ICCs and Bland-Altman plots of EE for the 4 bouts showed high agreement (ICCs=.84-.99) and sufficient accuracy for quantifying EE during exercise in patients with FMS. CONCLUSIONS The body monitoring device provided a valid and reliable estimate of EE in patients with FMS during walking on horizontal and inclined surfaces in a laboratory setting across various exercise intensities.
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Epstein Y, Roberts WO. The pathopysiology of heat stroke: an integrative view of the final common pathway. Scand J Med Sci Sports 2011; 21:742-8. [PMID: 21635561 DOI: 10.1111/j.1600-0838.2011.01333.x] [Citation(s) in RCA: 137] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Heat stroke is defined as a condition in which body temperature is elevated to such a level that it becomes a noxious agent causing body tissue dysfunction and damage with a characteristic multi-organ clinical and pathological syndrome. Marked hyperthermia, usually above 40.5°C and associated encephalopathy, occurs after thermoregulation is subordinated to circulatory and metabolic demands and to the associated systemic inflammatory reaction. Exertional heat stroke is a function of both intrinsic and extrinsic modulators. Intrinsic modulators like genetics, fitness, acclimatization, illness, medications, and sleep quality can alter individual risk and outcomes, while extrinsic modulators like exercise intensity and duration, clothing and equipment, ambient temperature, relative humidity, and solar radiation can affect the group risk and outcomes. This review integrates the current theoretical and accepted knowledge of physiological alterations into one model that depicts a common pathway from heat stress to heat stroke.
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Affiliation(s)
- Y Epstein
- Sheba Medical Center, Heller Institute of Medical Research, Tel Hashomer, Israel.
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Xu X, Gonzalez J. Determination of the cooling capacity for body ventilation system. Eur J Appl Physiol 2011; 111:3155-60. [PMID: 21455613 DOI: 10.1007/s00421-011-1941-0] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2010] [Accepted: 03/21/2011] [Indexed: 11/24/2022]
Abstract
Body ventilation systems (BVS) are effective in reducing heat strain, but the amount of heat that a BVS removes from a human body is unclear. The purpose of this study was to propose a method for quantifying BVS cooling capacity using manikin evaluation and modeling. Cooling capacity was calculated as the product of maximum cooling potential and cooling efficiency. The maximum cooling potential is calculated as the difference in enthalpy between the air entering and exiting the BVS where the outlet air temperature is equal to skin temperature with a relative humidity of 100%. The cooling efficiency, defined as a ratio of the cooling capacity to the maximum cooling potential, can be determined through measurements on sweating thermal manikins. A BVS system was evaluated on a manikin with the ventilation fan ON (flow rate 4.7 L/s) or OFF under eleven ambient conditions. The measured cooling efficiencies were 0.31 ± 0.02 and almost constant. Using this cooling efficiency, the BVS cooling capacities at various skin temperature and ambient conditions were estimated. This two-step approach can be used to quantify BVS cooling effectiveness during physiology studies. First, the cooling efficiency is determined on sweating thermal manikins. Second, the cooling capacity is calculated from the skin temperature, ambient temperature and relative humidity. However, various factors may reduce the actual cooling provided by the BVS, and the calculated cooling capacity should be considered the upper limit for cooling.
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Affiliation(s)
- Xiaojiang Xu
- Biophysics and Biomedical Modeling Division, US Army Research Institute of Environmental Medicine, 42 Kansas Street, Natick, MA 01760, USA.
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Sawka MN, Wenger CB, Pandolf KB. Thermoregulatory Responses to Acute Exercise‐Heat Stress and Heat Acclimation. Compr Physiol 2011. [DOI: 10.1002/cphy.cp040109] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Abstract
Human body temperature is regulated within a very narrow range. When exposed to hyperthermic conditions, via environmental factors and/or increased metabolism, heat dissipation becomes vital for survival. In humans, the primary mechanism of heat dissipation, particularly when ambient temperature is higher than skin temperature, is evaporative heat loss secondary to sweat secretion from eccrine glands. While the primary controller of sweating is the integration between internal and skin temperatures, a number of non-thermal factors modulate the sweating response. In addition to summarizing the current understanding of the neural pathways from the brain to the sweat gland, as well as responses at the sweat gland, this review will highlight findings pertaining to studies of proposed non-thermal modifiers of sweating, namely, exercise, baroreceptor loading state, and body fluid status. Information from these studies not only provides important insight pertaining to the basic mechanisms of sweating, but also perhaps could be useful towards a greater understanding of potential mechanisms and consequences of disease states as well as aging in altering sweating responses and thus temperature regulation.
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Affiliation(s)
- Manabu Shibasaki
- Department of Environmental and Life Sciences, Nara Women’s University Graduate School of Humanities and Sciences, Nara Japan
| | - Craig G. Crandall
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital of Dallas, TX
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Ely BR, Ely MR, Cheuvront SN, Kenefick RW, Degroot DW, Montain SJ. Evidence against a 40 degrees C core temperature threshold for fatigue in humans. J Appl Physiol (1985) 2009; 107:1519-25. [PMID: 19713430 DOI: 10.1152/japplphysiol.00577.2009] [Citation(s) in RCA: 101] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Evidence suggests that core temperatures of approximately 40 degrees C can induce fatigue, although this may be confounded by coincident elevations in skin temperatures and maximal cardiovascular strain. In an observational field study to examine core temperature threshold for fatigue, we investigated whether running performance is impaired when rectal temperature (T(re)) is >40 degrees C and skin temperature remains modest. Seventeen competitive runners (7/10 women/men: 8 km best 1,759 +/- 78/1,531 +/- 60 s) completed 8-km track time trials in cool (WBGT approximately 13 degrees C; n = 6), warm (WBGT approximately 27 degrees C; n = 4), or both (n = 7) conditions. T(re), chest skin temperature, and heart rate were logged continuously; elapsed time was recorded every 200 m. Running velocity for T(re) >40 degrees C was compared with that for T(re) <40 degrees C for each runner. Changes in running velocity over the last 600 m were compared between runners with T(re) >40 degrees C and <40 degrees C. Twelve runners achieved T(re) >40.0 degrees C with >or=600 m remaining (range 600-3,400 m). Average running velocity for T(re) <40 degrees C (282 +/- 27 m/min) was not different from that for T(re) >40 degrees C (279 +/- 28 m/min; P = 0.82). There were no differences in running velocity during the final 600 m between runners with final T(re) >40 degrees C or <40 degrees C (P = 0.16). Chest skin temperature ranged from 30 to 34 degrees C, and heart rate was >95% of age-predicted maximum. Our observation that runners were able to sustain running velocity despite T(re) >40 degrees C is evidence against 40 degrees C representing a "critical" core temperature limit to performance.
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Affiliation(s)
- Brett R Ely
- US Army Research Institute of Environmental Medicine, Thermal and Mountain Medicine Division, Kansas St., Natick, MA 01760-5007, USA.
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Gonzalez RR, Cheuvront SN, Montain SJ, Goodman DA, Blanchard LA, Berglund LG, Sawka MN. Expanded prediction equations of human sweat loss and water needs. J Appl Physiol (1985) 2009; 107:379-88. [DOI: 10.1152/japplphysiol.00089.2009] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The Institute of Medicine expressed a need for improved sweating rate (ṁsw) prediction models that calculate hourly and daily water needs based on metabolic rate, clothing, and environment. More than 25 years ago, the original Shapiro prediction equation (OSE) was formulated as ṁsw (g·m−2·h−1) = 27.9· Ereq·( Emax)−0.455, where Ereq is required evaporative heat loss and Emax is maximum evaporative power of the environment; OSE was developed for a limited set of environments, exposures times, and clothing systems. Recent evidence shows that OSE often overpredicts fluid needs. Our study developed a corrected OSE and a new ṁsw prediction equation by using independent data sets from a wide range of environmental conditions, metabolic rates (rest to ≤450 W/m2), and variable exercise durations. Whole body sweat losses were carefully measured in 101 volunteers (80 males and 21 females; >500 observations) by using a variety of metabolic rates over a range of environmental conditions (ambient temperature, 15–46°C; water vapor pressure, 0.27–4.45 kPa; wind speed, 0.4–2.5 m/s), clothing, and equipment combinations and durations (2–8 h). Data are expressed as grams per square meter per hour and were analyzed using fuzzy piecewise regression. OSE overpredicted sweating rates ( P < 0.003) compared with observed ṁsw. Both the correction equation (OSEC), ṁsw = 147·exp (0.0012·OSE), and a new piecewise (PW) equation, ṁsw = 147 + 1.527· Ereq − 0.87· Emax were derived, compared with OSE, and then cross-validated against independent data (21 males and 9 females; >200 observations). OSEC and PW were more accurate predictors of sweating rate (58 and 65% more accurate, P < 0.01) and produced minimal error (standard error estimate < 100 g·m−2·h−1) for conditions both within and outside the original OSE domain of validity. The new equations provide for more accurate sweat predictions over a broader range of conditions with applications to public health, military, occupational, and sports medicine settings.
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KENNY GLENP, DORMAN LUCYE, WEBB PAUL, DUCHARME MICHELB, GAGNON DANIEL, REARDON FRANCISD, HARDCASTLE STEPHENG, JAY OLLIE. Heat Balance and Cumulative Heat Storage during Intermittent Bouts of Exercise. Med Sci Sports Exerc 2009; 41:588-96. [DOI: 10.1249/mss.0b013e31818c97a9] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Kenny GP, Jay O, Journeay WS. Disturbance of thermal homeostasis following dynamic exercise. Appl Physiol Nutr Metab 2007; 32:818-31. [PMID: 17622300 DOI: 10.1139/h07-044] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Recovery from dynamic exercise results in significant perturbations of thermoregulatory control. These perturbations evoke a prolonged elevation in core body temperature and a concomitant decrease in sweating, skin blood flow, and skin temperature to pre-exercise baseline values within the early stages of recovery. Cutaneous vasodilation and sweating are critical responses necessary for effective thermoregulation during heat stress in humans. The ability to modulate the rate of heat loss through adjustments in vasomotor and sudomotor activity is a fundamental mechanism of thermoregulatory homeostasis. There is a growing body of evidence in support of a possible relationship between hemodynamic changes postexercise and heat loss responses. Specifically, nonthermoregulatory factors, such as baroreceptors, associated with hemodynamic changes, influence the regulation of core body temperature during exercise recovery. The following review will examine the etiology of the post-exercise disturbance in thermal homeostasis and evaluate possible thermal and nonthermal factors associated with a prolonged hyperthermic state following exercise.
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Affiliation(s)
- Glen P Kenny
- Laboratory for Human Bioenergetics and Environmental Physiology, Faculty of Health Sciences, School of Human Kinetics, 125 University Ave., Montpetit Hall, University of Ottawa, Ottawa, ON K1N 6N5, Canada.
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Patel SA, Benzo RP, Slivka WA, Sciurba FC. Activity monitoring and energy expenditure in COPD patients: a validation study. COPD 2007; 4:107-12. [PMID: 17530503 PMCID: PMC3391963 DOI: 10.1080/15412550701246658] [Citation(s) in RCA: 97] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
There is increasing interest in the objective measurement of physical activity in chronic obstructive pulmonary disease (COPD) patients due to the close relationship between physical activity level, health, disability and mortality. We aimed to (a) determine the validity and reproducibility of an activity monitor that integrates accelerometry with multiple physiologic sensors in the determination of energy expenditure in COPD subjects and (b) to document the independent contribution of the additional physiologic sensors to accelerometry measures in improving true energy expenditure determination. Eight subjects (4 male, FEV(1) 56.4 +/- 14.1%, RV 145.0 +/- 75.7%) performed 2 separate 6-minute walk and 2 incremental shuttle walk exercise tests. Energy expenditure was calculated during each exercise test using the physiologic activity monitor and compared to a validated exhaled breath metabolic system. Test-retest reproducibility of physiologic activity monitor during the walking tests was comparable to an exhaled breath metabolic system. Physiologic sensor data significantly improved the explained variance in energy expenditure determination (r(2)=0.88) compared to accelerometry data alone (r(2)=0.68). This physiologic activity monitor provides a valid and reproducible estimate of energy expenditure during slow to moderate paced walking in a laboratory setting and represents an objective method to assess activity in COPD subjects.
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Shibasaki M, Wilson TE, Crandall CG. Neural control and mechanisms of eccrine sweating during heat stress and exercise. J Appl Physiol (1985) 2006; 100:1692-701. [PMID: 16614366 DOI: 10.1152/japplphysiol.01124.2005] [Citation(s) in RCA: 171] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
In humans, evaporative heat loss from eccrine sweat glands is critical for thermoregulation during exercise and/or exposure to hot environmental conditions, particularly when environmental temperature is greater than skin temperature. Since the time of the ancient Greeks, the significance of sweating has been recognized, whereas our understanding of the mechanisms and controllers of sweating has largely developed during the past century. This review initially focuses on the basic mechanisms of eccrine sweat secretion during heat stress and/or exercise along with a review of the primary controllers of thermoregulatory sweating (i.e., internal and skin temperatures). This is followed by a review of key nonthermal factors associated with prolonged heat stress and exercise that have been proposed to modulate the sweating response. Finally, mechanisms pertaining to the effects of heat acclimation and microgravity exposure are presented.
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Affiliation(s)
- Manabu Shibasaki
- Department of Environmental Health, Nara Women's University, Nara, Japan.
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Kacin A, Golja P, Eiken O, Tipton MJ, Gorjanc J, Mekjavic IB. Human temperature regulation during cycling with moderate leg ischaemia. Eur J Appl Physiol 2005; 95:213-20. [PMID: 16075299 DOI: 10.1007/s00421-005-1387-3] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/02/2005] [Indexed: 10/25/2022]
Abstract
The effect of graded ischaemia in the legs on the regulation of body temperature during steady-state exercise was investigated in seven healthy males. It was hypothesised that graded ischaemia in the working muscles increases heat storage within the muscles, which in turn potentiates sweat secretion during exercise. Blood perfusion in the working muscles was reduced by applying a supra-atmospheric pressure (+6.6 kPa) around the legs, which reduced maximal working capacity by 29%. Each subject conducted three separate test trials comprising 30 min of steady-state cycling in a supine position. Exercise with unrestricted blood flow (Control trial) was compared to ischaemic exercise conducted at an identical relative work rate (Relative trial), as well as at an identical absolute work rate (Absolute trial); the latter corresponding to a 20% increase in relative workload. The average (SD) increases in both the rectal and oesophageal temperatures during steady-state cycling was 0.3 (0.2) degrees C and did not significantly differ between the three trials. The increase in muscle temperature was similar in the Control (2.7 (0.3) degrees C) and Absolute (2.4 (0.7) degrees C) trials, but was substantially lower (P < 0.01) in the Relative trial (1.4 (0.8) degrees C). Ischaemia potentiated (P < 0.01) sweating on the forehead in the Absolute trial (24.2 (7.3) g m(-2) min(-1)) compared to the Control trial (13.4 (6.2) g m(-2) min(-1)), concomitant with an attenuated (P < 0.05) vasodilatation in the skin during exercise. It is concluded that graded ischaemia in working muscles potentiates the exercise sweating response and attenuates vasodilatation in the skin initiated by increased core temperature, effects which may be attributed to an augmented muscle metaboreflex.
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Affiliation(s)
- Alan Kacin
- Department of Automation, Biocybernetics and Robotics, Institute Jozef Stefan, Ljubljana, Slovenia.
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Kenny GP, Reardon FD, Zaleski W, Reardon ML, Haman F, Ducharme MB. Muscle temperature transients before, during, and after exercise measured using an intramuscular multisensor probe. J Appl Physiol (1985) 2003; 94:2350-7. [PMID: 12598487 DOI: 10.1152/japplphysiol.01107.2002] [Citation(s) in RCA: 83] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Seven subjects (1 woman) performed an incremental isotonic test on a Kin-Com isokinetic apparatus to determine their maximal oxygen consumption during bilateral knee extensions (Vo(2 sp)). A multisensor thermal probe was inserted into the left vastus medialis (middiaphysis) under ultrasound guidance. The deepest sensor (tip) was located approximately 10 mm from the femur and deep femoral artery (T(mu 10)), with additional sensors located 15 (T(mu 25)) and 30 mm (T(mu 40)) from the tip. Esophageal temperature (T(es)) was measured as an index of core temperature. Subjects rested in an upright seated position for 60 min in an ambient condition of 22 degrees C. They then performed 15 min of isolated bilateral knee extensions (60% of Vo(2 sp)) on a Kin-Com, followed by 60 min of recovery. Resting T(es) was 36.80 degrees C, whereas T(mu 10), T(mu 25), and T(mu 40) were 36.14, 35.86, and 35.01 degrees C, respectively. Exercise resulted in a T(es) increase of 0.55 degrees C above preexercise resting, whereas muscle temperature of the exercising leg increased by 2.00, 2.37, and 3.20 degrees C for T(mu 10), T(mu 25), and T(mu 40), respectively. Postexercise T(es) showed a rapid decrease followed by a prolonged sustained elevation approximately 0.3 degrees C above resting. Muscle temperature decreased gradually over the course of recovery, with values remaining significantly elevated by 0.92, 1.05, and 1.77 degrees C for T(mu 10), T(mu 25), and T(mu 40), respectively, at end of recovery (P < 0.05). These results suggest that the transfer of residual heat from previously active musculature may contribute to the sustained elevation in postexercise T(es).
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Affiliation(s)
- G P Kenny
- Faculty of Health Sciences, School of Human Kinetics, Faculty of Medicine, and Faculty of Sciences, University of Ottawa, Ottawa, Canada K1N 6N5.
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Kenny GP, Reardon FD, Ducharme MB, Reardon ML, Zaleski W. Tissue temperature transients in resting contra-lateral leg muscle tissue during isolated knee extension. CANADIAN JOURNAL OF APPLIED PHYSIOLOGY = REVUE CANADIENNE DE PHYSIOLOGIE APPLIQUEE 2002; 27:535-50. [PMID: 12500993 DOI: 10.1139/h02-030] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
This study was designed to evaluate the role of non-active tissue in the retention and dissipation of heat during and following intense isolated muscle activity. Six subjects performed an incremental isotonic test (constant angular velocity, increases in force output) on a KIN-COM isokinetic apparatus to determine their maximal oxygen consumption during single knee extensions (VO2sp). In a subsequent session, a thin wire multi-sensor temperature probe was inserted into the left vastus medialis under ultrasound guidance at a specific internal marker. The deepest temperature sensor (tip, Tmu10) was located approximately 10 mm from the femur and deep femoral artery with 2 additional sensors located at 15 (Tmu25) and 30 (Tmu40) mm from the tip. Implant site was midway between and medial to a line joining the anterior superior iliac spine and base of patella. Esophageal temperature (Tes) temperature was measured as an index of core temperature. Subjects rested in a supine position for 60 min followed by 30 min of seated rest in an ambient condition of 22 degree C. Subjects then performed 15 min of isolated single right knee extensions against a dynamic resistance on a KIN COM corresponding to 60% of VO2sp at 60 degree x sec(-1). Exercise was followed by 60 min of seated rest. Resting Tes was 37 degree C while Tmu10, Tmu25, and Tmu40 were 36.58, 36.55 and 36.45 degree C, respectively. Exercise resulted in a Tes increase of 0.31 C above pre-exercise resting. Tmu of the non-exercising leg increased 0.23, 0.19 and 0.09 degree C for Tmu10, Tmu25, and Tmu40, respectively. While Tes decreased to baseline values within approximately 15 min of end-exercise, Tmu10 reached resting values following approximately 40 min of recovery. These results suggest that during isolated muscle activity, convective heat transfer by the blood to non-active muscle tissue may have a significant role in maintaining resting core temperature.
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Affiliation(s)
- Glen P Kenny
- Faculty of Health Sciences, University of Ottawa, Ottawa, ON
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Fukuoka Y, Kaneko Y, Takita C, Hirakawa M, Kagawa H, Nakamura Y. The effects of exercise intensity on thermoregulatory responses to exercise in women. Physiol Behav 2002; 76:567-74. [PMID: 12126994 DOI: 10.1016/s0031-9384(02)00781-3] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We investigated the influence of altering exercise intensity (150, 300, and 450 kpm/min) on the resetting of the core temperature threshold for the onset of the sweating rate (M(sw)) and the alteration of sweating sensitivity during the menstrual cycle in women. Five women underwent cycling exercise for 30 min in both the luteal and follicular phases under controlled neutral environmental conditions (T: 25 degrees C, RH: 55%). A significantly higher rectal temperature (T(re)) was seen in the luteal phase at all exercise intensities, and the same time course of the T(re) response with a constant difference of approximately 0.2 degrees C was shown between the follicular phase and the luteal phase. The T(re) threshold for M(sw) was also apparently shifted rightward a constant value of 0.2 degrees C from the follicular phase to the luteal phase, independent of the alteration of exercise intensity. The slope of the M(sw)-T(re) relationship in the follicular phase did not differ from that in the luteal phase. These results indicate that (1) a rightward shift in the T(re) threshold from the follicular phase to the luteal phase can be observed independent of any alteration of the exercise intensity; and (2) the sensitivity of M(sw) is also not physiologically influenced by exercise intensity. Thus, alterative thermoregulation during the menstrual cycle was fundamentally unaffected by the change of exercise intensity.
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Affiliation(s)
- Yoshiyuki Fukuoka
- Faculty of Environmental and Symbiotic Science, Laboratory of Applied and Environmental Physiology, Prefectural University of Kumamoto, Kumamoto 862-8502, Japan.
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Gonzalez RR, Blanchard LA, Allison WF, Gonzalez JA. Thermoregulatory Sweating during Cold Transients and Exercise: Effect of Menstrual Cycle phase. ACTA ACUST UNITED AC 2002. [DOI: 10.1618/jhes.6.9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Affiliation(s)
- R. R. Gonzalez
- Biophysics and Biomedical Modeling Division, U.S. Army Research Institute of Environmental Medicine
| | - L. A. Blanchard
- Biophysics and Biomedical Modeling Division, U.S. Army Research Institute of Environmental Medicine
| | - W. F. Allison
- Biophysics and Biomedical Modeling Division, U.S. Army Research Institute of Environmental Medicine
| | - J. A. Gonzalez
- Biophysics and Biomedical Modeling Division, U.S. Army Research Institute of Environmental Medicine
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Kondo N, Tominaga H, Shibasaki M, Aoki K, Okada S, Nishiyasu T. Effects of exercise intensity on the sweating response to a sustained static exercise. J Appl Physiol (1985) 2000; 88:1590-6. [PMID: 10797117 DOI: 10.1152/jappl.2000.88.5.1590] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
To investigate how the sweating response to a sustained handgrip exercise depends on changes in the exercise intensity, the sweating response to exercise was measured in eight healthy male subjects. Each subject lay in the supine position in a climatic chamber (35 degrees C and 50% relative humidity) for approximately 60 min. This exposure caused sudomotor activation by increasing skin temperature without a marked change in internal temperature. After this period, each subject performed isometric handgrip exercise [15, 30, 45, and 60% maximal voluntary contraction (MVC)] for 60 s. Although esophageal and mean skin temperatures did not change with a rise in exercise intensity and were similar at all exercise intensities, the sweating rate (SR) on the forearm increased significantly (P < 0.05) from baseline (0.094 +/- 0.021 mg. cm(-2). min(-1) at 30% MVC, 0.102 +/- 0.022 mg. cm(-2). min(-1) at 45% MVC, 0.059 +/- 0.009 mg. cm(-2). min(-1) at 60% MVC) in parallel with exercise intensity above exercise intensity at 30% MVC (0.121 +/- 0.023 mg. cm(-2). min(-1) at 30% MVC, 0.242 +/- 0.051 mg. cm(-2). min(-1) at 45% MVC, 0.290 +/- 0.056 mg. cm(-2). min(-1) at 60% MVC). Above 45% MVC, SR on the palm increased significantly from baseline (P < 0.05). Although SR on the forearm and palm tended to increase with a rise in exercise intensity, there was a difference in the time courses of SR between sites. SR on the palm showed a plateau after abrupt increase, whereas SR on the forearm increased progressively during exercise. These results suggest that the increase in SR with the increase in sustained handgrip exercise intensity is due to nonthermal factors and that the magnitude of these factors during the exercise may be responsible for the magnitude of SR.
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Affiliation(s)
- N Kondo
- Laboratory for Applied Human Physiology, Faculty of Human Development, Kobe University, Kobe 657-8501, Japan.
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Kondo N, Takano S, Aoki K, Shibasaki M, Tominaga H, Inoue Y. Regional differences in the effect of exercise intensity on thermoregulatory sweating and cutaneous vasodilation. ACTA PHYSIOLOGICA SCANDINAVICA 1998; 164:71-8. [PMID: 9777027 DOI: 10.1046/j.1365-201x.1998.00407.x] [Citation(s) in RCA: 83] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
To investigate regional body differences in the effect of exercise intensity on the thermoregulatory sweating response, nine healthy male subjects (23.2 +/- 0.4 year) cycled at 35, 50 and 65% of their maximal O2 uptake (VO2max) for 30 min at an ambient temperature of 28.3 +/- 0.2 degrees C and a relative humidity of 42.6 +/- 2.4%. Local sweating rate (msw) on the forehead, chest, back, forearm and thigh increased significantly with increases in the exercise intensity from 35 to 50% VO2max and from 50 to 65% VO2max (P < 0.05). The mean values for the density of activated sweat glands (ASG) at 50 and 65% VO2max at the five sites were significantly greater than at 35% VO2max. The mean value of the sweat output per gland (SGO) also increased significantly with the increase in exercise intensity (P < 0.05). The patterns of changes in ASG and SGO with an increase in exercise intensity differed from one region of the body to another. Although esophageal temperature (Tes) threshold for the onset of sweating at each site was not altered by exercise intensity, the sensitivity of the sweating response on the forehead increased significantly from 35 to 50 and 65% VO2max (P < 0.05). The threshold for cutaneous vasodilation tend to increase with exercise intensity, although the exercise intensity did not affect the sensitivity (the slope in the relationship Tes vs. percentage of the maximal skin blood flow) at each site. Tes threshold for cutaneous vasodilation on the forearm was significantly higher at 65% VO2max than at either 35 or 50% VO2max, but this was not observed at the other sites, such as on the forehead and chest. These results suggest that the increase in msw seen with an increasing intensity of exercise depends first on ASG, and then on SGO, and the dependence of ASG and SGO on the increase in msw differs for different body sites. In addition, there are regional differences in the Tes threshold for vasodilation in response to an increase in exercise intensity.
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Affiliation(s)
- N Kondo
- Laboratory for Applied Human Physiology, Faculty of Human Development, Kobe University, Japan
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Kenny GP, Giesbrecht GG, Thoden JS. Post-exercise thermal homeostasis as a function of changes in pre-exercise core temperature. EUROPEAN JOURNAL OF APPLIED PHYSIOLOGY AND OCCUPATIONAL PHYSIOLOGY 1996; 74:258-63. [PMID: 8897032 DOI: 10.1007/bf00377448] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
We have previously reported that, following continuous exercise, a prolonged elevated plateau of esophageal temperature (Tes) was directly related to the Tes at the time of cutaneous vasodilation (Thdil) during exercise. In order to investigate the hypothesis that the factors which result in an increase of the post-exercise Thdil and define the post-exercise Tes elevation are related to pre-exercise Tes, nine healthy, young [24.0 (1.9) years], non-training males rested at 29 degrees C, 50% humidity for > 1 h (control). They then completed three successive cycles of 15 min treadmill running at 70% maximal oxygen consumption (VO2max) followed by 30 min rest. Esophageal, rectal (Tre) and skin (Tsk) temperatures and forearm cutaneous blood flow were recorded at 5-s intervals throughout. Laser-Doppler flowmetry of forearm skin blood flow was used to identify the Thdil during exercise. Pre-exercise Tes was 36.74 (0.25) degrees C and post-exercise Tes fell to stable and significant (P < 0.05) elevations above pre-exercise values at 37.22 (0.27) degrees C, 37.37 (0.27) degrees C and 37.48 (0.26) degrees C following each successive work bout respectively. Correspondingly, Thdil during each work bout rose in proportion to, and was not different than, the post-exercise Tes in the following recovery [37.20(0.23) degrees C, 37.41 (0.24) degrees C and 37.58 (0.24) degrees C]. Although the increases were less with each successive exercise bout, the differences between each exercise bout, in terms of post-exercise Tes and Thdil values, were significant (P < 0.05). These results reinforce our previous observations of elevations in Thdil and post-exercise Tes after a single exercise bout and lead to the tentative conclusions that (1) pre-exercise Tes has a direct influence on Thdil and post-exercise Tes, and (2) the exercise-induced increase of Thdil persists into recovery, influencing post-exercise thermal recovery.
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Affiliation(s)
- G P Kenny
- University of Ottawa, Faculty of Medicine, Department of Physiology, Canada
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Torii M, Yamasaki M, Sasaki T. Effect of prewarming in the cold season on thermoregulatory responses during exercise. Br J Sports Med 1996; 30:102-11. [PMID: 8799592 PMCID: PMC1332370 DOI: 10.1136/bjsm.30.2.102] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
OBJECTIVE To assess whether thermoregulation in the cold season can be affected by prewarming before exercise. METHODS Four healthy non-athletic unacclimatised males were exercised to the same degree in summer and winter on a bicycle ergometer without prewarming (experiment 1) and after prewarming by sitting for 30 min in a room at 30 degrees C (experiment 2). During exercise, sweat production and rectal and skin temperatures were measured continuously. RESULTS There was seasonal variation in sweating capacity and sensitivity and in heat storage during exercise without prewarming (experiment 1). After the subjects were warmed before exercise, there was no such seasonal variation in their sweat rates during exercise at 30 degrees C and 40 degrees C (experiment 2). In both cases, the sweat rate and skin temperature were dependent on the environmental temperature, and the sweat rate and core temperature were dependent on the workload. In the cold season, sweating sensitivity and evaporative cooling response could be enhanced by thermal stimulation. There was no seasonal difference in the relation between evaporative heat loss and metabolic rate in the two thermal conditions. These values did not differ significantly between winter after prewarming and summer (P > 0.05), neither did heat storage and metabolic heat production at various workloads (P > 0.05). CONCLUSIONS There is adaptation of the thermoregulatory mechanisms during temperature acclimatisation. Body warming enhances not only the heat dissipating activity of the thermoregulatory centre but also the induction of peripheral sweat gland activity. Seasonal change of sweat rate in exercising men can be eliminated through a different type of acclimatisation by prewarming in the cold season.
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Affiliation(s)
- M Torii
- Laboratory for Environmental Bioregulation, Faculty of Engineering, Kyushu Institute of Technology, Kitakyushu, Japan
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Refinetti R. Contribution of locomotor activity to the generation of the daily rhythm of body temperature in golden hamsters. Physiol Behav 1994; 56:829-31. [PMID: 7800756 DOI: 10.1016/0031-9384(94)90251-8] [Citation(s) in RCA: 47] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The locomotor activity and body temperature of 40 golden hamsters maintained under a 14L:10D light:dark cycle were studied by telemetry. Body temperature was found to be highly correlated with activity. On average, an increase from 0 to 200 units of activity was associated with a 0.7 degrees C increase in body temperature. However, body temperature during the dark phase of the light:dark cycle was 0.3 degrees C higher than during the light phase, irrespective of the activity level. These results indicate that, although activity can affect body temperature, the increase in activity during the dark phase is not the cause of the temperature rhythm. At least 30% of the total daily variation in body temperature is independent of variations in the activity level.
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Affiliation(s)
- R Refinetti
- Department of Psychology, College of William & Mary, Williamsburg, VA 23187
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Yamazaki F, Sone R, Fujii N, Ikegami H. A comparison of sweating responses during exercise and recovery in terms of sweating rate and body temperature. INTERNATIONAL JOURNAL OF BIOMETEOROLOGY 1993; 37:212-217. [PMID: 8112879 DOI: 10.1007/bf01387526] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Based on the hypothesis that the relation between sweating rate and body temperature should be different during exercise and rest after exercise, we compared the sweating response during exercise and recovery at a similar body temperature. Healthy male subjects performed submaximal exercise (Experiment 1) and maximal exercise (Experiment 2) in a room at 27 degrees C and 35% relative humidity. During exercise and recovery of 20 min after exercise, esophageal temperature (Tes), mean skin temperature, mean body temperature (Tb), chest sweating rate (msw), and the frequency of sweat expulsion (Fsw) were measured. In both experiments, msw and Fsw were clearly higher during exercise than recovery at a similar body temperature (Tes, Tb). msw was similar during exercise and recovery, or a little less during the former, at a similar Fsw. It is concluded that the sweating rate during exercise is greater than that during recovery at the same body temperature, due to greater central sudomotor activity during exercise. The difference between the two values is thought to be related to non-thermal factors and the rate of change in mean skin temperature.
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Affiliation(s)
- F Yamazaki
- Doctoral Program in Health and Sport Sciences, University of Tsukuba, Japan
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Abstract
The effect of temperature on the mechanical failure properties of rabbit skeletal muscle (tibialis anterior and extensor digitorum longus) was examined. For all tests, one leg was maintained at 25 degrees C and the contralateral leg at 40 degrees C. Muscles were pulled to failure according to assignment into one of three groups: 1) passive failure at 10 cm/sec, 2) passive failure at 1 cm/sec, or 3) active (muscle is stimulated to contract as it is pulled) failure at 10 cm/sec. Load to failure was higher in the cold muscle for all groups tested. Total deformation was the same except in Group 1, when the warm muscle had a greater deformation. Energy absorbed before failure was greater in the cold muscle in Groups 2 and 3. Stiffness was higher in cold muscles for all muscles except the extensor digitorum longus in Group 1. In this study, temperature had a significant effect on the tensile properties; these thermal effects were dependent on both loading rate and contractile state. Comparing loading rates, warm muscle tested at 10 cm/sec had higher failure loads than that tested at 1 cm/sec. Comparing stimulated versus unstimulated muscle (Group 1 versus Group 3), the stimulated tibialis anterior muscle absorbed more energy than unstimulated ones. Stimulated extensor digitorum longus muscles had higher failure loads, absorbed more energy, and were stiffer than nonstimulated muscles. This study offers experimental data to support the theory that warming muscles can aid in injury prevention and improvement in athletic performance.
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Affiliation(s)
- T J Noonan
- Orthopaedic Research Laboratories, Duke University Medical Center, Durham, North Carolina 27710
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Abstract
This paper reviews the literature on the circadian rhythm of body temperature (CRT). The review starts with a brief discussion of methodological procedures followed by the description of known patterns of oscillation in body temperature, including ultradian and infradian rhythms. Special sections are devoted to issues of species differences, development and aging, and the relationships between the CRT and the circadian rhythm of locomotor activity, between the CRT and the thermoregulatory system, and between the CRT and states of disease. A section on the nervous control of the CRT is followed by summary and conclusions.
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Affiliation(s)
- R Refinetti
- Department of Biology, University of Virginia, Charlottesville 22901
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