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Otani H, Goto T, Kobayashi Y, Goto H, Hosokawa Y, Tokizawa K, Shirato M. The fan cooling vest use reduces thermal and perceptual strain during outdoor exercise in the heat on a sunny summer day. INTERNATIONAL JOURNAL OF BIOMETEOROLOGY 2024:10.1007/s00484-024-02690-w. [PMID: 38771319 DOI: 10.1007/s00484-024-02690-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/24/2023] [Revised: 04/07/2024] [Accepted: 04/21/2024] [Indexed: 05/22/2024]
Abstract
The fan cooling vest is coming into very common use by Japanese outdoor manual workers. We examined that to what extent using this vest reduces thermal strain and perception during outdoor exercise in the heat on a sunny summer day. Ten male baseball players in high school conducted two baseball training sessions for 2-h with (VEST) or without (CON) a commercially available fan cooling vest on a baseball uniform. These sessions commenced at 10 a.m. on separate days in early August. The fan airflow rate attached the vest was 62 L·s-1. Neither ambient temperature (Mean ± SD: VEST 31.9 ± 0.2°C; CON 31.8 ± 0.7°C), wet-bulb globe temperature (VEST 31.2 ± 0.4°C; CON 31.4 ± 0.5°C) nor solar radiation (VEST 1008 ± 136 W·m-2; CON 1042 ± 66 W·m-2) was different between trials. Mean skin temperature (VEST 34.5 ± 1.1°C; CON 35.1 ± 1.4°C), infrared tympanic temperature (VEST 38.9 ± 0.9°C; CON 39.2 ± 1.2°C), heart rate (VEST 127 ± 31 bpm; CON 139 ± 33 bpm), body heat storage (VEST 140 ± 34 W·m-2; CON 160 ± 22 W·m-2), thermal sensation (- 4-4: VEST 0 ± 2; CON 3 ± 1) and rating of perceived exertion (6-20: VEST 11 ± 2; CON 14 ± 2) were lower in VEST than CON (all P < 0.05). Total distance measured with a global positioning system (VEST 3704 ± 293 m; CON 3936 ± 501 m) and body fluid variables were not different between trials. This study indicates that the fan cooling vest use can reduce thermal strain and perception during outdoor exercise in the heat on a sunny summer day. Cooling with this vest would be effective to mitigate thermal risks and perceptual stress in athletes and sports participants under such settings.
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Affiliation(s)
- Hidenori Otani
- Faculty of Health Care Sciences, Himeji Dokkyo University, 7-2-1 Kamiono, Himeji, Hyogo, 670-8524, Japan.
| | - Takayuki Goto
- National Institute of Technology, Akashi College, Uozumi-Cho, 679-3 Nishioka, Akashi, Hyogo, 674-0084, Japan
| | - Yuki Kobayashi
- National Institute of Technology, Akashi College, Uozumi-Cho, 679-3 Nishioka, Akashi, Hyogo, 674-0084, Japan
| | - Heita Goto
- Kyushu Kyoritsu University, 1-8 Jiyugaoka, Yahatanishi-Ku, Kitakyushu, Fukuoka, 807-8585, Japan
| | - Yuri Hosokawa
- Faculty of Sport Sciences, Waseda University, 2-579-15 Mikajima, Tokorozawa, Saitama, 359-1164, Japan
| | - Ken Tokizawa
- National Institute of Occupational Safety and Health, 1-4-6 Umezono, Kiyose, Tokyo, 204-0024, Japan
| | - Minayuki Shirato
- Meiji Gakuin University, 1-2-37 Shiroganedai, Minato-Ku, Tokyo, 108-8636, Japan
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Ebisuda Y, Mukai K, Takahashi Y, Yoshida T, Matsuhashi T, Kawano A, Miyata H, Kuwahara M, Ohmura H. Heat acclimation improves exercise performance in hot conditions and increases heat shock protein 70 and 90 of skeletal muscles in Thoroughbred horses. Physiol Rep 2024; 12:e16083. [PMID: 38789393 PMCID: PMC11126422 DOI: 10.14814/phy2.16083] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2024] [Revised: 05/09/2024] [Accepted: 05/12/2024] [Indexed: 05/26/2024] Open
Abstract
This study aimed to determine whether heat acclimation could induce adaptations in exercise performance, thermoregulation, and the expression of proteins associated with heat stress in the skeletal muscles of Thoroughbreds. Thirteen trained Thoroughbreds performed 3 weeks of training protocols, consisting of cantering at 90% maximal oxygen consumption (VO2max) for 2 min 2 days/week and cantering at 7 m/s for 3 min 1 day/week, followed by a 20-min walk in either a control group (CON; Wet Bulb Globe Temperature [WBGT] 12-13°C; n = 6) or a heat acclimation group (HA; WBGT 29-30°C; n = 7). Before and after heat acclimation, standardized exercise tests (SET) were conducted, cantering at 7 m/s for 90 s and at 115% VO2max until fatigue in hot conditions. Increases in run time (p = 0.0301), peak cardiac output (p = 0.0248), and peak stroke volume (p = 0.0113) were greater in HA than in CON. Pulmonary artery temperature at 7 m/s was lower in HA than in CON (p = 0.0332). The expression of heat shock protein 70 (p = 0.0201) and 90 (p = 0.0167) increased in HA, but not in CON. These results suggest that heat acclimation elicits improvements in exercise performance and thermoregulation under hot conditions, with a protective adaptation to heat stress in equine skeletal muscles.
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Affiliation(s)
- Yusaku Ebisuda
- Sports Science DivisionEquine Research Institute, Japan Racing AssociationShimotsukeJapan
| | - Kazutaka Mukai
- Sports Science DivisionEquine Research Institute, Japan Racing AssociationShimotsukeJapan
| | - Yuji Takahashi
- Sports Science DivisionEquine Research Institute, Japan Racing AssociationShimotsukeJapan
| | - Toshinobu Yoshida
- Sports Science DivisionEquine Research Institute, Japan Racing AssociationShimotsukeJapan
| | - Tsubasa Matsuhashi
- Department of Biological Sciences, Graduate School of Sciences and Technology for InnovationYamaguchi UniversityYamaguchiJapan
| | - Aoto Kawano
- Department of Biological Sciences, Graduate School of Sciences and Technology for InnovationYamaguchi UniversityYamaguchiJapan
| | - Hirofumi Miyata
- Department of Biological Sciences, Graduate School of Sciences and Technology for InnovationYamaguchi UniversityYamaguchiJapan
| | - Masayoshi Kuwahara
- Department of Veterinary Pathophysiology and Animal Health, Graduate School of Agricultural and Life SciencesThe University of TokyoTokyoJapan
| | - Hajime Ohmura
- Sports Science DivisionEquine Research Institute, Japan Racing AssociationShimotsukeJapan
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3
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Meade RD, Notley SR, Kirby NV, Kenny GP. A critical review of the effectiveness of electric fans as a personal cooling intervention in hot weather and heatwaves. Lancet Planet Health 2024; 8:e256-e269. [PMID: 38580427 DOI: 10.1016/s2542-5196(24)00030-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2022] [Revised: 01/26/2024] [Accepted: 02/22/2024] [Indexed: 04/07/2024]
Abstract
Health agencies worldwide have historically cautioned that electric fans accelerate body-heat gain during hot weather and heatwaves (typically in air temperatures ≥35°C). However, guidance published since 2021 has suggested that fans can still cool the body in air temperatures up to 40°C by facilitating sweat evaporation, and therefore are an inexpensive yet sustainable alternative to air conditioning. In a critical analysis of the reports cited to support this claim, we found that although fan use improves sweat evaporation, these benefits are of insufficient magnitude to exert meaningful reductions in body core temperature in air temperatures exceeding 35°C. Health agencies should continue to advise against fan use in air temperatures higher than 35°C, especially for people with compromised sweating capacity (eg, adults aged 65 years or older). Improving access to ambient cooling strategies (eg, air conditioning or evaporative coolers) and minimising their economic and environmental costs through policy initiatives, efficient cooling technology, and combined use of low-cost personal interventions (eg, skin wetting or fan use) are crucial for climate adaptation.
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Affiliation(s)
- Robert D Meade
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, ON, Canada; Harvard T H Chan School of Public Health, Harvard University, Boston, MA, USA
| | - Sean R Notley
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, ON, Canada
| | - Nathalie V Kirby
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, ON, Canada
| | - Glen P Kenny
- Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, ON, Canada; Clinical Epidemiology Program, Ottawa Hospital Research Institute, Ottawa, ON, Canada.
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4
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Wait SO, Charkoudian N, Skinner JW, Smith CJ. Combining hypoxia with thermal stimuli in humans: physiological responses and potential sex differences. Am J Physiol Regul Integr Comp Physiol 2023; 324:R677-R690. [PMID: 36971421 PMCID: PMC10202487 DOI: 10.1152/ajpregu.00244.2021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2021] [Revised: 03/08/2023] [Accepted: 03/20/2023] [Indexed: 03/29/2023]
Abstract
Increasing prevalence of native lowlanders sojourning to high altitudes (>2,500 m) for recreational, occupational, military, and competitive reasons has generated increased interest in physiological responses to multistressor environments. Exposure to hypoxia poses recognized physiological challenges that are amplified during exercise and further complicated by environments that might include combinations of heat, cold, and high altitude. There is a sparsity of data examining integrated responses in varied combinations of environmental conditions, with even less known about potential sex differences. How this translates into performance, occupational, and health outcomes requires further investigation. Acute hypoxic exposure decreases arterial oxygen saturation, resulting in a reflex hypoxic ventilatory response and sympathoexcitation causing an increase in heart rate, myocardial contractility, and arterial blood pressure, to compensate for the decreased arterial oxygen saturation. Acute altitude exposure impairs exercise performance, for example, reduced time to exhaustion and slower time trials, largely owing to impairments in pulmonary gas exchange and peripheral delivery resulting in reduced V̇o2max. This exacerbates with increasing altitude, as does the risk of developing acute mountain sickness and more serious altitude-related illnesses, but modulation of those risks with additional stressors is unclear. This review aims to summarize and evaluate current literature regarding cardiovascular, autonomic, and thermoregulatory responses to acute hypoxia, and how these may be affected by simultaneous thermal environmental challenges. There is minimal available information regarding sex as a biological variable in integrative responses to hypoxia or multistressor environments; we highlight these areas as current knowledge gaps and the need for future research.
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Affiliation(s)
- Seaver O Wait
- Department of Public Health and Exercise Science, Appalachian State University, Boone, North Carolina, United States
| | - Nisha Charkoudian
- United States Army Research Institute of Environmental Medicine, Natick, Massachusetts, United States
| | - Jared W Skinner
- Department of Public Health and Exercise Science, Appalachian State University, Boone, North Carolina, United States
| | - Caroline J Smith
- Department of Public Health and Exercise Science, Appalachian State University, Boone, North Carolina, United States
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Ebisuda Y, Mukai K, Takahashi Y, Ohmura H. Effect of high ambient temperature on physiological responses during incremental exercise in Thoroughbred horses. COMPARATIVE EXERCISE PHYSIOLOGY 2023. [DOI: 10.3920/cep220018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/19/2023]
Abstract
Several reports have suggested that the risk of exertional heat illness (EHI) in Thoroughbred racehorses increases in high ambient temperatures. Heat dissipation in horses during exercise becomes less efficient when the body temperature and ambient temperature are close. Therefore, we hypothesised that exercise at 40 °C may increase body temperature, oxygen consumption, and cardiac output during incremental exercise tests compared to 20 and 30 °C. Six trained Thoroughbred horses were studied in a randomised, crossover design at three ambient temperatures with a 6-day washout period. Using a 3% inclined treadmill, horses performed incremental exercise tests at 1.7, 3.5, 6, 8, and 10 m/s for 90 s at ambient temperatures of 20, 30, and 40 °C. The effects of ambient temperature at 10 m/s on physiological variables were analysed using mixed models (P<0.05). Pulmonary arterial temperature and rectal temperature at 40 °C were higher than those at 20 °C (P<0.001) and 30 °C (P<0.001). Similarly, oxygen consumption (vs 20 °C, P=0.009; vs 30 °C, P=0.006) and cardiac output (vs 20 °C, P=0.001; vs 30 °C, P=0.001) at 40 °C were higher than those at 20 and 30 °C. Arterial O2 partial pressure, O2 saturation, and pH at 40 °C were lower than those at 20 and 30 °C. Arterial CO2 partial pressure at 40 °C was higher than that at 20 and 30 °C. No differences were observed in arterial-mixed venous O2 concentration difference (P=0.391) and plasma lactate concentration (P=0.134) at different ambient temperatures. These results indicate that exercise at 40 °C causes excessive high body temperature, decreased running economy, and increased cardiac output compared to exercise at 20 and 30 °C. We strongly suggest that trainers and veterinarians should anticipate the occurrence of increased thermal stresses when ambient temperature is extremely high even in dry conditions and prepare to mitigate the risk of EHI from the perspective of equine welfare.
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Affiliation(s)
- Y. Ebisuda
- Sports Science Division, Equine Research Institute, Japan Racing Association, Shiba1400-4, Shimotsuke, Tochigi 329-0412, Japan
| | - K. Mukai
- Sports Science Division, Equine Research Institute, Japan Racing Association, Shiba1400-4, Shimotsuke, Tochigi 329-0412, Japan
| | - Y. Takahashi
- Sports Science Division, Equine Research Institute, Japan Racing Association, Shiba1400-4, Shimotsuke, Tochigi 329-0412, Japan
| | - H. Ohmura
- Sports Science Division, Equine Research Institute, Japan Racing Association, Shiba1400-4, Shimotsuke, Tochigi 329-0412, Japan
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Abstract
In this review, we highlight recent studies from our group and others that have characterized the cardiovascular adjustments that occur after acute heat exposure. Special emphasis will be placed on underlying mechanisms and clinical implications. Finally, we postulate that these acute cardiovascular adjustments may predict the long-term adaptive response to chronic heat therapy.
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Affiliation(s)
- Steven A. Romero
- Human Vascular Physiology Laboratory, Department of Physiology and Anatomy, University of North Texas Health Science Center
| | - Rauchelle E. Richey
- Human Vascular Physiology Laboratory, Department of Physiology and Anatomy, University of North Texas Health Science Center
| | - Holden W. Hemingway
- Human Vascular Physiology Laboratory, Department of Physiology and Anatomy, University of North Texas Health Science Center
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Chou TH, Coyle EF. Cardiovascular responses to hot skin at rest and during exercise. Temperature (Austin) 2022; 10:326-357. [PMID: 37554384 PMCID: PMC10405766 DOI: 10.1080/23328940.2022.2109931] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2022] [Revised: 07/25/2022] [Accepted: 07/30/2022] [Indexed: 10/15/2022] Open
Abstract
Integrative cardiovascular responses to heat stress during endurance exercise depend on various variables, such as thermal stress and exercise intensity. This review addresses how increases in skin temperature alter and challenge the integrative cardiovascular system during upright submaximal endurance exercise, especially when skin is hot (i.e. >38°C). Current evidence suggests that exercise intensity plays a significant role in cardiovascular responses to hot skin during exercise. At rest and during mild intensity exercise, hot skin increases skin blood flow and abolishes cutaneous venous tone, which causes blood pooling in the skin while having little impact on stroke volume and thus cardiac output is increased with an increase in heart rate. When the heart rate is at relatively low levels, small increases in heart rate, skin blood flow, and cutaneous venous volume do not compromise stroke volume, so cardiac output can increase to fulfill the demands for maintaining blood pressure, heat dissipation, and the exercising muscle. On the contrary, during more intense exercise, hot skin does not abolish exercise-induced cutaneous venoconstriction possibly due to high sympathetic nerve activities; thus, it does not cause blood pooling in the skin. However, hot skin reduces stroke volume, which is associated with a decrease in ventricular filling time caused by an increase in heart rate. When the heart rate is high during moderate or intense exercise, even a slight reduction in ventricular filling time lowers stroke volume. Cardiac output is therefore not elevated when skin is hot during moderate intensity exercise.
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Affiliation(s)
- Ting-Heng Chou
- Center for Regenerative Medicine, The Research Institute at Nationwide Children’s Hospital, Columbus, OH, USA
| | - Edward F. Coyle
- Department of Kinesiology and Health Education, The University of Texas at Austin, Texas, Tx, USA
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Lloyd A, Fiala D, Heyde C, Havenith G. A mathematical model for predicting cardiovascular responses at rest and during exercise in demanding environmental conditions. J Appl Physiol (1985) 2022; 133:247-261. [PMID: 35652831 PMCID: PMC9342140 DOI: 10.1152/japplphysiol.00619.2021] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The present research describes the development and validation of a cardiovascular model (CVR Model) for use in conjunction with advanced thermophysiological models, where usually only a total cardiac output is estimated. The CVR Model detailed herein estimates cardio-dynamic parameters (changes in cardiac output, stroke volume, and heart rate), regional blood flow, and muscle oxygen extraction, in response to rest and physical workloads, across a range of ages and aerobic fitness levels, as well as during exposure to heat, dehydration, and altitude. The model development strategy was to first establish basic resting and exercise predictions for cardio-dynamic parameters in an "ideal" environment (cool, sea level, and hydrated person). This basic model was then advanced for increasing levels of altitude, heat strain, and dehydration, using meta-analysis and reaggregation of published data. Using the estimated altitude- and heat-induced changes in maximum oxygen extraction and maximum cardiac output, the decline in maximum oxygen consumption at high altitude and in the heat was also modeled. A validation of predicted cardiovascular strain using heart rate was conducted using a dataset of 101 heterogeneous individuals (1,371 data points) during rest and exercise in the heat and at altitude, demonstrating that the CVR Model performs well (R2 = 0.82-0.84) in predicting cardiovascular strain, particularly at a group mean level (R2 = 0.97). The development of the CVR Model is aimed at providing the Fiala thermal Physiology & Comfort (FPC) Model and other complex thermophysiological models with improved estimations of cardiac strain and exercise tolerance, across a range of individuals during acute exposure to environmental stressors.NEW & NOTEWORTHY The present research promotes the adaption of thermophysiological modeling to the estimation of cardiovascular strain in individuals exercising under acute environmental stress. Integration with advanced models of human thermoregulation opens doors for detailed numerical analysis of athletes' performance and physiology during exercise, occupational safety, and individual work tolerability. The research provides a simple-to-validate metric of cardiovascular function (heart rate), as well as a method to evaluate key principles influencing exercise- and thermoregulation in humans.
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Affiliation(s)
- Alex Lloyd
- 1Environmental Ergonomics Research Centre, Loughborough University, Loughborough, United Kingdom
| | - Dusan Fiala
- 2ERGONSIM—Human Thermal Modelling, Messstetten, Germany
| | | | - George Havenith
- 1Environmental Ergonomics Research Centre, Loughborough University, Loughborough, United Kingdom
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Physiological Function during Exercise and Environmental Stress in Humans-An Integrative View of Body Systems and Homeostasis. Cells 2022; 11:cells11030383. [PMID: 35159193 PMCID: PMC8833916 DOI: 10.3390/cells11030383] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2021] [Revised: 01/18/2022] [Accepted: 01/19/2022] [Indexed: 11/26/2022] Open
Abstract
Claude Bernard’s milieu intérieur (internal environment) and the associated concept of homeostasis are fundamental to the understanding of the physiological responses to exercise and environmental stress. Maintenance of cellular homeostasis is thought to happen during exercise through the precise matching of cellular energetic demand and supply, and the production and clearance of metabolic by-products. The mind-boggling number of molecular and cellular pathways and the host of tissues and organ systems involved in the processes sustaining locomotion, however, necessitate an integrative examination of the body’s physiological systems. This integrative approach can be used to identify whether function and cellular homeostasis are maintained or compromised during exercise. In this review, we discuss the responses of the human brain, the lungs, the heart, and the skeletal muscles to the varying physiological demands of exercise and environmental stress. Multiple alterations in physiological function and differential homeostatic adjustments occur when people undertake strenuous exercise with and without thermal stress. These adjustments can include: hyperthermia; hyperventilation; cardiovascular strain with restrictions in brain, muscle, skin and visceral organs blood flow; greater reliance on muscle glycogen and cellular metabolism; alterations in neural activity; and, in some conditions, compromised muscle metabolism and aerobic capacity. Oxygen supply to the human brain is also blunted during intense exercise, but global cerebral metabolism and central neural drive are preserved or enhanced. In contrast to the strain seen during severe exercise and environmental stress, a steady state is maintained when humans exercise at intensities and in environmental conditions that require a small fraction of the functional capacity. The impact of exercise and environmental stress upon whole-body functions and homeostasis therefore depends on the functional needs and differs across organ systems.
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Wearable Sensors and Machine Learning for Hypovolemia Problems in Occupational, Military and Sports Medicine: Physiological Basis, Hardware and Algorithms. SENSORS 2022; 22:s22020442. [PMID: 35062401 PMCID: PMC8781307 DOI: 10.3390/s22020442] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/05/2021] [Revised: 12/14/2021] [Accepted: 12/30/2021] [Indexed: 11/16/2022]
Abstract
Hypovolemia is a physiological state of reduced blood volume that can exist as either (1) absolute hypovolemia because of a lower circulating blood (plasma) volume for a given vascular space (dehydration, hemorrhage) or (2) relative hypovolemia resulting from an expanded vascular space (vasodilation) for a given circulating blood volume (e.g., heat stress, hypoxia, sepsis). This paper examines the physiology of hypovolemia and its association with health and performance problems common to occupational, military and sports medicine. We discuss the maturation of individual-specific compensatory reserve or decompensation measures for future wearable sensor systems to effectively manage these hypovolemia problems. The paper then presents areas of future work to allow such technologies to translate from lab settings to use as decision aids for managing hypovolemia. We envision a future that incorporates elements of the compensatory reserve measure with advances in sensing technology and multiple modalities of cardiovascular sensing, additional contextual measures, and advanced noise reduction algorithms into a fully wearable system, creating a robust and physiologically sound approach to manage physical work, fatigue, safety and health issues associated with hypovolemia for workers, warfighters and athletes in austere conditions.
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11
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Ahmedov S, Amirjanov A. Genetic-fuzzy logic model for a non-invasive measurement of a stroke volume. COMPUTER METHODS AND PROGRAMS IN BIOMEDICINE 2021; 203:106046. [PMID: 33743490 DOI: 10.1016/j.cmpb.2021.106046] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/20/2020] [Accepted: 03/05/2021] [Indexed: 06/12/2023]
Abstract
BACKGROUND Despite the importance of stroke volume readings in understanding the work of the cardiovascular system in patients, its routine daily measurement outside of a hospital in the absence of special equipment presents a problem for a comprehensive assessment of the heart performance. OBJECTIVE The purpose of this study was to develop a new non-invasive technique for measuring a stroke volume based on the relationship between time skin warming and a blood flow. METHODS . Ninety two randomly selected volunteers (54 males, aged 30.1 ± 11.9 years old, and 38 females, aged 35.8 ± 12.4 years old) were recruited for this study. The time skin warming was determined by applying on the wrist above the arterial pulsation a thermoelectric cooler using the Peltier effect. During recording the participants were in the supine position. Blood pressure was measured by sphygmomanometer. Heart performance was assessed by Murata ballistocardiographic sensor, detecting displacement of the whole body during each cardiac ejection of blood. The data provided by this sensor included heart rate, respiratory rate, heart rate variability and a stroke volume. Linear, non-linear statistical regression models and fuzzy logic were used to analyse the degree of interrelation between BCG-measured stroke volume and the time skin warming. RESULTS Comparative analysis of results indicated that the generic-fuzzy logic model demonstrated a high level of dependency (R = 0.803) between input (participants' time skin warming, pulse pressure and age) and output (ballistocardiographic stroke volume) parameters. CONCLUSIONS The method described in the paper offers a simple, portable, and low-cost solution that can even be used in a home setting to measure the stroke volume. The principle of the proposed method is based on the interrelation between time skin warming and blood flow. The latter, corrected by corresponding age and pulse pressure, expresses the participant's stroke volume. Adopting the genetic-fuzzy model significantly improved the accuracy of stroke volume's measurement and made the proposed method reliable for assessing of the cardiovascular system. This daily practice technique would help healthcare provider get an early diagnosis of cardiac dysfunctions and track heart changes during stress, e.g., in sport.
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Affiliation(s)
- Shahin Ahmedov
- School of Health, Cyprus Health and Social Sciences University, Guzelyurt, Kutlu Adali Bulvari, Turkey
| | - Adil Amirjanov
- Computer Engineering Department, Near East University, Nicosia, N. Cyprus (via Mersin-10, Turkey).
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12
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Périard JD, Eijsvogels TMH, Daanen HAM. Exercise under heat stress: thermoregulation, hydration, performance implications, and mitigation strategies. Physiol Rev 2021; 101:1873-1979. [PMID: 33829868 DOI: 10.1152/physrev.00038.2020] [Citation(s) in RCA: 127] [Impact Index Per Article: 42.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
A rise in body core temperature and loss of body water via sweating are natural consequences of prolonged exercise in the heat. This review provides a comprehensive and integrative overview of how the human body responds to exercise under heat stress and the countermeasures that can be adopted to enhance aerobic performance under such environmental conditions. The fundamental concepts and physiological processes associated with thermoregulation and fluid balance are initially described, followed by a summary of methods to determine thermal strain and hydration status. An outline is provided on how exercise-heat stress disrupts these homeostatic processes, leading to hyperthermia, hypohydration, sodium disturbances, and in some cases exertional heat illness. The impact of heat stress on human performance is also examined, including the underlying physiological mechanisms that mediate the impairment of exercise performance. Similarly, the influence of hydration status on performance in the heat and how systemic and peripheral hemodynamic adjustments contribute to fatigue development is elucidated. This review also discusses strategies to mitigate the effects of hyperthermia and hypohydration on exercise performance in the heat by examining the benefits of heat acclimation, cooling strategies, and hyperhydration. Finally, contemporary controversies are summarized and future research directions are provided.
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Affiliation(s)
- Julien D Périard
- University of Canberra Research Institute for Sport and Exercise, Bruce, Australia
| | - Thijs M H Eijsvogels
- Department of Physiology, Radboud Institute for Health Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Hein A M Daanen
- Department of Human Movement Sciences, Faculty of Behavioural and Movement Sciences, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands
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13
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Otani H, Fukuda M, Tagawa T. Cooling Between Exercise Bouts and Post-exercise With the Fan Cooling Jacket on Thermal Strain in Hot-Humid Environments. Front Physiol 2021; 12:640400. [PMID: 33664676 PMCID: PMC7920971 DOI: 10.3389/fphys.2021.640400] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2020] [Accepted: 01/25/2021] [Indexed: 11/13/2022] Open
Abstract
This study investigated the effects of cooling between exercise bouts and post-exercise with a commercially available fan cooling jacket on thermal and perceptual responses during and following exercise in hot-humid environments. Ten male athletes completed two 30 min cycling bouts at a constant workload (1.4 watts⋅kg-1 of body mass) with a 5 min recovery period in between. Exercise was followed by a 10 min recovery period. In an environmental chamber (33°C, 65% relative humidity), participants performed two trials with (FCJ) or without (CON) the fan cooling jacket on a T-shirt during the 5 min inter-exercise and 10 min post-exercise recovery periods. Mean, chest and upper arm skin temperatures, and thermal sensation and comfort were lower in FCJ than CON trial during and following exercise (P < 0.05). Thigh and calf skin temperatures, infrared tympanic temperature and heart rate were lower in FCJ than CON trial during the experimental trials (P < 0.05). The rates of fall in mean, chest and upper arm skin temperatures, infrared tympanic temperature and thermal sensation and comfort were faster in FCJ than CON trial during both recovery periods (P < 0.05). There were faster rates of fall in thigh and calf skin temperatures and heart rate in FCJ than CON trial during the post-exercise recovery period (P < 0.05). No difference was observed between trials in the rating of perceived exertion (P > 0.05). This study indicates that cooling between exercise bouts and post-exercise with the fan cooling jacket would effectively mitigate thermal strain and perception/discomfort during and following exercise in hot-humid environments. This garment would reduce whole-body skin temperature quickly while promoting falls in lower-body as well as upper-body skin temperatures.
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Affiliation(s)
- Hidenori Otani
- Faculty of Health Care Sciences, Himeji Dokkyo University, Himeji, Japan
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Eiken T, Harrison AJ, Burdon CA, Groeller H, Peoples GE. Elevated body temperature contributes to the increased heart rate response during eccentric compared to concentric cycling when matched for oxygen consumption. Temperature (Austin) 2021; 8:30-38. [PMID: 33553503 DOI: 10.1080/23328940.2020.1810199] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022] Open
Abstract
A cardiovascular requirement to facilitate thermal homeostasis may partly contribute to the elevated heart rate during eccentric cycling. This study compared the body temperature response to a bout of eccentric (ECC) and concentric (CON) cycling to account for the difference in heart rate. Eight (N = 8) aerobically trained males (age 35 y [SD 8], peak oxygen consumption 3.82 L.min-1 [SD 0.79]) completed an ECC cycling trial (60% PPO) followed by an oxygen consumption/duration matched CON trial (30 ∘ C , 35% RH) on a separate day. Trial termination was determined as an elevation in aural temperature, a surrogate of deep body temperature, by +0.5 ∘ C during ECC. Mean skin (8-sites) and body temperature (weighting of 80:20 for auditory canal and mean skin temperature) were calculated. Matching the oxygen consumption between the trials increased external work during ECC cycling (CON: 71 [SD 14] ECC: 194 [SD 38] W, p < 0.05) and elevated aural temperature (+0.5 ∘ C ) by 20 min 32 s [SD 9 min 19 s] in that trial. The peak rate of rise in aural temperature was significantly greater in ECC (CON: 0.012 [SD 0.007] ECC: 0.031 [SD 0.002] oC.s-1, p < 0.05). Aural, mean skin and body temperature were significantly higher during the ECC trial (p < 0.05) and this was accompanied by elevated mean heart rate (CON: 103 [SD 14] ECC: 118 [SD 12] b.min-1, p < 0.05) and thermal discomfort (p < 0.05). Moderate load eccentric cycling imposes an elevated thermal strain when compared to concentric cycling. This requirement for dissipating heat, in part, explains the elevated heart rate during eccentric cycling.
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Affiliation(s)
- Tor Eiken
- Graduate Medicine, School of Medicine, University of Wollongong, Wollongong, Australia.,Centre for Medical and Exercise Physiology, School of Medicine, University of Wollongong, Wollongong, Australia
| | - Amelia J Harrison
- Centre for Medical and Exercise Physiology, School of Medicine, University of Wollongong, Wollongong, Australia.,Medical and Exercise Science, School of Medicine, University of Wollongong, Wollongong, Australia
| | - Catriona A Burdon
- Centre for Medical and Exercise Physiology, School of Medicine, University of Wollongong, Wollongong, Australia.,Medical and Exercise Science, School of Medicine, University of Wollongong, Wollongong, Australia
| | - Herbert Groeller
- Centre for Medical and Exercise Physiology, School of Medicine, University of Wollongong, Wollongong, Australia.,Medical and Exercise Science, School of Medicine, University of Wollongong, Wollongong, Australia
| | - Gregory E Peoples
- Graduate Medicine, School of Medicine, University of Wollongong, Wollongong, Australia.,Centre for Medical and Exercise Physiology, School of Medicine, University of Wollongong, Wollongong, Australia
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15
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Rivas E, Allie KN, Salvador PM. Progressive dry to humid hyperthermia alters exercise cerebral blood flow. J Therm Biol 2019; 84:398-406. [PMID: 31466779 DOI: 10.1016/j.jtherbio.2019.07.036] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2019] [Revised: 07/27/2019] [Accepted: 07/29/2019] [Indexed: 11/27/2022]
Abstract
INTRODUCTION Exercising in hot conditions may increase the risk for exertional heat-related illness due to reduction in cerebral blood flow (CBF); however, the acute effect of exercise-induced changes on CBF during compensable and uncompensable heat stress remain unclear. We tested the hypothesis that exercising in hot dry and humid conditions would have different CBF responses. METHODS Nine healthy active males completed a 30 min baseline rest then 60 min of low intensity self-paced exercise (12 rating of perceived exertion) in a 1) control compensable neutral dry (CN; 23.7 ± 0.7 °C; 10.7 ± 0.8%Rh) and 2) compensable hot dry (CH; 42.3 ± 0.3 °C; 10.7 ± 1.8%Rh) that progressively increased to an uncompensable hot humid (UCH; 42.3 ± 0.3 °C; 55.2 ± 7.7%Rh) environment in random order separated by at least 4 days. RESULTS We observed that during CN environments from rest through 60 min of exercise, middle cerebral velocity (MCAvmean) and conductance (MCAvmean CVC) remained unchanged. In contrast, during CH, MCAvmean, MCAvmean CVC, and cardiac output (Q) increased and systemic vascular resistance (SVR) decreased. However, under UCH, MCAvmean, MCAvmean CVC, and Q was reduced. No difference in mean arterial pressure or ventilation was observed during any condition. Only during UCH, end-tidal PO2 increased and PCO2 decreased. The redistribution of blood to the skin for thermoregulation (heart rate, skin blood flow and sweat rate) remained higher during exercise in UCH environments. CONCLUSIONS Collectively, exercise cerebral blood flow is altered by an integrative physiological manner that differs in CN, CH, and UCH environments. The control of CBF may be secondary to thermoregulatory control which may provide an explanation for the cause of exertional heat illness.
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Affiliation(s)
- Eric Rivas
- Exercise & Thermal Integrative Physiology Laboratory, Texas Tech University, Lubbock, TX, USA; Department of Kinesiology & Sport Management, Texas Tech University, Lubbock, TX, USA.
| | - Kyleigh N Allie
- Exercise & Thermal Integrative Physiology Laboratory, Texas Tech University, Lubbock, TX, USA; Department of Kinesiology & Sport Management, Texas Tech University, Lubbock, TX, USA
| | - Paolo M Salvador
- Exercise & Thermal Integrative Physiology Laboratory, Texas Tech University, Lubbock, TX, USA; Department of Kinesiology & Sport Management, Texas Tech University, Lubbock, TX, USA
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16
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Horiuchi M, Fukuoka Y. Absence of cardiovascular drift during prolonged arm-crank exercise in individuals with spinal cord injury. Spinal Cord 2019; 57:942-952. [DOI: 10.1038/s41393-019-0301-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2019] [Revised: 05/15/2019] [Accepted: 05/18/2019] [Indexed: 11/09/2022]
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17
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CHOU TINGHENG, AKINS JOHND, CRAWFORD CHARLESK, ALLEN JAKOBR, COYLE EDWARDF. Low Stroke Volume during Exercise with Hot Skin Is Due to Elevated Heart Rate. Med Sci Sports Exerc 2019; 51:2025-2032. [DOI: 10.1249/mss.0000000000002029] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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18
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The effects of walking posture on affective and physiological states during stress. J Behav Ther Exp Psychiatry 2019; 62:80-87. [PMID: 30261357 DOI: 10.1016/j.jbtep.2018.09.004] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/05/2017] [Revised: 07/29/2018] [Accepted: 09/14/2018] [Indexed: 11/21/2022]
Abstract
BACKGROUND AND OBJECTIVES Embodiment theory proposes that motor processes are associated with emotions and cognitions. Previous research has shown that walking posture can influence affective memory bias. This study further investigated this theory by looking at the effects of an upright versus slumped walking posture on psychological and physiological states when faced with a psychological stressor. METHODS Seventy-three healthy adults completed baseline self-report measures of affect, power, and sleepiness, and physiological measures of blood pressure, galvanic skin response, and skin temperature. After walking in their usual posture, the same self-report and physiological measures were obtained. Participants were then randomly allocated into one of two groups where they were asked to walk in either an upright posture or a slumped posture. While walking, participants underwent a psychological stressor. After experimental walking, the same self-report and physiological measures were obtained. RESULTS The upright walking posture group showed significantly improved psychological states including less low arousal negative affect, less sleepiness, less pain and marginally greater feelings of power than the slumped walking posture group. Physiologically, the upright walking posture group showed significantly lower systolic blood pressure, galvanic skin response, and marginally lower skin temperature than the slumped walking posture group. LIMITATIONS This was a short-term laboratory-based experiment and results may not generalise to other situations. CONCLUSIONS Walking posture can affect both psychological and physiological states. Applications of these findings may have implications for improving mental and physiological health.
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Paulsen KM, Butts CL, McDermott BP. Observation of Women Soccer Players' Physiology During a Single Season. J Strength Cond Res 2018; 32:1702-1707. [PMID: 29786626 DOI: 10.1519/jsc.0000000000002025] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Paulsen, KM, Butts, CL, and McDermott, BP. Observation of women soccer players' physiology during a single season. J Strength Cond Res 32(6): 1702-1707, 2018-The purpose of this study was to observe heart rate (HR) responses in match settings over the course of a conference season in National Collegiate Athletic Association Division I women's soccer. Twenty-one female collegiate soccer players were provided a HR monitor and instructed to wear it for the duration of match play. Player positions included 6 defenders (DEF), 6 midfielders (MID), and 9 forwards (FWD). Defenders were further identified as either center defenders (CD) or outside defenders (OD). A 1-way analysis of variance was used to determine if mean HR varied between FWD, MID, and DEF. An independent t-test was used to determine if there was a difference between CD and OD HRs. The FWD, MID, and DEF did have significantly different mean HR (p ≤ 0.05), but post-hoc analysis revealed no significant differences (p ≥ 0.05). However, CD demonstrated significantly lower HRs than OD (p = 0.009). Player position, specifically in the CD and OD role, impact the intensity of exercise in match settings and may be used to specify training and conditioning sessions.
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Affiliation(s)
- Kathleen M Paulsen
- Exercise Science Research Center, University of Arkansas, Fayetteville, Arkansas
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20
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Fulghum K, Hill BG. Metabolic Mechanisms of Exercise-Induced Cardiac Remodeling. Front Cardiovasc Med 2018; 5:127. [PMID: 30255026 PMCID: PMC6141631 DOI: 10.3389/fcvm.2018.00127] [Citation(s) in RCA: 46] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2018] [Accepted: 08/23/2018] [Indexed: 12/13/2022] Open
Abstract
Exercise has a myriad of physiological benefits that derive in part from its ability to improve cardiometabolic health. The periodic metabolic stress imposed by regular exercise appears fundamental in driving cardiovascular tissue adaptation. However, different types, intensities, or durations of exercise elicit different levels of metabolic stress and may promote distinct types of tissue remodeling. In this review, we discuss how exercise affects cardiac structure and function and how exercise-induced changes in metabolism regulate cardiac adaptation. Current evidence suggests that exercise typically elicits an adaptive, beneficial form of cardiac remodeling that involves cardiomyocyte growth and proliferation; however, chronic levels of extreme exercise may increase the risk for pathological cardiac remodeling or sudden cardiac death. An emerging theme underpinning acute as well as chronic cardiac adaptations to exercise is metabolic periodicity, which appears important for regulating mitochondrial quality and function, for stimulating metabolism-mediated exercise gene programs and hypertrophic kinase activity, and for coordinating biosynthetic pathway activity. In addition, circulating metabolites liberated during exercise trigger physiological cardiac growth. Further understanding of how exercise-mediated changes in metabolism orchestrate cell signaling and gene expression could facilitate therapeutic strategies to maximize the benefits of exercise and improve cardiac health.
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Affiliation(s)
- Kyle Fulghum
- Department of Medicine, Envirome Institute, Institute of Molecular Cardiology, Diabetes and Obesity Center, Louisville, KY, United States
- Department of Physiology, University of Louisville, Louisville, KY, United States
| | - Bradford G. Hill
- Department of Medicine, Envirome Institute, Institute of Molecular Cardiology, Diabetes and Obesity Center, Louisville, KY, United States
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21
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Chou TH, Allen JR, Hahn D, Leary BK, Coyle EF. Cardiovascular responses to exercise when increasing skin temperature with narrowing of the core-to-skin temperature gradient. J Appl Physiol (1985) 2018; 125:697-705. [PMID: 29745802 DOI: 10.1152/japplphysiol.00965.2017] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The decline in stroke volume (SV) during exercise in the heat has been attributed to either an increase in cutaneous blood flow (CBF) that reduces venous return or an increase in heart rate (HR) that reduces cardiac filling time. However, the evidence supporting each mechanism arises under experimental conditions with different skin temperatures (Tsk; e.g., ≥38°C vs. ≤36°C, respectively). We systematically studied cardiovascular responses to progressively increased Tsk (32°C-39°C) with narrowing of the core-to-skin gradient during moderate intensity exercise. Eight men cycled at 63 ± 1% peak oxygen consumption for 20-30 min. Tsk was manipulated by having subjects wear a water-perfused suit that covered most of the body and maintained Tsk that was significantly different between trials and averaged 32.4 ± 0.2, 35.5 ± 0.1, 37.5 ± 0.1, and 39.5 ± 0.1°C, respectively. The graded heating of Tsk ultimately produced a graded elevation of esophageal temperature (Tes) at the end of exercise. Incrementally increasing Tsk resulted in a graded increase in HR and a graded decrease in SV. CBF reached a similar average plateau value in all trials when Tes was above ~38°C, independent of Tsk. Tsk had no apparent effect on forearm venous volume (FVV). In conclusion, the CBF and FVV responses suggest no further pooling of blood in the skin when Tsk is increased from 32.4°C to 39.5°C. The decrease in SV during moderate intensity exercise when heating the skin to high levels appears related to an increase in HR and not an increase in CBF. NEW & NOTEWORTHY This study systematically investigated the effect of increasing skin temperature (Tsk) to high levels on cardiovascular responses during moderate intensity exercise. We conclude that the declines in stroke volume were related to the increases in heart rate but not the changes in cutaneous blood flow (CBF) and forearm venous volume (FVV) during moderate intensity exercise when Tsk increased from ~32°C to ~39°C. High Tsk (≥38°C) did not further elevate CBF and FVV compared with lower Tsk during moderate intensity exercise.
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Affiliation(s)
- Ting-Heng Chou
- Human Performance Laboratory, Department of Kinesiology and Health Education, University of Texas at Austin , Austin, Texas
| | - Jakob R Allen
- Human Performance Laboratory, Department of Kinesiology and Health Education, University of Texas at Austin , Austin, Texas
| | - Dongwoo Hahn
- Human Performance Laboratory, Department of Kinesiology and Health Education, University of Texas at Austin , Austin, Texas
| | - Brian K Leary
- Human Performance Laboratory, Department of Kinesiology and Health Education, University of Texas at Austin , Austin, Texas
| | - Edward F Coyle
- Human Performance Laboratory, Department of Kinesiology and Health Education, University of Texas at Austin , Austin, Texas
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MacRae BA, Annaheim S, Spengler CM, Rossi RM. Skin Temperature Measurement Using Contact Thermometry: A Systematic Review of Setup Variables and Their Effects on Measured Values. Front Physiol 2018. [PMID: 29441024 DOI: 10.3389/fphys.2018.00029, 10.3389/fpls.2018.00029] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Background: Skin temperature (Tskin) is commonly measured using Tskin sensors affixed directly to the skin surface, although the influence of setup variables on the measured outcome requires clarification. Objectives: The two distinct objectives of this systematic review were (1) to examine measurements from contact Tskin sensors considering equilibrium temperature and temperature disturbance, sensor attachments, pressure, environmental temperature, and sensor type, and (2) to characterise the contact Tskin sensors used, conditions of use, and subsequent reporting in studies investigating sports, exercise, and other physical activity. Data sources and study selection: For the measurement comparison objective, Ovid Medline and Scopus were used (1960 to July 2016) and studies comparing contact Tskin sensor measurements in vivo or using appropriate physical models were included. For the survey of use, Ovid Medline was used (2011 to July 2016) and studies using contact temperature sensors for the measurement of human Tskinin vivo during sport, exercise, and other physical activity were included. Study appraisal and synthesis methods: For measurement comparisons, assessments of risk of bias were made according to an adapted version of the Cochrane Collaboration's risk of bias tool. Comparisons of temperature measurements were expressed, where possible, as mean difference and 95% limits of agreement (LoA). Meta-analyses were not performed due to the lack of a common reference condition. For the survey of use, extracted information was summarised in text and tabular form. Results: For measurement comparisons, 21 studies were included. Results from these studies indicated minor (<0.5°C) to practically meaningful (>0.5°C) measurement bias within the subgroups of attachment type, applied pressure, environmental conditions, and sensor type. The 95% LoA were often within 1.0°C for in vivo studies and 0.5°C for physical models. For the survey of use, 172 studies were included. Details about Tskin sensor setup were often poorly reported and, from those reporting setup information, it was evident that setups widely varied in terms of type of sensors, attachments, and locations used. Conclusions: Setup variables and conditions of use can influence the measured temperature from contact Tskin sensors and thus key setup variables need to be appropriately considered and consistently reported.
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Affiliation(s)
- Braid A MacRae
- Empa, Swiss Federal Laboratories for Materials Science and Technology, Laboratory for Biomimetic Membranes and Textiles, St. Gallen, Switzerland.,Exercise Physiology Lab, Institute of Human Movement Sciences and Sport, Department of Health Sciences and Technology, ETH Zurich, Zurich, Switzerland
| | - Simon Annaheim
- Empa, Swiss Federal Laboratories for Materials Science and Technology, Laboratory for Biomimetic Membranes and Textiles, St. Gallen, Switzerland
| | - Christina M Spengler
- Exercise Physiology Lab, Institute of Human Movement Sciences and Sport, Department of Health Sciences and Technology, ETH Zurich, Zurich, Switzerland.,Zurich Center for Integrative Human Physiology, University of Zurich, Zurich, Switzerland
| | - René M Rossi
- Empa, Swiss Federal Laboratories for Materials Science and Technology, Laboratory for Biomimetic Membranes and Textiles, St. Gallen, Switzerland
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MacRae BA, Annaheim S, Spengler CM, Rossi RM. Skin Temperature Measurement Using Contact Thermometry: A Systematic Review of Setup Variables and Their Effects on Measured Values. Front Physiol 2018; 9:29. [PMID: 29441024 PMCID: PMC5797625 DOI: 10.3389/fphys.2018.00029] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2017] [Accepted: 01/09/2018] [Indexed: 11/13/2022] Open
Abstract
Background: Skin temperature (Tskin) is commonly measured using Tskin sensors affixed directly to the skin surface, although the influence of setup variables on the measured outcome requires clarification. Objectives: The two distinct objectives of this systematic review were (1) to examine measurements from contact Tskin sensors considering equilibrium temperature and temperature disturbance, sensor attachments, pressure, environmental temperature, and sensor type, and (2) to characterise the contact Tskin sensors used, conditions of use, and subsequent reporting in studies investigating sports, exercise, and other physical activity. Data sources and study selection: For the measurement comparison objective, Ovid Medline and Scopus were used (1960 to July 2016) and studies comparing contact Tskin sensor measurements in vivo or using appropriate physical models were included. For the survey of use, Ovid Medline was used (2011 to July 2016) and studies using contact temperature sensors for the measurement of human Tskinin vivo during sport, exercise, and other physical activity were included. Study appraisal and synthesis methods: For measurement comparisons, assessments of risk of bias were made according to an adapted version of the Cochrane Collaboration's risk of bias tool. Comparisons of temperature measurements were expressed, where possible, as mean difference and 95% limits of agreement (LoA). Meta-analyses were not performed due to the lack of a common reference condition. For the survey of use, extracted information was summarised in text and tabular form. Results: For measurement comparisons, 21 studies were included. Results from these studies indicated minor (<0.5°C) to practically meaningful (>0.5°C) measurement bias within the subgroups of attachment type, applied pressure, environmental conditions, and sensor type. The 95% LoA were often within 1.0°C for in vivo studies and 0.5°C for physical models. For the survey of use, 172 studies were included. Details about Tskin sensor setup were often poorly reported and, from those reporting setup information, it was evident that setups widely varied in terms of type of sensors, attachments, and locations used. Conclusions: Setup variables and conditions of use can influence the measured temperature from contact Tskin sensors and thus key setup variables need to be appropriately considered and consistently reported.
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Affiliation(s)
- Braid A. MacRae
- Empa, Swiss Federal Laboratories for Materials Science and Technology, Laboratory for Biomimetic Membranes and Textiles, St. Gallen, Switzerland
- Exercise Physiology Lab, Institute of Human Movement Sciences and Sport, Department of Health Sciences and Technology, ETH Zurich, Zurich, Switzerland
| | - Simon Annaheim
- Empa, Swiss Federal Laboratories for Materials Science and Technology, Laboratory for Biomimetic Membranes and Textiles, St. Gallen, Switzerland
| | - Christina M. Spengler
- Exercise Physiology Lab, Institute of Human Movement Sciences and Sport, Department of Health Sciences and Technology, ETH Zurich, Zurich, Switzerland
- Zurich Center for Integrative Human Physiology, University of Zurich, Zurich, Switzerland
| | - René M. Rossi
- Empa, Swiss Federal Laboratories for Materials Science and Technology, Laboratory for Biomimetic Membranes and Textiles, St. Gallen, Switzerland
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24
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Mueller PJ, Clifford PS, Crandall CG, Smith SA, Fadel PJ. Integration of Central and Peripheral Regulation of the Circulation during Exercise: Acute and Chronic Adaptations. Compr Physiol 2017; 8:103-151. [DOI: 10.1002/cphy.c160040] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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25
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Trangmar SJ, Chiesa ST, Kalsi KK, Secher NH, González-Alonso J. Whole body hyperthermia, but not skin hyperthermia, accelerates brain and locomotor limb circulatory strain and impairs exercise capacity in humans. Physiol Rep 2017; 5:5/2/e13108. [PMID: 28108645 PMCID: PMC5269410 DOI: 10.14814/phy2.13108] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2016] [Revised: 12/08/2016] [Accepted: 12/09/2016] [Indexed: 12/26/2022] Open
Abstract
Cardiovascular strain and hyperthermia are thought to be important factors limiting exercise capacity in heat‐stressed humans, however, the contribution of elevations in skin (Tsk) versus whole body temperatures on exercise capacity has not been characterized. To ascertain their relationships with exercise capacity, blood temperature (TB), oxygen uptake (V̇O2), brain perfusion (MCA Vmean), locomotor limb hemodynamics, and hematological parameters were assessed during incremental cycling exercise with elevated skin (mild hyperthermia; HYPmild), combined core and skin temperatures (moderate hyperthermia; HYPmod), and under control conditions. Both hyperthermic conditions increased Tsk versus control (6.2 ± 0.2°C; P < 0.001), however, only HYPmod increased resting TB, leg blood flow and cardiac output (Q̇), but not MCA Vmean. Throughout exercise, Tsk remained elevated in both hyperthermic conditions, whereas only TB was greater in HYPmod. At exhaustion, oxygen uptake and exercise capacity were reduced in HYPmod in association with lower leg blood flow, MCA Vmean and mean arterial pressure (MAP), but similar maximal heart rate and TB. The attenuated brain and leg perfusion with hyperthermia was associated with a plateau in MCA and two‐legged vascular conductance (VC). Mechanistically, the falling MCA VC was coupled to reductions in PaCO2, whereas the plateau in leg vascular conductance was related to markedly elevated plasma [NA] and a plateau in plasma ATP. These findings reveal that whole‐body hyperthermia, but not skin hyperthermia, compromises exercise capacity in heat‐stressed humans through the early attenuation of brain and active muscle blood flow.
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Affiliation(s)
- Steven J Trangmar
- Centre for Human Performance, Exercise and Rehabilitation, Brunel University London, Uxbridge, United Kingdom
| | - Scott T Chiesa
- Centre for Human Performance, Exercise and Rehabilitation, Brunel University London, Uxbridge, United Kingdom
| | - Kameljit K Kalsi
- Centre for Human Performance, Exercise and Rehabilitation, Brunel University London, Uxbridge, United Kingdom
| | - Niels H Secher
- Centre for Human Performance, Exercise and Rehabilitation, Brunel University London, Uxbridge, United Kingdom.,The Copenhagen Muscle Research Centre, Department of Anaesthesia, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
| | - José González-Alonso
- Centre for Human Performance, Exercise and Rehabilitation, Brunel University London, Uxbridge, United Kingdom
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27
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Sawka MN, Cheuvront SN, Kenefick RW. Hypohydration and Human Performance: Impact of Environment and Physiological Mechanisms. Sports Med 2016; 45 Suppl 1:S51-60. [PMID: 26553489 PMCID: PMC4672008 DOI: 10.1007/s40279-015-0395-7] [Citation(s) in RCA: 106] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Body water losses of >2 % of body mass are defined as hypohydration and can occur from sweat loss and/or diuresis from both cold and altitude exposure. Hypohydration elicits intracellular and extracellular water loss proportionate to water and solute deficits. Iso-osmotic hypovolemia (from cold and high-altitude exposure) results in greater plasma loss for a given water deficit than hypertonic hypovolemia from sweat loss. Hypohydration does not impair submaximal intensity aerobic performance in cold–cool environments, sometimes impairs aerobic performance in temperate environments, and usually impairs aerobic performance in warm–hot environments. Hypohydration begins to impair aerobic performance when skin temperatures exceed 27 °C, and with each additional 1 °C elevation in skin temperature there is a further 1.5 % impairment. Hypohydration has an additive effect on impairing aerobic performance in warm–hot high-altitude environments. A commonality of absolute hypovolemia (from plasma volume loss) combined with relative hypovolemia (from tissue vasodilation) is present when aerobic performance is impaired. The decrement in aerobic exercise performance due to hypohydration is likely due to multiple physiological mechanisms, including cardiovascular strain acting as the ‘lynchpin’, elevated tissue temperatures, and metabolic changes which are all integrated through the CNS to reduce motor drive to skeletal muscles.
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Affiliation(s)
- Michael N Sawka
- School of Applied Physiology, Georgia Institute of Technology, 555 14th Street, Atlanta, GA, 30332, USA.
| | - Samuel N Cheuvront
- Thermal and Mountain Medicine Division, US Army Research Institute of Environmental Medicine, Natick, MA, USA
| | - Robert W Kenefick
- Thermal and Mountain Medicine Division, US Army Research Institute of Environmental Medicine, Natick, MA, USA
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28
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Rivas E, Newmire DE, Crandall CG, Hooper PL, Ben-Ezra V. An acute bout of whole body passive hyperthermia increases plasma leptin, but does not alter glucose or insulin responses in obese type 2 diabetics and healthy adults. J Therm Biol 2016; 59:26-33. [PMID: 27264884 DOI: 10.1016/j.jtherbio.2016.04.010] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2015] [Revised: 03/28/2016] [Accepted: 04/26/2016] [Indexed: 01/02/2023]
Abstract
Acute and chronic hyperthermic treatments in diabetic animal models repeatedly improve insulin sensitivity and glycemic control. Therefore, the purpose of this study was to test the hypothesis that an acute 1h bout of hyperthermic treatment improves glucose, insulin, and leptin responses to an oral glucose challenge (OGTT) in obese type 2 diabetics and healthy humans. Nine obese (45±7.1% fat mass) type 2 diabetics (T2DM: 50.1±12y, 7.5±1.8% HbA1c) absent of insulin therapy and nine similar aged (41.1±13.7y) healthy non-obese controls (HC: 33.4±7.8% fat mass, P<0.01; 5.3±0.4% HbA1c, P<0.01) participated. Using a randomized design, subjects underwent either a whole body passive hyperthermia treatment via head-out hot water immersion (1h resting in 39.4±0.4°C water) that increased internal temperature above baseline by ∆1.6±0.4°C or a control resting condition. Twenty-four hours post treatments, a 75g OGTT was administered to evaluate changes in plasma glucose, insulin, C-peptide, and leptin concentrations. Hyperthermia itself did not alter area under the curve for plasma glucose, insulin, or C-peptide during the OGTT in either group. Fasting absolute and normalized (kg·fat mass) plasma leptin was significantly increased (P<0.01) only after the hyperthermic exposure by 17% in T2DM and 24% in HC groups (P<0.001) when compared to the control condition. These data indicate that an acute hyperthermic treatment does not improve glucose tolerance 24h post treatment in moderate metabolic controlled obese T2DM or HC individuals.
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Affiliation(s)
- Eric Rivas
- Institute for Clinical and Translational Science & Department of Pediatrics, The University of California, Irvine, CA, USA; Department of Kinesiology, Texas Woman's University, Denton, TX, USA; Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital of Dallas, Dallas, TX, USA and Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX, USA.
| | - Dan E Newmire
- Department of Kinesiology, Texas Woman's University, Denton, TX, USA
| | - Craig G Crandall
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital of Dallas, Dallas, TX, USA and Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Philip L Hooper
- Division of Endocrinology, Metabolism and Diabetes, Department of Medicine, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
| | - Vic Ben-Ezra
- Department of Kinesiology, Texas Woman's University, Denton, TX, USA
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Etemadi M, Inan OT, Heller JA, Hersek S, Klein L, Roy S. A Wearable Patch to Enable Long-Term Monitoring of Environmental, Activity and Hemodynamics Variables. IEEE TRANSACTIONS ON BIOMEDICAL CIRCUITS AND SYSTEMS 2016; 10:280-8. [PMID: 25974943 PMCID: PMC4643430 DOI: 10.1109/tbcas.2015.2405480] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
We present a low power multi-modal patch designed for measuring activity, altitude (based on high-resolution barometric pressure), a single-lead electrocardiogram, and a tri-axial seismocardiogram (SCG). Enabled by a novel embedded systems design methodology, this patch offers a powerful means of monitoring the physiology for both patients with chronic cardiovascular diseases, and the general population interested in personal health and fitness measures. Specifically, to the best of our knowledge, this patch represents the first demonstration of combined activity, environmental context, and hemodynamics monitoring, all on the same hardware, capable of operating for longer than 48 hours at a time with continuous recording. The three-channels of SCG and one-lead ECG are all sampled at 500 Hz with high signal-to-noise ratio, the pressure sensor is sampled at 10 Hz, and all signals are stored to a microSD card with an average current consumption of less than 2 mA from a 3.7 V coin cell (LIR2450) battery. In addition to electronic characterization, proof-of-concept exercise recovery studies were performed with this patch, suggesting the ability to discriminate between hemodynamic and electrophysiology response to light, moderate, and heavy exercise.
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Affiliation(s)
- Mozziyar Etemadi
- Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco, San Francisco, CA 94158 USA
| | - Omer T. Inan
- School of Electrical and Computer Engineering, Georgia Institute of Technology, Atlanta, GA 30332 USA
| | - J. Alex Heller
- Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco, San Francisco, CA 94158 USA
| | - Sinan Hersek
- School of Electrical and Computer Engineering, Georgia Institute of Technology, Atlanta, GA 30332 USA
| | - Liviu Klein
- Department of Medicine, University of California, San Francisco, San Francisco, CA 94131 USA
| | - Shuvo Roy
- Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco, San Francisco, CA 94158 USA
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Abstract
Heat stress increases human morbidity and mortality compared to normothermic conditions. Many occupations, disease states, as well as stages of life are especially vulnerable to the stress imposed on the cardiovascular system during exposure to hot ambient conditions. This review focuses on the cardiovascular responses to heat stress that are necessary for heat dissipation. To accomplish this regulatory feat requires complex autonomic nervous system control of the heart and various vascular beds. For example, during heat stress cardiac output increases up to twofold, by increases in heart rate and an active maintenance of stroke volume via increases in inotropy in the presence of decreases in cardiac preload. Baroreflexes retain the ability to regulate blood pressure in many, but not all, heat stress conditions. Central hypovolemia is another cardiovascular challenge brought about by heat stress, which if added to a subsequent central volumetric stress, such as hemorrhage, can be problematic and potentially dangerous, as syncope and cardiovascular collapse may ensue. These combined stresses can compromise blood flow and oxygenation to important tissues such as the brain. It is notable that this compromised condition can occur at cardiac outputs that are adequate during normothermic conditions but are inadequate in heat because of the increased systemic vascular conductance associated with cutaneous vasodilation. Understanding the mechanisms within this complex regulatory system will allow for the development of treatment recommendations and countermeasures to reduce risks during the ever-increasing frequency of severe heat events that are predicted to occur.
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Affiliation(s)
- Craig G Crandall
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas and University of Texas Southwestern Medical Center, Dallas, Texas Marian University College of Osteopathic Medicine, Indianapolis, Indiana
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31
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Personalized cardiorespiratory fitness and energy expenditure estimation using hierarchical Bayesian models. J Biomed Inform 2015; 56:195-204. [DOI: 10.1016/j.jbi.2015.06.008] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2014] [Revised: 03/23/2015] [Accepted: 06/08/2015] [Indexed: 11/21/2022]
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LEE JOSHUAF, CHRISTMAS KEVINM, MACHIN DANIELR, MCLEAN BLAKED, COYLE EDWARDF. Warm Skin Alters Cardiovascular Responses to Cycling after Preheating and Precooling. Med Sci Sports Exerc 2015; 47:1168-76. [DOI: 10.1249/mss.0000000000000539] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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33
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De Blois J, Kjellstrom T, Agewall S, Ezekowitz JA, Armstrong PW, Atar D. The Effects of Climate Change on Cardiac Health. Cardiology 2015; 131:209-17. [DOI: 10.1159/000398787] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/28/2015] [Accepted: 04/08/2015] [Indexed: 11/19/2022]
Abstract
The earth's climate is changing and increasing ambient heat levels are emerging in large areas of the world. An important cause of this change is the anthropogenic emission of greenhouse gases. Climate changes have a variety of negative effects on health, including cardiac health. People with pre-existing medical conditions such as cardiovascular disease (including heart failure), people carrying out physically demanding work and the elderly are particularly vulnerable. This review evaluates the evidence base for the cardiac health consequences of climate conditions, with particular reference to increasing heat exposure, and it also explores the potential further implications.
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Altini M, Casale P, Penders JF, Amft O. Personalization of Energy Expenditure Estimation in Free Living Using Topic Models. IEEE J Biomed Health Inform 2015; 19:1577-86. [PMID: 25838531 DOI: 10.1109/jbhi.2015.2418256] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
We introduce an approach to personalize energy expenditure (EE) estimates in free living. First, we use topic models to discover activity composites from recognized activity primitives and stay regions in daily living data. Subsequently, we determine activity composites that are relevant to contextualize heart rate (HR). Activity composites were ranked and analyzed to optimize the correlation to HR normalization parameters. Finally, individual-specific HR normalization parameters were used to normalize HR. Normalized HR was then included in activity-specific regression models to estimate EE. Our HR normalization minimizes the effect of individual fitness differences from entering in EE regression models. By estimating HR normalization parameters in free living, our approach avoids dedicated individual calibration or laboratory tests. In a combined free-living and laboratory study dataset, including 34 healthy volunteers, we show that HR normalization in 14-day free-living data improves accuracy compared to no normalization and normalization based on activity primitives only ( 29.4% and 19.8 % error reduction against lab reference). Based on acceleration and HR, both recorded from a necklace, and GPS acquired from a smartphone, EE estimation error was reduced by 10.7 % in a leave-one-participant-out analysis.
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Buller MJ, Tharion WJ, Duhamel CM, Yokota M. Real-time core body temperature estimation from heart rate for first responders wearing different levels of personal protective equipment. ERGONOMICS 2015; 58:1830-41. [PMID: 25967760 DOI: 10.1080/00140139.2015.1036792] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
UNLABELLED First responders often wear personal protective equipment (PPE) for protection from on-the-job hazards. While PPE ensembles offer individuals protection, they limit one's ability to thermoregulate, and can place the wearer in danger of heat exhaustion and higher cardiac stress. Automatically monitoring thermal-work strain is one means to manage these risks, but measuring core body temperature (Tc) has proved problematic. An algorithm that estimates Tc from sequential measures of heart rate (HR) was compared to the observed Tc from 27 US soldiers participating in three different chemical/biological training events (45-90 min duration) while wearing PPE. Hotter participants (higher Tc) averaged (HRs) of 140 bpm and reached Tc around 39 °C. Overall the algorithm had a small bias (0.02 °C) and root mean square error (0.21 °C). Limits of agreement (LoA ± 0.48 °C) were similar to comparisons of Tc measured by oesophageal and rectal probes. The algorithm shows promise for use in real-time monitoring of encapsulated first responders. PRACTITIONER SUMMARY An algorithm to estimate core temperature (Tc) from non-invasive measures of HR was validated. Three independent studies (n = 27) compared the estimated Tc to the observed Tc in humans participating in chemical/ biological hazard training. The algorithm’s bias and variance to observed data were similar to that found from comparisons of oesophageal and rectal measurements.
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Affiliation(s)
- Mark J Buller
- a United States Army Research Institute of Environmental Medicine , Kansas Street, Natick , MA , USA
| | - William J Tharion
- a United States Army Research Institute of Environmental Medicine , Kansas Street, Natick , MA , USA
| | - Cynthia M Duhamel
- a United States Army Research Institute of Environmental Medicine , Kansas Street, Natick , MA , USA
| | - Miyo Yokota
- a United States Army Research Institute of Environmental Medicine , Kansas Street, Natick , MA , USA
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Nybo L, Rasmussen P, Sawka MN. Performance in the heat-physiological factors of importance for hyperthermia-induced fatigue. Compr Physiol 2014; 4:657-89. [PMID: 24715563 DOI: 10.1002/cphy.c130012] [Citation(s) in RCA: 201] [Impact Index Per Article: 20.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
This article presents a historical overview and an up-to-date review of hyperthermia-induced fatigue during exercise in the heat. Exercise in the heat is associated with a thermoregulatory burden which mediates cardiovascular challenges and influence the cerebral function, increase the pulmonary ventilation, and alter muscle metabolism; which all potentially may contribute to fatigue and impair the ability to sustain power output during aerobic exercise. For maximal intensity exercise, the performance impairment is clearly influenced by cardiovascular limitations to simultaneously support thermoregulation and oxygen delivery to the active skeletal muscle. In contrast, during submaximal intensity exercise at a fixed intensity, muscle blood flow and oxygen consumption remain unchanged and the potential influence from cardiovascular stressing and/or high skin temperature is not related to decreased oxygen delivery to the skeletal muscles. Regardless, performance is markedly deteriorated and exercise-induced hyperthermia is associated with central fatigue as indicated by impaired ability to sustain maximal muscle activation during sustained contractions. The central fatigue appears to be influenced by neurotransmitter activity of the dopaminergic system, but inhibitory signals from thermoreceptors arising secondary to the elevated core, muscle and skin temperatures and augmented afferent feedback from the increased ventilation and the cardiovascular stressing (perhaps baroreceptor sensing of blood pressure stability) and metabolic alterations within the skeletal muscles are likely all factors of importance for afferent feedback to mediate hyperthermia-induced fatigue during submaximal intensity exercise. Taking all the potential factors into account, we propose an integrative model that may help understanding the interplay among factors, but also acknowledging that the influence from a given factor depends on the exercise hyperthermia situation.
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Affiliation(s)
- Lars Nybo
- Department of Nutrition, Exercise and Sport Sciences, University of Copenhagen, Denmark
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Influence of single bout of aerobic exercise on aortic pulse pressure. Eur J Appl Physiol 2014; 115:739-46. [PMID: 25428726 DOI: 10.1007/s00421-014-3061-0] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2014] [Accepted: 11/18/2014] [Indexed: 10/24/2022]
Abstract
PURPOSE Regular aerobic exercise has come to the forefront of non-pharmacological treatment for hypertension. In this line, post-exercise hypotension may have a potential tool for efficient blood pressure management. However, less is known about the influence of acute aerobic exercise on aortic pulse pressure (PP), an important property underlying the pathophysiology of cardiovascular disease. We tested the hypotheses that aortic PP would be attenuated with a single aerobic exercise and that its extent would be associated with the delayed return of reflected wave and the leg vasodilatory capacity. METHODS In 23 apparent healthy men (22 ± 4 years), hemodynamic variables and aortic pulse wave velocity (PWV) were measured before and 20 and 50 min after a 60-min bout of cycling exercise at moderate intensity (corresponding to 65-75 % heart rate reserve). Aortic pressure was estimated from applanation tonometrically measured radial arterial pressure waveform via general transfer function. Peak calf vascular dilatory capacity was measured with the ischemic exercise-induced hyperemia (via venous occlusion plethysmography). RESULTS Finger, brachial, and aortic PP were significantly attenuated following the exercise. At 20 min after the exercise cessation, individual changes in aortic PWV significantly correlated with corresponding changes in aortic PP (r = 0.541, P < 0.05), but this correlation was no longer significant at 50 min after the exercise cessation. Peak calf vascular dilatory capacity was not associated with change in aortic PP. CONCLUSIONS We conclude that in young men the aortic PP would be attenuated with the moderate-intensity dynamic exercise partly due to the delayed return of reflection wave from periphery.
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Experimental and numerical study of physiological responses in hot environments. J Therm Biol 2014; 45:54-61. [PMID: 25436951 DOI: 10.1016/j.jtherbio.2014.07.010] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2014] [Revised: 07/13/2014] [Accepted: 07/25/2014] [Indexed: 11/22/2022]
Abstract
This paper proposed a multi-node human thermal model to predict human thermal responses in hot environments. The model was extended based on the Tanabe's work by considering the effects of high temperature on heat production, blood flow rate, and heat exchange coefficients. Five healthy men dressed in shorts were exposed in thermal neutral (29 °C) and high temperature (45 °C) environments. The rectal temperatures and skin temperatures of seven human body segments were continuously measured during the experiment. Validation of this model was conducted with experimental data. The results showed that the current model could accurately predict the skin and core temperatures in terms of the tendency and absolute values. In the human body segments expect calf and trunk, the temperature differences between the experimental data and the predicted results in high temperature environment were smaller than those in the thermally neutral environment conditions. The extended model was proved to be capable of predicting accurately human physiological responses in hot environments.
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Corbett J, Neal RA, Lunt HC, Tipton MJ. Adaptation to Heat and Exercise Performance Under Cooler Conditions: A New Hot Topic. Sports Med 2014; 44:1323-31. [DOI: 10.1007/s40279-014-0212-8] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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40
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Bandodkar AJ, Molinnus D, Mirza O, Guinovart T, Windmiller JR, Valdés-Ramírez G, Andrade FJ, Schöning MJ, Wang J. Epidermal tattoo potentiometric sodium sensors with wireless signal transduction for continuous non-invasive sweat monitoring. Biosens Bioelectron 2013; 54:603-9. [PMID: 24333582 DOI: 10.1016/j.bios.2013.11.039] [Citation(s) in RCA: 243] [Impact Index Per Article: 22.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2013] [Revised: 11/10/2013] [Accepted: 11/12/2013] [Indexed: 11/16/2022]
Abstract
This article describes the fabrication, characterization and application of an epidermal temporary-transfer tattoo-based potentiometric sensor, coupled with a miniaturized wearable wireless transceiver, for real-time monitoring of sodium in the human perspiration. Sodium excreted during perspiration is an excellent marker for electrolyte imbalance and provides valuable information regarding an individual's physical and mental wellbeing. The realization of the new skin-worn non-invasive tattoo-like sensing device has been realized by amalgamating several state-of-the-art thick film, laser printing, solid-state potentiometry, fluidics and wireless technologies. The resulting tattoo-based potentiometric sodium sensor displays a rapid near-Nernstian response with negligible carryover effects, and good resiliency against various mechanical deformations experienced by the human epidermis. On-body testing of the tattoo sensor coupled to a wireless transceiver during exercise activity demonstrated its ability to continuously monitor sweat sodium dynamics. The real-time sweat sodium concentration was transmitted wirelessly via a body-worn transceiver from the sodium tattoo sensor to a notebook while the subjects perspired on a stationary cycle. The favorable analytical performance along with the wearable nature of the wireless transceiver makes the new epidermal potentiometric sensing system attractive for continuous monitoring the sodium dynamics in human perspiration during diverse activities relevant to the healthcare, fitness, military, healthcare and skin-care domains.
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Affiliation(s)
- Amay J Bandodkar
- Department of NanoEngineering, University of California, San Diego La Jolla, CA 92093, USA
| | - Denise Molinnus
- Department of NanoEngineering, University of California, San Diego La Jolla, CA 92093, USA; Institute of Nano- and Biotechnologies, Aachen University of Applied Sciences, D-52428 Jülich, Germany
| | - Omar Mirza
- Department of NanoEngineering, University of California, San Diego La Jolla, CA 92093, USA
| | - Tomás Guinovart
- Department of NanoEngineering, University of California, San Diego La Jolla, CA 92093, USA; Departamento de Química Analítica, Universitat Rovira i Virgili, 43007 Tarragona, Spain
| | - Joshua R Windmiller
- Department of NanoEngineering, University of California, San Diego La Jolla, CA 92093, USA; Electrozyme LLC, Executive Square (Suite 485), San Diego, CA 92037, USA
| | | | - Francisco J Andrade
- Departamento de Química Analítica, Universitat Rovira i Virgili, 43007 Tarragona, Spain
| | - Michael J Schöning
- Institute of Nano- and Biotechnologies, Aachen University of Applied Sciences, D-52428 Jülich, Germany
| | - Joseph Wang
- Department of NanoEngineering, University of California, San Diego La Jolla, CA 92093, USA.
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Petrofsky J, Berk L, Bains G, Khowailed IA, Hui T, Granado M, Laymon M, Lee H. Moist heat or dry heat for delayed onset muscle soreness. J Clin Med Res 2013; 5:416-25. [PMID: 24171053 PMCID: PMC3808259 DOI: 10.4021/jocmr1521w] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/10/2013] [Indexed: 02/04/2023] Open
Abstract
Background Heat is commonly used in physical therapy following exercise induced delayed onset muscle soreness (DOMS). Most heat modalities used in a clinical setting for DOMS are only applied for 5 to 20 minutes. This minimal heat exposure causes little, if any, change in deep tissue temperature. For this reason, long duration dry chemical heat packs are used at home to slowly and safely warm tissue and reduce potential heat damage while reducing pain associated from DOMS. Clinically, it has been shown that moist heat penetrates deep tissue faster than dry heat. Therefore, in home use chemical moist heat may be more efficacious than dry heat to provide pain relief and reduce tissue damage following exercise DOMS. However, chemical moist heat only lasts for 2 hours compared to the 8 hours duration of chemical dry heat packs. The purpose of this study was to compare the beneficial effect of dry heat versus moist heat on 100 young subjects after exercise induce DOMS. Methods One hundred subjects exercised for 15 minutes accomplishing squats. Before and for 3 days after, strength, muscle soreness, tissue resistance, and the force to passively move the knee were recorded. Heat and moist heat were applied in different groups either immediately after exercise or 24 hours later. Results The research results of this study showed that immediate application of heat, either dry (8 hours application) or moist (2 hours application), had a similar preservation of quadriceps muscle strength and muscle activity. Results also revealed that the greatest pain reduction was shown after immediate application of moist heat. Never the less, immediate application of dry heat had a similar effect but to a lesser extent. Conclusion It should be noted that moist heat had not only similar benefits of dry heat but in some cases enhanced benefits, and with only 25% of the time of application of the dry heat.
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Affiliation(s)
- Jerrold Petrofsky
- Department of Physical Therapy, Loma Linda University, Loma Linda, California, USA
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Kellogg DL, Zhao JL, Wu Y, Johnson JM. Nitric oxide and receptors for VIP and PACAP in cutaneous active vasodilation during heat stress in humans. J Appl Physiol (1985) 2012; 113:1512-8. [PMID: 22961270 DOI: 10.1152/japplphysiol.00859.2012] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
VPAC2 receptors sensitive to vasoactive intestinal polypeptide (VIP) and pituitary adenylyl cyclase activating polypeptide (PACAP), PAC1 receptors sensitive to PACAP, and nitric oxide (NO) generation by NO synthase (NOS) are all implicated in cutaneous active vasodilation (AVD) through incompletely defined mechanisms. We hypothesized that VPAC2/PAC1 receptor activation and NO are synergistic and interdependent in AVD and tested our hypothesis by examining the effects of VPAC2/PAC1 receptor blockade with and without NOS inhibition during heat stress. The VPAC2/PAC1 antagonist, pituitary adenylate cyclase activating peptide 6-38 (PACAP6-38) and the NOS inhibitor, N(G)-nitro-l-arginine methyl ester (l-NAME) were administered by intradermal microdialysis. PACAP6-38, l-NAME, a combination of PACAP6-38 and l-NAME, or Ringer's solution alone were perfused at four separate sites. Skin blood flow was monitored by laser-Doppler flowmetry at each site. Body temperature was controlled with water-perfused suits. Blood pressure was monitored by Finapres, and cutaneous vascular conductance (CVC) calculated (CVC = laser-Doppler flowmetry/mean arterial pressure). The protocol began with a 5- to 10-min baseline period without antagonist perfusion, followed by perfusion of PACAP6-38, l-NAME, or combined PACAP6-38 and l-NAME at the different sites in normothermia (45 min), followed by 3 min of whole body cooling. Whole body heating was then performed to induce heat stress and activate AVD. Finally, 58 mM sodium nitroprusside were perfused at all sites to effect maximal vasodilation for normalization of blood flow data. No significant differences in CVC (normalized to maximum) were found among Ringer's PACAP6-38, l-NAME, or combined antagonist sites during normothermia (P > 0.05 among sites) or cold stress (P > 0.05 among sites). CVC responses at all treated sites were attenuated during AVD (P < 0.05 vs. Ringer's). Attenuation was greater at l-NAME and combined PACAP6-38- and l-NAME-treated sites than at PACAP6-38 sites (P > 0.05). Because responses did not differ between l-NAME and combined treatment sites (P > 0.05), we conclude that VPAC2/PAC1 receptors require NO in series to effect AVD.
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Affiliation(s)
- Dean L Kellogg
- Geriatric Research, Education, and Clinical Center, Department of Veterans Affairs, South Texas Veterans Health Care System, Audie L. Murphy Memorial Veterans Hospital Division, San Antonio, TX 78229, USA.
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Abstract
Cardiovascular drift, the progressive increase in heart rate and decrease in stroke volume that begins after approximately 10 min of prolonged moderate-intensity exercise, is associated with decreased maximal oxygen uptake, particularly during heat stress. Consequently, the increased heart rate reflects an increased relative metabolic intensity during prolonged exercise in the heat when cardiovascular drift occurs, which has implications for exercise prescription.
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Al-Nakhli HH, Petrofsky JS, Laymon MS, Arai D, Holland K, Berk LS. The use of thermal infrared imaging to assess the efficacy of a therapeutic exercise program in individuals with diabetes. Diabetes Technol Ther 2012; 14:159-67. [PMID: 22011006 DOI: 10.1089/dia.2011.0187] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
BACKGROUND Exercise is of great value for individuals with diabetes in helping to control their hemoglobin A1c levels and in increasing their insulin sensitivity. Delayed-onset muscle soreness (DOMS) is a common problem in healthy individuals and in people who have diabetes. People with diabetes are also faced with metabolic and endothelial impairments, which could make DOMS even worse. But because they usually have neuropathies, they may not feel this soreness appropriately, leading to premature return to exercise and causing further injuries. RESEARCH DESIGN One hundred eighteen subjects participated in this study and were divided into four groups. Two groups (healthy and diabetes) performed a series of abdominal exercises, and the other two groups (healthy and diabetes) performed a series of arm exercises to induce DOMS. Skin temperature above the muscle was assessed using a thermal infrared camera, and perceived soreness of the exercised muscle was assessed using a 100-mm visual analog scale. Serum myoglobin concentrations were also measured. RESULTS There was a significant increase in skin temperature 24 h post-exercise for all four exercise groups (P<0.05), where the combined average increase in skin temperature for all four groups was approximately 0.65°C from baseline. Also, 24 h post-exercise, all four groups were significantly sorer than they were at baseline (P<0.05). Serum myoglobin levels were also significantly higher on day 3 compared with day 1 (P<0.05). CONCLUSION Infrared thermal imaging may be a valuable technique of seeing which muscles are sore hours or even days after the exercise is over. Thus, thermal imaging would be an efficient and painless way of looking at DOMS in both healthy individuals and individuals who have diabetes, even if they are facing neurological problems.
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Crandall CG, Wilson TE, Marving J, Bundgaard-Nielsen M, Seifert T, Klausen TL, Andersen F, Secher NH, Hesse B. Colloid volume loading does not mitigate decreases in central blood volume during simulated haemorrhage while heat stressed. J Physiol 2012; 590:1287-97. [PMID: 22219334 DOI: 10.1113/jphysiol.2011.223602] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Heat stress results in profound reductions in the capacity to withstand a simulated haemorrhagic challenge; however, this capacity is normalized if the individual is volume loaded prior to the challenge. The present study tested the hypothesis that volume loading during passive heat stress attenuates the reduction in regional blood volumes during a simulated haemorrhagic challenge imposed via lower-body negative pressure (LBNP). Seven subjects underwent 30 mmHg LBNP while normothermic, during passive heat stress (increased internal temperature ∼1◦C), and while continuing to be heated after intravenous colloid volume loading (11 ml kg⁻¹). Relative changes in torso and regional blood volumes were determined by gamma camera imaging with technetium-99m labelled erythrocytes. Heat stress reduced blood volume in all regions (ranging from 7 to 16%), while subsequent volume loading returned those values to normothermic levels. While normothermic,LBNP reduced blood volume in all regions (torso: 22 ± 8%; heart: 18 ± 6%; spleen: 15 ± 8%). During LBNP while heat stressed, the reductions in blood volume in each region were markedly greater when compared to LBNP while normothermic (torso: 73 ± 2%; heart: 72 ± 3%; spleen: 72 ± 5%, all P<0.001 relative to normothermia). Volume loading during heat stress did not alter the extent of the reduction in these blood volumes to LBNP relative to heat stress alone (torso: 73 ± 1%; heart: 72 ± 2%; spleen: 74 ± 3%, all P>0.05 relative to heat stress alone). These data suggest that blood volume loading during passive heat stress (via 11 ml kg⁻¹ of a colloid solution) normalizes regional blood volumes in the torso, but does not mitigate the reduction in central blood volume during a simulated haemorrhagic challenge combined with heat stress.
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Affiliation(s)
- C G Crandall
- Institute for Exercise and Environmental Medicine, Presbyterian Hospital of Dallas, 7232 Greenville Ave, Dallas, TX 75231, USA.
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Schlader ZJ, Stannard SR, Mündel T. Is peak oxygen uptake a determinant of moderate-duration self-paced exercise performance in the heat? Appl Physiol Nutr Metab 2011; 36:863-72. [DOI: 10.1139/h11-111] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
This study aimed to identify whether reductions in peak oxygen uptake (VO2peak) dictate performance outcomes during 30 min of self-paced exercise in the heat, which is expected to induce minimal hyperthermia. On 4 occasions, 11 male subjects completed peak and self-paced exercise in both hot (HOT, 40.2 ± 0.3 °C) and moderate (MOD; 20.4 ± 0.7 °C) conditions. During peak exercise, submaximal oxygen uptake (VO2) was ∼8% higher in HOT, but VO2peak (MOD, 4.64 ± 0.83 L·min–1; HOT, 4.54 ± 0.77 L·min–1) and peak cardiac output (Qpeak) were similar. Self-paced exercise performance was reduced by ∼21% in HOT. VO2 was similar through 15 min, but lower in HOT thereafter. Relative to MOD, this represented a higher and lower %VO2peak during the initial and latter stages. Cardiac output was similar in both trials (MOD, 31.6 ± 6.6 L·min–1; HOT, 30.1 ± 6.0 L·min–1), representing a similar percentage of Qpeak throughout. Rectal temperature was similar in both conditions until 30 min (MOD, 38.5 ± 0.3 °C; HOT, 38.7 ± 0.3 °C), while skin temperature was higher throughout in HOT (mean: MOD, 32.4 ± 1.1 °C; HOT, 37.3 ± 0.4 °C). Perceived exertion rose similarly in both conditions, while thermal discomfort was higher in HOT. These data indicate that when only skin temperature is elevated, reductions in exercise performance during moderate-duration self-paced exercise are not associated with changes in VO2peak. Rather, increases in VO2 at a given submaximal external workload and (or) thermal discomfort appear to play a larger role.
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Affiliation(s)
- Zachary J. Schlader
- School of Sport and Exercise, Massey University, Private Bag 11 222, Palmerston North, 4442, New Zealand
| | - Stephen R. Stannard
- School of Sport and Exercise, Massey University, Private Bag 11 222, Palmerston North, 4442, New Zealand
| | - Toby Mündel
- School of Sport and Exercise, Massey University, Private Bag 11 222, Palmerston North, 4442, New Zealand
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The role of aerobic fitness and exercise intensity on endurance performance in uncompensable heat stress conditions. Eur J Appl Physiol 2011; 112:1989-99. [DOI: 10.1007/s00421-011-2165-z] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2011] [Accepted: 09/02/2011] [Indexed: 10/17/2022]
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Nelson MD, Altamirano-Diaz LA, Petersen SR, DeLorey DS, Stickland MK, Thompson RB, Haykowsky MJ. Left ventricular systolic and diastolic function during tilt-table positioning and passive heat stress in humans. Am J Physiol Heart Circ Physiol 2011; 301:H599-608. [PMID: 21536844 DOI: 10.1152/ajpheart.00127.2011] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The ventricular response to passive heat stress has predominantly been studied in the supine position. It is presently unclear how acute changes in venous return influence ventricular function during heat stress. To address this question, left ventricular (LV) systolic and diastolic function were studied in 17 healthy men (24.3 ± 4.0 yr; mean ± SD), using two-dimensional transthoracic echocardiography with Doppler ultrasound, during tilt-table positioning (supine, 30° head-up tilt, and 30° head-down tilt), under normothermic and passive heat stress (core temperature 0.8 ± 0.1°C above baseline) conditions. The supine heat stress LV volumetric and functional response was consistent with previous reports. Combining head-up tilt with heat stress reduced end-diastolic (25.2 ± 4.1%) and end-systolic (65.4 ± 10.5%) volume from baseline, whereas heart rate (37.7 ± 2.0%), ejection fraction (9.4 ± 2.4%), and LV elastance (37.7 ± 3.6%) increased, and stroke volume (-28.6 ± 9.4%) and early diastolic inflow (-17.5 ± 6.5%) and annular tissue (-35.6 ± 7.0%) velocities were reduced. Combining head-down tilt with heat stress restored end-diastolic volume, whereas LV elastance (16.8 ± 3.2%), ejection fraction (7.2 ± 2.1%), and systolic annular tissue velocities (22.4 ± 5.0%) remained elevated above baseline, and end-systolic volume was reduced (-15.3 ± 3.9%). Stroke volume and the early and late diastolic inflow and annular tissue velocities were unchanged from baseline. This investigation extends previous work by demonstrating increased LV systolic function with heat stress, under varied levels of venous return, and highlights the preload dependency of early diastolic function during passive heat stress.
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Affiliation(s)
- Michael D Nelson
- Faculty of Physical Education and Recreation, University of Alberta, Canada.
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Kellogg DL, Zhao JL, Wu Y, Johnson JM. Antagonism of soluble guanylyl cyclase attenuates cutaneous vasodilation during whole body heat stress and local warming in humans. J Appl Physiol (1985) 2011; 110:1406-13. [PMID: 21292837 DOI: 10.1152/japplphysiol.00702.2010] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
We hypothesized that nitric oxide activation of soluble guanylyl cyclase (sGC) participates in cutaneous vasodilation during whole body heat stress and local skin warming. We examined the effects of the sGC inhibitor, 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ), on reflex skin blood flow responses to whole body heat stress and on nonreflex responses to increased local skin temperature. Blood flow was monitored by laser-Doppler flowmetry, and blood pressure by Finapres to calculate cutaneous vascular conductance (CVC). Intradermal microdialysis was used to treat one site with 1 mM ODQ in 2% DMSO and Ringer, a second site with 2% DMSO in Ringer, and a third site received Ringer. In protocol 1, after a period of normothermia, whole body heat stress was induced. In protocol 2, local heating units warmed local skin temperature from 34 to 41°C to cause local vasodilation. In protocol 1, in normothermia, CVC did not differ among sites [ODQ, 15 ± 3% maximum CVC (CVC(max)); DMSO, 14 ± 3% CVC(max); Ringer, 17 ± 6% CVC(max); P > 0.05]. During heat stress, ODQ attenuated CVC increases (ODQ, 54 ± 4% CVC(max); DMSO, 64 ± 4% CVC(max); Ringer, 63 ± 4% CVC(max); P < 0.05, ODQ vs. DMSO or Ringer). In protocol 2, at 34°C local temperature, CVC did not differ among sites (ODQ, 17 ± 2% CVC(max); DMSO, 18 ± 4% CVC(max); Ringer, 18 ± 3% CVC(max); P > 0.05). ODQ attenuated CVC increases at 41°C local temperature (ODQ, 54 ± 5% CVC(max); DMSO, 86 ± 4% CVC(max); Ringer, 90 ± 2% CVC(max); P < 0.05 ODQ vs. DMSO or Ringer). sGC participates in neurogenic active vasodilation during heat stress and in the local response to direct skin warming.
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Affiliation(s)
- Dean L Kellogg
- Geriatric Research, Education, and Clinical Center, Department of Veterans Affairs, South Texas Veterans Health Care System, Audie L. Murphy Memorial Veterans Hospital Division, San Antonio, Texas, USA.
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