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Willmott AGB, Gibson OR, James CA, Hayes M, Maxwell NS. Physiological and perceptual responses to exercising in restrictive heat loss attire with use of an upper-body sauna suit in temperate and hot conditions. Temperature (Austin) 2018; 5:162-174. [PMID: 30377634 DOI: 10.1080/23328940.2018.1426949] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2017] [Accepted: 01/08/2018] [Indexed: 10/18/2022] Open
Abstract
The aim of this experiment was to quantify physiological and perceptual responses to exercise with and without restrictive heat loss attire in hot and temperate conditions. Ten moderately-trained individuals (mass; 69.44±7.50 kg, body fat; 19.7±7.6%) cycled for 30-mins (15-mins at 2 W.kg-1 then 15-mins at 1 W.kg-1) under four experimental conditions; temperate (TEMP, 22°C/45%), hot (HOT, 45°C/20%) and, temperate (TEMPSUIT, 22°C/45%) and hot (HOTSUIT, 45°C/20%) whilst wearing an upper-body "sauna suit". Core temperature changes were higher (P<0.05) in TEMPSUIT (+1.7±0.4°C.hr-1), HOT (+1.9±0.5°C.hr-1) and HOTSUIT (+2.3±0.5°C.hr-1) than TEMP (+1.3±0.3°C.hr-1). Skin temperature was higher (P<0.05) in HOT (36.53±0.93°C) and HOTSUIT (37.68±0.68°C) than TEMP (33.50±1.77°C) and TEMPSUIT (33.41±0.70°C). Sweat rate was greater (P<0.05) in TEMPSUIT (0.89±0.24 L.hr-1), HOT (1.14±0.48 L.hr-1) and HOTSUIT (1.51±0.52 L.hr-1) than TEMP (0.56±0.27 L.hr-1). Peak heart rate was higher (P<0.05) in TEMPSUIT (155±23 b.min-1), HOT (163±18 b.min-1) and HOTSUIT (171±18 b.min-1) than TEMP (151±20 b.min-1). Thermal sensation and perceived exertion were greater (P<0.05) in TEMPSUIT (5.8±0.5 and 14±1), HOT (6.4±0.5 and 15±1) and HOTSUIT (7.1±0.5 and 16±1) than TEMP (5.3±0.5 and 14±1). Exercising in an upper-body sauna suit within temperate conditions induces a greater physiological strain and evokes larger sweat losses compared to exercising in the same conditions, without restricting heat loss. In hot conditions, wearing a sauna suit increases physiological and perceptual strain further, which may accelerate the stimuli for heat adaptation and improve HA efficiency.
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Affiliation(s)
| | - Oliver R Gibson
- Environmental Extremes Laboratory, University of Brighton, Eastbourne, UK.,Centre for Human Performance, Exercise and Rehabilitation, Brunel University London, Uxbridge, UK
| | - Carl A James
- Environmental Extremes Laboratory, University of Brighton, Eastbourne, UK.,National Sports Institute, Institut Sukan Negara, National Sport Complex, Bukit Jalil, 57000 Kuala Lumpur, Malaysia
| | - Mark Hayes
- Environmental Extremes Laboratory, University of Brighton, Eastbourne, UK
| | - Neil S Maxwell
- Environmental Extremes Laboratory, University of Brighton, Eastbourne, UK
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202
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Malheiros-Lima MR, Pires W, Fonseca IAT, Joviano-Santos JV, Ferreira AJ, Coimbra CC, Lima NRV, Wanner SP. Physical Exercise-Induced Cardiovascular and Thermoregulatory Adjustments Are Impaired in Rats Subjected to Cutaneous Artery Denervation. Front Physiol 2018. [PMID: 29515451 PMCID: PMC5826067 DOI: 10.3389/fphys.2018.00074] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
This study aimed to investigate the chronic effects of caudal artery denervation on morphometric parameters of the tail vascular smooth muscle and on physical exercise-induced thermoregulatory and cardiovascular adjustments in rats. Male Wistar rats were subjected to caudal artery denervation or the sham procedure. Approximately 26-28 days after these procedures, their thermoregulatory and cardiovascular parameters were evaluated at rest and during or following a fatiguing treadmill run. At the end of the experiments, the rats were euthanized, and samples of their tails were removed to evaluate morphometric parameters of the vascular smooth muscle surrounding the caudal artery. Denervated rats showed morphological adaptations, including increased arterial wall thickness and wall-to-lumen ratios. In resting rats and following the fatiguing exercise, caudal artery denervation barely affected the thermoregulatory and cardiovascular parameters evaluated. By contrast, caudal artery denervation attenuated the increase in tail skin temperature, decreased the spontaneous baroreflex sensitivity, and exacerbated the increases in mean arterial pressure in exercising rats. The increased wall-to-lumen ratio of denervated rats correlated negatively with the maximum tail skin temperature attained or cutaneous heat loss sensitivity but correlated positively with the maximum diastolic blood pressure attained during exercise. In conclusion, cutaneous denervation induces vascular remodeling characterized by morphological adaptations of the tail vascular smooth muscle. This vascular remodeling likely underlies the impaired tail heat loss and blood pressure adjustments in denervated rats subjected to physical exercise. Therefore, we have highlighted the importance of cutaneous vascular innervation integrity in thermal and cardiovascular control in stress-challenged rats. In this sense, our findings advance the understanding of thermoregulatory and cardiovascular system reactions after a sustained cutaneous vascular innervation injury, which is essential for the treatment of some diseases, such as Parkinson's disease and type 1 and type 2 diabetes mellitus.
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Affiliation(s)
- Milene R Malheiros-Lima
- Exercise Physiology Laboratory, Department of Physical Education, School of Physical Education, Physiotherapy and Occupational Therapy, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| | - Washington Pires
- Exercise Physiology Laboratory, Department of Physical Education, School of Physical Education, Physiotherapy and Occupational Therapy, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil.,Department of Physical Education, Institute of Life Sciences, Universidade Federal de Juiz de Fora, Governador Valadares, Brazil
| | - Ivana A T Fonseca
- Exercise Physiology Laboratory, Department of Physical Education, School of Physical Education, Physiotherapy and Occupational Therapy, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| | - Julliane V Joviano-Santos
- Department of Morphology, Institute of Biological Sciences, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| | - Anderson J Ferreira
- Department of Morphology, Institute of Biological Sciences, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| | - Cândido C Coimbra
- Department of Physiology and Biophysics, Institute of Biological Sciences, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| | - Nilo R V Lima
- Exercise Physiology Laboratory, Department of Physical Education, School of Physical Education, Physiotherapy and Occupational Therapy, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| | - Samuel P Wanner
- Exercise Physiology Laboratory, Department of Physical Education, School of Physical Education, Physiotherapy and Occupational Therapy, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
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203
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Post Junctional Sudomotor and Cutaneous Vascular Responses in Noninjured Skin Following Heat Acclimation in Burn Survivors. J Burn Care Res 2018; 38:e284-e292. [PMID: 27359190 DOI: 10.1097/bcr.0000000000000372] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Thermal tolerance is improved in burn survivors following 7 days of exercise heat acclimation. It is unknown whether post junctional sudomotor and/or cutaneous vascular adaptations in noninjured skin contribute to this improvement. Thirty-three burn survivors were stratified into moderately (17-40% BSA grafted, n = 19) and highly (>40% BSA grafted, n = 14) skin-grafted groups. Nine nonburned subjects served as controls. All subjects underwent a 7-day heat acclimation protocol, which improved thermal tolerance in all groups. Before and after this heat acclimation protocol, post junctional cutaneous vascular responses were assessed by administering increasing doses of sodium nitroprusside (SNP) and methacholine (MCh) using intradermal microdialysis in noninjured skin. MCh infusion was also used to assess post junctional responses in sudomotor function in noninjured skin. Cutaneous vascular responses to SNP and MCh were not different between pre- and post heat acclimation in either group of burn survivors (both P > .05). The maximal sweating rate to MCh increased post acclimation in the control group (0.41 ± 0.20 to 0.54 ± 0.21 mg·min·cm; P = .016) but was unchanged in both groups of burn survivors (both P > .05). The number of sweat glands activated during the highest dose of MCh was elevated in the >40% BSA-grafted group (49 ± 16 to 56 ± 18 glands·cm; P = .005) but was unchanged in control subjects and the <40% BSA-grafted group (both P > .05). Given that post junctional administration of MCh and SNP did not alter sweating or skin blood flow from noninjured skin of burn survivors, improved thermal tolerance in these individuals following heat acclimation is more likely a result of either an increased sweating efficiency or an increased neural drive for sweating.
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204
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Otani H, Kaya M, Tamaki A, Watson P, Maughan RJ. Air velocity influences thermoregulation and endurance exercise capacity in the heat. Appl Physiol Nutr Metab 2018; 43:131-138. [DOI: 10.1139/apnm-2017-0448] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
This study examined the effects of variations in air velocity on time to exhaustion and thermoregulatory and perceptual responses to exercise in a hot environment. Eight male volunteers completed stationary cycle exercise trials at 70% peak oxygen uptake until exhaustion in an environmental chamber maintained at 30 °C and 50% relative humidity. Four air velocity conditions, 30, 20, 10, and 0 km/h, were tested, and the headwind was directed at the frontal aspect of the subject by 2 industrial fans, with blade diameters of 1 m and 0.5 m, set in series and positioned 3 m from the subject’s chest. Mean ± SD time to exhaustion was 90 ± 17, 73 ± 16, 58 ± 13, and 41 ± 10 min in 30-, 20-, 10-, and 0-km/h trials, respectively, and was different between all trials (P < 0.05). There were progressive elevations in the rate of core temperature rise, mean skin temperature, and perceived thermal sensation as airflow decreases (P < 0.05). Core temperature, heart rate, cutaneous vascular conductance, and perceived exertion were higher and evaporative heat loss was lower without airflow than at any given airflow (P < 0.05). Dry heat loss and plasma volume were similar between trials (P > 0.05). The present study demonstrated a progressive reduction in time to exhaustion as air velocity decreases. This response is associated with a faster rate of core temperature rise and a higher skin temperature and perceived thermal stress with decreasing airflow. Moreover, airflow greater than 10 km/h (2.8 m/s) might contribute to enhancing endurance exercise capacity and reducing thermoregulatory, cardiovascular, and perceptual strain during exercise in a hot environment.
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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
| | - Mitsuharu Kaya
- Hyogo University of Health Sciences, 1-3-6 Minatojima, Chuo-ku, Kobe, Hyogo 650-8530, Japan
| | - Akira Tamaki
- Hyogo University of Health Sciences, 1-3-6 Minatojima, Chuo-ku, Kobe, Hyogo 650-8530, Japan
| | - Phillip Watson
- Department of Human Physiology, Vrije Universiteit Brussel, Pleinlaan 2, B-1050 Brussels, Belgium
| | - Ronald J. Maughan
- School of Medicine, University of St Andrews, St Andrews KY16 9AJ, UK
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205
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Spector JT, Krenz J, Calkins M, Ryan D, Carmona J, Pan M, Zemke A, Sampson PD. Associations between heat exposure, vigilance, and balance performance in summer tree fruit harvesters. APPLIED ERGONOMICS 2018; 67:1-8. [PMID: 29122180 PMCID: PMC5912891 DOI: 10.1016/j.apergo.2017.09.002] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/18/2017] [Revised: 07/12/2017] [Accepted: 09/02/2017] [Indexed: 05/29/2023]
Abstract
BACKGROUND We sought to evaluate potential mediators of the relationship between heat exposure and traumatic injuries in outdoor agricultural workers. METHODS Linear mixed models were used to estimate associations between maximum work-shift Wet Bulb Globe Temperature (WBGTmax) and post-shift vigilance (reaction time) and postural sway (total path length) in a cross-sectional sample of 46 Washington State tree fruit harvesters in August-September 2015. RESULTS The mean (SD) WBGTmax was 27.4 (3.2)°C in August and 21.2 (2.0)°C in September. The mean pre-work-shift participant urine specific gravity indicated minimal dehydration. Twenty-four percent of participants exhibited possible excessive sleepiness. There was no association between WBGTmax and post-shift reaction time or total path length. CONCLUSIONS Heat exposure was not associated with impaired vigilance or balance in this study, in which the overall mean (SD) WBGTmax was 25.9 (4.2)°C. However, the study identified opportunities to ensure adequate pre-work-shift hydration and to optimize sleep and work-shift timing in order to reduce occupational injury and heat-related illness risk.
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Affiliation(s)
- June T Spector
- Department of Environmental and Occupational Health Sciences, University of Washington, Seattle, WA, USA; Department of Medicine, University of Washington, Seattle, WA, USA.
| | - Jennifer Krenz
- Department of Environmental and Occupational Health Sciences, University of Washington, Seattle, WA, USA.
| | - Miriam Calkins
- Department of Environmental and Occupational Health Sciences, University of Washington, Seattle, WA, USA.
| | - Dawn Ryan
- Department of Environmental and Occupational Health Sciences, University of Washington, Seattle, WA, USA.
| | - Jose Carmona
- Department of Environmental and Occupational Health Sciences, University of Washington, Seattle, WA, USA.
| | - Mengjie Pan
- Department of Statistics, University of Washington, Seattle, WA, USA.
| | - Anna Zemke
- College of Medicine, The Ohio State University, Columbus, OH, USA.
| | - Paul D Sampson
- Department of Statistics, University of Washington, Seattle, WA, USA.
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206
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Etemadi M, Inan OT. Wearable ballistocardiogram and seismocardiogram systems for health and performance. J Appl Physiol (1985) 2018; 124:452-461. [PMID: 28798198 PMCID: PMC5867366 DOI: 10.1152/japplphysiol.00298.2017] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2017] [Revised: 07/21/2017] [Accepted: 08/01/2017] [Indexed: 12/29/2022] Open
Abstract
Cardiovascular diseases (CVDs) are prevalent in the US, and many forms of CVD primarily affect the mechanical aspects of heart function. Wearable technologies for monitoring the mechanical health of the heart and vasculature could enable proactive management of CVDs through titration of care based on physiological status as well as preventative wellness monitoring to help promote lifestyle choices that reduce the overall risk of developing CVDs. Additionally, such wearable technologies could be used to optimize human performance in austere environments. This review describes our progress in developing wearable ballistocardiogram (BCG)- and seismocardiogram-based systems for monitoring relative changes in cardiac output, contractility, and blood pressure. Our systems use miniature, low-noise accelerometers to measure the movements of the body in response to the heartbeat and novel machine learning algorithms to provide robustness against motion artifacts and sensor misplacement. Moreover, we have mathematically related wearable BCG signals-representing local, cardiogenic movements of a point on the body-to better understood whole body BCG signals, and thereby improved estimation of key health parameters. We validated these systems with experiments in healthy subjects, studies in patients with heart failure, and measurements in austere environments such as water immersion. The systems can be used in future work as a tool for clinicians and physiologists to measure the mechanical aspects of cardiovascular function outside of clinical settings, and to thereby titrate care for patients with CVDs, provide preventative screening, and optimize performance in austere environments by providing real-time in-depth information regarding performance and risk.
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Affiliation(s)
- Mozziyar Etemadi
- Department of Anesthesiology, Feinberg School of Medicine, Northwestern University , Chicago, Illinois
- Department of Biomedical Engineering, McCormick School of Engineering, Northwestern University , Evanston, Illinois
| | - Omer T Inan
- School of Electrical and Computer Engineering and Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology , Atlanta, Georgia
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207
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Choi J, Ghaffari R, Baker LB, Rogers JA. Skin-interfaced systems for sweat collection and analytics. SCIENCE ADVANCES 2018; 4:eaar3921. [PMID: 29487915 PMCID: PMC5817925 DOI: 10.1126/sciadv.aar3921] [Citation(s) in RCA: 213] [Impact Index Per Article: 35.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/03/2017] [Accepted: 01/16/2018] [Indexed: 05/09/2023]
Abstract
Recent interdisciplinary advances in materials, mechanics, and microsystem designs for biocompatible electronics, soft microfluidics, and electrochemical biosensors establish the foundations for emerging classes of thin, skin-interfaced platforms capable of capturing, storing, and performing quantitative, spatiotemporal measurements of sweat chemistry, instantaneous local sweat rate, and total sweat loss. This review summarizes scientific and technical progress in this area and highlights the implications in real time and ambulatory modes of deployment during physical activities across a broad range of contexts in clinical health, physiology research, fitness/wellness, and athletic performance.
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Affiliation(s)
- Jungil Choi
- Department of Materials Science and Engineering, McCormick School of Engineering, Northwestern University, Evanston, IL 60208, USA
| | - Roozbeh Ghaffari
- Epicore Biosystems Inc., Evanston, IL 60208, USA
- Center for Bio-Integrated Electronics, Northwestern University, Evanston, IL 60208, USA
| | - Lindsay B. Baker
- Gatorade Sports Science Institute, 617 W. Main St., Barrington, IL 60010, USA
| | - John A. Rogers
- Department of Materials Science and Engineering, McCormick School of Engineering, Northwestern University, Evanston, IL 60208, USA
- Center for Bio-Integrated Electronics, Northwestern University, Evanston, IL 60208, USA
- Departments of Biomedical Engineering, Mechanical Engineering, and Electrical Engineering and Computer Science, McCormick School of Engineering, Northwestern University, Evanston, IL 60208, USA
- Department of Chemistry, Weinberg College of Arts and Sciences, Northwestern University, Evanston, IL 60208, USA
- Department of Neurological Surgery, Feinberg School of Medicine, and Simpson Querrey Institute for BioNanotechnology, Northwestern University, Chicago, IL 60611, USA
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208
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Sauna exposure immediately prior to short-term heat acclimation accelerates phenotypic adaptation in females. J Sci Med Sport 2018; 21:190-195. [DOI: 10.1016/j.jsams.2017.06.024] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2016] [Revised: 06/21/2017] [Accepted: 06/27/2017] [Indexed: 01/10/2023]
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209
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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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210
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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: 31] [Impact Index Per Article: 5.2] [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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211
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Davis SL, Jay O, Wilson TE. Thermoregulatory dysfunction in multiple sclerosis. HANDBOOK OF CLINICAL NEUROLOGY 2018; 157:701-714. [PMID: 30459034 DOI: 10.1016/b978-0-444-64074-1.00042-2] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Multiple sclerosis (MS) is a progressive neurologic disorder that disrupts axonal myelin in the central nervous system. Demyelination produces alterations in saltatory conduction, slowed conduction velocity, and a predisposition to conduction block. An estimated 60-80% of MS patients experience temporary worsening of clinical signs and neurologic symptoms with heat exposure (Uhthoff's phenomenon). This heat intolerance in MS is related to the detrimental effects of increased temperature on action potential propagation in demyelinated axons, resulting in conduction slowing and/or block. Additionally, MS may produce impaired neural control of autonomic and endocrine functions. Isolating and interpreting mechanisms responsible for autonomic dysfunction due to MS can be difficult as it may involve sensory impairments, altered neural integration within the central nervous system, impaired effector responses, or combinations of all of these factors. MS lesions occur in areas of the brain responsible for the control and regulation of body temperature and thermoregulatory effector responses, resulting in impaired neural control of sudomotor pathways or neural-induced changes in eccrine sweat glands, as evidenced by observations of reduced sweating responses in MS patients. Although not comprehensive, some evidence exists concerning treatments (cooling, precooling, and pharmacologic) for the MS patient to preserve function and decrease symptom worsening during heat stress. This review focuses on four main themes influencing current understanding of thermoregulatory dysfunction in MS: (1) heat intolerance; (2) central regulation of body temperature; (3) thermoregulatory effector responses; and (4) countermeasures to improve or maintain function during thermal stress.
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Affiliation(s)
- Scott L Davis
- Department of Applied Physiology and Wellness, Southern Methodist University, Dallas, TX, United States.
| | - Ollie Jay
- Faculty of Health Sciences, University of Sydney, Sydney, Australia
| | - Thad E Wilson
- Biomedical Sciences, Marian University College of Osteopathic Medicine, Indianapolis, IN, United States
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212
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Kunstetter AC, Barbosa NHS, Moraes MM, Pinto VA, Soares DD, Pires W, Wanner SP. Pre-exercise exposure to the treadmill setup changes the cardiovascular and thermoregulatory responses induced by subsequent treadmill running in rats. Temperature (Austin) 2017; 5:109-122. [PMID: 30377632 DOI: 10.1080/23328940.2017.1388343] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2017] [Revised: 09/28/2017] [Accepted: 09/29/2017] [Indexed: 10/18/2022] Open
Abstract
Different methodological approaches have been used to conduct experiments with rats subjected to treadmill running. Some experimenters have exposed rats to the treadmill setup before initiating exercise to minimize the influences of handling and being placed in an anxiety-inducing environment on the physiological responses to subsequent running. Other experimenters have subjected rats to exercise immediately after placing them on the treadmill. Thus, the present study aimed to evaluate the effects of pre-exercise exposure to the treadmill on physical performance and cardiovascular and thermoregulatory responses during subsequent exercise. Male Wistar rats were subjected to fatiguing incremental-speed exercise at 24°C immediately after being placed on the treadmill or after being exposed to the treadmill for 70 min following removal from their home cages. Core body temperature (TCORE), tail-skin temperature (TSKIN), heart rate (HR) and mean arterial pressure (MAP) were recorded throughout the experiments. Rats exposed to the treadmill started exercise with higher TCORE, lower HR and MAP, and unaltered TSKIN. This exposure did not influence performance, but it markedly affected the exercise-induced increases in the four physiological parameters evaluated; for example, the TSKIN increased earlier and at a higher TCORE. Moreover, previous treadmill exposure notably allowed expected exercise-induced changes in cardiovascular parameters to be observed. Collectively, these data indicate that pre-exercise exposure to the treadmill induces important effects on physiological responses during subsequent treadmill running. The present data are particularly relevant for researchers planning experiments involving physical exercise and the recording of physiological parameters in rats.
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Affiliation(s)
- Ana C Kunstetter
- Exercise Physiology Laboratory, School of Physical Education, Physiotherapy and Occupational Therapy, Universidade Federal de Minas Gerais, Belo Horizonte (MG), Brazil
| | - Nicolas H S Barbosa
- Exercise Physiology Laboratory, School of Physical Education, Physiotherapy and Occupational Therapy, Universidade Federal de Minas Gerais, Belo Horizonte (MG), Brazil
| | - Michele M Moraes
- Exercise Physiology Laboratory, School of Physical Education, Physiotherapy and Occupational Therapy, Universidade Federal de Minas Gerais, Belo Horizonte (MG), Brazil
| | - Valéria A Pinto
- Exercise Physiology Laboratory, School of Physical Education, Physiotherapy and Occupational Therapy, Universidade Federal de Minas Gerais, Belo Horizonte (MG), Brazil
| | - Danusa D Soares
- Exercise Physiology Laboratory, School of Physical Education, Physiotherapy and Occupational Therapy, Universidade Federal de Minas Gerais, Belo Horizonte (MG), Brazil
| | - Washington Pires
- Exercise Physiology Laboratory, School of Physical Education, Physiotherapy and Occupational Therapy, Universidade Federal de Minas Gerais, Belo Horizonte (MG), Brazil.,Department of Physical Education, Institute of Life Sciences, Universidade Federal de Juiz de Fora, Governador Valadares (MG), Brazil
| | - Samuel P Wanner
- Exercise Physiology Laboratory, School of Physical Education, Physiotherapy and Occupational Therapy, Universidade Federal de Minas Gerais, Belo Horizonte (MG), Brazil
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213
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Quiller G, Krenz J, Ebi K, Hess JJ, Fenske RA, Sampson PD, Pan M, Spector JT. Heat exposure and productivity in orchards: Implications for climate change research. ARCHIVES OF ENVIRONMENTAL & OCCUPATIONAL HEALTH 2017; 72:313-316. [PMID: 28139172 PMCID: PMC5562533 DOI: 10.1080/19338244.2017.1288077] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/27/2016] [Accepted: 01/25/2017] [Indexed: 05/27/2023]
Abstract
Recent studies suggest that heat exposure degrades work productivity, but such studies have not considered individual- and workplace-level factors. Forty-six tree-fruit harvesters (98% Latino/a) from 6 orchards participated in a cross-sectional study in central/eastern Washington in 2015. The association between maximum measured work-shift wet-bulb globe temperature (WBGTmax) and productivity (total weight of fruit bins collected per time worked) was estimated using linear mixed-effects models, adjusting for relevant confounders. The mean (standard deviation) WBGTmax was 27.9°C (3.6°C) in August and 21.2°C (2.0°C) in September. There was a trend of decreasing productivity with increasing WBGTmax, but this association was not statistically significant. When individual- and workplace-level factors were included in the model, the association approached the null. Not considering individual, work, and economic factors that affect rest and recovery in projections of the effects of climate change could result in overestimates of reductions in future productivity and underestimate risk of heat illness.
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Affiliation(s)
- Grant Quiller
- Department of Environmental and Occupational Health Sciences, University of Washington, Seattle, Washington, United States
| | - Jennifer Krenz
- Department of Environmental and Occupational Health Sciences, University of Washington, Seattle, Washington, United States
| | - Kristie Ebi
- Department of Environmental and Occupational Health Sciences, University of Washington, Seattle, Washington, United States
- Department of Global Health, University of Washington, Seattle, Washington, United States
| | - Jeremy J. Hess
- Department of Environmental and Occupational Health Sciences, University of Washington, Seattle, Washington, United States
- Department of Global Health, University of Washington, Seattle, Washington, United States
- Department of Medicine, University of Washington, Seattle, Washington, United States
| | - Richard A. Fenske
- Department of Environmental and Occupational Health Sciences, University of Washington, Seattle, Washington, United States
| | - Paul D. Sampson
- Department of Statistics, University of Washington, Seattle, Washington, United States
| | - Mengjie Pan
- Department of Statistics, University of Washington, Seattle, Washington, United States
| | - June T. Spector
- Department of Environmental and Occupational Health Sciences, University of Washington, Seattle, Washington, United States
- Department of Medicine, University of Washington, Seattle, Washington, United States
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214
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Lee BJ, Thake CD. Heat and Hypoxic Acclimation Increase Monocyte Heat Shock Protein 72 but Do Not Attenuate Inflammation following Hypoxic Exercise. Front Physiol 2017; 8:811. [PMID: 29085305 PMCID: PMC5650636 DOI: 10.3389/fphys.2017.00811] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2017] [Accepted: 10/02/2017] [Indexed: 12/11/2022] Open
Abstract
Acclimation to heat or hypoxic stress activates the heat shock response and accumulation of cytoprotective heat shock proteins (HSPs). By inhibiting the NF-κB pathway HSP72 can preserve epithelial function and reduce systemic inflammation. The aim of this study was to determine the time course of mHSP72 accumulation during acclimation, and to assess intestinal barrier damage and systemic inflammation following hypoxic exercise. Three groups completed 10 × 60-min acclimation sessions (50% normoxic VO2peak) in control (n = 7; 18°C, 35% RH), hypoxic (n = 7; FiO2 = 0.14, 18°C, 35% RH), or hot (n = 7; 40°C, 25% RH) conditions. Tumor necrosis factor-α (TNF-α), interleukin 6 (IL-6), interleukin 10 (IL-10), and intestinal fatty acid binding protein (I-FABP) were determined at rest and following a cycling normoxic stress test (NST; ~2 weeks before acclimation), pre-acclimation hypoxic stress test (HST1; FiO2 = 0.14, both at 50% normoxic VO2peak; ~1 week before acclimation) and post-acclimation HST (48 h; HST2). Monocyte HSP72 (mHSP72) was determined before and after exercise on day 1, 3, 5, 6, and 10 of acclimation. Accumulation of basal mHSP72 was evident from day 5 (p < 0.05) of heat acclimation and increased further on day 6 (p < 0.01), and day 10 (p < 0.01). In contrast, basal mHSP72 was elevated on the final day of hypoxic acclimation (p < 0.05). Following the NST, plasma TNF-α (–0.11 ± 0.27 ng.mL−1), IL-6 (+0.62 ± 0.67 ng.mL−1) IL-10 (+1.09 ± 9.06 ng.mL−1) and I-FABP (+37.6 ± 112.8 pg.mL−1) exhibited minimal change. After HST1, IL-6 (+3.87 ± 2.56 ng.mL−1), IL-10 (+26.15 ± 26.06 ng.mL−1) and I-FABP (+183.7 ± 182.1 pg.mL−1) were elevated (p < 0.01), whereas TNF-α was unaltered (+0.08 ± 1.27; p > 0.05). A similar trend was observed after HST2, with IL-6 (+3.09 ± 1.30 ng.mL−1), IL-10 (+23.22 ± 21.67 ng.mL−1) and I-FABP (+145.9 ±123.2 pg.mL−1) increased from rest. Heat acclimation induces mHSP72 accumulation earlier and at a greater magnitude compared to matched work hypoxic acclimation, however neither acclimation regime attenuated the systemic cytokine response or intestinal damage following acute exercise in hypoxia.
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Affiliation(s)
- Ben J Lee
- Occupational Performance Research Group, Department of Sport and Exercise Sciences, University of Chichester, Chichester, United Kingdom.,Centre for Applied Biological and Exercise Sciences, Coventry University, Coventry, United Kingdom
| | - Charles D Thake
- Occupational Performance Research Group, Department of Sport and Exercise Sciences, University of Chichester, Chichester, United Kingdom
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215
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McCleave EL, Slattery KM, Duffield R, Saunders PU, Sharma AP, Crowcroft SJ, Coutts AJ. Temperate Performance Benefits after Heat, but Not Combined Heat and Hypoxic Training. Med Sci Sports Exerc 2017; 49:509-517. [PMID: 27787334 DOI: 10.1249/mss.0000000000001138] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
PURPOSE Independent heat and hypoxic exposure can enhance temperate endurance performance in trained athletes, although their combined effects remain unknown. This study examined whether the addition of heat interval training during "live high, train low" (LHTL) hypoxic exposure would result in enhanced performance and physiological adaptations as compared with heat or temperate training. METHODS Twenty-six well-trained runners completed 3 wk of interval training assigned to one of three conditions: 1) LHTL hypoxic exposure plus heat training (H + H; 3000 m for 13 h·d, train at 33°C, 60% relative humidity [RH]), 2) heat training with no hypoxic exposure (HOT, live at <600 m and train at 33°C, 60% RH), or 3) temperate training with no hypoxic exposure (CONT; live at <600 m and train at 14°C, 55% RH). Performance 3-km time-trials (3-km TT), running economy, hemoglobin mass, and plasma volume were assessed using magnitude-based inferences statistical approach before (Baseline), after (Post), and 3 wk (3wkP) after exposure. RESULTS Compared with Baseline, 3-km TT performance was likely increased in HOT at 3wkP (-3.3% ± 1.3%; mean ± 90% confidence interval), with no performance improvement in either H + H or CONT. Hemoglobin mass increased by 3.8% ± 1.8% at Post in H + H only. Plasma volume in HOT was possibly elevated above H + H and CONT at Post but not at 3wkP. Correlations between changes in 3-km TT performance and physiological adaptations were unclear. CONCLUSION Incorporating heat-based training into a 3-wk training block can improve temperate performance at 3 wk after exposure, with athlete psychology, physiology, and environmental dose all important considerations. Despite hematological adaptations, the addition of LHTL to heat interval training has no greater 3-km TT performance benefit than temperate training alone.
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Affiliation(s)
- Erin L McCleave
- 1Sport and Exercise Science Discipline Group, Faculty of Health, University of Technology Sydney (UTS), Moore Park, AUSTRALIA; 2New South Wales Institute of Sport (NSWIS), Sydney Olympic Park, AUSTRALIA; 3Department of Physiology, Australian Institute of Sport (AIS), Canberra, AUSTRALIA; and 4University of Canberra Research Institute for Sport and Exercise (UCRISE), Canberra, AUSTRALIA
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216
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Akerman AP, Lucas SJE, Katare R, Cotter JD. Heat and Dehydration Additively Enhance Cardiovascular Outcomes following Orthostatically-Stressful Calisthenics Exercise. Front Physiol 2017; 8:756. [PMID: 29062280 PMCID: PMC5640974 DOI: 10.3389/fphys.2017.00756] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2017] [Accepted: 09/19/2017] [Indexed: 02/04/2023] Open
Abstract
Exercise and exogenous heat each stimulate multiple adaptations, but their roles are not well delineated, and that of the related stressor, dehydration, is largely unknown. While severe and prolonged hypohydration potentially “silences” the long-term heat acclimated phenotype, mild and transient dehydration may enhance cardiovascular and fluid-regulatory adaptations. We tested the hypothesis that exogenous heat stress and dehydration additively potentiate acute (24 h) cardiovascular and hematological outcomes following exercise. In a randomized crossover study, 10 physically-active volunteers (mean ± SD: 173 ± 11 cm; 72.1 ± 11.5 kg; 24 ± 3 year; 6 females) completed three trials of 90-min orthostatically-stressful calisthenics, in: (i) temperate conditions (22°C, 50% rh, no airflow; CON); (ii) heat (40°C, 60% rh) whilst euhydrated (HEAT), and (iii) heat with dehydration (no fluid ~16 h before and during exercise; HEAT+DEHY). Using linear mixed effects model analyses, core temperature (TCORE) rose 0.7°C more in HEAT than CON (95% CL: [0.5, 0.9]; p < 0.001), and another 0.4°C in HEAT+DEHY ([0.2, 0.5]; p < 0.001, vs. HEAT). Skin temperature also rose 1.2°C more in HEAT than CON ([0.6, 1.8]; p < 0.001), and similarly to HEAT+DEHY (p = 0.922 vs. HEAT). Peak heart rate was 40 b·min−1 higher in HEAT than in CON ([28, 51]; p < 0.001), and another 15 b·min−1 higher in HEAT+DEHY ([3, 27]; p = 0.011, vs. HEAT). Mean arterial pressure at 24-h recovery was not consistently below baseline after CON or HEAT (p ≥ 0.452), but was reduced 4 ± 1 mm Hg after HEAT+DEHY ([0, 8]; p = 0.020 vs. baseline). Plasma volume at 24 h after exercise increased in all trials; the 7% increase in HEAT was not reliably more than in CON (5%; p = 0.335), but was an additional 4% larger after HEAT+DEHY ([1, 8]; p = 0.005 vs. HEAT). Pooled-trial correlational analysis showed the rise in TCORE predicted the hypotension (r = −0.4) and plasma volume expansion (r = 0.6) at 24 h, with more hypotension reflecting more plasma expansion (r = −0.5). In conclusion, transient dehydration with heat potentiates short-term (24-h) hematological (hypervolemic) and cardiovascular (hypotensive) outcomes following calisthenics.
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Affiliation(s)
- Ashley P Akerman
- School of Physical Education, Sport and Exercise Sciences, Division of Sciences, University of Otago, Dunedin, New Zealand.,Department of Physiology, Division of Health Sciences, University of Otago, Dunedin, New Zealand
| | - Samuel J E Lucas
- Department of Physiology, Division of Health Sciences, University of Otago, Dunedin, New Zealand.,School of Sport, Exercise and Rehabilitation Sciences, University of Birmingham, Birmingham, United Kingdom
| | - Rajesh Katare
- Department of Physiology, Division of Health Sciences, University of Otago, Dunedin, New Zealand
| | - James D Cotter
- School of Physical Education, Sport and Exercise Sciences, Division of Sciences, University of Otago, Dunedin, New Zealand
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217
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Rivas E, Rao M, Castleberry T, Ben-Ezra V. The change in metabolic heat production is a primary mediator of heat acclimation in adults. J Therm Biol 2017; 70:69-79. [PMID: 29108560 DOI: 10.1016/j.jtherbio.2017.10.001] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2017] [Revised: 10/03/2017] [Accepted: 10/04/2017] [Indexed: 11/28/2022]
Abstract
PURPOSE This study examined whether heat acclimation (HA) results in either predominate improvements in heat dissipation or reduced endogenous heat production via individual components of the human heat balance equation. METHODS Twelve healthy inactive subjects (5 females, mean ± SD): age 28 ± 6y, 77.9 ± 2kg), completed a 10-day HA (42°C, 28% RH) hyperthermia clamp (90min/day exercise, ∆1.5°C in rectal temperature (Tre)) and control workload matched (CON: 23°C, 42% RH) protocols in a counterbalanced design separated by at least 2 mo. Pre-and post-HA were matched for external work rate (EXWR; day 1 and day 10 first 30min at 118 ± 29W, last 60min at 11 ± 5W); and metabolic heat production (Hprod; day 1 and day 9, first 30min at 296 ± 26Wm-2, last 60min 187 ± 33Wm-2). RESULTS When Pre- and post- HA was matched for Hprod, there was no difference during the first 30 or last 60min of exercise for metabolic energy expenditure (MEE 363 ± 70/ 195 ± 32Wm-2), Hprod (296 ± 67/ 187 ± 33Wm-2) or Tre (∆2.1 ± 0.5°C). When pre- and post-HA was EXWR equivalent, HA significantly attenuated MEE during the first 30 and last 60min (303 ± 49/ 174 ± 35Wm-2), Hprod (241 ± 44/ 168 ± 33, W·m-2), and ∆Tre (∆1.3 ± 0.4°C) (each P < 0.0001). When ∆Tre, ∆Tsk, ∆Tb were each normalized per 100W Hprod, no differences were found for any pre-to post-HA comparison. Heat loss required (Ereq) to maintain steady state internal temperature (Ereq = 220 ± 32Wm-2), maximal capacity of the climate for evaporative heat loss (Emax = 266 ± 56Wm-2), evaporative heat loss from skin (Esk = 207 ± 38Wm-2) or skin wettedness (Ereq/Emax = 0.88 ± 0.23Wm-2) were not different among each condition during the last 60min. CONCLUSION The mechanisms that underlie heat acclimation are not wholly attributed to heat dissipation enhancements per se, but are significantly influenced by metabolic heat production alterations under uncompensable heat stress environments.
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Affiliation(s)
- Eric Rivas
- Exercise and Thermal Integrative Physiology Laboratory, Department of Kinesiology and Sport Management, Texas Tech University, Lubbock, TX, USA.
| | - Manisha Rao
- Exercise Physiology and Biochemistry Laboratory, Department of Kinesiology, Texas Woman's University, Denton, TX, USA
| | - Todd Castleberry
- Exercise Physiology and Biochemistry Laboratory, Department of Kinesiology, Texas Woman's University, Denton, TX, USA
| | - Vic Ben-Ezra
- Exercise Physiology and Biochemistry Laboratory, Department of Kinesiology, Texas Woman's University, Denton, TX, USA
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218
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Nuccio RP, Barnes KA, Carter JM, Baker LB. Fluid Balance in Team Sport Athletes and the Effect of Hypohydration on Cognitive, Technical, and Physical Performance. Sports Med 2017; 47:1951-1982. [PMID: 28508338 PMCID: PMC5603646 DOI: 10.1007/s40279-017-0738-7] [Citation(s) in RCA: 95] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Sweat losses in team sports can be significant due to repeated bursts of high-intensity activity, as well as the large body size of athletes, equipment and uniform requirements, and environmental heat stress often present during training and competition. In this paper we aimed to: (1) describe sweat losses and fluid balance changes reported in team sport athletes, (2) review the literature assessing the impact of hypohydration on cognitive, technical, and physical performance in sports-specific studies, (3) briefly review the potential mechanisms by which hypohydration may impact team sport performance, and (4) discuss considerations for future directions. Significant hypohydration (mean body mass loss (BML) >2%) has been reported most consistently in soccer. Although American Football, rugby, basketball, tennis, and ice hockey have reported high sweating rates, fluid balance disturbances have generally been mild (mean BML <2%), suggesting that drinking opportunities were sufficient for most athletes to offset significant fluid losses. The effect of hydration status on team sport performance has been studied mostly in soccer, basketball, cricket, and baseball, with mixed results. Hypohydration typically impaired performance at higher levels of BML (3-4%) and when the method of dehydration involved heat stress. Increased subjective ratings of fatigue and perceived exertion consistently accompanied hypohydration and could explain, in part, the performance impairments reported in some studies. More research is needed to develop valid, reliable, and sensitive sport-specific protocols and should be used in future studies to determine the effects of hypohydration and modifying factors (e.g., age, sex, athlete caliber) on team sport performance.
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Affiliation(s)
- Ryan P Nuccio
- Gatorade Sports Science Institute, 617 W. Main St., Barrington, IL, 60010, USA.
| | - Kelly A Barnes
- Gatorade Sports Science Institute, 617 W. Main St., Barrington, IL, 60010, USA
| | - James M Carter
- Gatorade Sports Science Institute, 617 W. Main St., Barrington, IL, 60010, USA
| | - Lindsay B Baker
- Gatorade Sports Science Institute, 617 W. Main St., Barrington, IL, 60010, USA
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219
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Timpmann S, Hackney AC, Tamm M, Kreegipuu K, Unt E, Ööpik V. Influence of Rhodiola rosea on the heat acclimation process in young healthy men. Appl Physiol Nutr Metab 2017; 43:63-70. [PMID: 28873320 DOI: 10.1139/apnm-2017-0372] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The adaptogen Rhodiola rosea (RR) may mitigate stress responses and have beneficial effects on endurance capacity (EC) and mental performance. Heat acclimation (HA) improves EC in the heat, but the potential impact of RR on the HA process is unknown. Therefore, our intent was to determine if RR has a positive impact on HA. Twenty male subjects (age, 22.5 ± 3.0 years) completed 2 EC tests involving walking (6 km·h-1) until volitional exhaustion in a climate chamber (air temperature, 42 °C; relative humidity, 18%) before (H1) and after (H2) an 8-day HA period. One group (SHR; n = 10) ingested standardised extract SHR-5 of RR (a single daily dose of 432 mg), while a second group (PLC; n = 10) administered a placebo prior to each HA session. Efficacy of HA was evaluated on the basis of changes that occurred from H1 to H2 in the time to exhaustion (TTE), exercise heart rate (HR), core and skin temperatures (Tc, Tsk), stress hormones, ratings of perceived exertion (RPE) and fatigue (RPF), and thermal sensation (TS). HA significantly increased TTE (133.1 ± 44.1 min in H1; 233.4 ± 59.8 min in H2; p < 0.0001) and decreased (p < 0.0001) HR, Tc, Tsk, stress hormones as well as RPE, RPF, and TS. However, the magnitude of all these changes was similar (p > 0.05) in the SHR and PLC groups. These results suggest that the use of RR during HA has no beneficial performance, physiological, or perceptual effects in young healthy males.
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Affiliation(s)
- Saima Timpmann
- a Institute of Sport Sciences and Physiotherapy; Estonian Centre of Behavioral and Health Sciences, University of Tartu, 50090 Tartu, Estonia
| | - Anthony C Hackney
- b Department of Exercise and Sport Science; Department of Nutrition, School of Public Health, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Maria Tamm
- c Institute of Psychology; Estonian Centre of Behavioral and Health Sciences, University of Tartu, 50090 Tartu, Estonia
| | - Kairi Kreegipuu
- c Institute of Psychology; Estonian Centre of Behavioral and Health Sciences, University of Tartu, 50090 Tartu, Estonia
| | - Eve Unt
- d Department of Cardiology; Department of Sports Medicine and Rehabilitation, University of Tartu; Sports Medicine and Rehabilitation Clinic, Tartu University Hospital, 50406 Tartu, Estonia
| | - Vahur Ööpik
- a Institute of Sport Sciences and Physiotherapy; Estonian Centre of Behavioral and Health Sciences, University of Tartu, 50090 Tartu, Estonia
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220
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Racinais S, Cocking S, Périard JD. Sports and environmental temperature: From warming-up to heating-up. Temperature (Austin) 2017; 4:227-257. [PMID: 28944269 DOI: 10.1080/23328940.2017.1356427] [Citation(s) in RCA: 61] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2017] [Revised: 07/09/2017] [Accepted: 07/09/2017] [Indexed: 01/22/2023] Open
Abstract
Most professional and recreational athletes perform pre-conditioning exercises, often collectively termed a 'warm-up' to prepare for a competitive task. The main objective of warming-up is to induce both temperature and non-temperature related responses to optimize performance. These responses include increasing muscle temperature, initiating metabolic and circulatory adjustments, and preparing psychologically for the upcoming task. However, warming-up in hot and/or humid ambient conditions increases thermal and circulatory strain. As a result, this may precipitate neuromuscular and cardiovascular impairments limiting endurance capacity. Preparations for competing in the heat should include an acclimatization regimen. Athletes should also consider cooling interventions to curtail heat gain during the warm-up and minimize dehydration. Indeed, although it forms an important part of the pre-competition preparation in all environmental conditions, the rise in whole-body temperature should be limited in hot environments. This review provides recommendations on how to build an effective warm-up following a 3 stage RAMP model (Raise, Activate and Mobilize, Potentiate), including general and context specific exercises, along with dynamic flexibility work. In addition, this review provides suggestion to manipulate the warm-up to suit the demands of competition in hot environments, along with other strategies to avoid heating-up.
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Affiliation(s)
- Sébastien Racinais
- Aspetar Orthopaedic and Sports Medicine Hospital, Athlete Health and Performance Research Centre, Doha, Qatar.,French Institute of Sport (INSEP), Laboratory Sport, Expertise and Performance (EA 7370), Paris, France
| | - Scott Cocking
- Aspetar Orthopaedic and Sports Medicine Hospital, Athlete Health and Performance Research Centre, Doha, Qatar.,Research Institute for Sport and Exercise Science, Liverpool John Moores University, United Kingdom
| | - Julien D Périard
- Aspetar Orthopaedic and Sports Medicine Hospital, Athlete Health and Performance Research Centre, Doha, Qatar.,University of Canberra, Research Institute for Sport and Exercise, Canberra, Australia
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221
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Convertino VA, Sawka MN. Wearable technology for compensatory reserve to sense hypovolemia. J Appl Physiol (1985) 2017; 124:442-451. [PMID: 28751369 DOI: 10.1152/japplphysiol.00264.2017] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Traditional monitoring technologies fail to provide accurate or early indications of hypovolemia-mediated extremis because physiological systems (as measured by vital signs) effectively compensate until circulatory failure occurs. Hypovolemia is the most life-threatening physiological condition associated with circulatory shock in hemorrhage or sepsis, and it impairs one's ability to sustain physical exertion during heat stress. This review focuses on the physiology underlying the development of a novel noninvasive wearable technology that allows for real-time evaluation of the cardiovascular system's ability to compensate to hypovolemia, or its compensatory reserve, which provides an individualized estimate of impending circulatory collapse. Compensatory reserve is assessed by real-time changes (sampled millions of times per second) in specific features (hundreds of features) of arterial waveform analog signals that can be obtained from photoplethysmography using machine learning and feature extraction techniques. Extensive experimental evidence employing acute reductions in central blood volume (using lower-body negative pressure, blood withdrawal, heat stress, dehydration) demonstrate that compensatory reserve provides the best indicator for early and accurate assessment for compromises in blood pressure, tissue perfusion, and oxygenation in resting human subjects. Engineering challenges exist for the development of a ruggedized wearable system that can measure signals from multiple sites, improve signal-to-noise ratios, be customized for use in austere conditions (e.g., battlefield, patient transport), and be worn during strenuous physical activity.
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Affiliation(s)
- Victor A Convertino
- Battlefield Health & Trauma Center for Human Integrative Physiology, U. S. Army Institute of Surgical Research, Joint Base San Antonio-Fort Sam Houston, San Antonio, Texas
| | - Michael N Sawka
- School of Biological Sciences, Georgia Institute of Technology , Atlanta, Georgia
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222
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Tuttle JA, Chrismas BCR, Gibson OR, Barrington JH, Hughes DC, Castle PC, Metcalfe AJ, Midgley AW, Pearce O, Kabir C, Rayanmarakar F, Al-Ali S, Lewis MP, Taylor L. The Hsp72 and Hsp90α mRNA Responses to Hot Downhill Running Are Reduced Following a Prior Bout of Hot Downhill Running, and Occur Concurrently within Leukocytes and the Vastus Lateralis. Front Physiol 2017; 8:473. [PMID: 28747888 PMCID: PMC5506191 DOI: 10.3389/fphys.2017.00473] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2017] [Accepted: 06/21/2017] [Indexed: 12/14/2022] Open
Abstract
The leukocyte heat shock response (HSR) is used to determine individual's thermotolerance. The HSR and thermotolerance are enhanced following interventions such as preconditioning and/or acclimation/acclimatization. However, it is unclear whether the leukocyte HSR is an appropriate surrogate for the HSR in other tissues implicated within the pathophysiology of exertional heat illnesses (e.g., skeletal muscle), and whether an acute preconditioning strategy (e.g., downhill running) can improve subsequent thermotolerance. Physically active, non-heat acclimated participants were split into two groups to investigate the benefits of hot downhill running as preconditioning strategy. A hot preconditioning group (HPC; n = 6) completed two trials (HPC1HOTDOWN and HPC2HOTDOWN) of 30 min running at lactate threshold (LT) on -10% gradient in 30°C and 50% relative humidity (RH) separated by 7 d. A temperate preconditioning group (TPC; n = 5) completed 30 min running at LT on a -1% gradient in 20°C and 50% (TPC1TEMPFLAT) and 7 d later completed 30 min running at LT on -10% gradient in 30°C and 50% RH (TPC2HOTDOWN). Venous blood samples and muscle biopsies (vastus lateralis; VL) were obtained before, immediately after, 3, 24, and 48 h after each trial. Leukocyte and VL Hsp72, Hsp90α, and Grp78 mRNA relative expression was determined via RT-QPCR. Attenuated leukocyte and VL Hsp72 (2.8 to 1.8 fold and 5.9 to 2.4 fold; p < 0.05) and Hsp90α mRNA (2.9 to 2.4 fold and 5.2 to 2.4 fold; p < 0.05) responses accompanied reductions (p < 0.05) in physiological strain [exercising rectal temperature (-0.3°C) and perceived muscle soreness (~ -14%)] during HPC2HOTDOWN compared to HPC1HOTDOWN (i.e., a preconditioning effect). Both VL and leukocyte Hsp72 and Hsp90α mRNA increased (p < 0.05) simultaneously following downhill runs and demonstrated a strong relationship (p < 0.01) of similar magnitudes with one another. Hot downhill running is an effective preconditioning strategy which ameliorates physiological strain, soreness and Hsp72 and Hsp90α mRNA responses to a subsequent bout. Leukocyte and VL analyses are appropriate tissues to infer the extent to which the HSR has been augmented.
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Affiliation(s)
- James A Tuttle
- Muscle Cellular and Molecular Physiology Research Group, Department of Sport Science and Physical Activity, Institute of Sport and Physical Activity Research, University of BedfordshireBedford, United Kingdom
| | - Bryna C R Chrismas
- Sport Science Program, College of Arts and Sciences, Qatar UniversityDoha, Qatar
| | - Oliver R Gibson
- Centre for Human Performance, Exercise and Rehabilitation, Division of Sport, Health and Exercise Sciences, Department of Life Sciences, Brunel University LondonLondon, United Kingdom
| | - James H Barrington
- Muscle Cellular and Molecular Physiology Research Group, Department of Sport Science and Physical Activity, Institute of Sport and Physical Activity Research, University of BedfordshireBedford, United Kingdom
| | - David C Hughes
- Department of Neurobiology, Physiology and Behavior, University of California, DavisDavis, CA, United States
| | - Paul C Castle
- Muscle Cellular and Molecular Physiology Research Group, Department of Sport Science and Physical Activity, Institute of Sport and Physical Activity Research, University of BedfordshireBedford, United Kingdom
| | - Alan J Metcalfe
- Muscle Cellular and Molecular Physiology Research Group, Department of Sport Science and Physical Activity, Institute of Sport and Physical Activity Research, University of BedfordshireBedford, United Kingdom.,School of Exercise and Health Sciences, Edith Cowan UniversityPerth, WA, Australia
| | - Adrian W Midgley
- Department of Sport and Physical Activity, Edgehill UniversityOrmskirk, United Kingdom
| | - Oliver Pearce
- Milton Keynes University HospitalMilton Keynes, United Kingdom
| | - Chindu Kabir
- Milton Keynes University HospitalMilton Keynes, United Kingdom
| | | | - Sami Al-Ali
- Milton Keynes University HospitalMilton Keynes, United Kingdom
| | - Mark P Lewis
- National Centre for Sport and Exercise Medicine, School of Sport, Exercise and Health Sciences, Loughborough UniversityLoughborough, United Kingdom.,School of Sport, Exercise and Health Sciences, Loughborough UniversityLoughborough, United Kingdom
| | - Lee Taylor
- School of Sport, Exercise and Health Sciences, Loughborough UniversityLoughborough, United Kingdom.,ASPETAR, Qatar Orthopedic and Sports Medicine HospitalDoha, Qatar
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Charlot K, Tardo-Dino PE, Buchet JF, Koulmann N, Bourdon S, Lepetit B, Roslonski M, Jousseaume L, Malgoyre A. Short-Term, Low-Volume Training Improves Heat Acclimatization in an Operational Context. Front Physiol 2017; 8:419. [PMID: 28670286 PMCID: PMC5472681 DOI: 10.3389/fphys.2017.00419] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2017] [Accepted: 05/31/2017] [Indexed: 11/21/2022] Open
Abstract
Personnel who travel to areas with a hot climate (WBGT > 27°C) may suffer from the heat (physiological strain, thermal discomfort, increased probability of heat illness), making them partially or fully inoperative. Performing physical activities during heat acclimatization is known to improve this process (i.e., improve measures of acclimatization for the same duration of acclimation). However, it is unknown whether such training would be efficient in an operative context, characterized by a high volume of work-related physical activity. Thirty French soldiers (Training group, T) performed a short (5 days), progressive, moderate (from three to five 8-min running sets at 50% of the speed at VO2max for 32-56 min) aerobic training program upon arriving at their base in United Arab Emirates (~40°C and 12% RH). A control group (30 soldiers; No Training, NT) continued to perform their usual outdoor military activities (~6 h.d-1). A field heat stress test (HST; three 8-min running sets at 50% of the speed at VO2max) was performed, before and after the heat acclimatization period, to assess physiological and subjective changes. Rectal temperature, heart rate (HR), thermal discomfort at rest and at the end of exercise, rates of perceived exertion (RPE), and sweat loss and osmolality decreased following heat acclimatization in both groups. However, the decreases in the T group were larger than those in the NT group for HR at the end of exercise (-20 ± 13 vs. -13 ± 6 bpm, respectively, p = 0.044), thermal discomfort at rest (-2.6 ± 2.7 vs. -1.4 ± 2.1 cm, respectively, p = 0.013) and at the end of exercise (-2.6 ± 1.9 vs. -1.6 ± 1.7 cm, respectively, p = 0.037) and RPE (-2.3 ± 1.8 vs. -1.3 ± 1.7, respectively, p = 0.035). Thus, we showed that adding short (<60 min), daily, moderate-intensity training sessions during a professional mission in a hot and dry environment accelerated several heat-acclimatization-induced changes at rest and during exercise in only 5 days.
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Affiliation(s)
- Keyne Charlot
- Département Environnements Opérationnels, Unité de Physiologie des Exercices et Activités en Conditions Extrêmes, Institut de Recherche Biomédicale des ArméesBretigny-Sur-Orge, France
| | - Pierre-Emmanuel Tardo-Dino
- Département Environnements Opérationnels, Unité de Physiologie des Exercices et Activités en Conditions Extrêmes, Institut de Recherche Biomédicale des ArméesBretigny-Sur-Orge, France
- Ecole du Val de GrâceParis, France
| | - Jean-François Buchet
- Forces Françaises aux Émirats Arabes Unis, Centre Médical InterarméesZayed Military City, United Arab Emirates
| | - Nathalie Koulmann
- Département Environnements Opérationnels, Unité de Physiologie des Exercices et Activités en Conditions Extrêmes, Institut de Recherche Biomédicale des ArméesBretigny-Sur-Orge, France
- Ecole du Val de GrâceParis, France
| | - Stéphanie Bourdon
- Département Environnements Opérationnels, Unité de Physiologie des Exercices et Activités en Conditions Extrêmes, Institut de Recherche Biomédicale des ArméesBretigny-Sur-Orge, France
| | - Benoit Lepetit
- Département Environnements Opérationnels, Unité de Physiologie des Exercices et Activités en Conditions Extrêmes, Institut de Recherche Biomédicale des ArméesBretigny-Sur-Orge, France
| | - Martin Roslonski
- Forces Françaises aux Émirats Arabes Unis, Centre Médical InterarméesZayed Military City, United Arab Emirates
| | - Loïc Jousseaume
- Forces Françaises aux Émirats Arabes Unis, Centre Médical InterarméesZayed Military City, United Arab Emirates
| | - Alexandra Malgoyre
- Département Environnements Opérationnels, Unité de Physiologie des Exercices et Activités en Conditions Extrêmes, Institut de Recherche Biomédicale des ArméesBretigny-Sur-Orge, France
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Audet GN, Dineen SM, Stewart DA, Plamper ML, Pathmasiri WW, McRitchie SL, Sumner SJ, Leon LR. Pretreatment with indomethacin results in increased heat stroke severity during recovery in a rodent model of heat stroke. J Appl Physiol (1985) 2017; 123:544-557. [PMID: 28596269 DOI: 10.1152/japplphysiol.00242.2017] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2017] [Revised: 06/06/2017] [Accepted: 06/07/2017] [Indexed: 01/16/2023] Open
Abstract
It has been suggested that medications can increase heat stroke (HS) susceptibility/severity. We investigated whether the nonsteroidal anti-inflammatory drug (NSAID) indomethacin (INDO) increases HS severity in a rodent model. Core temperature (Tc) of male, C57BL/6J mice (n = 45) was monitored continuously, and mice were given a dose of INDO [low dose (LO) 1 mg/kg or high dose (HI) 5 mg/kg in flavored treat] or vehicle (flavored treat) before heating. HS animals were heated to 42.4°C and euthanized at three time points for histological, molecular, and metabolic analysis: onset of HS [maximal core temperature (Tc,Max)], 3 h of recovery [minimal core temperature or hypothermia depth (HYPO)], and 24 h of recovery (24 h). Nonheated (control) animals underwent identical treatment in the absence of heat. INDO (LO or HI) had no effect on physiological indicators of performance (e.g., time to Tc,Max, thermal area, or cooling time) during heating or recovery. HI INDO resulted in 45% mortality rate by 24 h (HI INDO + HS group). The gut showed dramatic increases in gross morphological hemorrhage in HI INDO + HS in both survivors and nonsurvivors. HI INDO + HS survivors had significantly lower red blood cell counts and hematocrit suggesting significant hemorrhage. In the liver, HS induced cell death at HYPO and increased inflammation at Tc,Max, HYPO, and 24 h; however, there was additional effect with INDO + HS group. Furthermore, the metabolic profile of the liver was disturbed by heat, but there was no additive effect of INDO + HS. This suggests that there is an increase in morbidity risk with INDO + HS, likely resulting from significant gut injury.NEW & NOTEWORTHY This paper suggests that in a translational mouse model, NSAIDs may be counterindicated in situations that put an individual at risk of heat injury. We show here that a small, single dose of the NSAID indomethacin before heat stroke has a dramatic and highly damaging effect on the gut, which ultimately leads to increased systemic morbidity.
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Affiliation(s)
- Gerald N Audet
- Thermal and Mountain Medicine Division, United States Army Research Institute of Environmental Medicine, Natick, Massachusetts;
| | - Shauna M Dineen
- Thermal and Mountain Medicine Division, United States Army Research Institute of Environmental Medicine, Natick, Massachusetts
| | - Delisha A Stewart
- National Institutes of Health Eastern Regional Comprehensive Metabolomics Resource Core, RTI International, Research Triangle Park, North Carolina; and
| | - Mark L Plamper
- Thermal and Mountain Medicine Division, United States Army Research Institute of Environmental Medicine, Natick, Massachusetts
| | - Wimal W Pathmasiri
- National Institutes of Health Eastern Regional Comprehensive Metabolomics Resource Core, RTI International, Research Triangle Park, North Carolina; and
| | - Susan L McRitchie
- National Institutes of Health Eastern Regional Comprehensive Metabolomics Resource Core, RTI International, Research Triangle Park, North Carolina; and
| | - Susan J Sumner
- National Institutes of Health Eastern Regional Comprehensive Metabolomics Resource Core, University of North Carolina at Chapel Hill Nutrition Research Institute, Kannapolis, North Carolina
| | - Lisa R Leon
- Thermal and Mountain Medicine Division, United States Army Research Institute of Environmental Medicine, Natick, Massachusetts
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James CA, Richardson AJ, Watt PW, Willmott AG, Gibson OR, Maxwell NS. Short-term heat acclimation improves the determinants of endurance performance and 5-km running performance in the heat. Appl Physiol Nutr Metab 2017; 42:285-294. [DOI: 10.1139/apnm-2016-0349] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
This study investigated the effect of 5 days of controlled short-term heat acclimation (STHA) on the determinants of endurance performance and 5-km performance in runners, relative to the impairment afforded by moderate heat stress. A control group (CON), matched for total work and power output (2.7 W·kg−1), differentiated thermal and exercise contributions of STHA on exercise performance. Seventeen participants (10 STHA, 7 CON) completed graded exercise tests (GXTs) in cool (13 °C, 50% relative humidity (RH), pre-training) and hot conditions (32 °C, 60% RH, pre- and post-training), as well as 5-km time trials (TTs) in the heat, pre- and post-training. STHA reduced resting (p = 0.01) and exercising (p = 0.04) core temperature alongside a smaller change in thermal sensation (p = 0.04). Both groups improved the lactate threshold (LT, p = 0.021), lactate turnpoint (LTP, p = 0.005) and velocity at maximal oxygen consumption (vV̇O2max; p = 0.031) similarly. Statistical differences between training methods were observed in TT performance (STHA, −6.2(5.5)%; CON, −0.6(1.7)%, p = 0.029) and total running time during the GXT (STHA, +20.8(12.7)%; CON, +9.8(1.2)%, p = 0.006). There were large mean differences in change in maximal oxygen consumption between STHA +4.0(2.2) mL·kg−1·min−1 (7.3(4.0)%) and CON +1.9(3.7) mL·kg−1·min−1 (3.8(7.2)%). Running economy (RE) deteriorated following both training programmes (p = 0.008). Similarly, RE was impaired in the cool GXT, relative to the hot GXT (p = 0.004). STHA improved endurance running performance in comparison with work-matched normothermic training, despite equality of adaptation for typical determinants of performance (LT, LTP, vV̇O2max). Accordingly, these data highlight the ergogenic effect of STHA, potentially via greater improvements in maximal oxygen consumption and specific thermoregulatory and associated thermal perception adaptations absent in normothermic training.
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Affiliation(s)
- Carl A. James
- Environmental Extremes Laboratory, Centre for Sport and Exercise Science and Medicine (SESAME), University of Brighton, Eastbourne BN20 7UR, UK
- National Sports Institute of Malaysia, Institut Sukan Negara, Bukit Jalil Stadium, Kuala Lumpur 57000, Malaysia
| | - Alan J. Richardson
- Environmental Extremes Laboratory, Centre for Sport and Exercise Science and Medicine (SESAME), University of Brighton, Eastbourne BN20 7UR, UK
| | - Peter W. Watt
- Environmental Extremes Laboratory, Centre for Sport and Exercise Science and Medicine (SESAME), University of Brighton, Eastbourne BN20 7UR, UK
| | - Ashley G.B. Willmott
- Environmental Extremes Laboratory, Centre for Sport and Exercise Science and Medicine (SESAME), University of Brighton, Eastbourne BN20 7UR, UK
| | - Oliver R. Gibson
- Centre for Human Performance, Exercise and Rehabilitation (CHPER), Brunel University London UB8 3PH, UK
| | - Neil S. Maxwell
- Environmental Extremes Laboratory, Centre for Sport and Exercise Science and Medicine (SESAME), University of Brighton, Eastbourne BN20 7UR, UK
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Effect of Indoor Temperature on Physical Performance in Older Adults during Days with Normal Temperature and Heat Waves. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2017; 14:ijerph14020186. [PMID: 28216585 PMCID: PMC5334740 DOI: 10.3390/ijerph14020186] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/19/2016] [Revised: 02/06/2017] [Accepted: 02/08/2017] [Indexed: 01/02/2023]
Abstract
Indoor temperature is relevant with regard to mortality and heat-related self-perceived health problems. The aim of this study was to describe the association between indoor temperature and physical performance in older adults. Eighty-one older adults (84% women, mean age 80.9 years, standard deviation 6.53) were visited every four weeks from May to October 2015 and additionally during two heat waves in July and August 2015. Indoor temperature, habitual gait speed, chair-rise performance and balance were assessed. Baseline assessment of gait speed was used to create two subgroups (lower versus higher gait speed) based on frailty criteria. The strongest effect of increasing temperature on habitual gait speed was observed in the subgroup of adults with higher gait speed (−0.087 m/s per increase of 10 °C; 95% confidence interval (CI): −0.136; −0.038). The strongest effects on timed chair-rise and balance performance were observed in the subgroup of adults with lower gait speed (2.03 s per increase of 10 °C (95% CI: 0.79; 3.28) and −3.92 s per increase of 10 °C (95% CI: −7.31; −0.52), respectively). Comparing results of physical performance in absentia of a heat wave and during a heat wave, habitual gait speed was negatively affected by heat in the total group and subgroup of adults with higher gait speed, chair-rise performance was negatively affected in all groups and balance was not affected. The study provides arguments for exercise interventions in general for older adults, because a better physical fitness might alleviate impediments of physical capacity and might provide resources for adequate adaptation in older adults during heat stress.
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228
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Willmott AGB, Bliss A, Simpson WH, Tocker SM, Cottingham R, Maxwell NS. CAERvest® - a novel endothermic hypothermic device for core temperature cooling: safety and efficacy testing. INTERNATIONAL JOURNAL OF OCCUPATIONAL SAFETY AND ERGONOMICS 2016; 24:118-128. [PMID: 27997307 DOI: 10.1080/10803548.2016.1273640] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
INTRODUCTION Cooling of the body is used to treat hyperthermic individuals with heatstroke or to depress core temperature below normal for neuroprotection. A novel, chemically activated, unpowered cooling device, CAERvest®, was investigated for safety and efficacy. METHODS Eight healthy male participants (body mass 79.9 ± 1.9 kg and body fat percentage 16.1 ± 3.8%) visited the laboratory (20 °C, 40% relative humidity) on four occasions. Following 30-min rest, physiological and perceptual measures were recorded. Participants were then fitted with the CAERvest® proof of concept (PoC) or prototype 1 (P1), 2 (P2) or 3 (P3) for 60 min. Temperature, cardiovascular and perceptual measures were recorded every 5 min. After cooling, the CAERvest® was removed and the torso checked for cold-related injuries. RESULTS Temperature measures significantly (p < 0.05) reduced pre to post in all trials. Larger reductions in core and skin temperatures were observed for PoC (-0.36 ± 0.18 and -1.55 ± 0.97 °C) and P3 (-0.36 ± 0.22 and -2.47 ± 0.82 °C), compared with P1 and P2. No signs of cold-related injury were observed at any stage. CONCLUSION This study demonstrates that the CAERvest® is an effective device for reducing body temperature in healthy normothermic individuals without presence of cold injury. Further research in healthy and clinical populations is warranted.
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Affiliation(s)
- Ashley G B Willmott
- a Centre for Sport and Exercise Science and Medicine (SeSAME), Environmental Extremes Laboratory , University of Brighton , UK
| | - Alex Bliss
- a Centre for Sport and Exercise Science and Medicine (SeSAME), Environmental Extremes Laboratory , University of Brighton , UK
| | | | | | | | - Neil S Maxwell
- a Centre for Sport and Exercise Science and Medicine (SeSAME), Environmental Extremes Laboratory , University of Brighton , UK
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Willmott AGB, Hayes M, Waldock KAM, Relf RL, Watkins ER, James CA, Gibson OR, Smeeton NJ, Richardson AJ, Watt PW, Maxwell NS. Short-term heat acclimation prior to a multi-day desert ultra-marathon improves physiological and psychological responses without compromising immune status. J Sports Sci 2016; 35:2249-2256. [PMID: 27935427 DOI: 10.1080/02640414.2016.1265142] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
Multistage, ultra-endurance events in hot, humid conditions necessitate thermal adaptation, often achieved through short term heat acclimation (STHA), to improve performance by reducing thermoregulatory strain and perceptions of heat stress. This study investigated the physiological, perceptual and immunological responses to STHA prior to the Marathon des Sables. Eight athletes (age 42 ± 4 years and body mass 81.9 ± 15.0 kg) completed 4 days of controlled hyperthermia STHA (60 min·day‒1, 45°C and 30% relative humidity). Pre, during and post sessions, physiological and perceptual measures were recorded. Immunological measures were recorded pre-post sessions 1 and 4. STHA improved thermal comfort (P = 0.02), sensation (P = 0.03) and perceived exertion (P = 0.04). A dissociated relationship between perceptual fatigue and Tre was evident after STHA, with reductions in perceived Physical (P = 0.04) and General (P = 0.04) fatigue. Exercising Tre and HR did not change (P > 0.05) however, sweat rate increased 14% (P = 0.02). No changes were found in white blood cell counts or content (P > 0.05). Four days of STHA facilitates effective perceptual adaptations, without compromising immune status prior to an ultra-endurance race in heat stress. A greater physiological strain is required to confer optimal physiological adaptations.
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Affiliation(s)
- Ashley G B Willmott
- a Environmental Extremes Laboratory, Centre for Sport and Exercise Science and Medicine (SESAME), Sport and Exercise Science Consultancy Unit (SESCU) , University of Brighton , Eastbourne , UK
| | - Mark Hayes
- a Environmental Extremes Laboratory, Centre for Sport and Exercise Science and Medicine (SESAME), Sport and Exercise Science Consultancy Unit (SESCU) , University of Brighton , Eastbourne , UK
| | - Kirsty A M Waldock
- a Environmental Extremes Laboratory, Centre for Sport and Exercise Science and Medicine (SESAME), Sport and Exercise Science Consultancy Unit (SESCU) , University of Brighton , Eastbourne , UK
| | - Rebecca L Relf
- a Environmental Extremes Laboratory, Centre for Sport and Exercise Science and Medicine (SESAME), Sport and Exercise Science Consultancy Unit (SESCU) , University of Brighton , Eastbourne , UK
| | - Emily R Watkins
- a Environmental Extremes Laboratory, Centre for Sport and Exercise Science and Medicine (SESAME), Sport and Exercise Science Consultancy Unit (SESCU) , University of Brighton , Eastbourne , UK
| | - Carl A James
- b National Sports Institute (Institut Sukan Negara) , National Sport Complex , Kuala Lumpur , Malaysia
| | - Oliver R Gibson
- c Centre for Human Performance, Exercise and Rehabilitation , Brunel University London , London , UK
| | - Nicholas J Smeeton
- a Environmental Extremes Laboratory, Centre for Sport and Exercise Science and Medicine (SESAME), Sport and Exercise Science Consultancy Unit (SESCU) , University of Brighton , Eastbourne , UK
| | - Alan J Richardson
- a Environmental Extremes Laboratory, Centre for Sport and Exercise Science and Medicine (SESAME), Sport and Exercise Science Consultancy Unit (SESCU) , University of Brighton , Eastbourne , UK
| | - Peter W Watt
- a Environmental Extremes Laboratory, Centre for Sport and Exercise Science and Medicine (SESAME), Sport and Exercise Science Consultancy Unit (SESCU) , University of Brighton , Eastbourne , UK
| | - Neil S Maxwell
- a Environmental Extremes Laboratory, Centre for Sport and Exercise Science and Medicine (SESAME), Sport and Exercise Science Consultancy Unit (SESCU) , University of Brighton , Eastbourne , UK
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King MA, Leon LR, Morse DA, Clanton TL. Unique cytokine and chemokine responses to exertional heat stroke in mice. J Appl Physiol (1985) 2016; 122:296-306. [PMID: 27909226 DOI: 10.1152/japplphysiol.00667.2016] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2016] [Revised: 11/08/2016] [Accepted: 11/28/2016] [Indexed: 01/19/2023] Open
Abstract
In heat stroke, cytokines are believed to play important roles in multiorgan dysfunction and recovery of damaged tissue. The time course of the cytokine response is well defined in passive heat stroke (PHS), but little is known about exertional heat stroke (EHS). In this study we used a recently developed mouse EHS model to measure the responses of circulating cytokines/chemokines and cytokine gene expression in muscle. A very rapid increase in circulating IL-6 was observed at maximum core temperature (Tc,max) that peaked at 0.5 h of recovery and disappeared by 3 h. IL-10 was not elevated at any time. This contrasts with PHS where both IL-6 and IL-10 peak at 3 h of recovery. Keratinocyte chemoattractant (KC), granulocyte-colony-stimulating factor (G-CSF), macrophage inflammatory protein (MIP)-2, MIP-1β, and monocyte chemoattractive factor-1 also demonstrated near peak responses at 0.5 h. Only G-CSF and KC remained elevated at 3 h. Muscle mRNA for innate immune cytokines (IL-6, IL-10, IL-1β, but not TNF-α) were greatly increased in diaphragm and soleus compared with similar measurements in PHS. We hypothesized that these altered cytokine responses in EHS may be due to a lower Tc,max achieved in EHS or a lower overall heat load. However, when these variables were controlled for, they could not account for the differences between EHS and PHS. We conclude that moderate exercise, superimposed on heat exposure, alters the pattern of circulating cytokine and chemokine production and muscle cytokine expression in EHS. This response may comprise an endocrine reflex to exercise in heat that initiates survival pathways and early onset tissue repair mechanisms. NEW & NOTEWORTHY Immune modulators called cytokines are released following extreme hyperthermia leading to heat stroke. It is not known whether exercise in hyperthermia, leading to EHS, influences this response. Using a mouse model of EHS, we discovered a rapid accumulation of interleukin-6 and other cytokines involved in immune cell trafficking. This response may comprise a protective mechanism for early induction of cell survival and tissue repair pathways needed for recovery from thermal injury.
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Affiliation(s)
- Michelle A King
- Department of Applied Physiology and Kinesiology, College of Health and Human Performance, The University of Florida; and
| | - Lisa R Leon
- Thermal and Mountain Medicine Division, United States Army Research Institute of Environmental Medicine, Natick, Massachusetts
| | - Deborah A Morse
- Department of Applied Physiology and Kinesiology, College of Health and Human Performance, The University of Florida; and
| | - Thomas L Clanton
- Department of Applied Physiology and Kinesiology, College of Health and Human Performance, The University of Florida; and
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Separate and combined effects of exposure to heat stress and mental fatigue on endurance exercise capacity in the heat. Eur J Appl Physiol 2016; 117:119-129. [PMID: 27864637 DOI: 10.1007/s00421-016-3504-x] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2016] [Accepted: 11/11/2016] [Indexed: 12/25/2022]
Abstract
PURPOSE This study investigated the effects of exposure to pre-exercise heat stress and mental fatigue on endurance exercise capacity in a hot environment. METHODS Eight volunteers completed four cycle exercise trials at 80% maximum oxygen uptake until exhaustion in an environmental chamber maintained at 30 °C and 50% relative humidity. The four trials required them to complete a 90 min pre-exercise routine of either a seated rest (CON), a prolonged demanding cognitive task to induce mental fatigue (MF), warm water immersion at 40 °C during the last 30 min to induce increasing core temperature (WI), or a prolonged demanding cognitive task and warm water immersion at 40 °C during the last 30 min (MF + WI). RESULTS Core temperature when starting exercise was higher following warm water immersion (~38 °C; WI and MF + WI) than with no water immersion (~36.8 °C; CON and MF, P < 0.001). Self-reported mental fatigue when commencing exercise was higher following cognitive task (MF and MF + WI) than with no cognitive task (CON and WI; P < 0.05). Exercise time to exhaustion was reduced by warm water immersion (P < 0.001) and cognitive task (P < 0.05). Compared with CON (18 ± 7 min), exercise duration reduced 0.8, 26.6 and 46.3% in MF (17 ± 7 min), WI (12 ± 5 min) and MF + WI (9 ± 3 min), respectively. CONCLUSIONS This study demonstrates that endurance exercise capacity in a hot environment is impaired by either exposure to pre-exercise heat stress or mental fatigue, and this response is synergistically increased during combined exposure to them.
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A Case-Crossover Study of Heat Exposure and Injury Risk in Outdoor Agricultural Workers. PLoS One 2016; 11:e0164498. [PMID: 27716794 PMCID: PMC5055365 DOI: 10.1371/journal.pone.0164498] [Citation(s) in RCA: 62] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2016] [Accepted: 09/26/2016] [Indexed: 11/29/2022] Open
Abstract
Background Recent research suggests that heat exposure may increase the risk of traumatic injuries. Published heat-related epidemiological studies have relied upon exposure data from individual weather stations. Objective To evaluate the association between heat exposure and traumatic injuries in outdoor agricultural workers exposed to ambient heat and internal heat generated by physical activity using modeled ambient exposure data. Methods A case-crossover study using time-stratified referent selection among 12,213 outdoor agricultural workers with new Washington State Fund workers’ compensation traumatic injury claims between 2000 and 2012 was conducted. Maximum daily Humidex exposures, derived from modeled meteorological data, were assigned to latitudes and longitudes of injury locations on injury and referent dates. Conditional logistic regression was used to estimate odds ratios of injury for a priori daily maximum Humidex categories. Results The mean of within-stratum (injury day and corresponding referent days) standard deviations of daily maximum Humidex was 4.8. The traumatic injury odds ratio was 1.14 (95% confidence interval 1.06, 1.22), 1.15 (95% confidence interval 1.06, 1.25), and 1.10 (95% confidence interval 1.01, 1.20) for daily maximum Humidex of 25–29, 30–33, and ≥34, respectively, compared to < 25, adjusted for self-reported duration of employment. Stronger associations were observed during cherry harvest duties in the June and July time period, compared to all duties over the entire study period. Conclusions Agricultural workers laboring in warm conditions are at risk for heat-related traumatic injuries. Combined heat-related illness and injury prevention efforts should be considered in high-risk populations exposed to warm ambient conditions in the setting of physical exertion.
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Sefton JM, McAdam JS, Pascoe DD, Lohse KR, Banda RL, Henault CB, Cherrington AR, Adams NE. Evaluation of 2 Heat-Mitigation Methods in Army Trainees. J Athl Train 2016; 51:936-945. [PMID: 27710091 DOI: 10.4085/1062-6050-51.10.13] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
CONTEXT Heat injury is a significant threat to military trainees. Different methods of heat mitigation are in use across military units. Mist fans are 1 of several methods used in the hot and humid climate of Fort Benning, Georgia. OBJECTIVES To determine if (1) the mist fan or the cooling towel effectively lowered participant core temperature in the humid environment found at Fort Benning and (2) the mist fan or the cooling towel presented additional physiologic or safety benefits or detriments when used in this environment. DESIGN Randomized controlled clinical trial. SETTING Laboratory environmental chamber. PATIENTS OR OTHER PARTICIPANTS Thirty-five physically active men aged 19 to 35 years. INTERVENTION(S) (1) Mist fan, (2) commercial cooling towel, (3) passive-cooling (no intervention) control. All treatments lasted 20 minutes. Participants ran on a treadmill at 60% V̇o2max. MAIN OUTCOME MEASURE(S) Rectal core temperature, heart rate, thermal comfort, perceived temperature, perceived wetness, and blood pressure. RESULTS Average core temperature increased during 20 minutes of cooling (F1,28 = 64.76, P < .001, ηp2 = 0.70), regardless of group (F1,28 = 3.41, P = .08, ηp2 = 0.11) or condition (F1,28 < 1.0). Core temperature, heart rate, and blood pressure did not differ among the 3 conditions. Perceived temperature during 20 minutes of cooling decreased (F1,30 = 141.19, P < .001, ηp2 = 0.83) regardless of group or condition. Perceived temperature was lower with the mist-fan treatment than with the control treatment (F1,15 = 7.38, P = .02, ηp2 = 0.32). The mist-fan group perceived themselves to be cooler even at elevated core temperatures. CONCLUSIONS The mist fan and cooling towel were both ineffective at lowering core temperature. Core temperature continued to increase after exercise in all groups. The mist fan produced feelings of coolness while the core temperature remained elevated, possibly increasing the risk of heat illness.
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Affiliation(s)
- JoEllen M Sefton
- Warrior Research Center, School of Kinesiology, Auburn University, AL
| | - J S McAdam
- Warrior Research Center, School of Kinesiology, Auburn University, AL
| | - David D Pascoe
- Warrior Research Center, School of Kinesiology, Auburn University, AL
| | - K R Lohse
- Warrior Research Center, School of Kinesiology, Auburn University, AL
| | | | - Corbin B Henault
- Warrior Research Center, School of Kinesiology, Auburn University, AL
| | | | - N E Adams
- Warrior Research Center, School of Kinesiology, Auburn University, AL
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234
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Fernandes AA, Moreira DG, Brito CJ, da Silva CD, Sillero-Quintana M, Pimenta EM, Bach AJE, Garcia ES, Bouzas Marins JC. Validity of inner canthus temperature recorded by infrared thermography as a non-invasive surrogate measure for core temperature at rest, during exercise and recovery. J Therm Biol 2016; 62:50-55. [PMID: 27839549 PMCID: PMC7117007 DOI: 10.1016/j.jtherbio.2016.09.010] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2016] [Revised: 09/28/2016] [Accepted: 09/28/2016] [Indexed: 12/15/2022]
Abstract
Research into obtaining a fast, valid, reliable and non-invasive measure of core temperature is of interest in many disciplinary fields. Occupational and sports medicine research has attempted to determine a non-invasive proxy for core temperature particularly when access to participants is limited and thermal safety is of a concern due to protective encapsulating clothing, hot ambient environments and/or high endogenous heat production during athletic competition. This investigation aimed to determine the validity of inner canthus of the eye temperature (TEC) as an alternate non-invasive measure of intestinal core temperature (TC) during rest, exercise and post-exercise conditions. Twelve physically active males rested for 30 min prior to exercise, performed 60 min of aerobic exercise at 60% V̇O2max and passively recovered a further 60 min post-exercise. TEC and TC were measured at 5 min intervals during each condition. Mean differences between TEC and TC were 0.61 °C during pre-exercise, −1.78 °C during exercise and −1.00 °C during post-exercise. The reliability between the methods was low in the pre-exercise (ICC=0.49 [−0.09 to 0.82]), exercise (ICC=−0.14 [−0.65 to 0.44]) and post-exercise (ICC=−0.25 [−0.70 to 0.35]) conditions. In conclusion, poor agreement was observed between the TEC values measured through IRT and TC measured through a gastrointestinal telemetry pill. Therefore, TEC is not a valid substitute measurement to gastrointestinal telemetry pill in sports and exercise science settings. Inner canthus of the eye is not a valid measure of intestinal core temperature. Inner canthus of the eye temperature has severe errors in exercises settings. The variability is more evident in the aerobic exercise and post-exercise conditions.
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Affiliation(s)
- Alex Andrade Fernandes
- Federal Institute for Education, Sciences and Technology of Minas Gerais, Campus Ipatinga and Governador Valadares, Brazil
| | - Danilo Gomes Moreira
- Federal Institute for Education, Sciences and Technology of Minas Gerais, Campus Ipatinga and Governador Valadares, Brazil.
| | - Ciro José Brito
- Department of Physical Education, Federal University of Juiz de Fora, Governador Valadares, Brazil
| | - Cristiano Diniz da Silva
- Department of Physical Education, Federal University of Juiz de Fora, Governador Valadares, Brazil
| | - Manuel Sillero-Quintana
- Faculty of Physical Activity and Sport Sciences, Universidad Politécnica de Madrid, Madrid, Spain
| | | | - Aaron J E Bach
- School of Exercise and Nutrition Sciences and Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, Australia
| | | | - João Carlos Bouzas Marins
- Department of Physical Education, Human Performance Laboratory, Federal University of Viçosa, Viçosa, Brazil
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235
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Morris NB, Coombs G, Jay O. Ice Slurry Ingestion Leads to a Lower Net Heat Loss during Exercise in the Heat. Med Sci Sports Exerc 2016; 48:114-22. [PMID: 26258857 DOI: 10.1249/mss.0000000000000746] [Citation(s) in RCA: 52] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
PURPOSE To compare the reductions in evaporative heat loss from the skin (Esk) to internal heat loss (Hfluid) induced by ice slurry (ICE) ingestion relative to 37 °C fluid and the accompanying body temperature and local thermoeffector responses during exercise in warm, dry conditions (33.5 °C ± 1.4 °C; 23.7% ± 2.6% relative humidity [RH]). METHODS Nine men cycled at approximately 55% VO2peak for 75 min and ingested 3.2 mL · kg(-1) aliquots of 37 °C fluid or ICE after 15, 30, and 45 min of exercise. Metabolic heat production (M-W), rectal temperature (Tre), mean skin temperature (Tsk), whole-body sweat loss (WBSL), local sweat rate (LSR), and skin blood flow (SkBF) were measured throughout. Net heat loss (HLnet) and heat storage (S) were estimated using partitional calorimetry. RESULTS Relative to the 37 °C trial, M-W was similar (P = 0.81) with ICE ingestion; however, the 200 ± 20 kJ greater Hfluid (P < 0.001) with ICE ingestion was overcompensated by a 381 ± 199-kJ lower Esk (P < 0.001). Net heat loss (HLnet) was consequently 131 ± 120 kJ lower (P = 0.01) and S was greater (P = 0.05) with ICE ingestion compared with 37 °C fluid ingestion. Concurrently, LSR and WBSL were lower by 0.16 ± 0.14 mg · min(-1) · cm(-2) (P < 0.01) and 191 ± 122 g (P < 0.001), respectively, and SkBF tended to be lower (P = 0.06) by 5.4%maxAU ± 13.4%maxAU in the ICE trial. Changes in Tre and Tsk were similar throughout exercise with ICE compared to 37 °C fluid ingestion. CONCLUSIONS Relative to 37 °C, ICE ingestion caused disproportionately greater reductions in Esk relative to Hfluid, resulting in a lower HLnet and greater S. Mechanistically, LSR and possibly SkBF were suppressed independently of Tre or Tsk, reaffirming the concept of human abdominal thermoreception. From a heat balance perspective, recommendations for ICE ingestion during exercise in warm, dry conditions should be reconsidered.
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Affiliation(s)
- Nathan B Morris
- 1School of Human Kinetics, University of Ottawa, Ottawa, ON, CANADA; and 2Thermal Ergonomics Laboratory, Exercise and Sports Science, Faculty of Health Sciences, University of Sydney, NSW, AUSTRALIA
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236
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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: 109] [Impact Index Per Article: 13.6] [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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237
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Ross JA, Shipp EM, Trueblood AB, Bhattacharya A. Ergonomics and Beyond: Understanding How Chemical and Heat Exposures and Physical Exertions at Work Affect Functional Ability, Injury, and Long-Term Health. HUMAN FACTORS 2016; 58:777-795. [PMID: 27125533 PMCID: PMC6894162 DOI: 10.1177/0018720816645457] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/03/2015] [Accepted: 03/12/2016] [Indexed: 06/05/2023]
Abstract
OBJECTIVE To honor Tom Waters's work on emerging occupational health issues, we review the literature on physical along with chemical exposures and their impact on functional outcomes. BACKGROUND Many occupations present the opportunity for exposure to multiple hazardous exposures, including both physical and chemical factors. However, little is known about how these different factors affect functional ability and injury. The goal of this review is to examine the relationships between these exposures, impairment of the neuromuscular and musculoskeletal systems, functional outcomes, and health problems with a focus on acute injury. METHOD Literature was identified using online databases, including PubMed, Ovid Medline, and Google Scholar. References from included articles were searched for additional relevant articles. RESULTS This review documented the limited existing literature that discussed cognitive impairment and functional disorders via neurotoxicity for physical exposures (heat and repetitive loading) and chemical exposures (pesticides, volatile organic compounds [VOCs], and heavy metals). CONCLUSION This review supports that workers are exposed to physical and chemical exposures that are associated with negative health effects, including functional impairment and injury. Innovation in exposure assessment with respect to quantifying the joint exposure to these different exposures is especially needed for developing risk assessment models and, ultimately, preventive measures. APPLICATION Along with physical exposures, chemical exposures need to be considered, alone and in combination, in assessing functional ability and occupationally related injuries.
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Affiliation(s)
- Jennifer A Ross
- Texas A&M University, College StationUniversity of Cincinnati, Ohio
| | - Eva M Shipp
- Texas A&M University, College StationUniversity of Cincinnati, Ohio
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238
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Akerman AP, Tipton M, Minson CT, Cotter JD. Heat stress and dehydration in adapting for performance: Good, bad, both, or neither? Temperature (Austin) 2016; 3:412-436. [PMID: 28349082 PMCID: PMC5356617 DOI: 10.1080/23328940.2016.1216255] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2016] [Revised: 07/15/2016] [Accepted: 07/20/2016] [Indexed: 01/14/2023] Open
Abstract
Physiological systems respond acutely to stress to minimize homeostatic disturbance, and typically adapt to chronic stress to enhance tolerance to that or a related stressor. It is legitimate to ask whether dehydration is a valuable stressor in stimulating adaptation per se. While hypoxia has had long-standing interest by athletes and researchers as an ergogenic aid, heat and nutritional stressors have had little interest until the past decade. Heat and dehydration are highly interlinked in their causation and the physiological strain they induce, so their individual roles in adaptation are difficult to delineate. The effectiveness of heat acclimation as an ergogenic aid remains unclear for team sport and endurance athletes despite several recent studies on this topic. Very few studies have examined the potential ergogenic (or ergolytic) adaptations to ecologically-valid dehydration as a stressor in its own right, despite longstanding evidence of relevant fluid-regulatory adaptations from short-term hypohydration. Transient and self-limiting dehydration (e.g., as constrained by thirst), as with most forms of stress, might have a time and a place in physiological or behavioral adaptations independently or by exacerbating other stressors (esp. heat); it cannot be dismissed without the appropriate evidence. The present review did not identify such evidence. Future research should identify how the magnitude and timing of dehydration might augment or interfere with the adaptive processes in behaviorally constrained versus unconstrained humans.
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Affiliation(s)
- Ashley Paul Akerman
- School of Physical Education, Sport and Exercise Sciences, Division of Sciences, University of Otago , New Zealand
| | - Michael Tipton
- Extreme Environments Laboratory, Department of Sport & Exercise Science, University of Portsmouth , UK
| | | | - James David Cotter
- School of Physical Education, Sport and Exercise Sciences, Division of Sciences, University of Otago , New Zealand
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239
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Mee JA, Gibson OR, Tuttle JA, Taylor L, Watt PW, Doust J, Maxwell NS. Leukocyte Hsp72 mRNA transcription does not differ between males and females during heat acclimation. Temperature (Austin) 2016; 3:549-556. [PMID: 28090558 DOI: 10.1080/23328940.2016.1214336] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2016] [Revised: 07/12/2016] [Accepted: 07/13/2016] [Indexed: 12/31/2022] Open
Abstract
Purpose: Thermotolerance is an acquired state of increased cytoprotection achieved following single or repeated exposures to heat stress, in part characterized by changes in the intracellular 72 kda heat shock protein (HSP72; HSPA1A). Females have demonstrated reduced exercise induced HSP72 in comparison to males. This study examined sex differences in heat shock protein 72 messenger ribonucleic acid (Hsp72 mRNA) transcription during heat acclimation (HA) to identify whether sex differences were a result of differential gene transcription. Methods: Ten participants (5M, 5F) performed 10, 90 min controlled hyperthermia [rectal temperature (Tre) ≥ 38.5°C] HA sessions over 12 d. Leukocyte Hsp72 mRNA was measured pre and post D1, D5, and D10, via Reverse transcription polymerase chain reaction (RT-QPCR). Results: HA was evidenced by a reduction in resting Tre (-0.4 ± 0.5°C) and resting heart rate [(HR); -13 ± 7 beats.min-1] following HA (p ≤ 0.05). During HA no difference (p > 0.05) was observed in ΔTre between males (D1 = 1.5 ± 0.2°C; D5 = 1.6 ± 0.4°C; D10 = 1.8 ± 0.3°C) and females (D1 = 1.5 ± 0.5°C; D5 = 1.4 ± 0.2°C; D10 = 1.8 ± 0.3°C). This was also true of mean Tre demonstrating equality of thermal stimuli for mRNA transcription and HA. There were no differences (p > 0.05) in Hsp72 mRNA expression between HA sessions or between males (D1 = +1.8 ± 1.5-fold; D5 = +2.0 ± 1.0 fold; D10 = +1.1 ± 0.4-fold) and females (D1 = +2.6 ± 1.8-fold; D5 = +1.8 ± 1.4-fold; D10 = +0.9 ± 1.9-fold). Conclusions: This experiment demonstrates that there is no difference in Hsp72 mRNA increases during HA between sexes when controlled hyperthermia HA is utilised. Gender specific differences in exercise-induced HSP72 reported elsewhere likely result from post-transcriptional events.
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Affiliation(s)
- J A Mee
- Centre for Sport and Exercise Science and medicine (SESAME), Environmental Extremes Laboratory, University of Brighton, Welkin Human Performance Laboratories, Denton Road, Eastbourne, UK; School of Sport, Health, and Exercise Science, Bangor University, Bangor, UK
| | - O R Gibson
- Centre for Sport and Exercise Science and medicine (SESAME), Environmental Extremes Laboratory, University of Brighton, Welkin Human Performance Laboratories, Denton Road, Eastbourne, UK; Centre for Human Performance, Exercise and Rehabilitation (CHPER), Brunel University, London, UK
| | - J A Tuttle
- Muscle Cellular and Molecular Physiology (MCMP) and Applied Sport and Exercise Science (ASEP) Research Groups, Institute of Sport and Physical Activity Research (ISPAR), University of Bedfordshire , Bedford, UK
| | - L Taylor
- ASPETAR, Qatar Orthopaedic and Sports Medicine Hospital, Athlete Health and Performance Research Centre, Aspire Zone, Doha, Qatar; School of Sport, Exercise and Health Sciences. Loughborough University, Loughborough, UK
| | - P W Watt
- Centre for Sport and Exercise Science and medicine (SESAME), Environmental Extremes Laboratory, University of Brighton, Welkin Human Performance Laboratories , Denton Road , Eastbourne, UK
| | - J Doust
- Centre for Sport and Exercise Science and medicine (SESAME), Environmental Extremes Laboratory, University of Brighton, Welkin Human Performance Laboratories , Denton Road , Eastbourne, UK
| | - N S Maxwell
- Centre for Sport and Exercise Science and medicine (SESAME), Environmental Extremes Laboratory, University of Brighton, Welkin Human Performance Laboratories , Denton Road , Eastbourne, UK
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240
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Lovering AT, Elliott JE, Davis JT. Physiological impact of patent foramen ovale on pulmonary gas exchange, ventilatory acclimatization, and thermoregulation. J Appl Physiol (1985) 2016; 121:512-7. [PMID: 27418686 DOI: 10.1152/japplphysiol.00192.2015] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
The foramen ovale, which is part of the normal fetal cardiopulmonary circulation, fails to close after birth in ∼35% of the population and represents a potential source of right-to-left shunt. Despite the prevalence of patent foramen ovale (PFO) in the general population, cardiopulmonary, exercise, thermoregulatory, and altitude physiologists may have underestimated the potential effect of this shunted blood flow on normal physiological processes in otherwise healthy humans. Because this shunted blood bypasses the respiratory system, it would not participate in either gas exchange or respiratory system cooling and may have impacts on other physiological processes that remain undetermined. The consequences of this shunted blood flow in PFO-positive (PFO+) subjects can potentially have a significant, and negative, impact on the alveolar-to-arterial oxygen difference (AaDO2), ventilatory acclimatization to high altitude and respiratory system cooling with PFO+ subjects having a wider AaDO2 at rest, during exercise after acclimatization, blunted ventilatory acclimatization, and a higher core body temperature (∼0.4(°)C) at rest and during exercise. There is also an association of PFO with high-altitude pulmonary edema and acute mountain sickness. These effects on physiological processes are likely dependent on both the presence and size of the PFO, with small PFOs not likely to have significant/measureable effects. The PFO can be an important determinant of normal physiological processes and should be considered a potential confounder to the interpretation of former and future data, particularly in small data sets where a significant number of PFO+ subjects could be present and significantly impact the measured outcomes.
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Affiliation(s)
- Andrew T Lovering
- University of Oregon, Department of Human Physiology, Eugene, Oregon;
| | - Jonathan E Elliott
- Oregon Health & Science University, Department of Neurology and VA Portland Health Care System, Portland, Oregon; and
| | - James T Davis
- Indiana State University, Department of Kinesiology, Recreation, and Sport, Terre Haute, Indiana
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241
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Taylor NA, Peoples GE, Petersen SR. Load carriage, human performance, and employment standards. Appl Physiol Nutr Metab 2016; 41:S131-47. [DOI: 10.1139/apnm-2015-0486] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
The focus of this review is on the physiological considerations necessary for developing employment standards within occupations that have a heavy reliance on load carriage. Employees within military, fire fighting, law enforcement, and search and rescue occupations regularly work with heavy loads. For example, soldiers often carry loads >50 kg, whilst structural firefighters wear 20–25 kg of protective clothing and equipment, in addition to carrying external loads. It has long been known that heavy loads modify gait, mobility, metabolic rate, and efficiency, while concurrently elevating the risk of muscle fatigue and injury. In addition, load carriage often occurs within environmentally stressful conditions, with protective ensembles adding to the thermal burden of the workplace. Indeed, physiological strain relates not just to the mass and dimensions of carried objects, but to how those loads are positioned on and around the body. Yet heavy loads must be borne by men and women of varying body size, and with the expectation that operational capability will not be impinged. This presents a recruitment conundrum. How do employers identify capable and injury-resistant individuals while simultaneously avoiding discriminatory selection practices? In this communication, the relevant metabolic, cardiopulmonary, and thermoregulatory consequences of loaded work are reviewed, along with concomitant impediments to physical endurance and mobility. Also emphasised is the importance of including occupation-specific clothing, protective equipment, and loads during work-performance testing. Finally, recommendations are presented for how to address these issues when evaluating readiness for duty.
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Affiliation(s)
- Nigel A.S. Taylor
- Centre for Human and Applied Physiology, School of Medicine, University of Wollongong, Wollongong, NSW 2522, Australia
| | - Gregory E. Peoples
- Centre for Human and Applied Physiology, School of Medicine, University of Wollongong, Wollongong, NSW 2522, Australia
| | - Stewart R. Petersen
- Faculty of Physical Education and Recreation, University of Alberta, Edmonton, AB T6G 2R3, Canada
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Wang J, Wang S, Zhang W, Wang T, Li P, Zhao X, Niu C, Liu Y, Wang X, Ma Q. Proteomic profiling of heat acclimation in cerebrospinal fluid of rabbit. J Proteomics 2016; 144:113-22. [PMID: 27208788 DOI: 10.1016/j.jprot.2016.04.028] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2015] [Revised: 04/06/2016] [Accepted: 04/20/2016] [Indexed: 10/21/2022]
Abstract
UNLABELLED Heat acclimation (AC) is a phenotypic adaptation to the high ambient temperatures. So far, the physiological effects of AC have been well studied, but the molecular mechanisms underlying it, especially the proteomic studies have been rarely reported. Conducting a protein profile of cerebrospinal fluid (CSF) can facilitate the understanding of molecular pathways involved in AC and identifying stress-specific proteins as a laboratory biomarker. In this study we carried out proteomic profiling of the AC in CSF of rabbit, which would allow a deep insight into molecular signals underlying the AC. For this purpose, rabbits were subjected to AC (dry bulb temperature of (36±1)°C, wet bulb temperature of (29±0.5)°C, black-bulb temperature of (40±1.0)°C, 100min per day for 21days, untreated rabbits were used as controls. We adopted a gel-free proteomic approach (iTRAQ) method to identify protein composition in CSF of rabbits with AC. In total, 1310 proteins were identified. Among which 127 were significant up-regulated and 77 were down-regulated. According to the functions, all AC-induced proteins were classified into 8 categories, including plasma protein factors, metabolism-related proteins, energy metabolism-related proteins, cell surface/intercellular matrix proteins, stress related proteins, tumor-related proteins, as well as housekeeping proteins and putative proteins. Meanwhile, a total of 21 pathways were found involved in the developing of AC. Further analysis indicated that proteins mostly close to AC were grouped into two signal pathways, the immune-related signal pathways and the carbohydrate/lipoprotein metabolism-related signal pathways. Our study was first to carry out the whole proteomic picture of AC, and screen out the critical signaling pathways involved in this physical procedure. BIOLOGICAL SIGNIFICANCE This study reported the comparative proteomic analysis of cerebrospinal fluid of rabbits between heat acclimation and normal conditions using the gel-free proteomic mass-spectrometry approach with isotope-labeled samples (iTRAQ) techniques. Mass spectrometry analysis of the proteins from heat acclimated rabbits resulted in the identification of a total of 1310 proteins, among these, 204 proteins were related to the formation of heat acclimation. These proteins were assigned to 8 categories according to their functions. Additionally, 21 pathways involved in infectious diseases, metabolism, immunology, blood circulation, transcriptional regulation and renin-angiotensin were identified by pathway analysis in heat acclimation. This study was the first to use rabbits as a model for unraveling the molecular pathways underlying the establishment of integrative heat acclimation.
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Affiliation(s)
- Jing Wang
- Department of Tropical Medicine, Tianjin Institute of Health and Environmental Medicine, Tianjin, China
| | - Shang Wang
- Department of Tropical Medicine, Tianjin Institute of Health and Environmental Medicine, Tianjin, China
| | - Wencheng Zhang
- Department of Tropical Medicine, Tianjin Institute of Health and Environmental Medicine, Tianjin, China
| | - Tao Wang
- Department of Tropical Medicine, Tianjin Institute of Health and Environmental Medicine, Tianjin, China
| | - Peiyao Li
- Department of Tropical Medicine, Tianjin Institute of Health and Environmental Medicine, Tianjin, China
| | - Xiaoling Zhao
- Department of Tropical Medicine, Tianjin Institute of Health and Environmental Medicine, Tianjin, China
| | - Chao Niu
- Department of Tropical Medicine, Tianjin Institute of Health and Environmental Medicine, Tianjin, China
| | - Ying Liu
- Department of Tropical Medicine, Tianjin Institute of Health and Environmental Medicine, Tianjin, China
| | - Xinxing Wang
- Department of Tropical Medicine, Tianjin Institute of Health and Environmental Medicine, Tianjin, China
| | - Qiang Ma
- Department of Occupational Health, Tianjin Institute of Health and Environmental Medicine, Tianjin, China.
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Castellani JW, Zambraski EJ, Sawka MN, Urso ML. Does high muscle temperature accentuate skeletal muscle injury from eccentric exercise? Physiol Rep 2016; 4:4/9/e12777. [PMID: 27185904 PMCID: PMC4873630 DOI: 10.14814/phy2.12777] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2016] [Accepted: 03/24/2016] [Indexed: 01/04/2023] Open
Abstract
Hyperthermia is suspected of accentuating skeletal muscle injury from novel exercise, but this has not been well studied. This study examined if high muscle temperatures alters skeletal muscle injury induced by eccentric exercise (ECC). Eight volunteers (age, 22.5 ± 4.1 year; height, 169.5 ± 10.8 cm; body mass, 76.2 ± 12.6 kg), serving as their own control, and who were not heat acclimatized, completed two elbow flexor ECC trials; in one trial the biceps were heated >40°C (HEAT) and in the other trial there was no heating (NON). HEAT was applied with shortwave diathermy (100 W) for 15 min immediately before the first ECC bout and for 2 min in between each bout. Individuals were followed for 10 days after each ECC session, with a 6‐week washout period between arms. The maximal voluntary isometric contraction decreased by 41 ± 17% and 46 ± 20% in the NON and HEAT trials, respectively. Bicep circumference increased by 0.07 ± 0.08 mm (4%, P = 0.04) and relaxed range of motion decreased by 11.5 ± 8.2° (30%, P < 0.001) in both trials. Serum creatine kinase peaked 72‐h following ECC (NON: 6289 ± 10407; HEAT: 5486 ± 6229 IU L−1, 38‐fold increase, P < 0.01) as did serum myoglobin (NON: 362 ± 483; HEAT: 355 ± 373 μg L−1, 13‐fold increase, P < 0.03). Plasma HSP 70 was higher (P < 0.02) in HEAT after 120‐h of recovery. There were no differences between treatments for plasma HSP27 and interleukins 1β, 6, and 10. The results indicate that >40°C muscle temperature does not alter skeletal muscle injury or functional impairments induced by novel ECC.
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Affiliation(s)
- John W Castellani
- U.S. Army Research Institute of Environmental Medicine, Natick, Massachusetts
| | - Edward J Zambraski
- U.S. Army Research Institute of Environmental Medicine, Natick, Massachusetts
| | - Michael N Sawka
- U.S. Army Research Institute of Environmental Medicine, Natick, Massachusetts
| | - Maria L Urso
- U.S. Army Research Institute of Environmental Medicine, Natick, Massachusetts
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Ruddock AD, Thompson SW, Hudson SA, James CA, Gibson OR, Mee JA. Combined active and passive heat exposure induced heat acclimation in a soccer referee before 2014 FIFA World Cup. SPRINGERPLUS 2016; 5:617. [PMID: 27330883 PMCID: PMC4870546 DOI: 10.1186/s40064-016-2298-y] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/19/2016] [Accepted: 05/06/2016] [Indexed: 11/10/2022]
Abstract
INTRODUCTION The 2014 FIFA World Cup was held in Brazil, where the climatic conditions presented a significant thermoregulatory and perceptual challenge to those unfamiliar with the heat and humidity. CASE PRESENTATION This case report documents the adaptation induced by a novel mixed methods (isothermic and passive) heat acclimation (HA) regime for a northern European professional soccer match official prior to the tournament. The intervention involved 13 HA sessions over an 18 day period comprising five isothermic HA sessions whereby intermittent running was used to target and maintain tympanic temperature (Tytemp) at 38 °C for 90 min, and seven passive HA sessions of 48 °C water bathing for 30 min. The athlete performed a heat stress test (HST) (35 min running at four incremental intensities in 30 °C) and a repeated high-intensity running test (as many 30 s self-paced efforts as possible, to a maximum of 20, with 30 s passive recovery) before and after the intervention. The mixed methods HA regime increased plasma volume (+7.1 %), and sweat loss (+0.9 L h(-1)), reduced exercising Tytemp (-0.6 °C), and mean body temperature (-0.5 °C). High-intensity running performance improved after HA (+29 %), as did the perception of thermal comfort during exercise (-0.3 units). CONCLUSION This data evidences the effectiveness of a practical, mixed methods HA strategy, remotely implemented around training and competition, at inducing the heat acclimation phenotype in a high-level soccer match official.
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Affiliation(s)
- A D Ruddock
- A016 Collegiate Hall, Centre for Sport and Exercise Science, Sheffield Hallam University, Sheffield, South Yorkshire S10 2BP UK
| | - S W Thompson
- Academy of Sport and Physical Activity, A209 Collegiate Hall, Sheffield Hallam University, Collegiate Crescent Campus, Eccelsall Road, Sheffield, S10 2BP UK
| | - S A Hudson
- Department of Sport, Health and Nutrition, Leeds Trinity University, Brownberrie Lane, Horsforth, Leeds, LS18 5HD UK
| | - C A James
- Environmental Extremes Laboratory, Centre for Sport and Exercise Science and Medicine (SESAME), University of Brighton, Welkin Laboratories, Denton Road, Eastbourne, East Sussex BN20 7SR UK
| | - O R Gibson
- Centre for Sports Medicine and Human Performance (CSMHP), Heinz Wolff Building, Brunel University London, Uxbridge, UB8 3PH UK
| | - J A Mee
- School of Sport and Health Sciences, George Building, Bangor University, Bangor, UK
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Casa DJ, DeMartini JK, Bergeron MF, Csillan D, Eichner ER, Lopez RM, Ferrara MS, Miller KC, O'Connor F, Sawka MN, Yeargin SW. National Athletic Trainers' Association Position Statement: Exertional Heat Illnesses. J Athl Train 2016; 50:986-1000. [PMID: 26381473 DOI: 10.4085/1062-6050-50.9.07] [Citation(s) in RCA: 331] [Impact Index Per Article: 41.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
OBJECTIVE To present best-practice recommendations for the prevention, recognition, and treatment of exertional heat illnesses (EHIs) and to describe the relevant physiology of thermoregulation. BACKGROUND Certified athletic trainers recognize and treat athletes with EHIs, often in high-risk environments. Although the proper recognition and successful treatment strategies are well documented, EHIs continue to plague athletes, and exertional heat stroke remains one of the leading causes of sudden death during sport. The recommendations presented in this document provide athletic trainers and allied health providers with an integrated scientific and clinically applicable approach to the prevention, recognition, treatment of, and return-to-activity guidelines for EHIs. These recommendations are given so that proper recognition and treatment can be accomplished in order to maximize the safety and performance of athletes. RECOMMENDATIONS Athletic trainers and other allied health care professionals should use these recommendations to establish onsite emergency action plans for their venues and athletes. The primary goal of athlete safety is addressed through the appropriate prevention strategies, proper recognition tactics, and effective treatment plans for EHIs. Athletic trainers and other allied health care professionals must be properly educated and prepared to respond in an expedient manner to alleviate symptoms and minimize the morbidity and mortality associated with these illnesses.
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Affiliation(s)
| | | | | | | | - E Randy Eichner
- University of Oklahoma Health Sciences Center, Oklahoma City
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Tyler CJ, Reeve T, Hodges GJ, Cheung SS. The Effects of Heat Adaptation on Physiology, Perception and Exercise Performance in the Heat: A Meta-Analysis. Sports Med 2016; 46:1699-1724. [DOI: 10.1007/s40279-016-0538-5] [Citation(s) in RCA: 167] [Impact Index Per Article: 20.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
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Davis JK, Baker LB, Barnes K, Ungaro C, Stofan J. Thermoregulation, Fluid Balance, and Sweat Losses in American Football Players. Sports Med 2016; 46:1391-405. [DOI: 10.1007/s40279-016-0527-8] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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Bain AR, Nybo L, Ainslie PN. Cerebral Vascular Control and Metabolism in Heat Stress. Compr Physiol 2016; 5:1345-80. [PMID: 26140721 DOI: 10.1002/cphy.c140066] [Citation(s) in RCA: 64] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
This review provides an in-depth update on the impact of heat stress on cerebrovascular functioning. The regulation of cerebral temperature, blood flow, and metabolism are discussed. We further provide an overview of vascular permeability, the neurocognitive changes, and the key clinical implications and pathologies known to confound cerebral functioning during hyperthermia. A reduction in cerebral blood flow (CBF), derived primarily from a respiratory-induced alkalosis, underscores the cerebrovascular changes to hyperthermia. Arterial pressures may also become compromised because of reduced peripheral resistance secondary to skin vasodilatation. Therefore, when hyperthermia is combined with conditions that increase cardiovascular strain, for example, orthostasis or dehydration, the inability to preserve cerebral perfusion pressure further reduces CBF. A reduced cerebral perfusion pressure is in turn the primary mechanism for impaired tolerance to orthostatic challenges. Any reduction in CBF attenuates the brain's convective heat loss, while the hyperthermic-induced increase in metabolic rate increases the cerebral heat gain. This paradoxical uncoupling of CBF to metabolism increases brain temperature, and potentiates a condition whereby cerebral oxygenation may be compromised. With levels of experimentally viable passive hyperthermia (up to 39.5-40.0 °C core temperature), the associated reduction in CBF (∼ 30%) and increase in cerebral metabolic demand (∼ 10%) is likely compensated by increases in cerebral oxygen extraction. However, severe increases in whole-body and brain temperature may increase blood-brain barrier permeability, potentially leading to cerebral vasogenic edema. The cerebrovascular challenges associated with hyperthermia are of paramount importance for populations with compromised thermoregulatory control--for example, spinal cord injury, elderly, and those with preexisting cardiovascular diseases.
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Affiliation(s)
- Anthony R Bain
- Centre for Heart Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia, Okanagan Campus, Kelowna, Canada
| | - Lars Nybo
- Department of Nutrition, Exercise and Sport Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Philip N Ainslie
- Centre for Heart Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia, Okanagan Campus, Kelowna, Canada
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Cardiovascular adaptations supporting human exercise-heat acclimation. Auton Neurosci 2016; 196:52-62. [DOI: 10.1016/j.autneu.2016.02.002] [Citation(s) in RCA: 148] [Impact Index Per Article: 18.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2015] [Revised: 01/29/2016] [Accepted: 02/04/2016] [Indexed: 11/22/2022]
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Abstract
Exercising in the heat induces thermoregulatory and other physiological strain that can lead to impairments in endurance exercise capacity. The purpose of this consensus statement is to provide up-to-date recommendations to optimize performance during sporting activities undertaken in hot ambient conditions. The most important intervention one can adopt to reduce physiological strain and optimize performance is to heat acclimatize. Heat acclimatization should comprise repeated exercise–heat exposures over 1–2 weeks. In addition, athletes should initiate competition and training in an euhydrated state and minimize dehydration during exercise. Following the development of commercial cooling systems (e.g., cooling vests), athletes can implement cooling strategies to facilitate heat loss or increase heat storage capacity before training or competing in the heat. Moreover, event organizers should plan for large shaded areas, along with cooling and rehydration facilities, and schedule events in accordance with minimizing the health risks of athletes, especially in mass participation events and during the first hot days of the year. Following the recent examples of the 2008 Olympics and the 2014 FIFA World Cup, sport governing bodies should consider allowing additional (or longer) recovery periods between and during events for hydration and body cooling opportunities when competitions are held in the heat.
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