1
|
Heydenreich J, Koehler K, Braun H, Grosshauser M, Heseker H, Koenig D, Lampen A, Mosler S, Niess A, Schek A, Carlsohn A. Effects of internal cooling on physical performance, physiological and perceptional parameters when exercising in the heat: A systematic review with meta-analyses. Front Physiol 2023; 14:1125969. [PMID: 37113693 PMCID: PMC10126464 DOI: 10.3389/fphys.2023.1125969] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2023] [Accepted: 03/27/2023] [Indexed: 04/29/2023] Open
Abstract
Background: An elevated core temperature (Tcore) increases the risk of performance impairments and heat-related illness. Internal cooling (IC) has the potential to lower Tcore when exercising in the heat. The aim of the review was to systematically analyze the effects of IC on performance, physiological, and perceptional parameters. Methods: A systematic literature search was performed in the PubMed database on 17 December 2021. Intervention studies were included assessing the effects of IC on performance, physiological, or perceptional outcomes. Data extraction and quality assessment were conducted for the included literature. The standardized mean differences (SMD) and 95% Confidence Intervals (CI) were calculated using the inverse-variance method and a random-effects model. Results: 47 intervention studies involving 486 active subjects (13.7% female; mean age 20-42 years) were included in the meta-analysis. IC resulted in significant positive effects on time to exhaustion [SMD (95% CI) 0.40 (0.13; 0.67), p < 0.01]. IC significantly reduced Tcore [-0.19 (22120.34; -0.05), p < 0.05], sweat rate [-0.20 (-0.34; -0.06), p < 0.01], thermal sensation [-0.17 (-0.33; -0.01), p < 0.05], whereas no effects were found on skin temperature, blood lactate, and thermal comfort (p > 0.05). IC resulted in a borderline significant reduction in time trial performance [0.31 (-0.60; -0.02), p = 0.06], heart rate [-0.13 (-0.27; 0.01), p = 0.06], rate of perceived exertion [-0.16 (-0.31; -0.00), p = 0.05] and borderline increased mean power output [0.22 (0.00; 0.44), p = 0.05]. Discussion: IC has the potential to affect endurance performance and selected physiological and perceptional parameters positively. However, its effectiveness depends on the method used and the time point of administration. Future research should confirm the laboratory-based results in the field setting and involve non-endurance activities and female athletes. Systematic review registration: https://www.crd.york.ac.uk/PROSPERO/, identifier: CRD42022336623.
Collapse
Affiliation(s)
- Juliane Heydenreich
- Working Group Sports Nutrition of German Nutrition Society, Bonn, Germany
- Institute of Sports Sciences, Johannes Gutenberg-University of Mainz, Mainz, Germany
- *Correspondence: Juliane Heydenreich,
| | - Karsten Koehler
- Working Group Sports Nutrition of German Nutrition Society, Bonn, Germany
- Department of Sport and Health Sciences, Technical University of Munich, Munich, Germany
| | - Hans Braun
- Working Group Sports Nutrition of German Nutrition Society, Bonn, Germany
- Manfred Donike Institute for Doping Analysis, Institute of Biochemistry, German Sport University Cologne, Cologne, Germany
| | - Mareike Grosshauser
- Working Group Sports Nutrition of German Nutrition Society, Bonn, Germany
- Olympic Center Rhineland-Palatinate/Saarland, Saarbrücken, Germany
| | - Helmut Heseker
- Working Group Sports Nutrition of German Nutrition Society, Bonn, Germany
- Institute of Nutrition, Consumption and Health, University of Paderborn, Paderborn, Germany
| | - Daniel Koenig
- Working Group Sports Nutrition of German Nutrition Society, Bonn, Germany
- Division of Sports Medicine, Exercise Physiology and Prevention, Center for Sport Science and University Sports, University of Vienna, Vienna, Austria
| | - Alfonso Lampen
- Working Group Sports Nutrition of German Nutrition Society, Bonn, Germany
- Risk Assessment Strategies, German Federal Institute for Risk Assessment, Berlin, Germany
| | - Stephanie Mosler
- Working Group Sports Nutrition of German Nutrition Society, Bonn, Germany
- Olympic Center Stuttgart, Stuttgart, Germany
| | - Andreas Niess
- Working Group Sports Nutrition of German Nutrition Society, Bonn, Germany
- Department of Sports Medicine, University Hospital Tübingen, Tübingen, Germany
| | - Alexandra Schek
- Working Group Sports Nutrition of German Nutrition Society, Bonn, Germany
- Editorial Team of the Journal Leistungssport, German Olympic Sports Confederation, Frankfurt, Germany
| | - Anja Carlsohn
- Working Group Sports Nutrition of German Nutrition Society, Bonn, Germany
- Department of Nutrition and Home Economics, University of Applied Science Hamburg, Hamburg, Germany
| |
Collapse
|
2
|
Jay O, Capon A, Berry P, Broderick C, de Dear R, Havenith G, Honda Y, Kovats RS, Ma W, Malik A, Morris NB, Nybo L, Seneviratne SI, Vanos J, Ebi KL. Reducing the health effects of hot weather and heat extremes: from personal cooling strategies to green cities. Lancet 2021; 398:709-724. [PMID: 34419206 DOI: 10.1016/s0140-6736(21)01209-5] [Citation(s) in RCA: 116] [Impact Index Per Article: 38.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/10/2020] [Revised: 12/19/2020] [Accepted: 05/20/2021] [Indexed: 01/01/2023]
Abstract
Heat extremes (ie, heatwaves) already have a serious impact on human health, with ageing, poverty, and chronic illnesses as aggravating factors. As the global community seeks to contend with even hotter weather in the future as a consequence of global climate change, there is a pressing need to better understand the most effective prevention and response measures that can be implemented, particularly in low-resource settings. In this Series paper, we describe how a future reliance on air conditioning is unsustainable and further marginalises the communities most vulnerable to the heat. We then show that a more holistic understanding of the thermal environment at the landscape and urban, building, and individual scales supports the identification of numerous sustainable opportunities to keep people cooler. We summarise the benefits (eg, effectiveness) and limitations of each identified cooling strategy, and recommend optimal interventions for settings such as aged care homes, slums, workplaces, mass gatherings, refugee camps, and playing sport. The integration of this information into well communicated heat action plans with robust surveillance and monitoring is essential for reducing the adverse health consequences of current and future extreme heat.
Collapse
Affiliation(s)
- Ollie Jay
- Thermal Ergonomics Laboratory, The University of Sydney, Sydney, NSW, Australia; Sydney School of Health Sciences, The University of Sydney, Sydney, NSW, Australia; Sydney School of Public Health, The University of Sydney, Sydney, NSW, Australia; Faculty of Medicine and Health, Charles Perkins Centre, The University of Sydney, Sydney, NSW, Australia.
| | - Anthony Capon
- Sydney School of Public Health, The University of Sydney, Sydney, NSW, Australia; Monash Sustainable Development Institute, Monash University, Melbourne, VIC, Australia
| | - Peter Berry
- Faculty of Environment, University of Waterloo, ON, Canada
| | - Carolyn Broderick
- School of Medical Sciences, UNSW Medicine, Sydney, UNSW, Australia; The Children's Hospital at Westmead, Sydney, NSW, Australia
| | - Richard de Dear
- Indoor Environmental Quality Laboratory, School of Architecture, Design, and Planning, The University of Sydney, Sydney, NSW, Australia
| | - George Havenith
- Environmental Ergonomics Research Centre, Loughborough University, Loughborough, UK
| | - Yasushi Honda
- Faculty of Health and Sport Sciences, University of Tsukuba, Tsukuba, Japan
| | - R Sari Kovats
- NIHR Health Protection Research Unit in Environmental Change and Health, London School of Hygiene and Tropical Medicine, London, UK
| | - Wei Ma
- School of Public Health, Shandong University, Jinan, China; Climate Change and Health Center, Shandong University, Jinan, China
| | - Arunima Malik
- School of Physics, Faculty of Science, ISA, The University of Sydney, Sydney, NSW, Australia; Discipline of Accounting, Business School, The University of Sydney, Sydney, NSW, Australia
| | - Nathan B Morris
- Thermal Ergonomics Laboratory, The University of Sydney, Sydney, NSW, Australia; Department of Nutrition, Exercise, and Sports, University of Copenhagen, Copenhagen, Denmark
| | - Lars Nybo
- Department of Nutrition, Exercise, and Sports, University of Copenhagen, Copenhagen, Denmark
| | - Sonia I Seneviratne
- Institute for Atmospheric and Climate Science, ETH Zurich, Zurich, Switzerland
| | - Jennifer Vanos
- School of Sustainability, Arizona State University, AZ, USA
| | - Kristie L Ebi
- Center for Health and the Global Environment, University of Washington, WA, USA
| |
Collapse
|
3
|
Rosales AM, Hailes WS, Dodds PS, Marks AN, Ruby BC. Influence of Fluid Delivery Schedule and Composition on Fluid Balance, Physiologic Strain, and Substrate Use in the Heat. Wilderness Environ Med 2021; 32:27-35. [PMID: 33431304 DOI: 10.1016/j.wem.2020.10.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2020] [Revised: 09/28/2020] [Accepted: 10/13/2020] [Indexed: 10/22/2022]
Abstract
INTRODUCTION Wildfire suppression is characterized by high total energy expenditure and water turnover rates. Hydration position stands outline hourly fluid intake rates. However, dose interval remains ambiguous. We aimed to determine the effects of microdosing and bolus-dosing water and microdosing and bolus-dosing carbohydrate-electrolyte solutions on fluid balance, heat stress (physiologic strain index [PSI]), and carbohydrate oxidation during extended thermal exercise. METHODS In a repeated-measures cross-over design, subjects completed four 120-min treadmill trials (1.3 m·s-1, 5% grade, 33°C, 30% relative humidity) wearing a US Forest Service wildland firefighter uniform and a 15-kg pack. Fluid delivery approximated losses calculated from a pre-experiment familiarization trial, providing 22 doses·h-1 or 1 dose·h-1 (46±11, 1005±245 mL·dose-1). Body weight (pre- and postexercise) and urine volume (pre-, during, and postexercise) were recorded. Heart rate, rectal temperature, skin temperature, and steady-state expired air samples were recorded throughout exercise. Statistical significance (P<0.05) was determined via repeated-measures analysis of variance. RESULTS Total body weight loss (n=11, -0.6±0.3 kg, P>0.05) and cumulative urine output (n=11, 677±440 mL, P>0.05) were not different across trials. The micro-dosed carbohydrate-electrolyte trial sweat rate was lower than that of the bolus-dosed carbohydrate-electrolyte, bolus-dosed water, and microdosed water trials (n=11, 0.8±0.2, 0.9±0.2, 0.9±0.2, 0.9±0.2 L·h-1, respectively; P<0.05). PSI was lower at 60 than 120 min (n=12, 3.6±0.7 and 4.5±0.9, respectively; P<0.05), with no differences across trials. The carbohydrate-electrolyte trial's carbohydrate oxidation was higher than water trial's (n=12, 1.5±0.3 and 0.8±0.2 g·min-1, respectively; P<0.05), with no dosing style differences. CONCLUSIONS Equal-volume diverse fluid delivery schedules did not affect fluid balance, PSI, or carbohydrate oxidation during extended thermal work.
Collapse
Affiliation(s)
- Alejandro M Rosales
- University of Montana, Montana Center for Work Physiology and Exercise Metabolism, Missoula, MT
| | - Walter S Hailes
- University of Montana, Montana Center for Work Physiology and Exercise Metabolism, Missoula, MT
| | - Patrick S Dodds
- University of Montana, Montana Center for Work Physiology and Exercise Metabolism, Missoula, MT
| | - Alexander N Marks
- University of Montana, Montana Center for Work Physiology and Exercise Metabolism, Missoula, MT
| | - Brent C Ruby
- University of Montana, Montana Center for Work Physiology and Exercise Metabolism, Missoula, MT.
| |
Collapse
|
4
|
Alhadad SB, Low ICC, Lee JKW. Thermoregulatory responses to ice slurry ingestion during low and moderate intensity exercises with restrictive heat loss. J Sci Med Sport 2020; 24:105-109. [PMID: 32711957 DOI: 10.1016/j.jsams.2020.07.002] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2020] [Revised: 07/03/2020] [Accepted: 07/04/2020] [Indexed: 11/26/2022]
Abstract
OBJECTIVES We investigated the thermoregulatory responses to ice slurry ingestion during low- and moderate-intensity exercises with restrictive heat loss. DESIGN Randomised, counterbalanced, cross-over design. METHODS Following a familiarisation trial, ten physically active males exercised on a motorised treadmill at low-intensity (L; 40% VO2max) or moderate-intensity (M; 70% VO2max) for 75-min, in four randomised, counterbalanced trials. Throughout the exercise bout, participants donned a raincoat to restrict heat loss. Participants ingested 2gkg-1 body mass of ambient water (L+AMB and M+AMB trials) or ice slurry (L+ICE and M+ICE trials) at 15-min intervals during exercise in environmental conditions of Tdb, 25.1±0.6°C and RH, 63±5%. Heart rate (HR), gastrointestinal temperature (Tgi), mean weighted skin temperature (Tsk), estimated sweat loss, ratings of perceived exertion (RPE) and thermal sensation (RTS) were recorded. RESULTS Compared to L+AMB, participants completed L+ICE trials with lower ΔTgi (0.8±0.3°C vs 0.6±0.2°C; p=0.03), mean RPE (10±1 vs 9±1; p=0.03) and estimated sweat loss (0.91±0.2L vs 0.78±0.27L; p=0.04). Contrastingly, Tgi (p=0.22), Tsk (p=0.37), HR (p=0.31), RPE (p=0.38) and sweat loss (p=0.17) were similar between M+AMB and M+ICE trials. RTS was similar during both low-intensity (4.9±0.5 vs 4.7±0.3; p=0.10) and moderate-intensity exercise (5.3±0.47 vs 5.0±0.4; p=0.09). CONCLUSIONS Per-cooling using ice slurry ingestion marginally reduced thermal strain during low-intensity but not during moderate-intensity exercise. Ice slurry may be an effective and practical heat mitigation strategy during low-intensity exercise such as in occupational and military settings, but a greater volume should be considered to ensure its efficacy.
Collapse
Affiliation(s)
- Sharifah B Alhadad
- NUS Graduate School for Integrative Sciences and Engineering, National University of Singapore, Singapore; Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore; Saw Swee Hock School of Public Health, National University of Singapore, Singapore
| | - Ivan C C Low
- Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
| | - Jason K W Lee
- Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore; Global Asia Institute, National University of Singapore, Singapore; N.1 Institute for Health, National University of Singapore, Singapore.
| |
Collapse
|
5
|
Marks AN, Sol JA, Domitrovich JW, West MR, Ruby BC. Total Energy Intake and Self-Selected Macronutrient Distribution During Wildland Fire Suppression. Wilderness Environ Med 2020; 31:188-196. [DOI: 10.1016/j.wem.2020.01.009] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2019] [Revised: 01/22/2020] [Accepted: 01/27/2020] [Indexed: 01/26/2023]
|
6
|
Picón-Jaimes YA, Orozco-Chinome JE, Molina-Franky J, Franky-Rojas MP. Control central de la temperatura corporal y sus alteraciones: fiebre, hipertermia e hipotermia. MEDUNAB 2020. [DOI: 10.29375/01237047.3714] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Introducción. En mamíferos, el control de la temperatura corporal es vital. El estado de consciencia y control motor en humanos, ocurren a una temperatura de 37°C y las desviaciones pueden alterar las propiedades celulares, generando disfunciones fisiológicas. En especies como los roedores (su relación área de superficie/volumen facilita la pérdida de calor) mantienen temperaturas basales cercanas a los 30°C. Distinto es con animales como los paquidermos, cuya temperatura es menor comparada con los humanos. El objetivo es identificar los aspectos fisiológicos de la termorregulación. Descripción de temas tratados. Revisión descriptiva de la literatura de artículos publicados en diferentes bases de datos. La termorregulación es la capacidad del cuerpo para establecer y mantener su temperatura, regulando producción y pérdida de calor para optimizar la eficiencia de procesos metabólicos. El protagonismo lo tiene el sistema nervioso central y su control neuro-hormonal en múltiples niveles. El centro regulador térmico está en el hipotálamo anterior. Este recibe información de los receptores de grandes vasos, vísceras abdominales, médula espinal y de la sangre que perfunde el hipotálamo. Cuando aumenta la temperatura central, el termorregulador activa fibras eferentes del sistema nervioso autónomo, provocando pérdida de calor por convección y evaporación. Ante el descenso de temperatura, la respuesta es disminuir la pérdida de calor (vasoconstricción y menor sudoración); además, incrementar la producción de calor, intensificando la actividad muscular. Conclusión. La termorregulación es liderada por el hipotálamo, quien regula aumento y disminución de la temperatura respondiendo a las necesidades del organismo para llegar a la homeostasis y compensación, enfrentando las alteraciones de la temperatura ambiental
Collapse
|
7
|
Abstract
Cold water or ice slurry ingestion during exercise seems to be an effective and practical means to improve endurance exercise performance in the heat. However, transient reductions in sweating appear to decrease the potential for evaporative heat loss from the skin by a magnitude that at least negates the additional internal heat loss as a cold ingested fluid warms up to equilibrate with body temperature; thus explaining equivalent core temperatures during exercise at a fixed heat production irrespective of the ingested fluid temperature. Internal heat transfer with cold fluid/ice is always 100% efficient; therefore, when a decrement occurs in the efficiency that sweat evaporates from the skin surface (i.e. sweating efficiency), a net cooling effect should begin to develop. Using established relationships between activity, climate and sweating efficiency, the boundary conditions beyond which cold ingested fluids are beneficial in terms of increasing net heat loss can be calculated. These conditions are warmer and more humid for cycling relative to running by virtue of the greater skin surface airflow, which promotes evaporation, for a given metabolic heat production and thus sweat rate. Within these boundary conditions, athletes should ingest fluids at the temperature they find most palatable, which likely varies from athlete to athlete, and therefore best maintain hydration status. The cooling benefits of cold fluid/ice ingestion during exercise are likely disproportionately greater for athletes with physiological disruptions to sweating, such as those with a spinal cord injury or burn injuries, as their capacity for skin surface evaporative heat loss is much lower; however, more research examining these groups is needed.
Collapse
|