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ALHADAD SHARIFAHBADRIYAH, PONAMPALAM R, LIM LOUISASIXIAN, LOW IVANCHERHCHIET, KSHITIJ RAHALKAR, ABDUL KARIM AZIZBIN, SALAMOON ZAMSHEKBIN, MARIMUTHU YOGARAJAHS, LEE JASONKAIWEI. Effects of Heat Exposure and Ice Slurry Ingestion on Risk-Taking Behavior in Healthcare Workers. Med Sci Sports Exerc 2024; 56:2016-2025. [PMID: 38767972 PMCID: PMC11419282 DOI: 10.1249/mss.0000000000003486] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/22/2024]
Abstract
PURPOSE Healthcare workers (HCWs) wearing personal protective equipment (PPE) experience physiological strain that can impair motor and psychological functions, potentially affecting patient care. We assessed the effects of heat exposure on maximal strength and risk-taking behavior among PPE-wearing HCWs and the efficacy of ice slurry to alleviate adverse effects. METHODS Seventeen HCWS completed two experimental trials in a crossover design, consuming 5 g·kg -1 of body mass of ambient drink (AMB) or ice slurry (ICE) before donning PPE and undergoing 2 h of simulated decontamination exercise (wet-bulb globe temperature (WBGT): 25.9°C ± 0.8°C, PPE microenvironment WBGT: 29.1°C ± 2.1°C). Body core temperature ( Tc ), heart rate (HR), chest skin temperature ( Tsk ), ratings of perceived exertion (RPE), thermal sensation (RTS), maximal voluntary contraction (MVC), risk-taking behavior (balloon analogue risk-taking task (BART)), and salivary cortisol were assessed. RESULTS Predrinking to postdrinking ∆ Tc was greater in ICE (-0.2°C ± 0.1°C) than AMB (-0.0°C ± 0.1°C, P = 0.003). Post-drinking RTS was lower in ICE (2.7 ± 1.2) than AMB (4.1 ± 0.4, P < 0.001). ICE and AMB had similar Tc and HR (both P > 0.05), but Tsk was lower in ICE than AMB ( P = 0.049). A lower MVC (30.3 ± 6.7 vs 27.4 ± 4.9 kg, P = 0.001) and higher BART-adjusted total pump count (472 ± 170 vs 615 ± 174 pumps, P = 0.017) was observed pretrial to posttrial in AMB but absent in ICE (both P > 0.05). Salivary cortisol was similar between trials ( P = 0.42). CONCLUSIONS Heat-exposed PPE-wearing HCWs had impaired maximal strength and elevated risk-taking behavior. This may increase the risk of avoidable workplace accidents that can jeopardize HCWs and patient care. Ice slurry ingestion alleviated these heat-related impairments, suggesting its potential as an ergogenic aid.
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Affiliation(s)
- SHARIFAH BADRIYAH ALHADAD
- Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, SINGAPORE
- Human Potential Translational Research Programme, Yong Loo Lin School of Medicine, National University of Singapore, SINGAPORE
- Heat Resilience & Performance Centre, Yong Loo Lin School of Medicine, National University of Singapore, SINGAPORE
| | - R PONAMPALAM
- Department of Emergency Medicine, Singapore General Hospital, SINGAPORE
| | - LOUISA SI XIAN LIM
- Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, SINGAPORE
- Human Potential Translational Research Programme, Yong Loo Lin School of Medicine, National University of Singapore, SINGAPORE
| | - IVAN CHERH CHIET LOW
- Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, SINGAPORE
- Human Potential Translational Research Programme, Yong Loo Lin School of Medicine, National University of Singapore, SINGAPORE
| | - RAHALKAR KSHITIJ
- Department of Emergency Medicine, Singapore General Hospital, SINGAPORE
| | | | | | | | - JASON KAI WEI LEE
- Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, SINGAPORE
- Human Potential Translational Research Programme, Yong Loo Lin School of Medicine, National University of Singapore, SINGAPORE
- Heat Resilience & Performance Centre, Yong Loo Lin School of Medicine, National University of Singapore, SINGAPORE
- Campus for Research Excellence and Technological Enterprise (CREATE), SINGAPORE
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Kakamu T, Ito T, Endo S, Hidaka T, Masuishi Y, Kasuga H, Fukushima T. Inappropriate timing of salt intake increases the risk of heat-related illness: An observational study. PLoS One 2024; 19:e0296388. [PMID: 38165857 PMCID: PMC10760686 DOI: 10.1371/journal.pone.0296388] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2023] [Accepted: 12/12/2023] [Indexed: 01/04/2024] Open
Abstract
The importance of salt intake in preventing heat-related illness (HRI) is well established, however, the specific method of ingestion has not been sufficiently studied. This study, therefore, aimed to investigate the optimal timing of salt intake to prevent HRI during hot outdoor work. We recruited 28 healthy male firefighters working at a fire department in Japan. They were provided a questionnaire to complete before and after receiving training in the summer season. We assessed their salt intake as before, during, and after training or none. In addition, they completed a brief self-administered diet history questionnaire to evaluate their daily salt and alcohol intake. HRI was determined through subjective and objective symptoms listed in the questionnaire, and environmental data were obtained from a national database. Subsequently, factors related to HRI were determined using a logistic regression model. The mean age of the participants was 31.0 ± 7.7 years. The study was performed within 250 working days, and we detected 28 HRI symptoms (11.2%). The median alcohol intake was 25.6 g/day when calculated according to the actual work system. Logistic mixed effect model analysis revealed that salt intake before training (OR: 5.893, 95% CI: 1.407-24.675), and salt intake before and during training (OR: 22.889, 95% CI: 4.276-122.516) were positively associated with HRI symptoms. The results indicate that inappropriate timing of salt intake increases the risks of HRI. Thus, a timely intake of salt in adequate amounts may be important in preventing these risks.
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Affiliation(s)
- Takeyasu Kakamu
- Department of Hygiene and Preventive Medicine, Fukushima Medical University, Fukushima, Fukushima, Japan
| | - Teruna Ito
- Department of Food and Nutrition, Koriyama Women’s University, Koriyama, Fukushima, Japan
| | - Shota Endo
- Department of Hygiene and Preventive Medicine, Fukushima Medical University, Fukushima, Fukushima, Japan
| | - Tomoo Hidaka
- Department of Hygiene and Preventive Medicine, Fukushima Medical University, Fukushima, Fukushima, Japan
| | - Yusuke Masuishi
- Department of Hygiene and Preventive Medicine, Fukushima Medical University, Fukushima, Fukushima, Japan
| | - Hideaki Kasuga
- Department of Hygiene and Preventive Medicine, Fukushima Medical University, Fukushima, Fukushima, Japan
| | - Tetsuhito Fukushima
- Department of Hygiene and Preventive Medicine, Fukushima Medical University, Fukushima, Fukushima, Japan
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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.
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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
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Naito T, Saito T, Morito A, Yamada S, Shimomasuda M, Nakamura M. Pre-cooling with ingesting a high-carbohydrate ice slurry on thermoregulatory responses and subcutaneous interstitial fluid glucose during heat exposure. J Physiol Anthropol 2022; 41:34. [PMID: 36217207 PMCID: PMC9549659 DOI: 10.1186/s40101-022-00309-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2022] [Accepted: 09/28/2022] [Indexed: 11/07/2022] Open
Abstract
The purpose of this study was to compare the effects of ingesting ice slurries with two different carbohydrate contents on body temperatures and the subcutaneous interstitial fluid glucose level during heat exposure. Seven physically active men underwent one of three interventions: the ingestion of 7.5 g/kg of a control beverage (CON: 26°C), a normal-carbohydrate ice slurry (NCIS: −1°C), or a high-carbohydrate ice slurry (HCIS: −5°C). The participants were monitored for a 120-min period that included 10 min of rest, 25 min of exposure to the experimental cooling intervention (during which the beverage was ingested), and 85 min of seated rest in a climate chamber (36°C, 50% relative humidity). The rectal temperature in the HCIS and NCIS trials was lower than that in the CON trial from 40 to 75 min. The infrared tympanic temperature was also lower in the HCIS and NCIS trials than in the CON trial from 20 to 50 min, whereas the deep thigh or mean skin temperatures were not significantly different among the three groups. From 90 to 120 min, the subcutaneous interstitial fluid glucose level in the NCIS trial was lower than that at 65 min; however, reductions were not seen in the HCIS and CON trials. These findings suggest that both HCIS ingestion and conventional NCIS ingestion were effective cooling strategies for reducing thermal strain, while HCIS ingestion may also enable a higher subcutaneous interstitial fluid glucose level to be maintained, ensuring an adequate supply of required muscle substrates.
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Affiliation(s)
- Takashi Naito
- grid.419627.fDepartment of Sports Research, Japan Institute of Sports Sciences, 3-15-1 Nishigaoka Kita-ku, Tokyo, 115-0056 Japan ,grid.440874.b0000 0001 2183 8345Faculty of Law, Hokkai-Gakuen University, 4-1-40 Asahimachi Toyohira-ku, Sapporo City, Hokkaido 062-8605 Japan
| | - Tatsuya Saito
- grid.419627.fDepartment of Sports Research, Japan Institute of Sports Sciences, 3-15-1 Nishigaoka Kita-ku, Tokyo, 115-0056 Japan ,grid.265107.70000 0001 0663 5064Faculty of Medicine, Tottori University, 4-101 Koyamachominami, Tottori City, Tottori 683-8550 Japan
| | - Akihisa Morito
- grid.419836.10000 0001 2162 3360Health Science Research R&D Laboratories, Taisho Pharmaceutical Co., Ltd., 1-403 Yoshinomachi Kita-ku, Saitama City, Saitama 331-9530 Japan
| | - Satoshi Yamada
- grid.419836.10000 0001 2162 3360Health Science Research R&D Laboratories, Taisho Pharmaceutical Co., Ltd., 1-403 Yoshinomachi Kita-ku, Saitama City, Saitama 331-9530 Japan
| | - Masatsugu Shimomasuda
- grid.419836.10000 0001 2162 3360Research & Development Headquarters, Self-Medication, Taisho Pharmaceutical Co., Ltd., 3-24-1, Takada, Toshima-ku, Tokyo, 170-8633 Japan
| | - Mariko Nakamura
- grid.419627.fDepartment of Sports Research, Japan Institute of Sports Sciences, 3-15-1 Nishigaoka Kita-ku, Tokyo, 115-0056 Japan
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Morito A, Inami T, Hirata A, Yamada S, Shimomasuda M, Haramoto M, Kato K, Tahara S, Oguma Y, Ishida H, Kohtake N. Ice slurry ingestion improves physical performance during high-intensity intermittent exercise in a hot environment. PLoS One 2022; 17:e0274584. [PMID: 36107972 PMCID: PMC9477354 DOI: 10.1371/journal.pone.0274584] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2022] [Accepted: 08/30/2022] [Indexed: 12/03/2022] Open
Abstract
Ice slurry ingestion enhances exercise performance by lowering the core body temperature. However, an operational issue related to this ingestion is the requirement for a high intake of 7.5 g·kg-1 to produce the desired effects. We investigated the effects of the intake of low amounts of ice slurry at −2°C on the tympanic temperature and exercise performance during repeated high-intensity intermittent exercises in a hot environment. This study was a randomized, crossover study, with a 6-day washout period. Twelve university rugby union players performed two 30-min sessions of high-intensity intermittent exercises separated by a 15-min half-time break on a cycle ergometer in a hot environment (28.8°C ± 0.1°C, 49.5% ± 0.6% relative humidity). The participants ingested 450 g of −2°C-ice slurry (ICE), or a 30°C-beverage (CON) having the same composition as ICE, or 30°C-water (WAT) during the half-time break. The tympanic temperature and skin temperature were measured as the physiological data, and the peak power and mean power as the exercise performance data. The tympanic temperature at the half-time break and beginning of the 2nd session was significantly lower in the ICE group as compared with the CON and WAT groups. The skin temperature at the half-time break was significantly lower in the ICE group as compared with the WAT group. While the peak power and mean power during the 2nd session were significantly greater in the ICE group as compared with the CON and WAT groups. Our findings suggest that even the intake of lower amounts, as compared with those used in previous studies, of low-temperature ice slurry can reduce the body temperature and improve the peak power. These results suggest that intake of low-temperature ice slurry as a strategy for internal body cooling is useful for improving endurance exercise performance in hot environments.
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Affiliation(s)
- Akihisa Morito
- Graduate School of System Design and Management, Keio University, Kanagawa, Japan
- R&D Laboratories, Self-Medication, Taisho Pharmaceutical Co., Ltd., Saitama, Japan
- * E-mail:
| | - Takayuki Inami
- Institute of Physical Education, Keio University, Kanagawa, Japan
| | - Akihiro Hirata
- Graduate School of System Design and Management, Keio University, Kanagawa, Japan
- Sports Medicine Research Center, Keio University, Kanagawa, Japan
| | - Satoshi Yamada
- R&D Laboratories, Self-Medication, Taisho Pharmaceutical Co., Ltd., Saitama, Japan
| | - Masatsugu Shimomasuda
- Research & Development Headquarters, Self-Medication, Taisho Pharmaceutical Co., Ltd., Tokyo, Japan
| | - Maki Haramoto
- Research & Development Headquarters, Self-Medication, Taisho Pharmaceutical Co., Ltd., Tokyo, Japan
| | - Keita Kato
- R&D Laboratories, Self-Medication, Taisho Pharmaceutical Co., Ltd., Saitama, Japan
| | - Shigeyuki Tahara
- Graduate School of System Design and Management, Keio University, Kanagawa, Japan
| | - Yuko Oguma
- Sports Medicine Research Center, Keio University, Kanagawa, Japan
| | - Hiroyuki Ishida
- Sports Medicine Research Center, Keio University, Kanagawa, Japan
| | - Naohiko Kohtake
- Graduate School of System Design and Management, Keio University, Kanagawa, Japan
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