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Thompson C, Ferrie L, Pearson SJ, Highlands B, Matthews MJ. In the heat of the moment: the effects of extreme temperatures on the cognitive functioning of firefighters. ERGONOMICS 2024:1-15. [PMID: 38477628 DOI: 10.1080/00140139.2024.2326584] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/05/2023] [Accepted: 02/22/2024] [Indexed: 03/14/2024]
Abstract
Exposure to high temperatures can have detrimental effects on cognitive processing and this is concerning for firefighters who routinely work in extreme temperatures. Whilst past research has studied the effects of heat on firefighter cognition, findings are mixed, and no work has measured the time course of cognitive recovery. This study compared working memory, vigilance, and cognitive flexibility of 37 firefighters before and after they engaged in a live-fire training exercise with temperatures exceeding 115 °C. To assess recovery, cognition was measured on exiting the fire, then 20- and 40-minutes post-fire. Results showed impaired vigilance and cognitive flexibility (increased errors, slower responses) immediately after the fire, but recovery at 20-minutes. These findings indicate that a live indoor fire negatively impacts cognitive processing, but this effect is relatively short-lived and return to baseline functioning is seen 20-minutes after exiting the fire. The findings could be used to inform re-entry and cooling decisions.
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Affiliation(s)
| | - Lucy Ferrie
- School of Health and Society, University of Salford, Salford, UK
| | | | - Brian Highlands
- School of Health and Society, University of Salford, Salford, UK
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Thompson C, Ferrie L, Pearson SJ, Highlands B, Matthews MJ. Do extreme temperatures affect cognition? A short review of the impact of acute heat stress on cognitive performance of firefighters. Front Psychol 2024; 14:1270898. [PMID: 38274689 PMCID: PMC10808688 DOI: 10.3389/fpsyg.2023.1270898] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2023] [Accepted: 12/29/2023] [Indexed: 01/27/2024] Open
Abstract
Research shows that exposure to high environmental temperatures can affect task performance. Theoretical explanations outline that heat is a source of stress that competes for limited-capacity resources, therefore if a task is resource-intensive, and/or if heat stress is extreme, performance will suffer. One occupation in which individuals complete demanding tasks and make difficult decisions, often in temperatures exceeding 200°C, is firefighting. Yet very little is currently known about the impact of heat stress on the cognitive functioning of firefighters. This short review summarizes the limited research in this area, focusing on studies that measured cognition of firefighters following a realistic training exercise. The findings are mixed with evidence that heat stress improves, impairs, and has no impact on cognitive functioning. While there are differences in the firefighting activities utilized, and the temperatures that participants were exposed to, it is argued that the varied findings can be attributed to the tasks used to assess cognitive processing, and the cognitive functions being measured. In accordance with the wider field of research, it is concluded that complex functioning, such as sustained attention, vigilance, and working memory is negatively impacted by acute exposure to extreme heat. Greater understanding of factors affecting cognition would inform safety practices and more research is needed to understand how and when heat stress may influence cognition in firefighting scenarios.
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Affiliation(s)
- Catherine Thompson
- Department of Psychology, Liverpool Hope University, Liverpool, United Kingdom
| | - Lucy Ferrie
- School of Health Sciences, University of Manchester, Manchester, United Kingdom
| | - Stephen J. Pearson
- School of Health Sciences, University of Salford, Salford, United Kingdom
| | - Brian Highlands
- School of Health Sciences, University of Salford, Salford, United Kingdom
| | - Martyn J. Matthews
- School of Health Sciences, University of Salford, Salford, United Kingdom
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Teixeira IG, Verzola MR, Filipini RE, Speretta GF. The effects of a firefighting simulation on the vascular and autonomic functions and cognitive performance: a randomized crossover study. Front Physiol 2023; 14:1215006. [PMID: 37811491 PMCID: PMC10551144 DOI: 10.3389/fphys.2023.1215006] [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: 05/01/2023] [Accepted: 09/12/2023] [Indexed: 10/10/2023] Open
Abstract
Introduction: During firefighting, physical and cognitive demands increase. However, the stress inherent to these events can decrease cognitive performance and increase the risk of cardiovascular events in firefighters. Thus, this crossover study aimed to evaluate the effects of a firefighting Simulation on cognitive performance and vascular and autonomic functions in military firefighters. Methods: Sixteen firefighters (37.8 ± 5.6 years) underwent anthropometry, mental health status, and sleep quality assessments. They randomly performed two interventions, Simulation (Firefighting tasks; 10.0 ± 1.1 min) and Control (rest for 10 min), on different days. After both interventions, cognitive performance was assessed using the Stroop Test, Paced Auditory Serial Addition Test, and Trail Making Test. Then, the vascular function was assessed using ultrasonography through the carotid artery reactivity to the cold pressor test. The arterial pressure, heart rate, and cardiac intervals were recorded before interventions. The cardiac intervals were also measured during the cold pressor test. Student's t-test and Wilcoxon were used for comparisons between Control and Simulation and the analysis of variance for repeated measures was used for comparison over time during the cold pressor test. A significance level of p < 0.05 was adopted. Results: Although the mean and maximum heart rate were higher before the Simulation (p < 0.0001), all the heart rate variability parameters (p > 0.05) and mean arterial pressure (p > 0.3795) were similar before the interventions. After Simulation, the cognitive performance was similar to Control (p > 0.05), except for the improvement in Stroop Test part B (p < 0.0001). After Simulation, carotid artery reactivity was attenuated (p < 0.0010). During the cold pressor test, the high-frequency band of the heart rate variability was lower after the Simulation (p < 0.0104). Discussion: Although firefighting Simulation did not substantially change cognitive performance, the lower carotid artery reactivity and parasympathetic modulation to the heart during the cold pressor test may contribute to greater vulnerability to cardiovascular events in firefighters on duty.
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Affiliation(s)
- Iara G. Teixeira
- Post-Graduate Program in Neurosciences, Federal University of Santa Catarina, Florianópolis, Brazil
- Department of Physiological Sciences, Biological Sciences Centre, Federal University of Santa Catarina, Florianópolis, Brazil
| | - Marcio R. Verzola
- Military Firefighters Corps of Santa Catarina, Florianópolis, Brazil
| | - Richard E. Filipini
- Department of Physiological Sciences, Biological Sciences Centre, Federal University of Santa Catarina, Florianópolis, Brazil
| | - Guilherme F. Speretta
- Post-Graduate Program in Neurosciences, Federal University of Santa Catarina, Florianópolis, Brazil
- Department of Physiological Sciences, Biological Sciences Centre, Federal University of Santa Catarina, Florianópolis, Brazil
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Seo MW, Gann J, Lee JM, Heffernan KS, Kim JY, Jung HC. Potential impact of metabolic syndrome on cognitive function in US firefighters. Front Public Health 2023; 11:1150121. [PMID: 37304116 PMCID: PMC10248177 DOI: 10.3389/fpubh.2023.1150121] [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: 01/23/2023] [Accepted: 05/11/2023] [Indexed: 06/13/2023] Open
Abstract
Objectives Among US firefighters, sudden cardiac arrest and psychological stress (i.e., PTSD) are the leading cause of on-duty death. Metabolic syndrome (MetSyn) may influence both cardiometabolic and cognitive health. Here, we examined differences in cardiometabolic disease risk factors, cognitive function, and physical fitness in US firefighters with vs. without MetSyn. Materials and methods One hundred fourteen male firefighters, aged 20 to 60 years, participated in the study. US firefighters with MetSyn vs. non-MetSyn were divided by AHA/NHLBI criteria. Of them, we performed a paired-match analysis with respect to the age and BMI of firefighters with (n = 18) vs. without MetSyn (n = 18). The cardiometabolic disease risk factors included blood pressure, fasting glucose, blood lipid profiles [HDL-C, triglyceride (TG)], and surrogate markers of insulin resistance [TG/HDL-C, TG glucose index (TyG)]. The cognitive test included a psychomotor vigilance task as a measure of reaction time and a delayed-match-to-sample task (DMS) as a measure of memory, using the computer-based Psychological Experiment Building Language Version 2.0 program. The differences between MetSyn and non-MetSyn groups in US firefighters were analyzed using an independent t-test adjusted for age and BMI. In addition, Spearman correlation and stepwise multiple regression were conducted. Results US firefighters with MetSyn exhibited severe insulin resistance estimated by TG/HDL-C and TyG (Cohen's d > 0.8, all p < 0.01) compared with their age- and BMI-matched counterparts without MetSyn. In addition, US firefighters with MetSyn exhibited higher DMS total time and reaction time compared with non-MetSyn (Cohen's d > 0.8, all p < 0.01). In stepwise linear regression, HDL-C predicted DMS total time (β = - 0.440, R2 = 0.194, p < 0.05), and TyG (β = 0.432, R2 = 0.186, p < 0.05) predicted DMS reaction time. Conclusion US firefighters with vs. without MetSyn were predisposed to metabolic risk factors, surrogate markers of insulin resistance, and cognitive function, even when matched for age and BMI, and there was a negative association between metabolic characteristics and cognitive function in US firefighters. The findings of this study suggest that the prevention of MetSyn may be beneficial to supporting firefighters' safety and occupational performance.
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Affiliation(s)
- Myong-Won Seo
- Department of Exercise Science, David B. Falk College of Sports and Human Dynamics, Syracuse University, Syracuse, NY, United States
| | - Joshua Gann
- Department of Kinesiology, School of Allied Health, University of Louisiana at Monroe, Monroe, LA, United States
| | - Jung-Min Lee
- Sports Science Research Center, Kyung Hee University, Yongin-si, Republic of Korea
- Department of Physical Education, College of Physical Education, Kyung Hee University, Yongin-si, Republic of Korea
| | - Kevin S. Heffernan
- Department of Exercise Science, David B. Falk College of Sports and Human Dynamics, Syracuse University, Syracuse, NY, United States
| | - Joon Young Kim
- Department of Exercise Science, David B. Falk College of Sports and Human Dynamics, Syracuse University, Syracuse, NY, United States
| | - Hyun Chul Jung
- Sports Science Research Center, Kyung Hee University, Yongin-si, Republic of Korea
- Department of Sports Coaching, College of Physical Education, Kyung Hee University, Yongin-si, Republic of Korea
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Kim M, Lee D, Kim W, Eun Lee J, Lee J, Tae Kim Y, Lee SK, Soo Oh S, Soo Park K, Baek Koh S, Kim C, Jung YC. Associations between altered functional connectivity of attentional networks and sleep quality among firefighters. Neurosci Lett 2022; 791:136924. [DOI: 10.1016/j.neulet.2022.136924] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2022] [Revised: 10/14/2022] [Accepted: 10/17/2022] [Indexed: 10/31/2022]
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Stepan ME, Wilckens KA, Hostler D, Wallace ML, Franzen PL. Physical Exertion Partially Mitigates Task-Switching Deficits From Sleep Loss: Implications for Firefighters. J Occup Environ Med 2022; 64:e622-e628. [PMID: 35901201 PMCID: PMC9529911 DOI: 10.1097/jom.0000000000002647] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
OBJECTIVE The aim of the study is to investigate effects of physical exertion on cognitive deficits from sleep loss under conditions that mimic a firefighting scenario. METHODS Twenty-four male participants completed a crossover study design with 3 conditions: total sleep deprivation, sleep disruption (three 60-minute awakenings), and rested control. Participants then completed 50 minutes of a physical exertion task involving treadmill exercise in a heated room while wearing firefighter protective clothing. Vigilant attention and task-switching performance were assessed pre- and post-sleep manipulation and pre- and post-physical exertion. Vigilant attention was also assessed mid-physical exertion. RESULTS Total sleep deprivation and sleep disruption increased attentional lapses and task-switching RT. Total sleep deprivation additionally reduced task-switching accuracy. Performance after physical exertion improved only for task-switching RT after total sleep deprivation. CONCLUSIONS Physical exertion selectively mitigated task-switching RT deficits from the most severe sleep loss condition, total sleep deprivation.
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Affiliation(s)
| | | | - David Hostler
- Department of Exercise and Nutrition Sciences, University at Buffalo, Buffalo, NY
| | | | - Peter L. Franzen
- Department of Psychiatry, University of Pittsburgh, Pittsburgh, PA
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Evaluating the effect of heat stress on cognitive performance of petrochemical workers: A field study. Heliyon 2022; 8:e08698. [PMID: 35028472 PMCID: PMC8741453 DOI: 10.1016/j.heliyon.2021.e08698] [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: 05/26/2021] [Revised: 06/27/2021] [Accepted: 12/27/2021] [Indexed: 11/30/2022] Open
Abstract
Introduction Heat stress disrupts blood hormones and reduces workers' cognitive performance. To further shed light on the dysfunction of heat stress, the present study aimed to evaluate its effect on cognitive performance of petrochemical workers. Materials and methods This descriptive-analytical cross-sectional study was conducted in 2020 in one of the Iranian petrochemical companies. Participants were divided into 2 case groups and 1 control group. They worked 12 h and their shift entialed one week working day and one week working night. According to the ISO 7243 standard, the heat stress index of employees was measured at the beginning, in the middle and at the end of the shift separately. Continuous Performance Test (CPT) and N-back cognitive performance tests were performed at the beginning, in the middle and at the end of the shift to determine the level of cognitive performance. The data were analyzed using SPSS software version 20 and the significance level was set at 0.05. Results Comparison of the results in the continuous performance test showed significant differences between the three groups with regard to the omission error and response time at the end of the shift. Moreover, according to the working memory test, participants reaction time during the shift significantly increased. Besides, average correct responses significantly reduced during the shift. Finally, the heat stress throughout the shift had a significant effect on the commission error and the response time of individuals. Conclusion Heat stress affects people's cognitive performance in such a way that it can decrease their cognitive performance by increasing the commission error and response time and reducing the average correct response of site operators, generally reducing the cognitive performance of people at the end of the shift.
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Canetti EFD, Gayton S, Schram B, Pope R, Orr RM. Psychological, Physical, and Heat Stress Indicators Prior to and after a 15-Minute Structural Firefighting Task. BIOLOGY 2022; 11:biology11010104. [PMID: 35053102 PMCID: PMC8773347 DOI: 10.3390/biology11010104] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/15/2021] [Revised: 01/07/2022] [Accepted: 01/07/2022] [Indexed: 11/16/2022]
Abstract
Firefighters work in strenuous conditions for prolonged periods wearing up to 20 kg of personal protective equipment. This often contributes to significant heat and cardiovascular strain. This study examined the relationships between psychological and physical measures taken prior to undertaking a 15 min firefighting task, and the occurrence of heat stress and high levels of fatigue following the task. Nine qualified firefighters completed a 15 min “live burn” scenario designed to mimic a fire started by a two-seater couch in a lounge room and completed simulated tasks throughout the duration. Logical reasoning, speed and accuracy, general motivation and fatigue, and physical and mental effort were recorded pre-scenario, and at 0- and 20-min post-scenario. General motivation and fatigue scores at 0- and 20-min post-scenario were highly correlated with each other (rs = 0.90; p = 0.001). The general motivation and fatigue scores, at 0- and 20-min post-scenario, were also strongly related to pre-task logic/reasoning test scores (Post 0 rs = −0.77, p = 0.016; Post 20 rs = −0.87, p = 0.002). Firefighters with lower logical reasoning and speed and accuracy scores were more susceptible to fatigue and impaired cognition when exposed to rises in core temperature and heat stress.
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Affiliation(s)
- Elisa F. D. Canetti
- Tactical Research Unit, Bond University, Gold Coast 4226, Australia; (S.G.); (B.S.); (R.P.); (R.M.O.)
- Faculty of Health Sciences and Medicine, Bond University, Gold Coast 4226, Australia
- Correspondence: ; Tel.: +61-(07)-5595-4106
| | - Scott Gayton
- Tactical Research Unit, Bond University, Gold Coast 4226, Australia; (S.G.); (B.S.); (R.P.); (R.M.O.)
| | - Ben Schram
- Tactical Research Unit, Bond University, Gold Coast 4226, Australia; (S.G.); (B.S.); (R.P.); (R.M.O.)
- Faculty of Health Sciences and Medicine, Bond University, Gold Coast 4226, Australia
| | - Rodney Pope
- Tactical Research Unit, Bond University, Gold Coast 4226, Australia; (S.G.); (B.S.); (R.P.); (R.M.O.)
- School of Allied Health, Exercise and Sports Sciences, Charles Sturt University, Albury-Wodonga 2640, Australia
| | - Robin M. Orr
- Tactical Research Unit, Bond University, Gold Coast 4226, Australia; (S.G.); (B.S.); (R.P.); (R.M.O.)
- Faculty of Health Sciences and Medicine, Bond University, Gold Coast 4226, Australia
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